Decision

GDA Step 2 of the Rolls-Royce SMR: fundamental assessment full report

Updated 30 July 2024

Applies to England and Wales

1. Introduction

This report sets out our findings following Step 2 of a generic design assessment (GDA) of the 470 megawatts of electricity (MWe) Rolls-Royce SMR Limited Small Modular Reactor nuclear power station design.

In 2021, Rolls-Royce SMR Limited – the ‘Requesting Party’ (RP) – applied to the Department for Business, Energy and Industrial Strategy for its design to enter the generic design assessment (GDA) process. The application was successful. The regulators – the Office for Nuclear Regulation (ONR), the Environment Agency and Natural Resources Wales – formally commenced the GDA on 3 April 2022.

Rolls-Royce SMR Limited planned a 3 step GDA taking a maximum of 57 months. Step 1 started in April 2022 and finished in March 2023, taking 12 months (Step 1: statement of findings). Step 2 started in April 2023 and finished in July 2024, taking 16 months. Step 3 is planned to start in August 2024 and to finish by December 2026, a proposed duration of 29 months. The objective for Rolls-Royce SMR Limited is to achieve a Statement of Design Acceptability (SoDA) from the Environment Agency and Natural Resources Wales and a Design Acceptance Confirmation (DAC) from ONR.

1.1 Step 2 objectives

Step 2 is the first substantive technical assessment step. It focuses on the environmental protection fundamentals of the reactor design. It includes assessing the methodologies, approaches, codes, standards and philosophies the RP is using to substantiate its environment case to demonstrate the fundamental acceptability of the design. The RP will complete the submissions needed for Step 2 and identify the submissions needed for Step 3.

The main objective for Step 2 is:

• for the Environment Agency to carry out an assessment to identify any fundamental environmental protection shortfalls in the design

In this report, we present:  

• the work we have done and the conclusions we have reached so far
• any fundamental shortfalls that may prevent us from issuing a SoDA in Step 3
• where we consider changes to the design might be needed
• whether the scope of the assessment remains meaningful and, if not, what changes are needed
• areas we will examine closely at Step 3 (detailed assessment)

We will consider any relevant comments received from the public or interested organisations and the responses the RP has made to those comments.

We carried out a readiness review with Rolls-Royce SMR Limited to make sure it can meet our requirements for Step 3 before progressing any further.

We will only start Step 3 if we consider that we, and the RP, are ready.

We worked with Natural Resources Wales to undertake our fundamental assessment during Step 2.

2. Rolls-Royce SMR Limited’s Small Modular Reactor

This section provides a brief outline of the reactor design and how waste will be created, processed and disposed of. Rolls-Royce SMR Limited is the Requesting Party (RP). The reactor itself is the Rolls-Royce SMR Limited’s Small Modular Reactor and is referred to as the ‘Rolls-Royce SMR design’.

2.1 Outline of design

There are currently around 300 pressurised water reactors (PWRs) operating around the world. There are a range of sizes and applications of PWRs, including power generation and marine propulsion. The Rolls-Royce SMR design uses standard PWR type technology but has some novel features. It is a 3-loop pressurised water reactor which can generate up to 470 megawatts (MW) of electricity (Rolls-Royce SMR Limited, 2024a). In the reactor core, the uranium oxide fuel is cooled by water under high pressure. The cooling water also acts as the neutron moderator necessary for sustained nuclear fission.

The water cooling the fuel is circulated in the ‘primary circuit’, including the reactor pressure vessel, using pumps. Water in the primary circuit is maintained under high pressure to prevent it from boiling. Heat in the primary circuit water is transferred into water in the secondary circuit through heat exchangers called ‘steam generators’.

Water in the secondary circuit boils, producing pressurised steam which directly drives turbine generators to produce electricity. Steam is then condensed in the turbine condenser, which is cooled using cooling water and returned to the secondary circuit. In the baseline design case considered in GDA, cooling water is provided by mechanical draught cooling towers (indirect cooling). (Rolls-Royce SMR Limited, 2024b).

The final decision on cooling will depend on site-specific factors. The option of direct once-through cooling remains open for the design.

The main ancillary facilities include:

• spent fuel storage pond
• spent fuel dry store
• chemical and volume control system (CVCS) for maintaining the chemistry of the water circuit
• radioactive waste treatment and storage facilities
• back-up systems for providing power in the event of loss of electrical supply to the reactor from the grid

Rolls-Royce SMR Limited is considering back-up systems for providing power, including the use of and options for diesel generators. (Rolls-Royce SMR Limited, 2024c). Diesel generators are a well understood and commonly used technology for this purpose. Other technologies and combustion fuels are also being considered.

The Rolls-Royce SMR is still being designed and is, therefore, not yet in operation. Assessment of the design has been facilitated by the RP developing its design and presenting the Environment, Safety, Security and Safeguards E3S case documentation during Step 2. This GDA is the first regulatory assessment of the Rolls-Royce SMR design globally.

2.2 Novel aspects of the design

The reactor coolant chemistry in the primary circuit is novel. In most PWRs, boron in the form of boric acid is injected into the reactor coolant to control reactivity. Boric acid lowers the pH of the coolant and so lithium hydroxide (LiOH) is added to the reactor coolant to counter this and control pH. Tritium is produced as a result of neutron interactions with boron and with lithium-6.

The Rolls-Royce SMR is being designed to avoid the use of boron dissolved in the reactor coolant to control reactivity. Potassium hydroxide (KOH) will be used in the primary circuit to control pH in place of lithium hydroxide (LiOH).

The Rolls-Royce SMR design will not have boron or lithium in its coolant, therefore, less tritium will be present in the Rolls-Royce SMR coolant compared with other PWRs that use boron and lithium. Compared with other PWRs, the liquid effluent treatment system may be simplified, and operational liquid effluent and tritium discharges to the environment are expected to be reduced.

The size of the Rolls-Royce SMR design has been optimised to allow construction and assembly in factory-built modules. The modules can then be transported to site for final construction. The modularisation construction approach may help to reduce the environmental impact of on-site construction and contribute to the sustainability of the design, by a quicker build and shorter period of construction.

The generic site description (GSD) underpins the GDA baseline case. It provides details of the site bounding characteristics and parameters within which the Rolls-Royce SMR is designed, and on which the radiological impact assessment of discharges is based.

The GSD is a coastal location, with cooling of the turbine condensers by indirect cooling using mechanical draught cooling towers which require much less water abstraction than direct cooling. Indirect cooling will have less impact on the water environment, including on biota. Where this cooling approach is used, it will contribute to the sustainability of the design and its operation from an environmental perspective. However, indirect cooling using mechanical draught cooling towers would reduce overall efficiency.

2.3 Sources, processing and disposal of radioactive waste

Radioactive waste in the form of solids, liquids and gases will arise from activities associated directly or indirectly with operating and maintaining the reactor, and ultimately, from decommissioning the plant. Spent fuel will arise during the life of the reactor and will need to be stored and managed and disposed of in a geological disposal facility (GDF). More information on progress with the development of a GDF can be found here: Geological Disposal – a programme like no other.

The operation of a PWR generates radioactive waste in the reactor coolant water (the primary circuit). Reactor coolant water is collected and treated and reused during operations. As noted previously, the use of potassium hydroxide in the primary coolant to control pH will result in less tritium generation than when lithium hydroxide is used. This, in turn, will lead to reduced tritium discharges.

Liquid radioactive waste arises mainly from effluent associated with systems for collecting and treating the reactor coolant water. Other sources of radioactive aqueous effluent may include:

• spent fuel storage pond
• washings from plant decontamination
• drainage from change rooms
• effluent from laboratories

Effluent treatment facilities include:

• accumulation, hold up and monitoring tanks
• filters
• demineraliser ion exchange resin beds
• membrane separation and evaporators
• chemical and volume control system (CVCS)

Facilities to monitor effluents for radioactivity prior to release are provided.

Gaseous radioactive waste discharges are mostly from the primary reactor circuit. Discharges from the primary circuit are collected by the gaseous radioactive effluent treatment system and passed through the carbon bed delay system to reduce the discharges of radioactive noble gases and iodine. The main process buildings are serviced by the heating, ventilation and air-conditioning (HVAC) systems. Discharges from these systems to the atmosphere will be from an appropriate stack. These discharges are monitored after filtration by high efficiency particulate air (HEPA) filters and, where appropriate, charcoal filters for adsorption of gases.

Solid radioactive waste arises from a number of operational processes on site and is usually stored before being disposed of and includes:

• spent ion exchange resins
• spent filter media
• reverse osmosis membranes
• evaporator concentrates
• operational wastes, such as worn-out plant components and parts, contaminated protective clothing and tools, rags and tissues, and waste oil

Facilities for managing these types of waste include:

• resin storage tanks
• treatment and packaging facilities
• storage areas for packaged low-level and intermediate level waste

All radioactive plant components including structural and non-fuel core components that have become activated over their lifetime are likely to become waste when the plant is decommissioned. The wastes expected to be produced during decommissioning should be included in the decommissioning waste plan which will be submitted in Step 3.

Spent fuel will be stored under water for up to 10 years in the spent fuel storage pond. The Rolls-Royce SMR design includes space for a dry store to allow further storage prior to ultimate disposal in a geological disposal facility (GDF).

2.4 Non-radioactive waste

Non-radioactive waste is produced from constructing, operating and maintaining the ‘conventional’ side of a PWR power station. It includes:

• combustion gases discharged to air from the diesel generators
• water containing water treatment chemicals from the turbine-condenser cooling system and other non-active cooling systems, which can be discharged to the sea, lakes or other water bodies in accordance with environmental permits
• oils and any other significant liquids or sludges
• worn-out plant and components and general waste materials

Non-radioactive substances will also be present in the radioactive waste and may affect how it is managed and its impact on the environment. The Rolls-Royce SMR design has adopted different reactor primary circuit water chemistry to most PWRs. PWRs generally use boric acid in their primary circuit coolant to provide reactivity control during normal operations. The Rolls-Royce SMR design does not use boric acid during normal operations. Therefore, boron will not normally be present in the primary circuit and there will be no need for treatment systems to remove boron from liquid effluents before they are discharged to the environment.

3. Scope of GDA and design developments

Rolls-Royce SMR Limited provided a plan for its Step 2 submissions, including an integrated Environment, Safety, Security and Safeguards Case (E3S case). The E3S case is designed around the structure for safety cases for new reactors proposed by the International Atomic Energy Agency (IAEA) in its safety series (IAEA SSG-61).

Rolls-Royce SMR Limited’s plan was for its E3S case submissions to be structured in 3 tiers of documents. Tier 1 documents were chapters. Tier 2 and Tier 3 documents provided more detailed information and evidence to support the Tier 1 chapters.

In SSG-61, the IAEA proposed 21 chapters for a safety case.

The first 19 chapters of the IAEA SSG-61 structure (IAEA SSG-61) are safety related. Chapters 2, 9 and 11 in the IAEA structure may contain content relevant to radioactive waste. Chapter 20 covers environmental aspects.

The IAEA assumes that the environmental aspects would be considered in a separate environmental impact assessment, which would be linked to the safety case through Chapter 20.

At the start of Step 2, the E3S case was made up of 33 chapters. The first 19 chapters of Rolls-Royce SMR Limited’s E3S case follow the IAEA SSG-61 structure. Chapter 20 of the E3S case is on chemistry. Specific environmental aspects are in 7 chapters of the E3S case (Chapters 25 to 31). Other chapters cover security, safeguards and UK specifics not considered in SSG-61. Rolls-Royce SMR Limited submitted the E3S case at the start of Step 2 (April 2023), with updates and additional information provided during Step 2. Four of the 7 environment chapters were available at the start of Step 2, 2 of the 7 chapters were submitted in August 2023, and one of the 7 was first submitted in October 2023. Tier 2 and Tier 3 documents supporting the E3S case chapters were provided between April 2023 and February 2024.

Our assessment considered the relevant content of the Tier 1, Tier 2 and Tier 3 documents.

The E3S case Tier 1 chapters’ content and structures were modified during Step 2. The content of Chapter 26 (radioactive waste management arrangements – RWMA) was transferred into Chapter 11 which covered management of radioactive waste. The sustainability topic is being developed and will be the content of Chapter 26.

Second versions of the E3S case chapters were submitted in May 2024, preceded by submissions of interim versions between February and April 2024.

3.1 Requirements for the scope of GDA

Requirements for the scope of GDA are defined in the Environment Agency: Guidance for Requesting Parties (2019). In 2023, after the start of this GDA, the Environment Agency guidance for Requesting Parties was republished. The Rolls-Royce SMR GDA has started and will continue to use the 2019 version of guidance for Requesting Parties.

Our Environment Agency: Guidance for Requesting Parties (2019) expects the RP to provide a scope of GDA with enough information and sufficient functional specifications for the design so that we can carry out a meaningful GDA.

A meaningful scope means that the combined scope and the information provided by the RP should cover the full breadth and depth necessary for the Office for Nuclear Regulation (ONR), the Environment Agency and Natural Resources Wales to carry out their assessments.

The scope of the environment case should include all relevant topics and sufficient details about the nuclear power plant design. The scope does not include the detailed content of specific documents.

Regulators require that the scope should include which structures, systems and components (SSCs) and regulatory assessment topics are considered and for the RP to declare at which step the GDA is proposed to conclude.

The design of the SSCs that support the environmental protection functions (relevant to waste and environmental assessment) need to be mature enough to enable meaningful assessment.

The previous GDA process was up to 4 steps. Previous GDAs have completed 4 steps, with each achieving a SoDA from the Environment Agency and a Design Acceptance Confirmation (DAC) from ONR. Where appropriate, the SoDA may be issued jointly by the Environment Agency and Natural Resources Wales. The GDA process has been modified by combining Steps 3 and 4. The current 3 step GDA process enables the most significant safety, security and environmental aspects to be addressed and helps reduce the uncertainty and project risks associated with subsequent regulatory processes. It also provides greater certainty for future operators and funding.

The scope of the GDA should include whether the RP is seeking a 2 or 3 step assessment, or a 3-step assessment targeting the issue of a SoDA and DAC.

Where the RP, the Environment Agency and Natural Resources Wales (where appropriate) have agreed that the scope of the GDA is to target the issue of a SoDA, we will consult on our preliminary findings during Step 3. Where the scope is not sufficient for a SoDA, we will not consult and the outcome from the GDA would be a Step 3 Statement.

3.2 Declared scope of GDA

During Step 1, Rolls-Royce SMR Limited presented a scope document of its environment case submission. The scope covers the:

• structures, systems and components (SSCs)
• plant design and layout
• relationship with the GDA activities

Information on the engineering and systems, the structures and components and the level of design maturity was also included.

The scope included detail for each of the environmental topics from the relevant parts of the E3S case, the modes of operation, the activities and the topics that affect the environment, including chemistry and the generation and management of radioactive and non-radioactive wastes. Rolls-Royce SMR Limited declared that these documents, together with the generic site description (GSD) and generic site envelope (GSE) provided the total scope of the assessment against which the Rolls-Royce SMR design is planned to be assessed in the GDA.

Rolls-Royce SMR Limited has included all the SSCs because it is aiming to develop a fleet of standard design SMRs, with reduced potential for design changes between units at different sites.

Rolls-Royce SMR Limited declared 11 exclusions from the scope of the GDA, mostly relating to site-specific aspects, including the site factory, factories for the heavy pressure vessel and mechanical, electrical and plumbing (MEP) module; transport to site and construction on site; site-specific permitting and licensing and emergency preparedness. Regulators agreed that these exclusions would not affect our GDA objectives, and all topics important to environmental protection at this stage of the process were included in the GDA scope.

Rolls-Royce SMR Limited intends to progress through all 3 GDA steps, targeting the issue of a SoDA and DAC. Therefore, the scope covers the complete GDA up to the end of Step 3. During Step 3, we plan to carry out a public consultation on our preliminary findings.

We accepted Rolls-Royce SMR Limited’s GDA scope in Step 1. At the end of Step 1, we issued a Step 1: statement of findings that included the scope of the GDA. We decided that there would be enough information for a meaningful GDA. The scope should also be sufficient for Rolls-Royce SMR Limited to aim for a SoDA to be issued, subject to acceptable assessment outcomes.

Rolls-Royce SMR Limited made no changes to the GDA scope in Step 2. Our view is that the scope that was agreed in Step 1 did not change in Step 2 and remains acceptable for Step 3.

3.3 Management of documents during GDA

During GDA, many documents are created and submitted to the regulators by the RP. The documents need to be managed and tracked. Rolls-Royce SMR Limited use a Master Document Submission List (MDSL) and a Document List (DL) to track and manage documents. The MDSL lists the current version of all submissions and the content changes regularly, therefore, updates are required at regular intervals. The MDSL allows the regulators to understand and reference what constitutes the latest versions of the GDA submissions.

The MDSL was developed at the end of Step 1. A version with updated content was submitted every month during Step 2. The MDSL is a crucial document for tracking submissions, and we have used this during Step 2, and it was adequate.

The submissions provided for our assessment are identified in the MDSL (Rolls-Royce SMR Limited 2024d)

3.4 Design developments during GDA

The Rolls-Royce SMR is a developing design that is not based on a reference plant. The design of the Rolls-Royce SMR continued to be developed during Step 1 and Step 2 of GDA.

A GDA carried out at this early stage of the design presents opportunities for environmental aspects to be considered early and to be included within optioneering and decision making. The developing design has influenced the development of the E3S case and the Step 2 GDA programme. The GDA-related information in the E3S case provided for assessment lagged the developing design. We have noted that for some topics early during Step 2 the design maturity affected the delivery and content of part of the submissions. However, we agreed with Rolls-Royce SMR Limited that the E3S case submissions would be revised and provided for assessment later in Step 2.

3.4.1 Design terminology used

At various points during the design, Rolls-Royce SMR carried out and will continue to carry out gate reviews to establish an overall baseline of design maturity for the Rolls-Royce SMR power station. Further gate reviews will be carried out as the design develops. These are the ‘reference design’ (RD) baseline. Submissions of the E3S case are aligned with the RD baseline. Issue 1 of the E3S case at the start of Step 2 was based on the reference design 5 (RD5) baseline, equivalent to preliminary concept definition (PCD). During Step 2, the Rolls-Royce SMR design continued to develop and reached RD7 baseline in November 2023 and RD8 baseline in July 2024, equivalent to final concept definition (FCD). For Step 2 of GDA Rolls-Royce SMR Limited prepared design reference points (DRP), aligning with these RD baselines.

3.4.2 Design reference point (DRP) for GDA

ONR, the Environment Agency and Natural Resources Wales expect the RP to prepare an initial design reference point (DRP) for the GDA and to update this periodically in light of changes made to the design. Our requirements are given in Environment Agency: Guidance for Requesting Parties (2019). ONR requirements for the DRP are given in ONR Guidance to Requesting Parties (2019). Our requirements are aligned with ONR’s.

To meet the requirements of the DRP, the RP needs to identify the baseline design reference configuration that the GDA submissions refer to at a point in time.

In December 2023, Rolls-Royce SMR Limited provided a Design Reference (DR) report, followed by a re-issue in April 2024 (Rolls-Royce SMR Limited, 2024e). The DR report presents a definition of the Rolls-Royce SMR design assessed during Step 2 of the GDA. The DR report defines the baseline design reference configuration that the GDA submissions refer to at a point in time. This was the first GDA design reference point (DRP1). The DR report lists all the documents that define the design of the nuclear power plant that the GDA submissions refer to. DRP1 aligns with the RD7 baseline reached in November 2023. The DR report includes the current list of documentation that defines the design based upon the islands and functional areas: reactor island; turbine island; cooling water island; balance of plant and electrical control and instrumentation.

The document type, date and issue are included on the submission listing. The change control process for the DRP is included. Rolls-Royce SMR Limited can update DRP1 using change control processes and will advise the regulators if it does so. Changes to any of the documents not related to the design will not result in a change to the DRP but can result in a re-issue of the DR report.

The environment, safety, security and safeguard cases must align with the plant design as described in the DR report. The DRP1 does not represent everything in the totality of the GDA scope because some systems need time to be developed and matured to reach RD7. The RP initially focused the development of the design on the main systems in the reactor island. Systems within the GDA scope will be added to future DRPs as they mature to RD7 and RD8. Our assessment was against the design given in DRP1.

At the end of Step 2 in July 2024, much of the Rolls-Royce SMR design reached a new baseline maturity (RD8). Rolls-Royce SMR Limited will set a second design reference point (DRP2) for the GDA in July 2024.

4. Our assessment

During Step 2 of GDA we carried out a fundamental assessment of the Rolls-Royce SMR design against our requirements to identify if there are any fundamental environmental protection shortfalls in the design. Our assessment was for the design given in DRP1.

We also considered if there are any matters which are unacceptable, or if any significant design modifications are likely to be needed to meet our regulatory expectations. We will look in more detail at the generic site description, the proposed discharges, the radiological assessment methodology and the BAT methodology.

Our assessment against the GDA environmental topics is considered in Section 5. In Section 6, we consider the implications of the proposed design and build of the Rolls-Royce SMR design on the environment that were not considered in Section 5. In Section 7, we identify matters that will be considered further in Step 3. Our conclusions are given in Section 8 of this document.

During Step 2, we continued to provide advice to Rolls-Royce SMR Limited on our expectations for the environment case.

Our assessment approach was to:

• assess relevant parts of the environment case submission and supporting documents against our regulatory requirements and expectations

• hold technical meetings with Rolls-Royce SMR Limited to clarify our understanding of the information presented and provide feedback on that information

• raise Regulatory Queries (RQs) to clarify our understanding of the information presented

• raise Regulatory Issues (RIs) or Regulatory Observations (ROs) where we believe there is a potential regulatory shortfall in the Rolls-Royce SMR design or its substantiation (note, no RIs or ROs have been raised within our assessment during Step 2 of this GDA)

• present our Step 2 assessment findings in this report, including identifying items which require further scrutiny in Step 3 of the Rolls-Royce SMR Limited GDA

4.1 How we assess

We assessed the design against our regulatory requirements and expectations Environment Agency Guidance for Requesting Parties (2019). This includes identifying any fundamental environmental protection shortfalls that could prevent the design from being potentially acceptable to build and operate at sites in England and Wales. We assessed methodologies, approaches, codes, standards and philosophies that Rolls-Royce SMR Limited used to substantiate its environment case. We included lessons learned from Step 1 of this GDA and from previous GDAs.

We made our assessment using our Environment Agency: Guidance for Requesting Parties (2019), our operational instructions and technical guides. We reviewed whether our Radioactive substances regulation (RSR): objective and principles and relevant RSR generic developed principles: were considered. We also used relevant parts of ONR Guidance to Requesting Parties (2019) in our assessment where appropriate.

4.1.1. Working with the Office for Nuclear Regulation (ONR) and Natural Resources Wales

GDA is a joint project with ONR who consider nuclear safety, conventional health and safety, security and safeguards during GDA. In this GDA we have also worked jointly with Natural Resources Wales on the environmental aspects of the design. This included joint meetings on matters of regulatory interest to each regulator, particularly at project level, on the joint assessment area of management systems and quality assurance (MSQA) and in ONR’s Nuclear Liability Regulation (NLR) assessment area. ONR have reported its assessment of Step 2 separately (ONR 2024).

Close working with ONR and Natural Resources Wales will continue where appropriate throughout the rest of the GDA.

4.2 Scope of our assessment

The assessment scope during Step 2 of GDA is a fundamental assessment of the design, which is an examination of the aspects of the submission that affect the environment.

There are 7 assessment topics for the environment. These are:

i) management arrangements and quality assurance (jointly with ONR – under its management of safety quality (MSQA) arrangements)

ii) demonstration of best available techniques (BAT) and radioactive waste management arrangements (RWMA)

iii) approach to discharges and limit setting

iv) approach to sampling and monitoring

v) generic site description and radiological impact assessment

vi) management of solid waste and spent fuel (working closely with ONR’s –NLR assessors)

vii) other environmental regulations

The last of these covers 6 topics:

a) water use and abstraction

b) discharges to surface water

c) discharges to groundwater

d) operation of combustion plant and incinerators

e) Control of Major Accident Hazards Regulations (COMAH)

f) fluorinated greenhouse gases (F-Gas) and ozone-depleting substances (ODS)

The scope and findings are detailed in Section 5. Rolls-Royce SMR Limited’s approach to considering and including sustainability was not explicitly in the scope of GDA when it entered the GDA process. However, we agreed to include a commentary and observations on how Rolls-Royce SMR Limited has considered sustainability in the Rolls-Royce SMR design.

We also considered public comments received on the Rolls-Royce SMR design and on our GDA process.

4.3 Standards and guidance

The RP is expected to show how it will take account of Environment Agency guidance, in particular our Radioactive substances regulation (RSR): objective and principles and our RSR generic developed principles

During Step 2, the RP is expected to provide information on strategies, methods, models and standards that it will use to demonstrate design acceptability.

Our assessment considered whether and how RSR objectives and principles and the RSR generic developed principles for regulatory assessment have been identified and considered in each topic during GDA.

Rolls-Royce SMR Limited’s design has not been licensed or permitted in another country. Therefore, design documents or approvals from regulators in other countries are not available to Rolls-Royce SMR Limited.

During our assessment, we noted that Rolls-Royce SMR Limited has provided information about how it will take account of guidance and relevant good practice for each of the topics. Where applicable, it has begun to lay out in summary form standards, methods, models, good practice and design and assessment principles. Rolls-Royce SMR Limited has identified that one of the important aspects of the E3S case is demonstrating that relevant good practice (RGP) and design and assessment principles and codes and standards are met.

Important national and international standards and guidance, including those from our Radioactive substances regulation (RSR): objective and principles and our RSR generic developed principles that are applicable have been summarised in submissions for the topics. We noted that for some topics it is not clear whether the Engineering: generic developed principles that are relevant to design and to environmental protection functions have been fully considered yet. Rolls-Royce SMR Limited will need to develop this further during Step 3 of GDA.

Rolls-Royce SMR Limited has identified information it will include, such as engineering design information, operational experience (OPEX) from PWRs, and relevant good practice (RGP) from recent permitting and licensing of new reactors. It is also making use of information from previous GDAs of PWRs. Rolls-Royce SMR Limited has made us aware that it is using commercial information from the Electric Power Research Institute (EPRI). The US Constellation Energy Group is an investor in the Rolls-Royce SMR design. The design gets operational information (OPEX) from Constellation and other shareholders to support the design and the GDA, some of which is commercially sensitive or export controlled.

4.4 Public comments

The comments process was launched at the start of Step 2, which enables the public to contribute to GDA by making comments on published submissions. The RP will respond to comments received as part of this process. We will respond to comments made that are relevant to the regulators.

Information about GDA and the comments process, with links to Rolls-Royce SMR Limited’s website, has been provided on the regulators’ joint GDA website ONR-EA-Natural Resources Wales generic design assessment.

Rolls-Royce SMR Limited published its main submissions (excluding any sensitive nuclear information or commercially confidential information) and a non-technical summary on its website, with provision for comments to be made electronically, or by post, to Rolls-Royce SMR Limited.

4.5 Our governance during GDA

For our assessment, we followed the GDA process in Environment Agency: Guidance for Requesting Parties (2019) and used appropriate Radioactive substances regulation (RSR): objective and principles and RSR generic developed principles and our public comments process. This ensured we met our GDA requirements.

As part of our continuous improvement, we undertook lessons learned at the end of previous GDAs and used the outcomes to modify and update our GDA processes and governance.

We undertook a ‘lessons learned’ exercise at the end of Step 1 of this GDA. We used the outcomes to refine our assessment and governance processes where appropriate.

For our internal governance, our assessment was subject to peer review, Natural Resources Wales’s review, technical and legal review, consistency checks with ONR and a factual accuracy check with Rolls-Royce SMR Limited. It was subject to a final Environment Agency and Natural Resources Wales governance process. This helped to ensure the outcomes are appropriate, legally, factually and technically correct and were consistent with our requirements and ONR outputs.

We followed publication accessible documents policy – Department for Environment, Food & Rural Affairs to ensure the reports are accessible and can be published.

5. Fundamental assessment outcomes

Our GDA guidance for requesting parties requires a fundamental assessment during Step 2 of GDA. This involves examining the aspects of the submission that could potentially affect the environment.

5.1 Management arrangements and quality assurance

Our aim in assessing management arrangements and quality assurance during GDA is to gain confidence in the quality of the RP’s GDA submission, and to confirm that adequate processes are in place to transfer the RP’s GDA information to a future operator. We work jointly with ONR using its management of safety and quality assurance (MSQA) assessment arrangements to consider how the design has been controlled and how the GDA submissions are produced and managed.

We want to know:

• that the design has been developed and the submission produced by suitably qualified and experienced people (SQEP) (whether in-house staff or contractors)

• whether there has been an appropriate level of verification, review and approval of design and submission documents, including those produced by contractors, and check that the submission accurately reflects the design

• if the design has been developed taking environmental requirements (for all plant lifecycle stages) into account

• how design changes are (and will be) controlled, evaluated for their impact on environmental matters, recorded and reflected in the submission

Through Step 2, Rolls-Royce SMR Limited provided enough information for us to complete the assessment, which we carried out by reviewing documents it had submitted, via scheduled meetings on specific MSQA topics, and by undertaking engagements to evaluate arrangements.

5.1.1 Assessment

In Step 2, we received management system documentation and other GDA documents from Rolls-Royce SMR Limited, including the E3S Case Chapter 17 management and quality arrangements (Rolls-Royce SMR Limited, 2024f) and a range of relevant procedures and guidance documents.

We assessed the submissions and, where appropriate, provided feedback to Rolls-Royce SMR Limited on our findings. Our assessment of these documents informed our subsequent engagements on specific topic areas via technical meetings and evaluation sessions.

As well as examining this information, we, ONR and Natural Resources Wales evaluated Rolls-Royce SMR Limited’s arrangements via interventions and meetings, which considered processes and procedures, to see how the management system worked in practice. We carried out 7 interventions in Step 2 up to April 2024. We considered Rolls-Royce SMR Limited’s arrangements for GDA internal assurance; managing the supply chain input to the GDA project; GDA assumptions and commitments; design change control; use of operating experience; production of the E3S case, and E3S case production quality issues.

These interventions were to check that Rolls-Royce SMR Limited has a quality management system that provides organisational and procedural arrangements that adequately support production of the submissions, that these arrangements have been implemented, and that Rolls-Royce SMR Limited continues to review arrangements to control its GDA-related activities and to inform our, Natural Resources Wales’s and ONR’s assessment of its submission.

During Step 2, we raised 3 RQs on MSQA:

• RQ-01011 – Implementation plans for the Teamcenter tool (closed)

• RQ-01051 – Management of findings from assurance activities (closed)

• RQ-01329 – Environmental requirements – identification, collation and verification – (linked to Regulatory Observation RO-RRSMR-001). A response was provided, and we have asked for further information

ONR raised one RO relevant to MSQA on the production of the E3S case (RO-RRSMR-001). Resolution of RO-RRSMR-001 will extend into Step 3 because some of the elements needed to close the RO will not be available to assess until the start of Step 3.

At the start of Step 2, the design maturity of the Rolls-Royce SMR was at RD5 baseline. This affected our ability to evaluate design change arrangements as at this stage of the design baseline formal design control arrangements were not in place. Therefore, during Step 2 there were no examples of design change control arrangements available for assessment. Design control arrangements will be assessed when they become available in Step 3.

5.1.2 Assessment findings

We determined that Rolls-Royce SMR Limited has developed an organisational structure to support implementation of GDA and is working to identify and clarify roles and responsibilities for developing the GDA design and the environment safety case (in the form of an integrated E3S case).

There is a defined GDA programme organisational structure and hierarchy that sits within Rolls-Royce SMR Limited’s wider business structure. GDA management and quality arrangements fall within Rolls-Royce SMR Limited’s Regulatory Affairs and Safety Directorate and its subordinate Health, Safety, Environment and Quality (HSEQ), Internal Assurance, and Regulatory Affairs. The SMR design development is progressed within Rolls-Royce SMR Limited’s Engineering Directorate.

There are defined arrangements in place for providing enough SQEP to carry out GDA roles, including leadership, governance and decision-making, design development, E3S case authoring, and assurance roles.

Rolls-Royce SMR Limited has implemented an integrated management system (IMS). This is a hierarchical arrangement of management policies, manuals and processes, consistent with established ‘plan-do-check-act’ good practice. Arrangements are integrated with respect to safety, security and environmental considerations. Quality management arrangements are incorporated into the IMS, and Rolls-Royce SMR Limited’s GDA management system is certified to the International Organization for Standardization (ISO) Quality Management ISO9001:2015 quality management standard. Following a recent Stage 2 audit, Rolls-Royce SMR Limited’s GDA management system has been recommended for certification to ISO14001:2015 environmental management system.

Rolls-Royce SMR Limited has put in place formal arrangements for engaging with regulators and responding to regulator correspondence. Our experience through Step 2 is that these arrangements are effective. There are documented procedures in place for the production and control of GDA documents and records.

There are defined arrangements in place for production of the E3S case and for developing the design, including introduction of design modifications during GDA. These arrangements address the interrelationship between design and safety case development and are supported by leading software tools for safety and environment cases (ASCE – Assurance and Safety Case Environment software for the creation and management of safety and assurance cases); requirements management (DOORS – Dynamic Object Orientated Requirements System) and product lifecycle management (Teamcenter). These arrangements provide the basis for collating the information that will ultimately be transferred to potential operators after conclusion of the GDA process.

The E3S case chapters are authored by SQEP in the E3S case team, supported by other technical functions (for example, engineering), and are subject to technical checking and independent review.

Generally, the arrangements were considered adequate for Step 2 of GDA. We noted that some arrangements are still being developed or are subject to further improvement and clarification following our Step 2 assessment feedback. Areas where continued or additional scrutiny will be appropriate as we progress into GDA Step 3 are:

• the control of design change, and implementation of the Siemens Teamcenter software tool

• arrangements for E3S case development (mainly actions in response to RO-RRSMR-001 and RQ-01329)

• the implementation and exercise of Intelligent Customer arrangements

• use of OPEX

• quality of submissions

• maintaining SQEP resources for Step 3 of GDA

• collation of design and E3S case information for transfer to a future licensee

We will include these areas in our plans for MSQA engagement and assessment for GDA Step 3.

5.1.3 Conclusion

Rolls-Royce SMR Limited has provided enough information for us to make our assessment during Step 2.

Our assessment during Step 2 showed that Rolls-Royce SMR Limited operates an appropriate and adequate management system, which includes and integrates aspects that control the content and accuracy of its submissions for GDA.

On that basis, the regulators (we, ONR and Natural Resources Wales) can have confidence that the production and update of submissions is adequately controlled for this stage of the design and that any issues raised will be properly dealt with.

There are, however, some matters that could be improved. These are related to the effectiveness of the arrangements for E3S case production and quality and linkage with Rolls-Royce SMR design development. ONR has raised this as an RO (RO-RRSMR-001).

In addition to the documentation provided to address the RO-RRSMR-001, we also requested further information via 3 RQs that we issued in Step 2. Two of those (RQ-01011 and RQ-01051) have now been closed. Rolls-Royce SMR Limited has provided an initial response to the third RQ (RQ-01329), and a full response is expected early in Step 3. Further work is needed to close the RO-RRSMR-001 and work will continue into Step 3 of the GDA.

We did not find anything unacceptable during our fundamental assessment.

Overall, our conclusion is that Rolls-Royce SMR Limited’s GDA management and quality arrangements are adequate for this stage of GDA.

5.2 E3S case

We assessed whether the Environment, Safety, Security and Safeguards (E3S) case has enough scope and content, and whether the structure and maturity were developed enough to support our fundamental assessment.

The E3S case is structured around International Atomic Energy Agency (IAEA) guidance for safety cases for new reactors (IAEA SSG-61). Rolls-Royce SMR Limited has adapted the structure to include 7 chapters to address environmental safety aspects.

The E3S case is being developed at the same time as the design of the Rolls-Royce SMR. We expect to see Rolls-Royce SMR Limited using an integrated approach on design and safety case development, to ensure that environmental requirements adequately inform the developing design and its alignment with BAT.

5.2.1 E3S case structure and the design of the Rolls-Royce SMR

At the start of Step 2, the Rolls-Royce SMR design was approaching or was at RD5 baseline (preliminary concept definition – PCD). During Step 2, Rolls-Royce SMR Limited progressed most systems from RD5 baseline to reach RD8 baseline (final concept definition – FCD) at the end of Step 2.

In demonstrating BAT and as low as reasonably practicable (ALARP), the E3S case uses a claims, arguments and evidence approach from ONR guidance (NS-TAST-GD-051 Issue 7.1) (Technical Assessment Guides (TAGs) – Nuclear Safety (onr.org.uk).

A crucial element in this approach is Rolls-Royce SMR Limited’s use of requirements to be met by the design. Requirements are being developed to provide input for the various aspects of the design. Some requirements are ‘functional’ (for example, the performance standards to be met by a system or component) and some are ‘non-functional’ (for example, the principles to be met). In the main, non-functional requirements are pertinent to the environmental performance aspects of the design.

We have noted that addressing requirements in the design is managed through third party software systems (DOORS, ASCE and Teamcenter). We raised RQ-01329 to ask Rolls-Royce SMR Limited how the environmental requirements have been included and how they are made visible to the designers, among many other requirements (see Section 5.1). The interaction between the design requirements and the E3S case requirements was being formalised via formal company standards which were produced April 2024. The claims, arguments and evidence (CAE) approach used for safety cases has been adopted into the process and will be formalised, with a company standard due in July 2024, which we will consider during Step 3.

5.2.2 Initial E3S case submission

We found that the environmental E3S case Tier 1 documents submitted at the start of Step 2 were not fully developed for all the topics. The reactor design and the E3S case were evolving and not all the information was available. Rolls-Royce SMR Limited indicated that the initial E3S case submissions were to inform and facilitate interactions with us early in Step 2. It acknowledged the incomplete sections in its submissions for the environmental parts. Some submissions included forward action plans (FAPs), identifying what will be provided, however the forward action plans were not always fully developed.

We raised a RQ (RQ-01058) on ‘Use and development of forward action plans’. The RQ asked Rolls-Royce SMR Limited to provide the required level of information in the FAPs and to ensure that it is clear which gaps the forward actions are intending to address, when they will be addressed, and by whom. The RQ also sought to understand how Rolls-Royce SMR Limited intends to manage FAPs during Step 2 of the GDA process and beyond, to ensure that forward actions can be tracked to completion.

Some sections of the Tier 1 documents adopted the CAE approach (NS-TAST-GD-051 Issue 7.1) (Technical Assessment Guides (TAGs) – Nuclear Safety (onr.org.uk). We found that the ‘arguments’ presented were not always arguments. An argument might be expected to be a reasoned statement to show that a claim is true. We found that there was a limited link between the arguments and the demonstration of claims. We noted that in some documents, claims were made that the design had been declared substantiated to meet regulatory requirements. However, as much of the design was at RD5 at the start of GDA Step 2, there was insufficient maturity to allow substantiation to be completed. 

Our interactions with Rolls-Royce SMR Limited were facilitated by the early submissions. We presented our findings on the early submissions to them via meetings and written feedback.

5.2.3 Maturity of the E3S case

We worked jointly with ONR to assess the maturity of the E3S case submitted at the start of Step 2. This was assessed using guidance from NS-TAST-GD-051 Issue 7.1 (Technical Assessment Guides (TAGs) – Nuclear Safety (onr.org.uk) – adapted for GDA.

We found that the overall structure of the E3S case was logical, but the thread of the arguments needed further development and clarification. Provision of information for future operators was not developed or missing, often being limited to placeholders in the documents.

For evidential support, underpinning justifications supporting information in Tier 2 and Tier 3 documents was needed but was not always available. The FAPs identifying what was needed were sometimes also unclear and the decision-making process and the rationale behind decisions needed clarifying. The relatively undeveloped status of the E3S case at this point was due to the relative immaturity of the design of the Rolls-Royce SMR. Rolls-Royce SMR Limited acknowledged that some shortfalls would be expected at this stage and not all the evidence would be available to support the early submissions.

ONR raised a RO in August 2023 (RO-RRSMR-001) (Ref ONR 2023, Regulatory Observation – Development of the generic E3S case, RO-RRSMR-001, Revision 0, August 2023) which covered the issues with the early draft of the E3S case noted above. The RO required Rolls-Royce SMR Limited to provide additional confidence to the regulators that suitable arrangements to support the E3S case were fully developed and implemented, to meet UK and international regulatory expectations, addressing:

1. how the E3S case is to be developed, in particular the overall strategy for the development, which shows what still needs to be completed

2. the oversight, governance and control arrangements for the E3S case development, including how this interacts with the evolving design

Rolls-Royce SMR Limited has implemented a resolution plan for the RO-RRSMR-001, with the intention of achieving closure in Step 3. The RO-RRSMR-001 will remain open until evidence is available that shows that the E3S case development arrangements are mature, sufficiently integrated with the design process, and are effective.

We will continue to scrutinise development of the E3S case in Step 3, including Rolls-Royce SMR Limited’s responses to RO-RRSMR-001.

A revised and updated E3S case was provided later in Step 2, which was more mature and addressed the issues we raised. Links between claims and arguments had been clarified and strengthened. The updated E3S case allowed us to carry out a fundamental assessment.

5.2.4 Conclusion

During Step 2 of GDA, the design of the Rolls-Royce SMR was still developing and maturing, and some design options were still being considered. This impacted on the completeness of the E3S case provided early in Step 2. However, the design developed and a revised E3S case was provided later in Step 2 that was sufficiently developed for us to complete our fundamental assessment. ONR raised an RO-RRSMR-001 seeking further confidence that the arrangements to support the E3S case were developed and integrated with the design process. The RO-RRSMR-001 is ongoing into Step 3.

5.3 Best available techniques (BAT)

The information we require within the environment case submission is defined in Environment Agency: Guidance for Requesting Parties (2019). Those aspects relevant to our assessment of BAT are primarily defined within the ‘detailed description of radioactive waste management arrangements’ section of the guidance.

Our Step 2 assessment has focused on Rolls-Royce SMR Limited’s BAT methodology and methods used (Environment Agency: Guidance for Requesting Parties (2019). This includes assessing Rolls-Royce SMR Limited’s progress with development of the BAT case, which once fully developed, will demonstrate BAT for the Rolls-Royce SMR design. A detailed assessment of the BAT case will be the focus of our assessment in Step 3.

Our assessment considered whether:

• Rolls-Royce SMR Limited had arrangements in place for managing the optimisation process

• the optimisation process enabled a proportionate and systematic determination of BAT, challenged the design and ensured alignment with UK legislation and relevant good practice

• the optimisation process ensured that the decision to be made and the scope of the study was clear and that all boundaries, constraints, assumptions and uncertainties relevant to optimisation were defined

• the optimisation process defined criteria to assess options against, and these were appropriate and balanced, with sufficient emphasis given to environment and sustainability

• the optimisation process ensured the identification of BAT was sufficiently recorded, justified, approved, implemented and reviewed

• the optimisation process aligned BAT and ALARP to ensure a single optimised outcome to any selected option

• the BAT case was developing sufficiently, and Rolls-Royce SMR Limited has appropriate SQEP resources to deliver it

We also observed the delivery of the BAT and Optimisation Engineer training delivered by Rolls-Royce SMR Limited for all its design engineers.

Rolls-Royce SMR Limited provided summary information on BAT in Chapter 27 of the E3S case (Rolls-Royce SMR Limited, 2024g) and a range of relevant supporting documents. Summary information relevant to BAT was provided in a number of other chapters of the E3S case, including Chapter 11 – Radioactive Wastes; (Rolls-Royce SMR Limited, 2024h); Chapter 29 on discharges (Rolls-Royce SMR Limited, 2024i); and the Integrated Waste Strategy (Rolls-Royce SMR Limited, 2023a).

A summary of our findings from the assessment of both the BAT methodology and development of the BAT case are presented in the sections below.

5.3.1 Best available techniques (BAT) methodology

The BAT methodology adopted by Rolls-Royce SMR Limited in the Rolls-Royce SMR design is described in the ‘Approach for optimisation’ (Rolls-Royce SMR Limited, 2024j). The methodology broadly meets our expectations for the current stage and maturity of the Rolls-Royce SMR design.

The ‘Approach for optimisation’ is presented as being integrated into the reactor design process as part of Rolls-Royce SMR Limited’s ‘conduct design optioneering’ process, which is held on its IMS. This approach is considered good practice as it should ensure all relevant factors that might influence design decisions, such as BAT and ALARP, are considered, and it enables the identification of a single optimised outcome.

Rolls-Royce SMR Limited has identified that the integration of BAT into the design is in 2 main stages. The first stage, in the early stages of the Rolls-Royce SMR design, focuses on the optioneering required to identify the techniques.

The second stage is the optimisation of the more mature design, including optimisation of the techniques identified by the optioneering stage and how they are implemented to improve performance. This applies to the latter design phase, and through the phases of procurement, construction, installation, commissioning and into operation. The arrangements will need to include the aspects of BAT for the latter stages of the design and into operation. Forward actions have been defined in the ‘Approach for optimisation’, one of which is to provide further detail on the optimisation stage of BAT to support later stages of the design.

The design optioneering process adopts a systematic approach which can be proportionately applied depending on the significance of the decision being made. The impact and complexity of the decision will inform the options evaluation method adopted. For the more complex decisions, the environment is one of 20 assessment criteria and is also integrated into several others. An environmental optioneering guidance document (Rolls-Royce SMR Limited, 2023b) and supporting template (Rolls-Royce SMR Limited, 2023c) have been produced to help with scoring options against the environment assessment criteria. This appears to be a comprehensive approach to considering relevant environmental factors which might influence the decision-making process. In Step 3 of GDA, we will seek evidence that the assessment criteria and weightings used to assess options are appropriate and balanced, with sufficient emphasis given to environment and sustainability. Decision records are used to capture the decision process and the rationale for consideration and selection of the preferred option.

The decision record template (Rolls-Royce SMR Limited, 2023d) is used for any decision that affects the environment case. The template appears to be comprehensive. However, during Step 2, we saw evidence of the decision record not being completed for a design decision potentially impacting the environment case, so we raised an RQ (RQ-01226). Rolls-Royce SMR Limited has proposed additional guidance to ensure design decisions are being sufficiently recorded in a proportionate way. In Step 3 of GDA, we will seek evidence from completed decision records and supporting information that the methodology is being implemented adequately and that BAT is being identified, recorded and justified by competent individuals.

All design decisions go through governance, which is proportionate to the significance of the decision. In Step 3 of GDA, we will seek evidence that appropriate governance has been applied to design decisions affecting the environment and that appropriate stakeholders have been involved.

The design optioneering process is iterative. As the Rolls-Royce SMR design matures, the viability of options and the data and information gathered to support option selection is subject to the definition review (DR) process, which provides a formal framework for assessing design maturity. As further work is undertaken, additional data and information may become available. Design decisions may then be revisited, and the steps within the design optioneering process repeated. In Step 3 of GDA, we will seek evidence of how decision records have been implemented and subsequently reviewed as part of Rolls-Royce SMR Limited’s engineering design process (in collaboration with the MSQA arrangements).

Rolls-Royce SMR Limited included an overview in the ‘Approach for optimisation’ of how relevant legislation, regulatory requirements, and RGP is used to inform design decisions. The E3S design principles have been derived from relevant legislation, regulatory requirements and RGP, and have been used to inform the development of the assessment criteria used in the options evaluation process. Our assessment of strategic considerations and environmental requirements and how they inform the design is included within the scope of both the radioactive waste management arrangements (RWMA) and MSQA assessment areas.

We raised one RQ on the BAT methodology during Step 2 (RQ-RRSMR-01075), seeking clarity on the identification and management of constraints, assumptions and uncertainties, the use of stakeholders, further optimisation of the design, consideration of non-foreclosure of options and how further optimisation of the design are identified and prioritised. As part of the response to this RQ, Rolls-Royce SMR Limited placed an action to update the decision record template (Rolls-Royce SMR Limited, 2023d). In Step 3, we will seek evidence of this update.

We have noted that Rolls-Royce SMR Limited needs to consider the potential radiological impact of discharges and wastes in prioritising optimisation of the design. We will look for evidence of this in Step 3.

In Step 3 of GDA, we will assess updated submissions and supporting information relevant to this assessment area and seek evidence of the closure of forward actions defined within ‘Approach for optimisation through the application of BAT’ (Rolls-Royce SMR Limited, 2024j). We will seek evidence that Rolls-Royce SMR Limited has applied the BAT methodology through decision records and supporting documents to confirm:

• the optimisation methodology is being implemented adequately in a proportionate way and BAT is being sufficiently identified, recorded and justified by individuals who are competent

• the assessment criteria and weightings used to assess options is appropriate and balanced, with sufficient emphasis given to environment and sustainability

• the appropriate governance has been applied to design decisions and that appropriate stakeholders have been involved in producing and approving decision records

• decision records are implemented and subsequently reviewed as part of Rolls-Royce SMR Limited’s engineering design process (in collaboration with the MSQA assessment area)

5.3.2 Demonstration of best available techniques (BAT)

Using the CAE approach to demonstrate BAT in the Rolls-Royce SMR design is considered good practice and meets our expectations. The high-level claims and sub-claims defined by Rolls-Royce SMR Limited align with the main considerations defined in Environment Agency: Guidance for Requesting Parties (2019).

The CAE structure is broadly aligned with that presented in previous GDAs and, at this stage in our assessment, appears to be reasonable. The development of the CAE structure is ongoing, and arguments and evidence will be refined as the design of the Rolls-Royce SMR matures. We will continue to engage with Rolls-Royce SMR Limited on this in Step 3.

We have seen evidence during our interactions with Rolls-Royce SMR Limited that the CAE approach is being applied within a series of technical reports which support the E3S case. This approach should provide an appropriate mechanism for demonstrating BAT within the Rolls-Royce SMR design. The technical reports for each high-level claim were not available for assessment during Step 2. This will be the focus of our detailed assessment in Step 3.

Further work is required by Rolls-Royce SMR Limited to systematically identify gaps in its CAE and define forward actions. This will inform the programme of work required by Rolls-Royce SMR Limited to collect the appropriate evidence for the claims and arguments it made. We recognise that design maturity has potentially had an impact on Rolls-Royce SMR Limited’s ability to systematically identify gaps in the CAE, with the Rolls-Royce SMR design still evolving during Step 2. As the design matures, we will expect to see evidence of this in Step 3.

We have not found any fundamental environmental protection shortfalls in the Rolls-Royce SMR design at this stage in our assessment. The Rolls-Royce SMR design as presented in the BAT claims and arguments broadly aligns with our expectations. This includes those aspects of the design which minimise the generation of radioactive wastes and spent fuel, the volume and activity of aqueous and gaseous effluent discharges, and the impact on the environment and members of the public. Further information on the management of solid and non-aqueous radioactive wastes and spent fuel is provided by the radioactive waste, spent fuel and disposability assessment area.

Rolls-Royce SMR Limited has continued to develop the Rolls-Royce SMR design and associated design justification during Step 2. An assessment of Rolls-Royce SMR Limited’s demonstration of BAT within the Rolls-Royce SMR design will be completed during Step 3. We expect Rolls-Royce SMR Limited to provide us with the necessary evidence in support of the claims and arguments to complete our detailed assessment.

We raised 7 RQs which are relevant to the demonstration of BAT.

RQ-01089 was on the use of reverse osmosis within the liquid effluent management system. We recognise this technology has not previously been used in the UK nuclear industry. Rolls-Royce SMR Limited has addressed part of this RQ, further information is required from the suppliers and operators of reverse osmosis systems to address the remainder of our query. We will continue to engage with Rolls-Royce SMR Limited on this in Step 3.

The other RQs were:

• RQ-01073 – Generation and management of sludges

• RQ-01074 – Spent fuel arisings

• RQ-01219 – Operational lifetime of the KNF20 evaporator

• RQ-01220 – Ion exchange materials

• RQ-01225 – Glycol and boronated fluid

• RQ-01226 – Component decontamination system

All of these RQs were answered – we will be following up some areas in Step 3.

One of the main features of the Rolls-Royce SMR design is that the reactor chemistry is not the same as many other PWRs. Rolls-Royce SMR Limited proposes a boron-free chemistry using potassium hydroxide (KOH) instead of lithium hydroxide for pH adjustment. Reactivity will be controlled using control rods. We note that this approach has significant environmental benefits, particularly in reducing the generation of tritium and the volume of liquid discharges. There are additional benefits in relation to sustainability, moving from a high demand resource (lithium) to a more readily available resource (potassium). This is considered further in Section 6.

We are broadly supportive of this approach as it appears advantageous to reduce discharges of the amount of liquid effluent and tritium to the environment. However, we are yet to assess whether there could be an impact on solid waste generation from potentially increasing the number of control rods. We are also yet to assess the use of KOH, the potential discharges of radioactive potassium-42 and doses to the public, and dose rates to wildlife in the environment. Rolls-Royce SMR Limited is also undertaking a materials test programme to better understand the potential impact of this chemistry regime on the corrosion of primary circuit materials. We will engage with Rolls-Royce SMR Limited on this in Step 3, in collaboration with the discharges, radiological impact assessment and solid waste assessment areas.

During Step 3, we will also consider Rolls-Royce SMR Limited’s response to the RO raised by ONR relating to the development of the generic E3S case (RO-RRSMR-001). This is being assessed primarily within the MSQA topic area, but there are likely to be aspects of Rolls-Royce SMR Limited’s response which are specifically relevant to the demonstration of BAT in the Rolls-Royce SMR design.

RQ-01329 – Environmental requirements – identification, collation and verification – was raised by MSQA and is of specific interest to BAT.

5.3.3 Radioactive waste management arrangements (RWMA)

The information we require within the environment case submission is defined in the Environment Agency: Guidance for Requesting Parties (2019). Those aspects relevant to our assessment of RWMA are primarily defined within the ‘detailed description of radioactive waste management arrangements’ section of the guidance.

The Integrated Waste Strategy (Rolls-Royce SMR Limited, 2023a) is an important submission for our assessment of RWMA. The Integrated Waste Strategy Issue 2 broadly meets our expectations for the current stage and maturity of the Rolls-Royce SMR design. Strategic considerations are clearly defined in relation to radioactive waste management. However, we have not yet seen the evidence for how these strategic considerations are used to underpin the Rolls-Royce SMR design, and we will look at this aspect as part of our Step 3 assessment.

A description of radioactive and conventional wastes and spent fuel arisings is provided within the Integrated Waste Strategy (Rolls-Royce SMR Limited, 2023a), as well as proposals for their subsequent management and disposal. Where there are gaps in the information provided on specific waste streams, these have been identified and captured in the FAPs.

In Step 3 of GDA, we will seek evidence that the FAPs defined within the Integrated Waste Strategy (Rolls-Royce SMR Limited, 2023a) are being addressed. We expect the next iteration of the Integrated Waste Strategy to include information on waste and spent fuel volumes and activity contents for all solid, liquid and gaseous radioactive waste and spent fuel arisings generated from the lifecycle of the Rolls-Royce SMR, and how they will be subsequently managed and disposed of.

We have raised 4 RQs which are relevant to RWMA and the Integrated Waste Strategy during Step 2:

• RQ-01059 – Radioactive waste management arrangements – strategic considerations

• RQ-01060 – Radioactive waste management arrangements – uncertainties, risks, opportunities, and assumptions

• RQ-01065 – Discharges – expected events

• RQ-01329 – Environmental requirements – identification, collation and verification

All the RQs were answered and resolved appropriately.

We did not raise any ROs in this assessment area.

5.3.4 Conclusion

The optimisation process used to identify and justify the proposed techniques as BAT broadly meets our expectations for the current stage and maturity of the Rolls-Royce SMR design.

The integration of the optimisation process into the engineering design process is considered good practice, as it ensures that all relevant factors that might influence design decisions, such as BAT and ALARP, are considered, and enables the identification of a single optimised outcome.

RGP has been identified and applied appropriately.

Our assessment of the optimisation process during Step 2 has mainly examined the process and how it is meant to be applied. In Step 3 of GDA, we will seek evidence of its application by Rolls-Royce SMR Limited through completed decision records and supporting documents.

Using the CAE approach to demonstrate BAT in the Rolls-Royce SMR design is considered good practice and meets our expectations. The CAE structure is broadly aligned with that presented in previous GDAs and, at this stage in our assessment, appears to be reasonable.

The development of the CAE structure is ongoing, and arguments and evidence will be refined as the design of the Rolls-Royce SMR matures. We will continue to engage with Rolls-Royce SMR Limited on this in Step 3.

Further work is required by Rolls-Royce SMR Limited to systematically identify gaps and define forward actions in its CAE. We recognise that design maturity has potentially had an impact on Rolls-Royce SMR Limited’s ability to systematically identify gaps in the CAE, with the Rolls-Royce SMR design still evolving during Step 2. We expect to see evidence of this in Step 3.

At this stage in our assessment, we have not found any fundamental environmental protection shortfalls within the Rolls-Royce SMR design.

The Rolls-Royce SMR design as presented in the BAT claims and arguments broadly aligns with our expectations. This includes those aspects of the design that minimises the generation of radioactive wastes and spent fuel, the volume and activity of aqueous and gaseous effluent, and the impact on the environment and members of the public. Further information on the management of solid and non-aqueous radioactive wastes and spent fuel is provided by the radioactive waste, spent fuel and disposability assessment area.

Rolls-Royce SMR Limited has continued to develop the Rolls-Royce SMR design and associated design justification during Step 2. An assessment of Rolls-Royce SMR Limited’s demonstration of BAT within the Rolls-Royce SMR design will be completed during Step 3. We expect Rolls-Royce SMR Limited to provide us with the necessary evidence in support of the claims and arguments to complete our detailed assessment.

The Integrated Waste Strategy broadly meets our expectations for the current stage and maturity of the Rolls-Royce SMR design. Strategic considerations are clearly defined in relation to radioactive waste management. However, we have not yet seen evidence of how these strategic considerations are used to underpin the Rolls-Royce SMR design, and we will look at this aspect as part of our Step 3 assessment.

In Step 3 of GDA, we will seek evidence that the forward actions defined within the Integrated Waste Strategy (Rolls-Royce SMR Limited, 2023a) are being addressed. We expect the next iteration of the Integrated Waste Strategy to include information on all solid, liquid and gaseous radioactive waste and spent fuel arisings generated from the lifecycle of the Rolls-Royce SMR, and how they will be subsequently managed and disposed of.

We were satisfied with how the BAT case is developing and that Rolls-Royce SMR Limited has appropriate SQEP resources to deliver it.

We have completed a fundamental assessment and we have not found anything that is not acceptable.

5.4 Environmental protection measures and functions

The RP is expected to provide information in its environment case relating to the identification of environmental protection functions” (Environment Agency: Guidance for Requesting Parties (2019).

Principle ENDP4, in our Engineering: generic developed principles provides additional guidance on our expectations for environmental protection functions and measures. Principle ENDP4 states that “Environment protection functions under normal and fault conditions should be identified, and it should be demonstrated that adequate environment protection measures are in place to deliver these functions”. Environmental protection functions are necessary in a facility to avoid or minimise (or both) radiological impacts to people and the environment. Environmental protection measures provide environmental protection functions.

Identifying environmental protection functions (EPFs) and environmental protection measures (EPMs) defines the process for identifying EPFs and for demonstrating how adequate EPMs are in place to carry out those functions (Rolls-Royce SMR Limited, 2023e).

We assessed this submission during Step 2 and provided feedback to Rolls-Royce SMR Limited during technical meetings. We observed that the process for identifying EPFs and EPMs is at the early stages of development. However, it broadly meets our expectations for the current stage and maturity of the Rolls-Royce SMR design. We raised several points of feedback on the submission and Rolls-Royce SMR Limited confirmed that it would consider these in developing its methodology.

We queried when the methodology will be implemented and how it will be used to inform and interact with other areas, such as the examination, inspection, maintenance and testing (EIMT) strategy. Rolls-Royce SMR Limited confirmed that these areas will be progressed in the remainder of Step 2 and into Step 3 of the GDA.

We note that Appendix A of Chapter 11 of the E3S case on management of radioactive wastes (Rolls-Royce SMR Limited, 2024h) presents a list of those SSCs currently identified as being environmentally significant for the radioactive waste management and treatment systems.

The process for identifying EPFs and EPMs broadly meets our expectations for the current stage and maturity of the Rolls-Royce SMR design. We will look at the development of the EPF and EPM methodology (Rolls-Royce SMR Limited, 2023e) and its subsequent implementation and interaction with other areas, such as EIMT, as part of our assessment during Step 3 of GDA.

5.5 Proposed discharges and limits

During Step 2, we carried out a more detailed assessment of the proposed discharges so we can give early assurances that the proposed design can comply with dose limits and constraints.

Our assessment considered how Rolls-Royce SMR Limited identified gaseous and aqueous radioactive waste arising from routine and reasonably foreseeable non-routine activities that can be expected to occur during the lifetime of the reactor.

Our assessment is based on the information requested in Environment Agency: Guidance for Requesting Parties (2019) and made against Environment Agency expectations in our RSR objectives and principles. Our assessment seeks to ensure that:

• all sources of gaseous and liquid radioactive waste have been identified

• all routes for gaseous and liquid aqueous radioactive waste to the environment have been identified

• the monthly and annual discharge estimates are quantified for an appropriate range of radionuclides

• all significant radionuclides relating to gaseous and liquid radioactive waste are identified, quantified and assigned an appropriate proposed discharge limit

• all the assumptions in the submission relating to gaseous and liquid radioactive waste are clearly visible, appropriate and justified

• annual discharge limits proposed by Rolls-Royce SMR Limited should:

  • have a clear method of derivation that can be followed and repeated

  • ensure that acceptable headroom has been given

  • take account of our limit-setting guidance

• the proposed discharges from the Rolls-Royce SMR do not exceed those of comparable stations around the world

We expect Rolls-Royce SMR Limited to provide numerical estimates for the following:

• source term and discharges of gaseous and aqueous radioactive wastes and combustible wastes for disposal by incineration either offsite or on-site if proposed

The estimates provided should allow for the operational fluctuations, trends and events that are expected to occur over the lifetime of the facility, such as start-up, shutdown and maintenance. They should not include increased discharges arising from other events, inconsistent with the use of BAT, such as accidents, inadequate maintenance and inadequate operation.

The estimates are needed to support the assessment of the impact of the discharges and the BAT analysis, and to provide a basis for limit setting. It is UK government policy that discharges and waste arisings from new nuclear power stations should not exceed those of comparable power stations across the world (2009 Radioactive Discharges Strategy).

We expect Rolls-Royce SMR Limited to provide proposed annual limits (on a rolling 12-month basis) for gaseous and aqueous discharges, together with ‘campaign’ limits (for example, to reflect an operating cycle) if it thinks these are appropriate. We expect the proposed limits to be consistent with our guidance in Discharges from nuclear sites: setting limits. The scope of the assessment is of the radioactive discharges from normal operations, including start-up, at power, shutdown, outage. Discharges resulting from any other reasonably foreseeable events expected to occur during the lifetime of the reactors (‘expected events’) are included.

Excluded from the scope of our Step 2 assessment are discharges resulting from decommissioning and from any interim radioactive waste or spent fuel stores. Discharges from commissioning are in GDA scope, but information has yet to be provided and will be followed up in our Step 3 assessment.

5.5.1 Assessment outcomes

Rolls-Royce SMR Limited provided enough information on the expected discharges from an operating Rolls-Royce SMR in Step 2 for a fundamental assessment to be carried out. A summary of relevant information was provided in Chapter 29 of the E3S case (Rolls-Royce SMR Limited, 2024i) and relevant supporting documents.

We raised 5 RQs as part of our assessment:

• RQ-01063 – Key decision dates

• RQ-01064 – Calculation of radioactive discharges

• RQ-01065 – Expected events

• RQ-01066 – Justification of assumptions and headroom factor

• RQ-01246 – A collated summary of discharges

We raised RQ-01063 so we have visibility of ongoing and planned work that could result in changes to the primary source term and derived discharges. The response included both design decision points and developments for supporting analyses. It was clear that important design work will be ongoing until late 2024. It was information about the pace of design developments that informed our decision to focus on methodology, rather than outcomes in Step 2.

We raised RQ-01064 on the calculation of radioactive discharges as we were unable to replicate all steps of the calculations presented. We had also identified some omissions related to abatement in the equations. In its response, Rolls-Royce SMR Limited provided all information necessary to allow us to follow the described calculations. Rolls-Royce SMR Limited also confirmed that the missing factors for abatement were included in the results of the calculations but were omitted from the equations in error. This has been rectified and will be correct in future documentation.

We raised RQ-01065 on expected events following discussions around how the expected events were derived, how they contribute to the discharges, and how the outcomes of this work could influence decision-making around BAT. Recognising that this work was still in progress, we asked for information on:

• the strategy and scope of the work on expected events

• the schedule for this work

• how this work could be incorporated into the discharges and solid waste inventory

• the schedule for the outcomes being incorporated into the E3S case

This work will be reflected in the E3S case revision issued at the end of Step 2 and to be assessed in Step 3.

We raised RQ-01066 on justification of assumptions and headroom factor as the initial factor presented in the E3S case Chapter 29 used a headroom factor of ‘2’ which was taken from a 2005 Environment Agency publication Developing guidance for setting limits on discharges from nuclear sites. That study was carried out to guide the Environment Agency in the production of our Discharges from nuclear sites: setting limits.

The headroom factor of 2 in the developing guidance report was not adopted into the final guidance Discharges from nuclear sites: setting limits. Therefore, the headroom factor was not appropriate to use unless fully justified. Therefore, we asked Rolls-Royce SMR Limited to provide further information on the intended strategy, approach and schedule for deriving a headroom factor to be used in proposing discharge limits.

As the documentation in support of the quantification of discharges developed, in response to our RQs and ongoing design development, Rolls-Royce SMR Limited restructured its documents for this topic. The submission for discharges was changed to 5 Tier 2 submissions supporting a summary in the Tier 1 E3S Chapter 29.

The Tier 2 submissions contain data based on the updated primary coolant source term and design information and were submitted before the updated Chapter 29. Our assessment used the information in the Tier 2 submissions relating to:

• reactor island waste systems (Rolls-Royce SMR Limited, 2023f)

• heating, ventilation and air conditioning (HVAC) and condenser air removal system (CARS) (Rolls-Royce SMR Limited, 2024k)

• expected events (Rolls-Royce SMR Limited, 2024l)

• headroom factors (Rolls-Royce SMR Limited, 2024m) and

• comparison with other Light Water Reactors (Rolls-Royce SMR Limited, 2024n)

As the Rolls-Royce SMR design work continues, there have subsequently been some small changes to the discharge estimates and limits that were submitted in the Tier 2 submissions listed above. This means that the data in the Tier 1 document (Chapter 29) submitted in May 2024 will not be completely consistent with those in the Tier 2 documents that we have used in our assessment. To ensure we are working to the latest data, we submitted RQ-01246 to request a collated summary of the numbers in advance of the submission of Chapter 29 in May 2024. We noted that the data presentation in the RQ response differed slightly from that in the Tier 2 technical note on reactor island waste systems (Rolls-Royce SMR Limited, 2023f). In the RQ response, the data is presented as a single annual discharge estimate, whereas in the Tier 2 documents there is a breakdown between operation and shutdown phases. This is a minor presentational issue.

We have now received and checked issue 3 of Chapter 29 in the E3S case (Rolls-Royce SMR Limited 2024i) and the most recent data is presented.

As a result of our assessment, we can make the following findings for Step 2:

• For the derivation of the primary coolant source term, from which the discharge estimates are derived:

  • the approach used was systematic and logical

  • a wide range of data sources were considered

  • all the radionuclides we would expect to see had been included

• For the methods used to calculate the discharges from the primary coolant source term or primary system source terms:

  • the methods are comprehensive and clearly presented

  • the assumptions are clearly visible and, overall, have been justified as being appropriate

  • data selection is systematic and supported by an appropriate rationale

  • we can sample and replicate the calculations (except for the CARS discharges)

• For expected events:

  • we are aware that work is ongoing to provide the content of its contribution to the discharges from the Rolls-Royce SMR

  • we are content that the contribution will be captured in the discharges as presented as the primary coolant source term is based predominantly on OPEX

• For the derivation of the headroom factors (HF):

  • significant radionuclides have been identified in line with our guidance

  • the method used to derive the HF is clear and appropriate

  • the HF are of a similar order of magnitude to those used in previous GDAs

• For comparison with other PWRs:

  • liquid discharges are predicted to be significantly below those of other PWRs, however there is an important assumption relating to the volume of liquid to be discharged, which still needs to be clearly justified

  • gaseous discharges of some radionuclides are likely to be below those of other PWRs. But for some radionuclides, predicted discharges appear to be significantly higher. This needs to be investigated and will be a focus of our assessment in Step 3

5.5.2 Conclusion

The design of the reactor was still developing during our Step 2 assessment and will continue in Step 3. Therefore, the information on discharge estimates is expected to change.

Our main assessment activity in Step 2 focused on the discharge methodology and calculations, rather than the outcomes.

The methods and calculations of discharges and proposed limits are thorough, systematic and appropriate for GDA, but they need to be further refined as a result of ongoing work. All the main operational phases have been considered, including expected events.

Initial estimates of discharges to the atmosphere from the design would be similar to or could exceed those of comparable PWRs. The proposed limits for discharges to the atmosphere presented in Step 2 are conservative and are based on provisional information. We requested the latest data via RQ-01246 to ensure we were using the correct data, which will be in the Tier 1 document issued in May 2024 (Rolls-Royce SMR Limited, 2024i).

Initial estimates of liquid discharges are lower than other comparable PWRs. Proposed limits for liquid discharges are low and are likely to be appropriate.

5 RQs were raised which were answered. No ROs and no RIs were raised. We did not find anything unacceptable during our fundamental assessment.

5.6 Sampling and monitoring

The information we require within the environment case submission is defined in Environment Agency: Guidance for Requesting Parties (2019).

For sampling arrangements, techniques and systems for measuring and assessing discharges and disposals of radioactive waste, our assessment covers the following:

• in-process monitoring

• monitoring final discharges of gaseous and aqueous wastes

• monitoring disposals of non-aqueous liquid and solid wastes

The RP must also demonstrate that its proposals represent BAT for monitoring and confirm that the sensitivity is sufficient to:

• readily demonstrate compliance with the proposed limits

• meet the levels of detection specified as good practice recommended by the EU in 2004/2/Euratom

The RP must describe the facilities provided for independent periodic sampling (by the regulator) of final discharges of gaseous and aqueous wastes.

Our assessment does not cover an environmental monitoring programme as this is not included within the scope of GDA due to the site-specific nature of such monitoring. The aspects of monitoring that are out of scope of GDA will need to be fully assessed at any future environmental permitting stage.

A summary of relevant information on sampling and monitoring is given in Chapter 28 of the E3S case (Rolls-Royce SMR Limited, 2024o) and relevant supporting documents.

Sufficient information was provided to allow a fundamental assessment to be made.

5.6.1 Assessment of monitoring for normal operation

Rolls-Royce SMR Limited’s stated intent is to ensure that all final discharge points to the environment will be sampled and monitored (demonstrating BAT).

The requirements it has identified for the design give us confidence at this stage that it understands what needs to be put in place in terms of monitoring.

The design of the monitoring arrangements for the Rolls-Royce SMR are still going though optioneering. Therefore, decisions are yet to be made around where integrated monitoring (sensor technology embedded within a system) or sampling for characterisation or analysis will be used. Therefore, our assessment approach has been to determine whether the processes it has for understanding the requirements and evaluating options, are appropriate.

In-process monitoring arrangements: Rolls-Royce SMR Limited’s intention regarding in-process monitoring is what we would expect to see, noting monitoring of main characterisation points upstream of final discharge will take place, and that systems will be designed to demonstrate processes are operating correctly. System design description documents demonstrate a clear process is being followed.

Gaseous discharges monitoring: Rolls-Royce SMR Limited states that it will monitor the final discharge from the main extract stack exhaust system. Generally, the identified requirements and location for final accountancy monitoring are satisfactory, with recognition of the need for isokinetic sampling of particulates and to provide for independent sampling.

Liquid (aqueous) discharge monitoring: The location for sampling and monitoring of final accountancy of liquid discharges has not been decided yet. We have assessed a monitoring philosophy for liquid effluent Rolls-Royce SMR Limited put forward, which does demonstrate an understanding of our requirements. This includes a baseline solution with sampling and monitoring points for accountancy purposes on both internal outfalls and the final outfall. This solution also identifies the requirement for Environment Agency Monitoring Certification Scheme (MCERTS) accredited flow measurement and composite sampling points (Monitoring discharges to water: guidance on selecting a monitoring approach). This would meet our requirements. However, this baseline solution has not been chosen as the final solution but is being used to score other options. It is understandable why Rolls-Royce SMR Limited is exploring different monitoring options for internal outfalls, and we are open to viable options based on justification and evidence supporting them and BAT being demonstrated. An area that will need careful consideration going forward is the outcome of its optioneering for the accountancy of the liquid radioactive effluent treatment system stream as some of the options deviate from OPEX and our normal expectations. Rolls-Royce SMR Limited recognised this and that the options chosen must be BAT.

Non-aqueous liquids: No specific information has been provided on non-aqueous liquids and, therefore, no assessment has been possible in Step 2.

Solid waste: Draft important information on current sampling and monitoring arrangements for the storage system for solid radioactive waste has been provided, but this is not enough to assess at this stage of GDA. More information will be expected for assessment during Step 3.

Other requirements: A demonstration of BAT for monitoring is required, however the design of the sampling and monitoring systems is not mature enough to demonstrate BAT currently, but Rolls-Royce SMR Limited is taking it into account in its optioneering. There is also a requirement to confirm the sensitivity of the monitoring will be sufficient to demonstrate compliance with proposed limits and meet the levels of detection specified in 2004/2/Euratom. It is too early for this to be demonstrated, but Rolls-Royce SMR Limited has stated that sampling and monitoring methods and techniques shall meet the requirements of the detection limit for the radionuclides listed in 2004/2/Euratom.

Facilities for independent monitoring: Rolls-Royce SMR Limited is aware of the requirements for independent sampling and monitoring arrangements for the final discharge point to the natural environment for gaseous and liquid discharges. Plans are not yet developed but are being considered alongside the design of the operator systems.

We raised one RQ – (RQ-01199 – Clarification of discharge sampling and monitoring considerations). No RIs or ROs were raised.

The Rolls-Royce SMR design has continued to develop, and we expect submissions during Step 3 will reflect the latest design stage. There are a number of areas that will need to continue to be addressed during Step 3 of the GDA as the design progresses. These are:

• selection of options for final accountancy monitoring and in-process monitoring

• detailed design information around monitoring and sampling systems, ports, sampling lines, pipework. It is recognised that the choice of actual instrumentation is likely to be deferred to near installation to benefit from developments up to that point

• radionuclides to be monitored and how the appropriate sensitivity will be achieved

• provisions for independent sampling facilities

• access arrangements for calibration and maintenance

• monitoring and sampling of solid radioactive wastes and non-aqueous liquid wastes

We will include these areas in our plans for engagement and assessment during Step 3.

5.6.2 Conclusion

Overall, our conclusion is that the considerations for monitoring are adequate for this stage of GDA and the maturity of the design. RGP, OPEX and guidance and standards have been identified and are being followed. The optioneering that is taking place to determine monitoring arrangements appears to be comprehensive and logical.

Information on the final proposals for monitoring (in-process and final discharge) with BAT assessments will be provided for assessment in Step 3. Once the locations and proposed approaches for monitoring are known, we will then be able to undertake an assessment of the techniques and facilities.

The optioneering to determine monitoring arrangements appears to be comprehensive and logical.

As the design is in the early stage of development, we have accepted Rolls-Royce SMR Limited’s intentions regarding independent sampling and the sensitivity of monitoring, but no information is available yet.

There were no matters from the assessment that were not acceptable. More detailed information for assessment will be provided in Step 3 as the design matures and options are selected.

5.7 Generic site description and radiological impact assessment

During Step 2, we carried out an assessment to identify any fundamental environmental protection shortfalls in the design, including the generic site description (GSD) and the radiological impact assessment.

During Step 2, we carry out a more detailed assessment of:

• GSD to make sure it appropriately reflects the constraints of any known or potential deployment sites

• proposed discharges so we can give early assurances that the proposed design can comply with dose limits and constraints

• radiological impact assessment methodology and assessment outcome

As part of the GDA process, the RP is required to provide a description of the type of sites where the power plant could be built; we call this the ‘generic site’. Rolls-Royce SMR Limited provided details of the generic site for the environment by defining the GSD. The GSD describes the aspects of the generic site that are needed to demonstrate environmental protection.

We carry out more detailed assessments of the GSD to make sure it appropriately reflects the constraints of any known or potential deployment sites. Our assessment of the generic site Rolls-Royce SMR Limited proposed includes determining if the generic site is representative of a site or sites in the UK; if the GSD is valid for the generic site proposed, and if the GSD is clearly described. We also consider if the site concept, parameters and assumptions selected for use in the radiological impact assessment are transparent, justified and consistent with the GSD.

The purpose of examining the generic site aspects in detail at this stage is to ensure that the relevant constraints of potential sites – those sites listed in the National Policy Statement for nuclear power generation (EN-6) are appropriately reflected, and to provide early assurance that dose constraints will be complied with.

Our assessment considered how doses to the public and dose rates to wildlife from the proposed discharges had been calculated. We considered whether Rolls-Royce SMR Limited had made a sufficiently detailed assessment; provided appropriate justification of the models, methods and data used in the assessment, and whether its assessment was consistent with the GSD.

We considered if the discharges assumed in the assessment were consistent with the discharges and limits assessment, and whether appropriate direct radiation data had been included.

We compared the assessed doses with dose limits and dose constraints for members of the public. We also compared the assessed dose rates with criteria for wildlife.

5.7.1 Assessment of generic site description (GSD)

Rolls-Royce SMR Limited provided summary information on the generic site and a definition of the GSD in Chapter 2 of the E3S case (Rolls-Royce SMR Limited, 2024b). The GSD is an input to and definition for the radiological impact assessment. Rolls-Royce SMR Limited summarised the radiological impact assessment in Chapter 30 of the E3S case (Rolls-Royce SMR Limited, 2024p).

Rolls-Royce SMR Limited provided enough information for us to carry out a fundamental assessment of the GSD.

Rolls-Royce SMR Limited stated that the GSD parameters were selected to provide realistic but cautious criteria against which environmental impacts can be assessed and should reflect the categories of site where the Rolls-Royce SMR is likely to be deployed.

Rolls-Royce SMR Limited stated that while the GSD and GSE share the same broad general characteristics, some criteria do differ. These differences are to make sure that the GSD and the generic site envelope (GSE) provide a bounding case for environment and safety assessments respectively. We consider that taking into account the different purpose of the GSD and GSE, the differences between them are acceptable.

Rolls-Royce SMR Limited has defined the generic site as a coastal site located 100 m from the sea. The Rolls-Royce SMR will be cooled using mechanical draught cooling towers, with the cooling water demand being met by abstracted seawater. The generic site:

• is assumed to lie on a flat plain with no large buildings in the immediate vicinity other than those which are part of the Rolls-Royce SMR nuclear power plant

• is not assumed to encompass or lie adjacent to any protected wildlife or habitat site

• is not located on an aquifer

• has no standing water

• has no water bodies or watercourses crossing the site

• has no ground or groundwater contamination present on the site

• is in a rural setting dominated by agricultural land use and fishing activity in the local seas

In line with the assumptions above, Rolls-Royce SMR Limited has defined the following parameter values for use in its radiological impact assessment:

• meteorological conditions associated with 70% Pasquill stability category D. These conditions are typical of much of the UK coastline

• a surface roughness (an air dispersion modelling parameter) of 0.3 m. This is a generic value typical of agricultural areas

• the volumetric exchange rate (a marine dispersion modelling parameter) is assumed to be 3.2 x 10⁹ m³/y. This value represents relatively low levels of dispersion and dilution in comparison to other nuclear sites around the UK, which will tend to lead to a cautious radiological impact assessment.

We note that some of the main generic site concepts and assumptions were not clearly presented. Therefore, the justification and implications of model selection and use appear incomplete. Further development and clearer presentation should be considered during the early stages of Step 3.

We noted that the GSD does not explicitly consider the effects of climate change on the characteristics of the generic site, however Rolls-Royce SMR Limited has noted the potential impacts of climate change on relevant parameters defined for the radiological impact assessment. There is potential for climate change to impact the behaviour of radionuclides in the environment, human habits such as food production, consumption and occupancy, and the distribution of wildlife. Rolls-Royce SMR Limited has stated that the impact of climate change on these parameters will be considered during the sensitivity analysis as part of the detailed radiological impact assessment. We will assess this during Step 3.

The level of design maturity of the Rolls-Royce SMR design in Step 2 did not have a direct effect on the GSD.

5.7.2 Assessment of radiological impact assessment

During Step 2, we carry out more detailed assessments of the radiological impact to make sure it appropriately reflects the constraints of any known potential deployment sites.

The purpose of examining the radiological impact assessment in detail at this stage is to ensure that the relevant constraints of potential sites – those sites listed in the

National Policy Statement for nuclear power generation (EN-6)

are appropriately reflected, and to provide early assurance that dose constraints will be complied with.

Our GDA guidance for RPs requires a radiological impact assessment to be provided that includes:

• annual doses from gaseous and liquid radioactive discharges and direct radiation (separately and in total)

• potential short-term doses based on the maximum anticipated short-term discharges from the facility in normal operation

• collective dose to the UK, European and world populations

• dose rate to wildlife

Rolls-Royce SMR Limited provided information on the GSD in Chapter 2 of the E3S case (Rolls-Royce SMR Limited, 2024b) and it summarised the radiological impact assessment in Chapter 30 of the E3S case (Rolls-Royce SMR Limited, 2024p).

Rolls-Royce SMR Limited provided enough information for us to carry out a fundamental assessment of the radiological impact assessment.

Rolls-Royce SMR Limited provided proposed discharge limits based on a preliminary source term at the beginning of Step 2. These were used in its assessment of radiological impact. The discharge limits were updated with more realistic predictions of aqueous and gaseous discharges at the end of Step 2 and used to update its radiological impact assessment. Use of the revised limits will be considered in our assessment in Step 3. The proposed discharge limits were changed during Step 2 as more information became available and conservative elements were removed from its calculations. These were, in part, affected by the level of design maturity of the reactor.

Rolls-Royce SMR Limited stated that the bulk of gaseous discharges will be made to the atmosphere via a single stack. It has indicated that other discharge routes are likely to be identified in Step 3.

Other possible discharge routes were not considered in the radiological impact assessment Rolls-Royce SMR Limited made in Step 2. We will expect it to assess the impacts from all identified discharge points during Step 3.

Rolls-Royce SMR Limited stated that aqueous discharges will be made directly to the sea and there is no proposed on-site incineration.

Four RQs were raised:

• RQ-01036 – Radiological impact assessment – continuous releases

• RQ-01037 – Radiological impact assessment – short-term releases

• RQ-01038 – Radiological impact assessment – wildlife

• RQ-01039 – Radiological impact assessment – general queries

The responses to the RQs were satisfactory.

No ROs or RIs were raised for these assessment topics.

5.7.3. Results of the radiological impact assessment

During Step 2, Rolls-Royce SMR Limited carried out a radiological impact assessment to determine the annual doses to people from continuous gaseous and liquid radioactive discharges and direct radiation (separately and in total). Dose rates to wildlife were also assessed. Collective doses and doses from short duration releases were not assessed during Step 2.

Rolls-Royce SMR Limited carried out an initial radiological impact assessment using the Environment Agency’s initial radiological assessment tool (IRAT). The discharges used in the assessment were the preliminary proposed limits for discharges for one Rolls-Royce SMR unit during normal operations.

Rolls-Royce SMR Limited used the in-built parameters of the initial radiological assessment methodology, which are broadly reflective of the generic site characteristics.

For atmospheric discharges, these include food production and human habitation nearby, habitats and the most sensitive species, food consumption rates and other human habits data.

Doses to people are the amount of energy absorbed by a material from ionising radiation passing through it. The most common unit of radiation dose to people is called ‘effective dose’, measured in units called sieverts (Sv). Effective dose takes account of the different sensitivities of organs in the body and the effects of different types of radiation.

A sievert (Sv) is a large dose of radiation and, in most cases, radiation dose will be given in microsieverts (µSv, one millionth of a sievert) or millisieverts (mSv, one thousandth of a sievert). (Basic concepts of radiation). The assessment outcome was annual radiation dose in microsieverts per year (µSv/y).

Using the preliminary discharge source term, the outcomes of the Stage 2 initial assessment carried out by Rolls-Royce SMR Limited were as follows:

• 7 µSv/y to the local resident from discharges to air

• 0.25 µSv/y to a member of a fishing family from discharges to sea

The dose rates to wildlife are absorbed dose rate in units of micro-gray per hour (µGy/h):

• 0.022 µGy/h to terrestrial wildlife from discharges to air

• 0.0024 µGy/h to marine wildlife from discharges to sea

Rolls-Royce SMR Limited has cautiously assumed a direct dose rate of 5 µSv/y from the Rolls-Royce SMR based on estimates from previous GDAs.

As a cautious estimate, the doses from the different exposure pathways considered in the initial assessment can be summed.

• The total dose to members of the public, assessed by summing the dose from discharges to air, discharges to sea and direct radiation, is 12.25 µSv/y.

• The total dose rate to wildlife, assessed by summing the dose rate to terrestrial wildlife from discharges to air and the dose rate to marine wildlife from discharges to sea, is 0.024 µGy/h.

The initial radiological impact assessment resulted in doses to people and dose rates to wildlife that were all below the relevant dose limit, the source constraint and the site dose constraint, and the current criteria for wildlife.

The relevant dose limit is:

• 1,000 µSv/y effective dose for members of the public (from all sources of radiation excluding nuclear accidents or radiological emergencies, natural background radiation and medical irradiation)

The relevant dose constraints are:

• 300 µSv/y for proposed discharges and direct radiation from any new source

• 500 µSv/y for discharges from any single site

For wildlife, we use an action level of 40 µGy/h, below which we consider there will be no significant adverse effects on wildlife. Because wildlife may be affected by discharges from more than one site, we also use a screening level of 10 µGy/h when considering the impact from a single source.

We verified the outcomes of the initial assessment carried out by Rolls-Royce SMR Limited by performing our own initial radiological impact assessment. We used the same preliminary discharge source term Rolls-Royce SMR Limited provided and the same assumptions for the generic site. We considered the parameters to be appropriate for verification. Our assessment resulted in the same dose outcomes to people and wildlife as presented by Rolls-Royce SMR Limited.

During Step 3, we will continue to review the assumptions made for the GSD and the radiological impact assessment, to ensure they remain appropriate for the design and defined generic site.

During Step 3, we expect a more detailed assessment of direct dose which uses a refined source term and considers all sources of direct radiation from the Rolls-Royce SMR.

During Step 3, Rolls-Royce SMR Limited plans to make a more detailed assessment of doses from continuous discharges and from enhanced short duration releases to atmosphere.

5.7.4 Conclusion – generic site description

We have concluded that:

• the GSD is broadly consistent with the characteristics of existing nuclear sites in the UK

• the parameters provided that define the generic site are enough to carry out an initial radiological impact assessment

• the parameters provided that define the generic site are consistent with the parameters defined in the detailed radiological impact assessment methodology

• Rolls-Royce SMR Limited provided justification of the parameters used in the GSD in supporting documents. We expect the justification of the site parameters to be further developed and clearly presented in Step 3

We note that the generic site is not assumed to encompass or lie adjacent to any designated site. This is not consistent with some existing nuclear power stations in the UK. However, the radiological impact assessment presented does make an assessment of impact on wildlife species near the site. This assessment is, therefore, likely to capture any potential impacts on protected sites. We expect a detailed assessment of the impact on protected sites and species to be undertaken at the site-specific permitting stage when details of the surrounding area are known.

The level of design maturity of the reactor did not directly affect the generic site presented.

During Step 2, we did not raise any RQs, ROs or RIs specifically on the generic site. However, RQs raised on the radiological impact assessment are relevant.

We did not find anything that was unacceptable during our fundamental assessment.

During Step 3, we will continue our assessment to ensure that the parameters used to define the generic site are valid and consistent with sites in the UK and with the parameters used in the radiological impact assessment.

5.7.5 Conclusion – radiological impact assessment

Rolls-Royce SMR Limited provided enough information for us to carry out a fundamental assessment. The level of design maturity of the reactor affected the estimated discharges and proposed limits which the dose assessment uses. The estimated discharges were subject to changes during Step 2.

Rolls-Royce SMR Limited provided a description of the generic site, an initial radiological impact assessment and a methodology for how a detailed radiological impact assessment will be carried out at the proposed discharge limits. The generic site is a coastal site.

The methodology proposed for radiological impact assessment is in line with relevant guidance and adequate justification of the models, methods and data was presented.

The parameters used in the detailed radiological impact assessment methodology are consistent with the GSD provided.

Our assessment of the radiological impact assessment of the Rolls-Royce SMR during normal operations found that the radiological impact is likely to be acceptable, however further detailed assessment is needed during Step 3.

For the estimated discharges, the assessed doses are well below the annual dose constraints and dose limits and the action level for wildlife. These low doses and dose rates present a very low radiological impact to people and the environment.

4 RQs were raised for the radiological impact assessment aspects. No ROs or RIs were raised.

There were no matters arising that were not acceptable.

5.8 Solid radioactive waste, spent fuel and disposability

During Step 2, our assessment covered spent fuel and waste management, including waste generation, pre-treatment, treatment, conditioning, storage and disposal. Solid radioactive wastes produced by the Rolls-Royce SMR include higher activity wastes (HAW) and lower activity wastes (LAW), which is made up of low-level waste (LLW) and very low-level waste (VLLW).

Step 2 of GDA is fundamental assessment to identify any fundamental environmental protection shortfalls in the design and to identify if any matters are unacceptable.

We worked closely with the BAT assessment and ONR’s NLR assessment.

During Step 2, we engaged with Nuclear Waste Services (NWS) and Rolls-Royce SMR Limited to obtain a provisional view as to whether the solid wastes and spent fuel produced by the Rolls-Royce SMR design can be disposed of. NWS are specialists in the treatment and disposal of nuclear waste in the UK and are part of the Nuclear Decommissioning Authority (NDA) group.

Our approach to fundamental assessment included the following:

Reviewing relevant information submitted by Rolls-Royce SMR Limited, covering the Integrated Waste Strategy, RWMA and supporting documentation on solid and non-aqueous radioactive wastes, the management of spent fuel, decommissioning strategy and the decommissioning and waste management plan, solid waste processing and storage systems, the disposability case and the NWS expert view on the potential disposability of the wastes arising from the operational and decommissioning phases of the Rolls-Royce SMR lifecycle. Rolls-Royce SMR Limited provided enough information for us to carry out a fundamental assessment of solid waste, spent fuel and disposability.

Summaries of relevant information are presented in several chapters in the E3S case, Chapter 9A on auxiliary systems including spent fuel arrangements (Rolls-Royce SMR Limited, 2024q); Chapter 11 on management of radioactive wastes (Rolls-Royce SMR Limited, 2024h); Chapter 21 on decommissioning and end of life aspects (Rolls-Royce SMR Limited, 2024r) and Chapter 27 on Best Available Techniques (BAT) (Rolls-Royce SMR Limited, 2024g). Additional relevant information was provided in several supporting documents.

• We held a series of technical meetings with Rolls-Royce SMR Limited to discuss and engage and to gain a better understanding of these documents and to provide early feedback.

• A high-level assessment of Rolls-Royce SMR Limited’s approach, focusing on the claims and arguments it put forward regarding the minimisation and management of waste and spent fuel. We considered whether Rolls-Royce SMR Limited had taken account of all the steps of waste management, including waste generation, the waste hierarchy; pre-treatment and segregation; waste treatment, including volume reduction, radionuclide removal or composition; storage, treatment and disposal.

We assessed whether Rolls-Royce SMR Limited had identified reasonable treatment and packaging options for spent fuel and waste to minimise waste arisings and provided credible options for treatment, packaging and storage.

We assessed whether Rolls-Royce SMR Limited had considered adequately how it would manage failed spent fuel, the use of dual-purpose flasks for storage and transport, and whether the significant radionuclides had been identified.

We also considered:

• raising RQs to clarify our understanding of the information presented to us

• identifying the areas we will be focusing on in our Step 3 assessment

During Step 2, we raised 14 RQs:

• RQ-01033 – Generation of orphan wastes and problematic wastes

• RQ-01055 – Design for decommissioning

• RQ-01056 – Solid waste optioneering and container selection

• RQ-01073 – Generation and management of sludges

• RQ-01074 – Spent fuel arisings

• RQ-01089 – Reverse osmosis membranes

• RQ-01216 – The use of source terms to derive the solid waste inventory

• RQ-10217 – Neutron leakage and activation of materials

• RQ-01218 – Hazardous substances and non-hazardous pollutants

• RQ-01219 – Operational lifetime of the KNF20 evaporator

• RQ-01220 – Ion exchange materials

• RQ-01225 – Glycol and boronated fluid

• RQ-01226 – Component decontamination system

• RQ-01242 – Solid waste inventory

No ROs or RIs were raised.

5.8.1 Lower activity wastes (LAW)

The wastes that will be LAW at the point of arising and disposal from the Rolls-Royce SMR will include contaminated maintenance wastes, air filters, pond skimmers and contaminated oil and solvents. Some of the waste streams may include a mixture of intermediate-level waste (ILW) and LLW. Examples of these are dry active wastes, back filter cartridges and reverse osmosis membranes. The LLW fraction of these waste streams will be managed via the LAW waste route. Rolls-Royce SMR Limited plans to ensure that NWS’s waste services contract can be used for its LAW.

Rolls-Royce SMR Limited has highlighted where a future operator may deploy decay storage to change the categorisation of the wastes from ILW to LLW (Ref: Rolls-Royce SMR Limited, 2023g). These wastes will subsequently be managed via the LAW route. They will typically be concentrates arising from the evaporator, sludges and ion exchange resins. In addition to decay storing several of the waste streams, Rolls-Royce SMR Limited has highlighted the potential for some ILW wastes to be decontaminated to LLW and then subsequently managed through the LLW route (Ref: Rolls-Royce SMR Limited, 2023h).

Our Radioactive substances management: generic developed principles principle RSMDP8, ‘Segregation of wastes’ and principle RSMDP9 ‘Characterisation’ highlight our expectations for segregation and characterisation of solid wastes. Rolls-Royce SMR Limited will need to demonstrate to us that it is starting to address these principles as part of GDA. Characterisation and segregation of wastes are crucial components for meeting the waste management hierarchy, applying BAT and ensuring that the disposal routes chosen will be optimal.

For our Step 2 assessment, Rolls-Royce SMR Limited has supplied some information on its proposals for sampling, characterisation and monitoring of LAW arising from the Rolls-Royce SMR, but we expect this to be developed further in Step 3 to address any gaps.

Rolls-Royce SMR Limited has provided enough information for our Step 2 assessment about how it will segregate a number of wastes streams, for example, the dry active wastes and ion exchange resins. However, we note that it will develop this area further as part of Step 3.

For the conditioning, packaging and disposal of LAW, Rolls-Royce SMR Limited is planning to use NWS’s waste services contract. This contract offers a range of services for the management of LAW, in particular the conditioning, treatment, packaging and disposal.

We expect Rolls-Royce SMR Limited to demonstrate that the options chosen for the conditioning, packaging and disposal of LAW will be BAT. Rolls-Royce SMR Limited has submitted a waste enquiry to NWS seeking advice on the options and a response from NWS is awaited. For wastes arising from the Rolls-Royce SMR that are similar to those assessed in previous GDAs, we have confidence that these are likely to be disposable.

For sludges and concentrates, the Rolls-Royce SMR Limited has identified encapsulation as its lead option for the treatment of these waste streams. We will seek evidence that NWS has been engaged about potentially using incineration to treat these wastes. For the Rolls-Royce SMR, the coolant chemistry uses potassium hydroxide (KOH) for pH control, therefore, the amount of particulates within these wastes could be lower and incineration more favourable. This could allow incineration to be used to treat these waste streams. We will be seeking further information, during Step 3, from Rolls-Royce SMR Limited to justify its selection of encapsulation as its lead option for the treatment of these waste streams.

Rolls-Royce SMR Limited has not fully defined its approach to managing the resins arising from the steam generator blowdown (LCQ) system. These resins have the potential to be LAW. This will be assessed in Step 3.

We also asked if any waste arising from the Rolls-Royce SMR would be problematic or orphan waste. Rolls-Royce SMR Limited noted that such wastes may not have been identified yet, however the strategies in place should ensure that no orphan wastes will be produced, and that all wastes will be disposable. We will continue during Step 3 to ensure that this is the case.

5.8.2 Higher activity wastes (HAW)

The wastes that will be HAW include non-fuel core components (NFCCs) such as thimble plug assemblies, rod cluster control assemblies (RCCAs), control rods, in core monitoring assemblies, reactor pressure vessel surveillance capsules, neutron sources, core outlet thermocouple instrument lances and the control rod housing columns (Ref: Rolls-Royce SMR Limited, 2023i).

HAW also includes wet solid wastes, including ion exchange resins, suspended filter solids, concentrates and sludges and dry solid wastes, removable cartridge filters and reverse osmosis membranes (Ref: Rolls-Royce SMR Limited, 2023i). Some of these wet and dry solid wastes may be boundary wastes at the point of generation. Rolls-Royce SMR Limited proposes to decay these wastes to LAW and subsequently manage them through the LAW route. Rolls-Royce SMR Limited has not yet demonstrated to us that these wastes can be decay stored, and we will require more information during Step 3.

Our Radioactive substances management: generic developed principles include RSMDP8, ‘Segregation of wastes’ and RSMDP9 ‘Characterisation’ which highlight our expectations for the segregation and characterisation of solid wastes. Rolls-Royce SMR Limited needs to demonstrate that it has started to address these principles. Characterisation and segregation of wastes are crucial components for meeting the waste management hierarchy, applying BAT, and in ensuring that the disposal route chosen is optimal. Rolls-Royce SMR Limited has provided enough information at this stage of our assessment to start to address these principles, but we will continue to assess this area during Step 3 to ensure that any gaps are addressed.

As part of GDA process, an RP needs to demonstrate that it has assessed a wide range of options for conditioning its HAW and provide evidence to support why it sees the chosen option as BAT. Rolls-Royce SMR Limited, within its optioneering document, has focused primarily on the options that have been used previously within the UK to treat similar wastes and were acceptable to NWS (Ref: Rolls-Royce SMR Limited, 2022).

For the conditioning and treatment of the wet ion exchange materials, Rolls-Royce SMR Limited has assessed 3 approaches: dewatering and drying; grout encapsulation and polymer encapsulation. Rolls-Royce SMR Limited has identified grout encapsulation as its lead option at this stage of our assessment, however we have yet to assess the evidence to support this decision, and we will undertake this during Step 3.

For back washable filter solids, Rolls-Royce SMR Limited has assessed a range of technologies to reduce the volume of liquid associated with this waste stream. These options were settling and decanting the liquor; evaporation of the liquor; vacuum drying and integral drying with concrete encapsulation. Rolls-Royce SMR Limited identified the lead option as settling and decanting the liquor which we see as reasonable. After settling and decanting the liquor, the wastes will still need to be converted into a disposable product. Therefore, Rolls-Royce SMR Limited assessed the potential use of 2 technologies to achieve this; these being grout encapsulation and in-situ drying. Rolls-Royce SMR Limited identified the lead option as grout encapsulation, which, at this stage in our assessment, appears reasonable. However, we will assess the evidence to support this decision as part of our Step 3 assessment. The disposal advice from NWS in Step 3 will need to be considered to ensure that there are no disposal issues.

Rolls-Royce SMR Limited has not assessed any options for the treatment of ILW reverse osmosis concentrates and sludges. It notes that the option chosen for conditioning stage of the back washable filter solids is likely to apply for the treatment of the sludges. We will continue to assess this area and seek further advice on the options chosen as part of our Step 3 assessment.

Rolls-Royce SMR Limited has begun an assessment of the options for importing, storage and exporting of the NFCCs, but has not yet identified a lead option. We will continue to engage with Rolls-Royce SMR Limited during Step 3.

A portion of the dry active wastes that are ILW at the time of arising, if acceptable to the waste acceptance criteria (WAC), will be decontaminated to LLW or decay stored. The remainder of this waste type will either be decay stored if possible or stored and conditioned along with the decommissioning ILW dry active wastes in the future. Rolls-Royce SMR Limited has yet to develop fully its approach for dealing with this waste stream.

For the decommissioning wastes, Rolls-Royce SMR Limited has not provided any optioneering evidence to support its selection for the conditioning and packaging of the wastes. It is expected to indicate how it will ensure that the conditioning and packaging of the decommissioning wastes is BAT, and that the disposal volume has been minimised.

Rolls-Royce SMR Limited is at the very early stages of developing its decommissioning wastes inventory and lifecycle management approaches, and this will be developed further during Step 3, but mainly during the 60-year operational lifetime of the plant, as more information becomes available.

Rolls-Royce SMR Limited will need to ensure that it has provided the relevant information to NWS to assess the options Rolls-Royce SMR Limited has put forward for conditioning and packaging of the decommissioning wastes.

During any interim storage periods, we expect the ILW packages to be stored under conditions that will ensure that they will remain disposable, and that BAT is being applied. Rolls-Royce SMR Limited has yet to provide us with a full inventory of the waste packages that will be stored within the ILW store.

Our Radioactive substances management: generic developed principles environmental principle RSMDP15 is for ‘Requirements and conditions for disposal of wastes’. We will expect Rolls-Royce SMR Limited to demonstrate that it is addressing this principle during Step 3.

The current assumption and scope of GDA assumes that all HAW will be disposed of at a GDF. Our requirements in Environment Agency: Guidance for Requesting Parties (2019) is for Rolls-Royce SMR Limited to obtain a view from NWS on the disposability of HAW.

The overall objective of the disposability assessment process is to provide confidence that the conditioning and packaging of the HAW will meet the NWS generic disposal system safety case. Rolls-Royce SMR Limited has sought advice from NWS on the HAW waste streams.

During Step 2, NWS provided an expert advice report to Rolls-Royce SMR Limited. The report highlighted some gaps within Rolls-Royce SMR Limited’s disposability case, some uncertainties, and 4 risks which are in the medium or low category, and one that is strategic. NWS has highlighted 5 uncertainties, which are areas where further information will be required from Rolls-Royce SMR Limited to confirm parameters to allow the disposability assessment during Step 3.

5.8.3 Spent fuel

Spent fuel management will include an initial period of underwater (wet) storage, followed by a longer period of dry storage, and then packaging for disposal to a GDF. The management of damaged fuel will be carried out in accordance with the Damaged Fuel Strategy (Ref: Rolls-Royce SMR Limited, 2023j) and will reflect the severity of the damaged sustained.

Rolls-Royce SMR Limited has assessed a range of options for the size of the spent fuel pool (Ref: Rolls-Royce SMR Limited, 2023k). The pool design option selected provides space for 10 years of fuel cooling in the pool, dry storage of damaged fuel, and high activity and fissile items and low activity/non-fissile items.

Undamaged fuel and damaged fuel will leave the spent fuel pool by the same export route and go for on-site dry storage.

As various design uncertainties remain and further work is planned by Rolls-Royce SMR Limited, it is too soon to conclude whether the plans and arrangements for wet storage of spent fuel are optimised and represent BAT.

Our Radioactive substances management: generic developed principles environmental principle RSMDP11 (Ref needed), ‘Storage in a passively safe state’ where there are worthwhile environmental, or safety benefits highlights our expectations for the storage of spent fuel waste. When making decisions on the optimisation of the Rolls-Royce SMR (taking account of the environmental impacts), Rolls-Royce SMR Limited should ensure that the full waste management lifecycle, including facilities and activities inside and outside of the reactor island, is addressed, and interdependencies between all steps in the generation and management of radioactive waste and spent fuel are considered.

Rolls-Royce SMR Limited indicated that the storage lifetime would be 120 to 125 years, based on between 50 and 55 years of plant operation, plus a 70-year fuel storage period following the end of generation (Ref: Rolls-Royce SMR Limited, 2023l) pending the availability of a GDF (Ref: Rolls-Royce SMR Limited, 2023g).

The level of spent fuel dry storage system design maturity means that the requirements for the spent fuel dry storage system have yet to be fully defined (Ref: Rolls-Royce SMR Limited, 2023m). Four options for the long-term storage of spent fuel have been assessed. Based on this, Rolls-Royce SMR Limited selected dry concrete cask storage. However, the type of dry storage cask to be used has not yet been identified.

NWS has provided advice on the potential disposability of the spent fuel from the Rolls-Royce SMR. NWS noted that the Rolls-Royce SMR is based around well-established PWR technology for which there is extensive operational experience and with which NWS is already familiar. This gives confidence that a disposability case could be made. We agree with this point.

NWS noted that the smaller size of the Rolls-Royce SMR fuel means that more spent fuel could be generated per unit of electricity output, potentially leading to more disposal containers. This highlights the need for more detailed assessment of spent fuel arisings at GDA Step 3.

NWS notes that the current planning assumption for the GDF is that there will not be any facilities available for waste packaging at the GDF. NWS suggests that Rolls-Royce SMR Limited would need to put plans in place for packaging of spent fuel into a final disposal container at the site where the spent fuel arises. Rolls-Royce SMR Limited will need to provide greater design certainty on the disposal package for spent fuel and on the plans for packaging of spent fuel in its information for Step 3 of the GDA process.

The Rolls-Royce SMR is at a relatively early stage in design maturity and, therefore, the arguments and examples of evidence provided so far are not comprehensive and need further work. More evidence will also be required to fully demonstrate BAT.

We will continue to assess the disposability of spent fuel and the plans for packaging and disposal of spent fuel as part of our Step 3 assessment.

5.8.4. Decommissioning

Rolls-Royce SMR Limited has started to identify the decommissioning waste streams that will arise from the Rolls-Royce SMR design, and the volumes, activities and constituents of the inventory. We reviewed the BAT claims and arguments for the minimisation of decommissioning solid radioactive wastes. We are content, at this stage in our assessment, that the claims and arguments seem reasonable. During Step 3, we will assess the evidence to support these claims and arguments.

Rolls-Royce SMR Limited provided an inventory and indicated volumes of HAW arising from decommissioning of the Rolls-Royce SMR. At this stage, these appear reasonable. However, we note there are gaps, and these will need to be addressed during Step 3.

Rolls-Royce SMR Limited has highlighted the potential for some decommissioning wastes streams to be segregated, so that the disposal routes will be optimised. A BAT/ALARP argument will need to be made before decommissioning starts. Rolls-Royce SMR Limited will provide further information on the potential for segregation of decommissioning wastes in Step 3 at a high level.

We raised an RQ (RQ-01055) to seek further information from Rolls-Royce SMR Limited about when the information on the design for decommissioning will be available. During Step 2 Rolls-Royce SMR Limited provided a limited amount of information on how the design has taken account of decommissioning. Rolls-Royce SMR Limited need to demonstrate that the design of the Rolls-Royce SMR has taken account of decommissioning and that the decommissioning wastes have been minimised or prevented. This is an important area that we will be focusing on in Step 3.

5.8.5 Conclusion

During Step 2, Rolls-Royce SMR Limited has made progress deriving a LAW waste inventory and identifying potential conditioning and treatment routes for these. However, we note that there are still a number of gaps that will need to be addressed going forward and, in some cases, Rolls-Royce SMR Limited will have to demonstrate to us that the options chosen will be BAT.

We will continue to assess this area as part of our Step 3 assessment. We will review the advice that Rolls-Royce SMR Limited receives from NWS, to ensure that the options chosen are acceptable and that no problematic wastes will arise.

Rolls-Royce SMR Limited has made progress in identifying the inventory of solid/non-aqueous waste and spent fuel that will arise from the Rolls-Royce SMR during the operational and decommissioning phases. Rolls-Royce SMR Limited has also started to provide information on the nature and quantities of these wastes.

There are a number of areas that will need to be addressed going forward in Step 3, in particular with regards to non-fuel core components (NFCCs) and decommissioning wastes.

Rolls-Royce SMR Limited has identified a series of claims and arguments relating to BAT and the minimisation of solid and non-aqueous wastes. The claims and arguments appear reasonable at this stage in our assessment. Most of the evidence to support these claims and arguments will be provided during Step 3. We examined Rolls-Royce SMR Limited’s proposals to manage LAW, HAW and spent fuel across the lifecycle (pre-disposal) covering characterisation, segregation, conditioning, packaging and storage. The information Rolls-Royce SMR Limited provided appears reasonable for this stage in our assessment, however we note that some areas are in the early stages of development and, therefore, further work will be required during Step 3. We will be raising a number of queries during Step 3 on the options chosen for the conditioning, packaging and storage of the wastes and spent fuel and the claims made that these represent BAT.

Rolls-Royce SMR Limited should continue to develop its approaches to the pre-disposal management of solid/non-aqueous wastes, including conditioning, packaging and storage of the HAW.

Spent fuel management will include an initial period of underwater (wet) storage, followed by a longer period of dry storage, and then packaging for disposal to a GDF. An environmental assessment for spent fuel pool was not available for review during Step 2; this is identified as future work for Step 3.

During Step 3, Rolls-Royce SMR Limited will need to address the nature and quantities of wastes and spent fuel in the inventory, including for the NFCCs and decommissioning wastes. Source terms for the wastes and spent fuel will need to be developed for Step 3 as these will be crucial inputs for the disposability case.

During Step 2, Rolls-Royce SMR Limited gave some consideration to decommissioning. However, more information will be needed in Step 3 and Rolls-Royce SMR Limited will need to demonstrate that the design of the Rolls-Royce SMR has taken account of decommissioning, and that the expected decommissioning wastes have been minimised or prevented.

Rolls-Royce SMR Limited has sought early advice from NWS, via an expert view on the potential for the HAW arisings from the Rolls-Royce SMR to be disposed of to a GDF. NWS provided a view to Rolls-Royce SMR Limited on the disposability of wastes and spent fuel that could arise from the operation and decommissioning of the proposed Rolls-Royce SMR.

NWS shared its view with us to support and inform the GDA process and our assessment. NWS noted that, in general terms, the wastes and spent fuel from the Rolls-Royce SMR are not significantly different to wastes that they are familiar with assessing, giving confidence that a disposability case could be made.

NWS has highlighted some risks and uncertainties, which will need to be addressed during Step 3 and managed going forward.

Rolls-Royce SMR Limited has also submitted relevant information to NWS for the treatment and disposal options for LAW, arising from the Rolls-Royce SMR.

At the time of our assessment, we had not received the NWS assessment report. Since then, NWS has provided its assessment report, and we will consider it in our Step 3 assessment.

At the time of our assessment, Rolls-Royce SMR Limited had not identified any hazardous material and non-hazardous pollutants associated with the waste streams. It has now made an initial assessment and we will consider this in Step 3.

We were able to complete a fundamental assessment and did not find anything that was unacceptable.

The level of design maturity of the reactor and the evolving nature of the design limited the content of some submissions and our assessment, notably around the management of spent fuel. During Step 3, we will consider spent fuel in more detail, including optimisation and minimisation.

5.9 Other environmental regulations

The RP is required to provide information explaining how it will meet other relevant environmental regulations. The other environmental regulations assessment considers the following conventional (non-radioactive) topics:

• water use and abstraction

• discharges to surface water

• discharges to groundwater

• operations of installations (combustion plants)

• Control of Major Accident Hazard Regulations (COMAH)

• fluorinated greenhouse gases (F-gases) and ozone-depleting substances (ODS)

Our assessment of water use and abstraction considered whether Rolls-Royce SMR Limited had demonstrated its requirements for water use; identified the sources of water to be used; determined whether any licences or permits might be required for water abstraction; demonstrated that the choice of cooling options proposed for the generic site is appropriate; and had identified any issues connected with water use.

Our assessment of discharges to surface water sought to determine if there were indicators that an environmental permit could not be granted at the site. It also considered whether Rolls-Royce SMR Limited has identified the different effluent streams produced, the non-radioactive contaminants present, and how each effluent stream produced is treated and disposed of.

Our assessment of discharges to groundwater considered whether Rolls-Royce SMR Limited has identified any planned discharges to groundwater, and whether there are appropriate measures in the design to prevent any accidental discharges to groundwater.

Our assessment of the operation of installations (combustion plant and incinerators) sought to determine that Rolls-Royce SMR Limited had made an impact assessment of combustion plants and incinerators using the H1 risk assessment tool. H1 was developed to allow screening assessment of emissions from sites permitted under the Environmental Permitting Regulations in England and Wales. Rolls-Royce SMR Limited assessed whether an environmental permit will be required for any of combustion processes; (incineration of hazardous wastes; or under the medium or large combustion plant directive) or the greenhouse gas emissions trading scheme.

Our assessment of the applicability of COMAH Regulations to the Rolls-Royce SMR design was intended to establish whether it would be a COMAH establishment and, if so, whether measures to prevent a Major Accident to The Environment (MATTE) were included.

Our assessment of F-gases and ODS in the Rolls-Royce SMR design was to identify if the use of any ODS was proposed; to identify any systems containing F-gases and to calculate the global warming potential (GWP) values and the arrangements for preventing and minimising leaks.

5.9.1 Outcomes of our assessment

Rolls-Royce SMR Limited provided enough information for us to carry out a fundamental assessment of 4 of 6 of the other environmental regulations topics, summarised in Chapter 31 (Rolls-Royce SMR Limited, 2024c) and several supporting documents.

During our assessment in Step 2, we did not identify any fundamental environmental protection shortfalls that would mean that the design could not be operated in line with environmental regulations, policies and guidance for England and Wales. In our assessment in Step 3 when further information is available, we will be able to make a detailed assessment and make further comparisons to existing nuclear power plants.

Rolls-Royce SMR Limited stated that the design maturity of the systems that will be used to minimise the conventional environmental impact is currently lower than other systems. No information was received in Step 2 regarding the likely chemical inventory, COMAH or F-gases and ODS as the design of these areas was not developed enough. Rolls-Royce SMR Limited has provided overviews of the other relevant systems, but not all details, such as the composition and concentration of some of the potential effluent contaminants have been defined.

Based on the information received in Step 2, the foreseeable impact to the environment from conventional (non-radioactive) activities at a Rolls-Royce SMR Limited designed SMR will be broadly similar to existing nuclear power plants, albeit at a much smaller scale.

For water use and abstraction, the largest abstraction requirement will be for the main cooling system. The current baseline design for the main cooling water system assumes a single reactor at a coastal site using seawater abstraction for indirect cooling via cooling towers. Rolls-Royce SMR Limited has stated that this baseline option may not necessarily be the chosen option. Depending on the location of future sites and operator requirements, a once-through direct cooling system similar to that used at Hinkley Point C may be adopted. A fish return system has been included in the design and a number of fish deterrent schemes have been considered, but these will be site-specific and are dependent on the marine species present in the surrounding environment.

The sources of discharges to surface waters have been identified, as have the likely effluent contaminants. Details of the concentrations of all contaminants have not been included, such as for the primary cooling system anti-scaling or corrosion inhibitor due to the relative immaturity of these aspects of the design at this stage. Little information regarding the means of control of unplanned contamination of the discharge is detected has been provided. We will expect these details to be included in Step 3.

The expected volume of the discharges to surface water has been estimated, as has the discharge temperature in multiple operating scenarios. No information has been submitted on the options for the beneficial use of the waste heat produced, but we expect Rolls-Royce SMR Limited to consider this in Step 3 of the assessment.

Rolls-Royce SMR Limited has stated that there are no planned discharges to groundwater and that this position is unlikely to change as the design matures.

Two mobile fuel boilers will be used to provide auxiliary steam when the main steam generation is unavailable. Rolls-Royce SMR Limited states that these boilers will be mobile and transported onto site as required. Therefore, they do not meet the definition of a stationary technical unit as defined in the Environmental Permitting (England and Wales) Regulations 2016. It is fundamentally acceptable for the Rolls-Royce SMR design to use mobile boilers to provide auxiliary steam. In the Step 3 assessment we will assess their status as mobile plant and whether permits would be needed.

Six fuel oil-fired diesel generator sets have been identified to provide emergency back-up power. This is fundamentally acceptable and is the most common solution for emergency electrical power at existing nuclear sites. Rolls-Royce SMR Limited has stated that other technologies and cleaner combustion fuels will be further considered as the design progresses. The generators will require a Medium Combustion Plant Directive permit (MCPD) as the thermal input is above 1 MWth and below 50 MWth. The diesel generators are likely to be excluded from requiring a specified generator permit as they are emergency back-up generators and are likely to have a defined nuclear safety role under a nuclear site licence issued by ONR.

Rolls-Royce SMR Limited has undertaken a generic air quality impact assessment to provide a representative estimate of the impacts from the currently proposed combustion plants. The predicted air quality impacts from all the combustion plant operating at the same time are relatively small. We would still expect Rolls-Royce SMR Limited to seek out opportunities to minimise the emissions by adopting RGP. A site-specific air emissions risk assessment will be required when applying for a MCPD permit.

The combustion plant proposed by Rolls-Royce SMR Limited does not exceed 50 MWth (aggregate) and will not require a large combustion plant (LCP) permit. There are currently no plans to have an on-site incinerator.

Rolls-Royce SMR Limited did not submit any information relating to COMAH, fluorinated greenhouse gases or ozone-depleting substances during the Step 2 assessment, because the design was not mature enough to allow it to provide a chemical inventory. For the COMAH and ozone depleting substances, this is not an issue for Step 2 as it does not impact the fundamental assessment of those elements of the design. It is not unusual for a nuclear site to be a lower tier COMAH establishment or to use fluorinated greenhouse gases or ozone-depleting substances, therefore, there is no evidence that the fundamental elements of the design are inconsistent with existing plants.

A COMAH topic report and a site chemical inventory are expected to be submitted in Step 3. A fluorinated greenhouse gases and ozone-depleting substances topic report is also expected to be submitted in Step 3. These will be assessed in Step 3, and we will review the chemical inventory quantities against similar existing sites.

5.9.2 Conclusion

This assessment has considered the foreseeable impact on the environment from conventional (non-radioactive) activities at a Rolls-Royce designed SMR. Based on the information that we have assessed at Step 2, we have not identified any fundamental environmental protection shortfalls that would mean that the design could not be operated in line with UK environmental regulations, policies and guidance (non-Radioactive Substances Regulation).

Rolls-Royce SMR Limited provided enough information for us to carry out a fundamental assessment of most of the topics, except for COMAH, greenhouse gases and ozone depleting gases, which were affected by the maturity of the Rolls-Royce SMR design. These will be assessed when information is provided in Step 3.

There were no matters arising from the assessment that were not acceptable, and no RQs, ROs or RIs were raised.

5.10 Sustainability

Sustainability is a topic of interest to the Environment Agency and Natural Resources Wales because of the statutory duties set out in the Environment Act 1995 and the goals and principles of the Well-being of Future Generations (Wales) Act 2015 and Part 1 of the Environment (Wales) Act 2016 respectively.

The sustainability of a nuclear power station design is not a formal area for assessment in GDA. However, we support the inclusion of sustainability as an engagement topic in the GDA and note Rolls-Royce SMR Limited’s willingness to include it as a separate topic. There is potential for significant positive impacts to be realised from design decisions which take sustainability into consideration. However, Rolls-Royce SMR Limited recognises the importance of considering sustainability in its decision-making throughout the design process.

We have engaged with Rolls-Royce SMR Limited on sustainability from early in Step 1 and have seen significant progress in the development of its capabilities in this area as well as enthusiastic support from the wider organisation. Rolls-Royce SMR Limited has developed a high-level policy on sustainability and has set out to align its corporate values and objectives with 17 sustainable development goals (United Nations SDGs) which is good practice. Rolls-Royce SMR Limited has developed an internal sustainability network which has rolled out training seminars to all parts of the organisation. It has also committed to several other outcomes that demonstrate strong credentials in this area, including making a commitment to become a net zero organisation in the future, commissioning a lifecycle analysis, and its IMS has been recommended for certification to ISO14001:2015 Environmental Management.

The submission, which supports sustainability during Step 2 of GDA, is the ‘Approach for Optimisation through the Application of BAT Issue 3’ (Rolls-Royce SMR Limited, 2024j). This document details the methodology Rolls-Royce SMR Limited adopted to demonstrate that the environmental performance of the Rolls-Royce SMR design has been optimised, and that the potential impacts on people and the environment predicted to arise from the operation of the Rolls-Royce SMR have been minimised.

The methodology defined within the approach for optimisation of the design is aligned with, and integrated into, Rolls-Royce SMR Limited’s ‘conduct design optioneering’, which is held on its IMS. This approach meets our expectations as it ensures consideration and optimisation of all major factors which might influence design decisions, including BAT, ALARP, safeguards by design, secure by design and sustainability.

The ‘Approach for optimisation’ (Rolls-Royce SMR Limited, 2024j) uses a systematic approach, which applies proportionality in how the decision-making process is applied depending on the significance of the decision being made. The impact and complexity of the decision informs the options evaluation method to be adopted.

For decisions with a medium impact and complexity score, a red (bad), amber (acceptable), green (good) assessment was used by Rolls-Royce SMR Limited for the options evaluation method. The rationale for the score is assigned. Rolls-Royce SMR Limited has set 9 criteria to analyse the options. These are technical (meets performance spec); cost and business case; programme timescale; build certainty; security compliance; nuclear safety/ALARP; conventional health and safety; environment/BAT; and social, economic, other. Rolls-Royce SMR Limited has noted that the environment, social and economic considerations provide a broad coverage of sustainability considerations.

The method Rolls-Royce SMR Limited used for decisions with a high impact/complexity score uses a set of 20 pre-defined assessment criteria with set weightings. Sustainability considerations are ‘mapped’ against the assessment criteria, including relevant goals from both the United Nations SDGs and the Well-being of Future Generations (Wales) Act 2015 (Wales) Act 2015.

We have observed that Rolls-Royce SMR Limited is including consideration of sustainability in its arrangements for making design decisions. We recognise that it plans further work, including producing a revised E3S case which will include sustainability in Chapter 26. We will continue to engage with Rolls-Royce SMR Limited on sustainability during Step 3.

The revised Chapter 26 will capture relevant information on how sustainability is considered within the design of the Rolls-Royce SMR, including the process which was adopted to ‘map’ the sustainability considerations against the assessment criteria.

Chapter 26 will present how sustainability is embedded into the culture and business practices of the organisation, including decisions on suppliers and procurement. Sustainability aims to be linked and provide a golden thread throughout the E3S case and to be captured within the other chapters. Therefore, sustainability should have an intrinsic influence during the development of the Rolls-Royce SMR design. Chapter 26 will link to and specifically draw out these sustainability considerations and aspects that are captured within other Tier 1 chapters. We consider these developments by Rolls-Royce SMR Limited to be very positive.

5.10.1 Conclusion

Sustainability aspects of the design, construction and operation of the Rolls-Royce SMR are being integrated into Rolls-Royce SMR Limited’s design optioneering and decisions. We consider this very positive. This will ensure all major factors that might influence design decisions, including BAT, ALARP, safeguards by design, secure by design and sustainability are considered and optimised.

Rolls-Royce SMR Limited has made significant progress in integrating sustainability into the organisation, rolling out training to engineers and managers and supporting internal initiatives to build a strong sustainability culture.

5.11 Public comments received

The comments process enables the public to contribute to GDA by making comments on published submissions.

By the end of February 2024, a total of 36 comments had been received for Rolls-Royce SMR Limited to consider. None of the comments directly affected our assessment or our GDA process. Some comments received were not related to the GDA process, alluding to site-specific matters that may follow on from GDA. These included the need for a safe site; minimising disruption to local residents from construction, operation and eventual decommissioning; the need for benefits for the hosting community; and for flood protection and drainage to be enhanced.

5.12 Readiness for Step 3

We carry out a readiness review for Step 3 to determine whether the RP is ready and whether we are ready.

5.12.1 Rolls-Royce SMR Limited’s readiness

Rolls-Royce SMR Limited carried out a readiness review to show if it would be able to meet the requirements for carrying out Step 3. As part of its readiness for Step 3, Rolls-Royce SMR Limited has identified the resources it has available, and the developments needed for submissions that will be made in Step 3. It has provided a schedule for the design maturity of the Rolls-Royce SMR and the E3S case submission schedule for Step 3. Rolls-Royce SMR Limited has provided scope and submission plans for Step 3, which indicate what it will submit that is relevant to the environment case and when it will make the submissions.

Rolls-Royce SMR Limited has assessed its readiness for Step 3 and risk to entry into Step 3 against 4 internal management expectations. These were:

1. the arrangements needed to carry out all work required in GDA Step 3 are either in place or are mature

2. the design and associated E3S case are mature enough and under suitable configuration control

3. organisational capacity and capability needed to carry out the GDA Step 3 is understood

4. the project is mature enough and ready

Each of the 4 expectations have been broken down into either 5 or 6 sub-criteria (total 22) and scored as red, amber or green. An amber score arises when a gap has been identified and a plan is in place but there is a risk to completion.

Rolls-Royce SMR Limited identified 4 sub-criteria as amber. Two were in the second management expectation (integration of the design and the E3S case and the maturity of the E3S case). The 3rd was the capability and resource needed for Step 3. The 4th was the maturity of the project plan.

The remaining 18 sub-criteria were declared green. No sub-criteria were red.

We carried out a review of the readiness of Rolls-Royce SMR Limited to progress to Step 3. We considered its readiness review report, the process it describes and the outcomes. We noted that Rolls-Royce SMR Limited’s readiness review process appears thorough, comprehensive and clearly described, and the outcomes are clearly presented. The readiness report reflects Rolls-Royce SMR Limited’s internal processes. However, the evidence used to judge readiness is not presented in the report. After discussion, Rolls-Royce SMR Limited provided evidence of its approach to Step 3 entry which showed clear identification and management of risks. We considered the scope and submission plans Rolls-Royce SMR Limited provided and the schedule of submissions for Step 3. This was to determine if the submissions would be developed sufficiently and in time for us to complete our detailed assessment to meet the Step 3 timeline. We reviewed the resources that Rolls-Royce SMR Limited has available to develop the environment part of the E3S case. We also reviewed the state of development of Rolls-Royce SMR Limited’s management system arrangements.

We concluded that the timetable for Step 3 that Rolls-Royce SMR Limited provided is achievable but challenging. It has included time for the Rolls-Royce SMR design to mature sufficiently and for the E3S case to be updated. The proposed timetable will allow us to make a detailed assessment and to hold a public consultation during Step 3.

We concluded that Rolls-Royce SMR Limited appears to have sufficient resources.

Rolls-Royce SMR Limited’s management systems are still developing, but they have achieved an adequate level of maturity for the current stage of their development.

5.12.2 Regulators readiness

We also carried out a review of our readiness to enter Step 3 of GDA. This was informed by the fundamental assessment we carried out in Step 2 and periodic reviews with ONR and Natural Resources Wales. We considered the schedule of submissions from Rolls-Royce SMR Limited, whether the project risks had been identified, and if they can be managed. We considered if we have enough resources to carry out the assessment. We used the submission information to develop a timetable for our assessment during Step 3 of GDA and including our public consultation.

We concluded that there is enough time in the Step 3 programme to allow us to make a detailed assessment and to carry out a public consultation. We have identified the risks, and they can be managed. GDA is still a strategic priority and we can continue to resource this work area.

5.13 Summary

Together with Natural Resources Wales, we have completed our fundamental assessment of the specified technical areas. There were no matters arising from the assessment that were not acceptable. During our assessment in Step 2, we raised 31 RQs on the environmental aspects of the submissions Rolls-Royce SMR Limited made. A number of the RQs were raised early in Step 2 and were related to information that was not provided in the submissions made at the start of Step 2. Information that was not provided was generally due to the relative immaturity of the reactor design development leading up to the start of Step 2. During Step 2, the design continued to be developed, and additional information was provided in the E3S case, as new or updated submissions. This additional and updated information enabled us to carry out a fundamental assessment.

For all environmental topics, additional information needs to be provided to enable a detailed assessment during Step 3.

6. Additional environmental aspects of the design

During Step 2 of GDA, we have considered the impact on the environment of the design, build and potential operation of the Rolls-Royce SMR. We have considered specific environmental topics in Section 5. There are additional aspects of the design that are not directly considered by our GDA technical assessment and crosscut some of the E3S case topics.

6.1 Reactor design parameters

We have reviewed which environmental aspects of the design are affected by the power output of the reactor.

There are potentially 4 environmental aspects that depend on the power output of the reactor. These are discharges of radioactive waste and predicted doses to the public; generation of operational solid wastes; spent fuel arisings, and estimated water flow rates (feedwater, cooling water and effluent).

Discharges are expected to depend on the power output of the reactor. Discharges of radioactive waste to the atmosphere or as liquids will be higher when the reactor is operating and potentially for a short period at the start of defueling. Discharges will reduce once the reactor is shut down for refuelling. Discharges of radioactive waste have a direct impact on doses to the public and dose rates to wildlife in the environment.

Solid waste radioactive waste arising from effluent treatment during operations may also increase as power output is increased.

There are significant differences between the cooling water and aqueous effluent flow rates at different reactor operating states. For the conventional heat and material balance, Rolls-Royce SMR Limited has given water flow rates for average and peak conditions related to different reactor operating states, including 100% power, typical powered operation and typical shutdown period.

Spent fuel arisings will depend on the power output of the Rolls-Royce SMR and its design and usage. Rolls-Royce SMR Limited has provided results from several individual calculations of the number of fuel assemblies arising and of fuel burn up for 4-batch and 3-batch core designs, based on assumptions regarding core design, fuel enrichment and fuel cycle length. We will want to review more detailed evidence during Step 3 of the GDA process, to support Rolls-Royce SMR Limited’s claims regarding the minimisation of spent fuel and waste arisings. This should include a more comprehensive sensitivity analysis for assumed lifetime power production of factors that may influence environmental impacts. An evaluation will be needed of intact and damaged spent fuel volumes and activities as a function of major factors, including fuel type, initial fuel enrichment and refuelling strategy.

6.2 Modularisation

Submissions for modularisation during Step 2 focused on the reactor island which is the most developed and most mature part (Rolls-Royce SMR Limited 2024s). The approach to modularisation for the rest of the reactor will follow during Step 3.

Our assessment in Step 2 was a review of the submissions and providing advice on our expectations. Rolls-Royce SMR Limited expects to provide more details in submissions during Step 3.

We expect Rolls-Royce SMR Limited to identify and present clearly the environmental aspects of the design that are likely to be affected by the modularisation approach for Step 3.

We have asked Rolls-Royce SMR Limited to ensure that the reactor design and modularisation process consider environmental aspects and impacts, including how the environmental protection measures and functions will be included in the modules.

We have noted to Rolls-Royce SMR Limited that there are specific matters around discharge accountancy monitoring, which are positioned in certain parts of the reactor. It has agreed to consider how to meet these expectations during its design and modularisation processes. Specifically, we asked Rolls-Royce SMR Limited to ensure it considers how modularisation could affect the following:

• Decommissioning requirements. Our interest in decommissioning regards the type and amount of wastes produced; arrangements for minimising the wastes produced; disposability of the wastes that could be generated, while allowing decommissioning and dismantling to be carried out. We expect the best design options to reduce and minimise the amounts of waste that might be produced during decommissioning to be considered. Rolls-Royce SMR Limited has acknowledged this but this was not developed during Step 2. We expect these matters to be explicitly considered during Step 3. Rolls-Royce SMR Limited indicated that it expects decommissioning and dismantling of the modular construction to be generally more efficient/easier compared with traditional construction. This is because the process of decommissioning of many similar or identical modules will become more efficient as experience and learning are developed and reused.

• Sampling arrangements, including extraction lines (for example, gaseous). We expect relevant standards and good practice to be met for line lengths, minimisation of the number of bends in lines and pipes and the number of joints where materials could get trapped/lost. As sample lines could pass through several modules, we have asked how joints at the boundary between modules will be minimised or avoided, using, for example, continuous runs in ducts across modules.

• The avoidance, where possible, of embedded pipework, ducts and equipment in floors and walls.

• Arrangements for planned discharges to atmosphere, including the stack design, height, the number of stacks, and the positions and heights of buildings close to the stacks.

• The sustainability of the design. Rolls-Royce SMR Limited expects economic benefits in terms of reduced cost of construction. During Step 2, we asked Rolls-Royce SMR Limited whether it had considered social or environmental impacts.

During Step 2, we asked Rolls-Royce SMR Limited to provide information in Step 3 on whether modularisation will need more or less steel, manufacturing effort and energy input compared to conventional build. We asked Rolls-Royce SMR Limited if it had considered whether the module frames could be recycled or reused after demolition. We also asked if any detriments from modularisation had been identified and optimised, considering the potential benefits from the expected ease of decommissioning, installation and reduced impacts on the environment during construction.

ONR engaged specialist support to assess the potential impact of modularisation Rolls-Royce SMR Limited used for the SMR and issues that could arise. The general conclusions are consistent with our view at this stage that there are no reasons why the Rolls-Royce SMR design, as proposed by Rolls-Royce SMR Limited, should not be successfully developed, while maintaining safety, security, environment and safeguards.

6.3 Layout

Submissions for layout was an architectural and layout summary (Rolls-Royce SMR Limited, 2024t) supported by other documents. During Step 2 the focus was on the reactor island which is the most developed and most mature part. The rest of the reactor layout will follow during Step 3. Some information on how layout decisions take into account the environmental aspects of the design was included in the submissions.

Our assessment in Step 2 was, limited to reviewing and feeding back on the submissions and providing advice on our expectations. Rolls-Royce SMR Limited expects to provide more detail in its submissions during Step 3.

From the layout documents submitted in January 2024, there are good indications that the environmental aspects are being included in the considerations. Rolls-Royce SMR Limited acknowledged that layout affects decommissioning and waste generated as a result of decommissioning. As the design is progressed, the layout will be optimised to reduce both decommissioning and BAT risks to as low as reasonably achievable (ALARA) through design assessment and iteration. However, the layout is not yet mature enough to be specific about these aspects.

Rolls-Royce SMR Limited needs to identify and present clearly the environmental aspects of the design that are likely to be affected by layout for Step 3.

We asked Rolls-Royce SMR Limited to inform us of the planned overall footprint and size for a single reactor; if there are any specific criteria related to layout and size that it is designing the reactor to meet; and whether there are any specific constraints.

We expect Rolls-Royce SMR Limited to ensure that the reactor design and layout considers environmental aspects and impacts, including how the environmental protection measures and functions will be positioned to ensure adequate space for operation, inspection and maintenance. There are some specific matters around discharge accountancy monitoring which will be affected by layout. Rolls-Royce SMR Limited will need to consider how these expectations can be met during its design and layout processes.

For Step 3, our expectation is that Rolls-Royce SMR Limited should consider how layout affects:

• the space available for potential future technology and equipment for environmental protection functions that might be added later, to avoid closing these off unnecessarily

• how decommissioning and dismantling can be carried out, and how the waste generated can be minimised. Our interest in decommissioning is around minimising and avoiding waste production and disposability, and ensuring that decommissioning and dismantling can be carried out

• positioning of environmental systems that should be close together, minimising pipework

• pipework and sample extraction lines (for example, gaseous). Lengths, bends and joints where materials could get trapped/lost need to be minimised. Pipes and ductwork installations should be arranged to minimise the hold-up and deposition of ‘crud’ (active corrosion particles) and active dust particulates, achieving relevant standards and good practice.

• minimisation or avoidance of embedding pipework, ducts and equipment in floors and walls. The design of systems such as active drains or pipes passing through conventional plant areas

• arrangements for solid waste treatment systems to be close to locations where the solid waste is generated

• provision of space for access to monitoring and sampling locations and equipment, extraction points for maintenance and calibration of monitors or samplers, flow meters, including access routes to them, allowing for human factors

• provision of access for EIMT of environmental equipment, allowing for human factors

• provision of separate areas for radioactive and non-radioactive systems

• arrangements for planned discharges to atmosphere, including the stack design, height, the number of stacks and building size and locations near to the stack

• sustainability, although it is not a required assessment area in this GDA

The expected interaction with the part of the E3S case covering radioactive waste (E3S Chapter 11) (Rolls-Royce SMR Limited, 2024h); decommissioning and end of life aspects (E3S Chapter 21) (Rolls-Royce SMR Limited, 2024r) and BAT (E3S Chapter 27) (Rolls-Royce SMR Limited, 2024g) and resulting claims are presented at a high level in the layout submissions. Rolls-Royce SMR Limited stated that the layout design is not yet mature enough to provide sufficient evidence that BAT has been applied.

Rolls-Royce SMR Limited will need to review the claims related to BAT to ensure they are consistent with the BAT claims presented in the BAT case chapter 27 (Ref Rolls-Royce SMR Limited, 2024g).

6.4 Reactivity control

Rolls-Royce SMR Limited declared that the boron-free design during normal operations and planned shutdowns will help to reduce the environmental impact of the Rolls-Royce SMR design.

Rolls-Royce SMR Limited noted that many PWRs operate with lithium hydroxide as the pH modifier. In a PWR, the primary coolant water containing dissolved boron as boric acid can control the nuclear reactions. Under typical PWR primary coolant conditions (15.7 MPa and 325 °C), the pH of pure water is reduced by the addition of boric acid. This relatively low pH would have a detrimental effect on the corrosion and integrity of metal components in the primary circuit. Therefore, the aim is to raise pH to a range where corrosion is minimised. In PWRs, a common pH raising additive is lithium hydroxide. Experimental testing has shown that high concentrations of lithium hydroxide can accelerate cladding corrosion. Fuel vendors place upper limits on the lithium hydroxide concentration allowable in the bulk coolant to reduce the risk of cladding failure.

Lithium hydroxide used in PWRs also needs to undergo isotopic enrichment to increase the lithium-7 isotopic content relative to lithium-6. Lithium-7 has a very low neutron cross section compared with lithium-6 and does not absorb neutrons emitted from the PWR.

The Rolls-Royce SMR is being designed to operate without soluble boron (as boric acid) in the primary circuit during normal operations. Rolls-Royce SMR Limited noted removing the requirement for soluble boron for reactivity control means that the primary coolant pH can be controlled by a strong base only.

Rolls-Royce SMR Limited declared that using potassium hydroxide as the base potentially offers benefits over lithium hydroxide because it does not require isotopic enrichment and, therefore, is the assumed enabler for soluble boron-free operation.

Rolls-Royce SMR Limited notes that one of the advantages of control of reactivity using dissolved boron is a reduction in the number of control rods that are needed. Therefore, by implication, operations without dissolved boron will require more control rods. Rolls-Royce SMR Limited notes that the main reactivity control mechanism for the Rolls-Royce SMR will be by control rods.

The Rolls-Royce SMR design will use more control rods than PWRs using dissolved boron in the coolant. Control rods may eventually become solid waste which will need to be disposed of. Therefore, the Rolls-Royce SMR design could potentially produce more solid waste.

An emergency boron injection (EBI) system is proposed to deliver concentrated potassium tetraborate solution to the high-pressure injection system which ultimately directs boron into the reactor system. Emergency boron injection is not an expected operational event and is outside the scope of the GDA for the Environment Agency and Natural Resources Wales. In Step 3, we will include assessment of potential spurious activation of the EBI system or leakage from the system.

6.5 Primary coolant chemistry

Rolls-Royce SMR Limited noted removing the requirement for soluble boron for reactivity control means that the primary coolant pH can be controlled by a strong base only – potassium hydroxide – which offers several benefits over lithium hydroxide which is often used in PWRs. These include the following:

1. Surety of chemical supply (potassium hydroxide versus lithium-7 hydroxide).

2. Mitigating known accelerated fuel cladding corrosion concerns, which are present in concentrated lithium hydroxide.

3. Reduction in tritium generation by neutron reactions with lithium-6. This is the second highest contributor to tritium generation in PWR coolant, with boron being the highest contributor. Therefore, eliminating dissolved boron and lithium from the coolant will potentially result in a substantially lower amount of tritium in coolant and in discharges. The Rolls-Royce SMR design will not require regular let down of primary coolant during a cycle to dilute boron as would be required for reactivity control. This provides the designers with the opportunity to explore the potential for a different type of operation, more akin to closed cycle operation. Closed cycle operation has minimal impact on steady state coolant concentrations of most radionuclides present in PWRs. However, tritium levels may still increase in coolant with time, as it is not removed by current technologies available in coolant purification systems.

In terms of hazards and environmental risks from manufacture and storage, LiOH and KOH are similar. However, KOH is easier to manufacture, cheaper, and may be more sustainable. There will be reduced levels of tritium production and, therefore, reduced discharges of tritium as liquids and gases. Instead, potassium-42 will be generated in the cooling circuit from the activation by neutrons of naturally occurring stable potassium isotope K-41. The half-life of K-42 is 12.4 hours – much shorter than tritium, which is 12.3 years. Boron-free primary coolant with potassium hydroxide means that the primary coolant can be re-used and recycled to a greater extent, potentially close to a closed cycle operation.

6.6 Minimising radioactive waste

During Step 2, Rolls-Royce SMR Limited identified a series of claims and arguments relating to the use of BAT to support the prevention and minimisation of solid and non-aqueous wastes. It claimed that the design of the Rolls-Royce SMR eliminates or reduces the generation of radioactive waste, and that material corrosion and activation will be controlled to minimise the generation and activity of the wastes. The potential for corrosion products to adhere to surfaces, become activated and released back into the coolant and subsequently be removed by the downstream processes will also be minimised.

Solid wastes arisings are planned to be minimised by controlling the primary water coolant chemistry using potassium hydroxide (KOH) and hydrogen injection. This is intended to minimise the concentration of corrosion products that will arise within the coolant and on the surrounding structures. Rolls-Royce SMR Limited has made arguments for spent fuel pool purification, focusing on the performance of the ion exchange resin beds and filters, control of the pool water temperature, and chemistry.

Rolls-Royce SMR Limited has claimed that the Rolls-Royce SMR systems and construction materials are designed for shielding and barriers. This should minimise the areas that will come into contact with radioactivity and reduce the potential for contamination and activation and, therefore, the amount of radioactive wastes produced during decommissioning. Rolls-Royce SMR Limited has produced a decommissioning strategy for the Rolls-Royce SMR, and its preferred option for decommissioning is immediate dismantling.

The design and manufacture of fuel rods and assemblies will aim to maximise their physical integrity and limit fuel pin failure, thereby minimising the release of radionuclides into the primary coolant and then into the environment. Rolls-Royce SMR Limited will be seeking to maximise the integrity of fuel rods, improve fuel efficiency and minimise the release of fission products from the fuel rods into the primary coolant, as well as minimise the potential for uranium oxide to spread onto external surfaces.

Reactor fuel condition will also be monitored during operations, including start-up and shutdown. Fuel monitoring will allow rapid detection of a fuel pin failure and initiate the actions needed to minimise the release of radioactivity into the primary coolant.

The evidence to support these claims and arguments will be provided and assessed during Step 3.

7. Matters to be resolved in Step 3

During the assessment of the specific environment topics in Step 2, the following matters were identified which will need to be considered further in Step 3. During Step 3, more developed detailed information should be provided to support a detailed assessment.

Management for safety and quality assurance (MSQA)

There are aspects that will need to be improved related to arrangements for E3S case production and integration with the Rolls-Royce SMR design development. These were raised in an RO–(RO-RRSMR-001) during Step 2. RO-RRSMR-001 will be resolved in Step 3.

Best available techniques (BAT)

Our assessment of the optimisation process during Step 2 has mainly examined the process and how it is meant to be applied. In Step 3 of GDA, we will seek evidence of its practical application by Rolls-Royce SMR Limited.

In Step 3 of GDA, we will assess updated submissions relevant to this assessment area and seek evidence of the closure of forward actions defined within the ‘Approach for Optimisation through the Application of BAT’ (Ref: Rolls-Royce SMR Limited, 2024j).

The development of the CAE structure is ongoing, and arguments and evidence will be refined as the design of the Rolls-Royce SMR matures. We will continue to engage with Rolls-Royce SMR Limited on this in Step 3. Rolls-Royce SMR Limited needs to identify if there are gaps in its CAE and define appropriate forward actions. We will expect to see evidence of this in Step 3.

Rolls-Royce SMR Limited has continued to develop the Rolls-Royce SMR design and associated design justification during Step 2. An assessment of its demonstration of BAT within the Rolls-Royce SMR design will be completed during Step 3. We expect Rolls-Royce SMR Limited to provide us with the necessary evidence in support of the claims and arguments to complete our detailed assessment.

Radioactive waste management arrangements (RWMA)

The Integrated Waste Strategy broadly meets our expectations for the current stage and maturity of the Rolls-Royce SMR design. Strategic considerations are clearly defined in relation to radioactive waste management. However, we have not yet seen the evidence for how these strategic considerations are used to underpin the Rolls-Royce SMR design, and we will look at this aspect as part of our Step 3 assessment.

In Step 3 of GDA, we will seek evidence that the forward actions defined within the Integrated Waste Strategy (Ref: Rolls-Royce SMR Limited, 2023a) are being addressed. We expect the next iteration of the Integrated Waste Strategy to include information on all solid, liquid and gaseous radioactive waste and spent fuel arisings generated from the lifecycle of the Rolls-Royce SMR, and how they will be subsequently managed and disposed of.

Environmental protection functions and measures

We have noted that Rolls-Royce SMR Limited’s process for identifying EPFs and EPMs is at the early stages of development. However, it broadly meets our expectations for the current stage and maturity of the Rolls-Royce SMR design. We raised several points of feedback on the submission, and Rolls-Royce SMR Limited confirmed that it would consider these when developing its methodology. We queried when the methodology will be implemented and how it will be used to inform and interact with other areas, such as the EIMT strategy. Rolls-Royce SMR Limited confirmed that these areas will be progressed in the remainder of Step 2 and into Step 3 of the GDA.

We will consider further the development of the EPF and EPM methodology and its subsequent implementation and interaction with other areas, such as EIMT, as part of our assessment during Step 3 of GDA.

Discharges

The design of the reactor was still developing during our Step 2 assessment and will continue into the start of Step 3. Therefore, the information on discharge estimates assessed is expected to change in Step 3.

Information on discharges from commissioning activities has yet to be provided and will be followed up in our Step 3 assessment.

Gaseous discharges

Of some radionuclides are likely to be below those of other PWRs. But for some radionuclides, predicted discharges appear to be significantly higher. This needs to be investigated and will be a focus of our assessment in Step 3.

Sampling and monitoring

More detailed information for assessment is expected in Step 3 as the design matures and options are selected. Information on the final proposals for monitoring (in-process and final discharge) with BAT assessments will be submitted for assessment in Step 3. Once Rolls-Royce SMR Limited has defined the locations and proposed approaches for monitoring, we will be able to carry out a more detailed assessment of the techniques and facilities.

Generic site description and radiological impact assessment

A more complete justification of the generic site description (GSD) is needed to ensure consistency and improve linkage to the current UK sites in Step 3. This will be to support the implementation of appropriate modelling for a detailed radiological impact assessment. The potential effects of climate change on the GSD will need to be considered.

Solid waste and spent fuel

Rolls-Royce SMR Limited has identified a series of claims and arguments relating to BAT and the minimisation of solid and non-aqueous wastes. The claims and arguments were presented in Step 2. Most of the evidence to support these claims and arguments will be provided during Step 3.

Rolls-Royce SMR Limited’s proposals to manage LAW, HAW and spent fuel across the lifecycle (pre-disposal) are in the early stages of development and, therefore, further work will be required during Step 3. We will be raising queries during Step 3 on the options chosen for the conditioning, packaging and storage of the wastes and spent fuel, and the claims made that these represent BAT.

Information on the nature and quantities of wastes and spent fuel in the inventory, including for the NFCC and decommissioning wastes will be needed in Step 3. Source terms for the wastes and spent fuel will need to be developed for Step 3 as these will be major inputs for the disposability case.

Rolls-Royce SMR Limited will need to present more detailed information to support claims regarding the minimisation of spent fuel arisings. An environmental assessment for the spent fuel pool will be needed during Step 3. Further details will be needed of plans for the long-term management of spent fuel outside the reactor island, including the type of dry storage cask, justification of long-term storage arrangements, the type of disposal container, and arrangements for packaging spent fuel for disposal.

Other environmental regulations

A COMAH topic report and a site chemical inventory are expected to be submitted in Step 3. A fluorinated greenhouse gases and ozone-depleting substances topic report is also expected to be submitted for assessment. We will expect more details to be included in Step 3 about potential contaminants in effluents that may be discharged to surface waters, such as the primary cooling system anti-scaling or corrosion inhibitor. We expect more information on the beneficial use of the waste heat produced and detail on auxiliary steam from mobile fuel boilers.

Sustainability

Rolls-Royce SMR Limited is including consideration of sustainability in its arrangements for making design decisions. We recognise that it plans further work, including producing a revised E3S case Chapter 26 on sustainability. We will continue to engage with Rolls-Royce SMR Limited on sustainability during Step 3.

Layout and modularisation

Submissions during Step 2 focused on the reactor island which is the most developed and most mature. The approach for the rest of the reactor will follow during Step 3. In Step 2, we reviewed the submissions and provided some advice on our expectations. Rolls-Royce SMR Limited needs to identify and present clearly the environmental aspects of the design that are likely to be affected by the layout and modularisation during Step 3. In Step 3, Rolls-Royce SMR Limited should provide information on how layout affects the space available for potential additions of technology and equipment for environmental protection functions, to avoid closing any off unnecessarily.

8. Conclusions, summary and next steps

8.1 Conclusions

Rolls-Royce SMR Limited has demonstrated to the satisfaction of the Environment Agency and Natural Resources Wales that there are no fundamental shortfalls with its reactor design that could prevent future deployment in England and Wales.

During Step 2 of GDA, the design of the Rolls-Royce SMR was still developing and maturing, and some design options were still being considered. This affected the completeness of the E3S case provided early in Step 2. However, a revised E3S case was provided later in Step 2 that was sufficiently developed for us to complete a fundamental assessment.

There are currently no identified areas that would prevent us from being able to issue a Statement of Design Acceptability at the end of Step 3.

There have been no RIs raised to date during this GDA.

We are satisfied the company has demonstrated that its design at this stage is likely to be consistent with the application of the best available techniques for minimising the impact of radioactive waste disposals on people and the environment.

Rolls-Royce SMR Limited has engaged Nuclear Waste Services (NWS) to provide an expert view on the future disposal of spent fuel and higher activity radioactive waste. NWS have concluded there is a low risk that radioactive waste from the Rolls-Royce SMR design will not be able to be disposed of in the future.

Rolls-Royce SMR Limited has made significant progress in considering sustainability when developing its organisation and design, even though this is not a requirement of our GDA guidance.

We consider Rolls-Royce SMR Limited has appropriate technical and management capabilities to successfully complete the next step of the GDA.

We agree the radiation dose to people and non-human biota from radioactive waste discharges and disposals is likely to be below the relevant dose limits and dose constraints during normal operations.

All the RQs we issued have been responded to.

We supported ONR in issuing an RO on the development and integration of the E3S case with design development. Rolls-Royce SMR Limited has taken satisfactory action and we expect full resolution in Step 3.

Rolls-Royce SMR Limited is applying relevant legislation, regulatory requirements and RGP in its design decisions. These have informed the development of the assessment criteria used in the options evaluation process.

The approach for optimisation is presented as being integrated into the reactor design process, using Rolls-Royce SMR Limited’s conduct design optioneering process. The integration of optimisation in the design is good practice. If the integration is effective, it should ensure all relevant factors that might influence design decisions, such as BAT and ALARP, are considered which will enable the identification of a single optimised outcome.

The CAE approach for demonstrating BAT in the Rolls-Royce SMR design is considered good practice and meets our expectations. The CAE structure presented is broadly aligned with previous GDAs.

Rolls-Royce SMR Limited has presented clear and comprehensive methods and demonstrated systematic approaches to the expected discharges. Optioneering to determine likely monitoring arrangements appears comprehensive and logical. Rolls-Royce SMR Limited is developing its arrangements for sustainability of the design and developing capability in this area.

8.2 Summary

We have completed our fundamental assessment. We did not find anything unacceptable.

The submissions received in Step 2 adequately address our information requirements for the topics as set out in our Environment Agency: Guidance for Requesting Parties (2019). However, in some areas some information in the submissions was limited while the design of the Rolls-Royce SMR is still developing and maturing.

The scope of the GDA and our assessment remain meaningful and currently no changes are required.

Initial estimates of discharges to the atmosphere from the design would be similar to or could exceed those of comparable PWRs. The proposed limits for discharges to the atmosphere presented in Step 2 are conservative and are based on provisional information. We will examine this in detail in Step 3.

We have not identified any significant design modifications that are likely to be needed before we could issue a SoDA. However, during Step 2 design options were still being assessed by Rolls-Royce SMR Limited so design changes initiated by Rolls-Royce SMR Limited remain possible until early in Step 3.

We have identified additional information required for detailed assessment at Step 3.

There is a considerable amount of work for Rolls-Royce SMR Limited to carry out during Step 3. The Rolls-Royce SMR design needs to be further developed and matured. The E3S case will also need to develop with more detail and evidence to allow our detailed assessment to proceed to completion.

We have carried out a readiness review with Rolls-Royce SMR Limited and have determined that the arrangements it has put in place to carry out the GDA are adequate to progress to Step 3 of GDA – the detailed assessment stage. Rolls-Royce SMR Limited has acknowledged the amount of work that it needs to do, it has prepared resources, and has scheduled the necessary work and the submissions for Step 3 to meet the required timelines.

We have previously agreed with Rolls-Royce SMR Limited that the scope of the GDA is suitable to target the issue of a full SoDA. Following our fundamental assessment, we consider this goal remains valid.

On this basis, we have concluded that we and Rolls-Royce SMR Limited can progress to Step 3 of GDA (detailed assessment stage).

8.3 Next steps

Our next step is to begin Step 3 of the GDA of the Rolls-Royce SMR design – detailed assessment. We expect to begin Step 3 in August 2024.

During Step 3, we will begin our detailed assessment to come to a view on whether the submissions are sufficient to achieve a SoDA. During Step 3, we will prepare and publish our preliminary findings from the detailed assessment and consult widely on our preliminary view.

We are planning to begin this public consultation in January 2026. At the end of the consultation, we will carefully consider all responses received and any further submissions or information provided by Rolls-Royce SMR Limited before deciding whether to issue a SoDA, an interim Statement of Design Acceptability (iSoDA) or neither. We plan to publish our decision and the findings of our detailed assessment in December 2026. We may also issue a SoDA or an iSoDA at the same time.

9. References

ONR, 2023, Regulatory Observation – Development of the generic E3S case, RO-RRSMR-001, Revision 0, August 2023.

ONR, 2024. Project Assessment Report – Generic Design Assessment of the Rolls-Royce SMR – Step 2 Summary July 2024.

Rolls-Royce SMR Limited 2022. Optioneering of Methods for the Treatment of Solid Radioactive Wastes, SMR0000579, Issue 1 Apr 2022.

Rolls-Royce SMR Limited, 2023a. Rolls-Royce Small Modular Reactor Integrated Waste Strategy October 2023a.

Rolls-Royce SMR Limited,2023b. Environmental Optioneering Matrix Guidance for engineers, SMR0002176, Issue 1 2023b.

Rolls-Royce SMR Limited, 2023c. Environmental Optioneering Matrix Template, TS DD 52, Issue 1 2023c.

Rolls-Royce SMR Limited, 2023d. Decision Record Template, TS-DD-002, Issue 5 2023d.

Rolls-Royce SMR Limited, 2023e. Identification of Environment Protection Functions and Environment Protection Measures SMR0005548, Issue 1 – Rolls-Royce SMR LIMITED, 2023e.

Rolls-Royce SMR Limited, 2023f. Quantification of Radiological Discharges During Normal Operations – Reactor Island Waste Systems SMR0006974 Issue 1 Nov 2023f.

Rolls-Royce SMR Limited, 2023g. Rolls-Royce Small Modular Reactor – Disposability Case Report, SMR0007665 Issue 1, September 2023g.

Rolls-Royce SMR Limited, 2023h. Waste Facilities Basis of Design, SMR0007007, Issue 1 Oct 2023h.

Rolls-Royce SMR Limited, 2023i. Rolls Royce Small Modular Reactor – Solid Operational Waste Identification, SMR0001122 Issue 4, Nov 2023i.

Rolls-Royce SMR Limited, 2023j. Damaged Fuel Strategy, SMR0008057 Issue 1, 23 October 2023j.

Rolls-Royce SMR Limited, 2023k. R01 – 501 – Fuel Storage Requirements and Strategy, SMR0003767 Issue 1, May 2023k.

Rolls-Royce SMR Limited, 2023l. System Outline Description for the Handling of Nuclear Equipment [F] System, SMR0000983 Issue 2, March 2023l.

Rolls-Royce SMR Limited, 2023m. SMR System Design Description for the External Dry Storage of Filled Casks System [FDB], SMR0009366 Issue 1, December 2023m.

Rolls-Royce SMR Limited,2024a. Environment, Safety, Security and Safeguards Case Chapter 1: Introduction, SMR0004294, Issue 3, May 2024a.

Rolls-Royce SMR Limited, 2024b. Environment, Safety, Security and Safeguards Case Version 2, Tier 1, Chapter 2: Generic Site Characteristics SMR0004542 Issue 3 May 2024b.

Rolls-Royce SMR Limited, 2024c. Environment, Safety, Security and Safeguards Case Version 2, Tier 1, Chapter 31: Conventional Environmental Impact and Other Environmental Regulations SMR0004514 Issue 3 May 2024c.

Rolls-Royce SMR Limited, 2024d. Rolls-Royce SMR Limited, Master Document Submission List and Document List, SMR0001724, Issue 13, May 2024d.

Rolls-Royce SMR Limited, 2024e. Rolls-Royce SMR – GDA Design Reference Report, SMR0009043, Issue 2, April 2024e.

Rolls-Royce SMR Limited, 2024f. Environment, Safety, Security and Safeguards Case Version 2, Tier 1 Chapter 17: Management of E3S and Quality Assurance SMR0004334 Issue 3 May 2024f.

Rolls-Royce SMR Limited, 2024g. Environment, Safety, Security and Safeguards Case Version 2, Tier 1, Chapter 27: Demonstration of Best Available Techniques SMR0008113 Issue 2 May 2024g.

Rolls-Royce SMR Limited, 2024h. Environment, Safety, Security and Safeguards Case Version 2, Tier 1, Chapter 11: Management of Radioactive Wastes SMR0004502 Issue 3 May 2024h.

Rolls-Royce SMR Limited, 2024i. Environment, Safety, Security and Safeguards Case Version 2, Tier 1, Chapter 29: Quantification of Radioactive Effluent Discharges and Proposed Limits SMR0004486 Issue 3 May 2024i.

Rolls-Royce SMR Limited, 2024j.- Approach for Optimisation through the Application of BAT SMR0004683 Issue 4 May 2024j.

Rolls-Royce SMR Limited, 2024k. Quantification of Radiological Discharges During Normal Operations – HVAC and CARS SMR0009249 Issue 1 Jan 2024k.

Rolls-Royce SMR Limited, 2024l. Review of Postulated RR SMR Expected Events SMR0009430 Issue 1 Jan 2024l.

Rolls-Royce SMR Limited, 2024m. Estimation of Headroom Factors for RR SMR Proposed Permit Limits SMR0009431 Issue 1 Feb 2024m.

Rolls-Royce SMR Limited, 2024n. Comparison of Discharges from RR SMR and Other Light Water Reactors SMR0009432 Issue 1 Feb 2024n.

Rolls-Royce SMR Limited, 2024o. Environment, Safety, Security and Safeguards Case Version 2, Tier 1, Chapter 28: Sampling and Monitoring Arrangements SMR0010323 Issue 2 May 2024o.

Rolls-Royce SMR Limited, 2024p. Environment, Safety, Security and Safeguards Case Version 2, Tier 1, Chapter 30: Prospective Radiological Assessment SMR0004490 Issue 4 May 2024p.

Rolls-Royce SMR Limited, 2024q. Environment, Safety, Security and Safeguards Case Version 2, Tier 1, Chapter 9A: Auxiliary Systems SMR0003863 Issue 3 May 2024q.

Rolls-Royce SMR Limited, 2024r. Environment, Safety, Security and Safeguards Case Version 2, Tier 1 Chapter 21: Decommissioning and End of Life Aspects SMR0004599 Issue 3 May 2024r.

Rolls-Royce SMR Limited, 2024s. Modular Kit of Parts Strategy SMR0008962 Issue 2 Jan 2024s.

Rolls-Royce SMR Limited, 2024t. Reactor Island Architectural and Layout Summary Report SMR0007298 Issue 1 2024t.