Decision

GDA Step 1 of the Holtec SMR: statement of findings full report

Published 1 August 2024

Applies to England and Wales

1. Introduction

Purpose

This report sets out our findings following the Step 1 (initiation) of a generic design assessment (GDA) for the SMR-300 nuclear power plant design.

Holtec International (the ‘Requesting Party’) applied to the Department for Energy Security and Net Zero for its design to enter into the GDA process. The application was successful. The regulators (The Environment Agency, The Office for Nuclear Regulation (ONR) and Natural Resources Wales (Natural Resources Wales) were asked by the Minister to begin a GDA for this design. Step 1 (initiation) of the GDA formally began on 18 October 2023.

About GDA

Our GDA process is described in our GDA guidance for Requesting Parties. GDA means that we assess the acceptability of the environmental aspects of a design, at a generic level, before site-specific applications are made.

ONR has introduced an equivalent and aligned process for assessing the safety and security aspects of a design, ONR GDA guidance to Requesting Parties.

GDA allows us as the regulators (Environment Agency, ONR and Natural Resources Wales if they join a project) to get involved with designers and potential operators at the earliest stage, where we can have most influence and where lessons can be learned that may apply to other submitted designs. This early involvement also reduces regulatory uncertainty for designers and potential operators.

Joint working with ONR

GDA is a joint project between the environment agencies and ONR. We work closely with ONR particularly on:

• GDA project management
• the requesting party’s management arrangements and quality assurance for GDA
• aspects of radioactive waste management

We expect this joint working to continue for the remainder of GDA.

We have:

• asked requesting parties to provide information about their designs as a single, integrated submission, addressing the requirements of both regulators
• set up a Joint Programme Office (JPO) to administer the assessment process on behalf of both the regulators as a ‘one-stop shop’

Our assessment

We carry out GDA in up to 3 steps.

During Step 1 (initiation), we make agreements with the requesting party and provide advice on the scope and development of a submission.

In Step 2 (fundamental assessment), we examine the requesting party’s submission at an outline level. Our aim is to identify whether we need any further information, if there are any matters that are obviously unacceptable, or if any significant design modifications may be needed.

Step 3 (detailed assessment) is when we examine the submission in detail to come to a preliminary view on whether or not to issue:

• a Statement of Design Acceptability (SoDA), because we have not found any GDA Issues and we consider that the design is capable of being constructed, operated and decommissioned in a way that complies with our regulatory requirements and expectations, ensuring that people and the environment are properly protected
• an interim Statement of Design Acceptability (iSoDA) – if we have completed our assessments and are happy with the environmental protection aspects, but there are still GDA Issues to be resolved and the requesting party has provided credible resolution plans for addressing them

We will not issue either of these if the design is unsuitable and will not provide the right levels of environmental protection, or if there are GDA Issues but no credible resolution plan.

We will only make our final decision after we have consulted the public and carefully considered the responses we receive.

There are two other GDA outcomes:

• Step 2 – the requesting party may stop or pause the GDA at the end of Step 2. We will publish a GDA Step 2 Statement setting out our regulatory position at this point, including our findings from Step 2

• Step 3 – the requesting party may end the GDA at the end of Step 3 without a SoDA. In this case, we will publish a GDA Step 3 Statement, which will set out our regulatory position and findings following Step 3

We will do this where we have agreed with the requesting party that the GDA can be carried out on the basis of a reduced but still meaningful scope. The Step 3 Statement will include Assessment Findings where appropriate. Where a Step 3 Statement is the outcome, no public consultation would be carried out.

Holtec International has applied for a 2-step GDA and are targeting a Step 2 statement as the GDA outcome. Holtec are not currently intending to complete Step 3 and are therefore not targeting the issue of a SoDA at the conclusion of this GDA

Regulation of nuclear power stations

The Environment Agency regulates nuclear power stations in England and Natural Resources Wales regulates nuclear power stations in Wales. The Environment Agency supports Natural Resources Wales with regulation of nuclear sites in Wales. Natural Resources Wales participates in GDA where a new nuclear power plant design is likely to be proposed for construction in Wales.

The generic design assessment we and Natural Resources Wales carry out is guided by standards and expectations set out in several regulatory regimes. However, our assessment focuses primarily on matters relevant to the disposal of radioactive waste.

This is for 2 reasons:

• radioactive waste is generated during operation and decommissioning of a nuclear reactor and its associated plant
• permitting the disposal and discharge of radioactive wastes has, historically, been the area of regulation with the longest lead time for our permitting of new nuclear power stations

Discharge and disposal of radioactive waste from a nuclear site require a permit under The Environmental Permitting (England and Wales) Regulations 2016 (EPR16).

The discharge of (non-radioactive) aqueous effluents, such as turbine condenser cooling water or from dewatering during construction, also require a permit under EPR16.

Some conventional plant, for example, combustion plant used as auxiliary boilers and standby power supplies, and incinerators used to dispose of combustible waste may require a permit under EPR16. Some combustion plant may also need a permit under  Greenhouse Gas Emissions Trading Scheme Regulations 2012.

The disposal of waste by depositing it on or into land, including excavation materials from construction, and other waste operations may require a permit under EPR16.

The abstraction of water, for example, for cooling or process use from inland waters or groundwater, except in some specific circumstances, requires a licence under The Water Resources Act 1991. Inland waters include rivers, ponds, estuaries and docks, among others.

The construction of new or enhanced flood defence structures, or modification of existing ones, requires an environmental permit under EPR16 (previously flood defence consent under The Water Resources Act 1991).

In England, the Environment Agency and ONR together form the competent authority for The Control of Major Accident Hazards Regulations 2015. In Wales, Natural Resources Wales and ONR form the competent authority. On-site storage of certain substances may fall under these regulations.

2. The SMR-300 design

This section provides a brief outline of the design and how waste will be created, processed and disposed of.

Outline of design

The SMR-300 is a pressurised water reactor (PWR) which can generate 300 megawatts (MW) of electricity (Holtec Britain Limited, SMR-300 Plant Overview, HI-2240590, Revision 0, May 2024). In the reactor core, the uranium oxide fuel (enriched up to 5.0% of uranium-235) is cooled by water under high pressure, which also acts as the neutron moderator necessary for sustained nuclear fission. The water cooling the fuel is circulated in the ‘primary circuit’ using pumps through the reactor pressure vessel and into a heat exchanger called a steam generator. Heat in the primary circuit is transferred to water in a secondary circuit via a steam generator. Water in the secondary circuit boils, producing steam, which directly drives a 2-stage turbine generator (high pressure and low pressure) to produce electricity. The steam is then condensed in the turbine condenser (which itself is cooled by a third water circuit), and the condensate is returned to the secondary circuit.

The SMR-300 design submitted for assessment in GDA is a twin-unit design comprising two SMR-300 reactors. The main facilities include a spent fuel storage pond, spent fuel dry store, water treatment systems for maintaining the chemistry of the water circuit, radioactive waste treatment and storage facilities and back-up systems for providing power in the event of loss of electrical supply from the grid. Holtec International intends to use diesel generators in some non-normal operation scenarios.

The SMR-300 is a PWR design with pumped circulation in normal operation. The design has one reactor pressure vessel and one steam generator with integral pressuriser connected by 2 hot legs and 2 cold legs, with reactor coolant pumps in each cold leg. There are two pipes that take the heated water from the reactor to the steam generator (hot legs) and two pipes that return the water to the reactor (cold legs). The reactor and steam circuit are located inside a stainless-steel containment structure The reactor is based on a standard PWR type technology, but with a novel annular reservoir (a large volume of water surrounding the containment structure to provide passive cooling in the event of an accident) and reduced size which will allow for modular construction.

The PWR type of reactor is widely used – there are currently around 300 PWRs operating around the world. There are a range of applications and sizes of PWRs, including power generation and marine propulsion.

Holtec International initially began GDA with its SMR-160 design. We received a letter in January 2024 (Holtec International, Letter 3295-R001_EA R0, January 2024) confirming the reactor design and name change to SMR-300. The name change is because the reactor output changed from 160 MW of electricity to 300 MW of electricity due to the water coolant circulation changing from passive to pumped circulation during normal operation.

The SMR-300 is still being designed and is, therefore, not in operation. The Canadian Nuclear Safety Commission (CNSC) completed a Phase 1 vendor design review (VDR) of the SMR-160 design in August 2020. The United States Nuclear Regulatory Commission (US NRC) has begun pre-licensing interactions with Holtec International initially on the SMR-160 design and currently on the SMR-300 design. Holtec International plans to construct the first of a kind (FOAK) SMR-300 at its Palisades site in Michigan, USA.

Sources, processing and disposal of radioactive waste

Radioactive waste in the form of solids, liquids and gases arise from activities associated directly or indirectly with operating and maintaining the reactor, and ultimately, from decommissioning the plant. 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. The SMR-300 radioactive waste systems are currently being designed. The liquid, gaseous and solid radioactive waste system design descriptions (SDDs) will be part of the supporting documents for the Safety, Security and Environment Case (SSEC) in Step 2 along with strategy, methodology and optioneering documents.

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

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

Effluent treatment facilities include:

• holdup and monitoring tanks
• filters
• demineraliser ion exchange resin beds
• heat exchangers

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

The main source of gaseous radioactive emissions is the primary circuit. Discharges from the primary circuit are collected by the gaseous radioactive waste system (GRW) and held for decay storage. Gaseous radioactivity will also be present in the main process buildings, which are serviced by the heating, ventilation and air-conditioning (HVAC) systems. Discharges from these systems to the atmosphere will be from an appropriate stack.

Radioactive wastes which are not discharged directly to the environment include spent ion exchange resins, spent filter media, evaporator concentrates and 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 holding tanks, treatment and packaging facilities, and storage areas for packaged waste. All radioactive plant components are likely to become waste when the plant is decommissioned.

Spent fuel will be stored under water for about 6 years in the spent fuel storage pool. The SMR-300 includes space for a dry fuel store to allow further storage prior to ultimate disposal in a geological disposal facility (GDF).

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
• oils and any other significant liquids or sludges
• worn-out plant and components and general waste materials

3. The environmental regulators’ process for the SMR-300 GDA

Process

We (the Environment Agency and Natural Resources Wales) and ONR are using the GDA to scrutinise Holtec International’s SMR-300 design and assess its acceptability for use in UK.

We are carrying out GDA of the SMR-300 before it has started construction. This allows us to identify potential regulatory design or technical issues early so that Holtec International (the Requesting Party) can address them.

GDA is not a legal requirement, and we are carrying out the GDA of the SMR-300 because the UK government has asked us to consider it. 

Step 1 is the preparatory part of the design assessment process when we make agreements with the Requesting Party and provide advice on the scope and development of a submission. The guideline length for Step 1 is 12 months. It includes a review and confirmation that the Requesting Party has established adequate arrangements for GDA. Step 1 of the GDA of the SMR-300 took 10 months, from October 2023 to August 2024. 

At the start of Step 1, the Environment Agency entered into an agreement with Holtec Britain Limited, a wholly owned UK subsidiary of Holtec International (the Requesting Party) under Section 37 of the Environment Act 1995 to carry out work and recover our costs for a 2-step GDA of the SMR-300. Natural Resources Wales entered into an agreement with Holtec Britain Limited under the Natural Resources Body for Wales (Establishment) Order 2012.  We began GDA of the SMR-300 after signing these agreements in October 2023.

We refer to Holtec International as the Requesting Party, and they are also the design authority. The GDA is being managed by Holtec Britain Limited, a wholly owned UK subsidiary of Holtec International.

We set out, jointly with ONR, a timetable for Step 1 of the GDA process in response to Holtec Britain Limited’s GDA programme. In addition to providing feedback and advice on the contents of the submissions, we agreed detailed working arrangements with Holtec Britain Limited covering matters such as:

• identifying and tracking documents
• how Holtec Britain Limited will document its environment case and submit it for assessment during the GDA process
• how Holtec Britain Limited will address any gaps in meeting our regulatory requirements, the expectations it has identified, and its plan for this work
• the arrangements Holtec Britain Limited has put in place to carry out the GDA
• the schedule and associated programme for subsequent steps
• the arrangements for initiating the public comments process

We carried out a regulatory readiness review which showed that we have all the necessary resources in place to begin work on Step 2 (fundamental assessment). Our review also considered the readiness review Holtec International carried out. This is considered in the detail of Step 1 activities in this report.

We have completed Step 1 of the GDA process. We discuss this in more detail in Section 4 – Details of Step 1 Activities, and give our conclusions.

Next steps

Our next step is to begin Step 2 (fundamental assessment). We expect to begin Step 2 of the SMR-300 GDA in August 2024. 

At the end of Step 2, we will publish a GDA Step 2 Statement setting out our regulatory position at this point and our findings from the fundamental assessment. Holtec International currently plans to stop GDA at the end of Step 2.

4. Details of initiation (Step 1) activities

This section summarises the outcome of the GDA Step 1 (initiation) activities.

Objectives

The objectives for Step 1 of GDA are: 

• that the Requesting Party should agree with the Environment Agency and Natural Resources Wales the process that will be followed in GDA
• to determine if the Requesting Party is ready to proceed to Step 2 of GDA

During Step 1, with the ONR, we carried out a joint assessment of the GDA project management arrangements to give us confidence in the quality of the GDA submissions. This is part of Holtec Britain Limited’s management for safety and quality assurance (MSQA) arrangements.  

We provided feedback and advice to Holtec Britain Limited on the GDA scope, the proposed schedule of submissions, the structure of the submissions, and our expectations of the contents of the parts of the submissions relevant to the environment case.

Scope of the GDA

Our GDA guidance expects the Requesting Party 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. The scope of the environment case should include all relevant topics and sufficient details about the nuclear power plant design. The scope should be clear about whether the GDA will be a 2 or 3 step assessment, and whether the Requesting Party is aiming for a SoDA to be issued. Full engineering details may not be available at the GDA stage, as some may only be finalised once the site-specific requirements are known and during the procurement and construction programme.

Where there is not enough information on a particular topic, we may agree to exclude that topic from the GDA scope, provided that the GDA remains meaningful, and the topic can be addressed effectively at a later stage. This could be during the application for site-specific environmental permits and during detailed design and procurement stages.

Holtec Britain Limited provided a scope document in February 2024 (Holtec Britain Limited, SMR-300 UK Generic Design Assessment Scope, HI-2240121, Revision 0, February 2024) and a revised version in May 2024 (Holtec Britain Limited, SMR-300 UK Generic Design Assessment Scope, HI-2240121, Revision 1, May 2024) following regulatory review. The scope covers the structures, systems and components (SSCs), the reactor design and layout, and the relationship with the GDA activities. Information on the engineering and systems, the structures and components and the level of design maturity is also included.

The scope indicates that Holtec International is intending to progress to the end of GDA Step 2. We agree the scope Holtec Britain proposes allows for meaningful assessment at Step 2.

The scope document is supported by topic engagement plans (TEPs) for Step 2 for each of our assessment topics. The TEPs aim to define the scope of the topic and set out an overall strategy for its development, to support the objectives of the Step 2 submissions. The TEPs are primarily a planning tool for the Requesting Party to help develop its strategy for the topic development and to identify required deliverables for the SSEC. We reviewed the scope and TEPs for the environmental topics and provided feedback to Holtec Britain Limited during May 2024. We agreed the scope and submission plans in June 2024.

There is an expectation to consider sustainability in the design and we have agreed with Holtec Britain Limited that sustainability will be included as a cross-cutting engagement topic within GDA. It is a topic of interest to us and Natural Resources Wales through our duties 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. Holtec Britain Limited recognises the importance of sustainable development, and all parties support the inclusion of sustainability as an engagement topic in GDA. We and Natural Resources Wales recognise Holtec Britain Limited’s willingness to explore this topic at a time when significant positive impacts could be realised from decisions made during the design process.

GDA timetable

GDA of the SMR-300 is currently planned to last 24 months.

Step 1 (initiation) started in October 2023 and finished in August 2024 – taking 10 months.

Step 2 is expected to start in August 2024 and finish in October 2025 – taking 14 months.

Project management and related arrangements for GDA

Our guidance states that during Step 1 of GDA the Requesting Party should set up:

• project management and technical teams
• arrangements for carrying out a GDA
• arrangements for preparing and submitting documents during Step 1
• arrangements for Step 2 of GDA

We worked with Holtec Britain Limited to make sure that it fully understood the requirements and processes that will be applied during GDA. We discussed its arrangements for resolving concerns and issues raised by the regulators through the regulatory questions process.

We also worked with Holtec Britain Limited to help develop and agree a project plan and other project management arrangements to support the submission of the SSEC during Step 2.

Interface arrangements

During GDA Step 1, the Requesting Party agrees with us and implements the interface arrangements to be used throughout GDA. This includes:

• meeting arrangements
• ensuring there is full access to any relevant commercially confidential information (including any which is the property of third parties)
• obtaining all the necessary export licences to enable the transfer of information to and from the UK for all relevant countries

The interface arrangements to be used throughout GDA were agreed and documented with Holtec Britain Limited, ONR, the Environment Agency and Natural Resources Wales (ONR, Generic Design Assessment Interface Arrangements with Holtec International, ONR-GDA-IN-001, Issue 1, February 2024). The interface arrangements ensure that all interactions, communications and information exchanges between the regulators and Holtec International, which are required as part of GDA, are properly defined and managed.

In all GDAs, the regulators review and assess submissions from the Requesting Party, using an agreed approach of 3 tiers of regulatory questions:

• Regulatory Query (RQ) – this is a request by the regulators for clarification and additional information – it does not necessarily indicate a perceived regulatory shortfall in the design or its substantiation
• Regulatory Observation (RO) – this is raised when the regulators identify a potential regulatory shortfall in the design or its substantiation – the Requesting Party must take action to resolve it
• Regulatory Issue (RI) – this is raised when the regulators identify a serious regulatory shortfall in the design or its substantiation which could prevent them from issuing a SoDA (or a Design Acceptance Confirmation (DAC) from ONR) – the Requesting Party must take action to resolve it

The interface arrangements define the approach to regulatory questions.

Review of Holtec Britain Limited’s arrangements for carrying out the GDA

During Step 1, we and ONR jointly assessed the management arrangements Holtec Britain Limited will use to carry out a GDA to give confidence in the quality of the submissions. This is part of Holtec Britain Limited’s MSQA arrangements. We carried out a relatively detailed assessment of the management arrangements, including quality assurance during Step 1 of the GDA to give us early confidence that:

• the design will be developed, and the submission produced, by suitably qualified and experienced people, including staff and contractors
• there will be an appropriate level of verification, review and approval of design and submission documents, including those produced by contractors, and the submission will accurately reflect the design
• the design will be developed, taking environmental requirements for all plant lifecycle stages into account
• design changes will be controlled, evaluated for their impact on the environment, recorded and reflected in the submission

Holtec Britain Limited’s GDA management arrangements are summarised in the project management plan (PMP) (Holtec Britain Limited, Holtec SMR-300 Generic Design Assessment Project Management Plan, HPP-3295-0001, Revision 3, April 2024) and the project quality plan (PQP) (Holtec Britain Limited, Holtec SMR-300 Generic Design Assessment Project Quality Plan, HPP-3295-0002, Revision 1, April 2024). The PMP sets out the scope of the project, management responsibilities, deliverables and project arrangements, including quality assurance, environment, health and safety (EH&S), project control, change management and stakeholder communications. The PQP sets out the quality assurance programme (QAP) for the 2-step SMR-300 GDA project.

Our expectations are set out in our GDA guidance for Requesting Parties. We carried out our assessment during Step 1 via reviews of submissions and an evaluation visit to Holtec Britain Limited’s office. Our guidance lists 9 topic areas that should be covered by Holtec Britain Limited’s management arrangements.

Developing the design

The SMR-300 design is being developed in the USA by Holtec International to the design freeze point under its project quality plan. This plan is based around the American Society of Mechanical Engineers’ (ASME) Nuclear Quality Assurance (NQA-1), but includes cross references to ISO9001 paragraphs, specifies the structure of the management system, and prescribes various quality related criteria, including design control.

We do not have concerns about the available arrangements that we have sampled that Holtec International has put in place to deliver the SMR-300 design. Further work will be required in Step 2 to confirm that the design principles Holtec Britain Limited is developing and the reviews it intends to carry out to test the design against UK requirements are likely to be sufficient to deliver an acceptable design.

Managing the GDA project

Holtec Britain Limited has adopted conventional project management arrangements, including setting project objectives, having quality assurance procedures, managing a schedule, and monitoring performance using metrics. Our engagement during Step 1 concludes that Holtec Britain Limited’s project management arrangements are good and that, following the appointment of additional staff in Step 1, we have no concerns with the implementation of Holtec Britain Limited’s project management arrangements.

Managing and controlling contractors and others involved in GDA

The Requesting Party’s staff include Holtec Britain Limited employees and embedded contractors from Mott MacDonald. Both categories are required to complete onboarding and on-the job-training (OJT) which was progressing well. During our evaluation visit we viewed information provided by contractor Mott MacDonald to Holtec Britain Limited on competencies of contractors working on the GDA project. The supplied list of qualifications and curricula vitae provided evidence that the contractors were qualified for their role.  Holtec Britain Limited appears to have suitable procedures in place to scope, manage and evaluate the work of staff and contractors.

Establishing the methodology used for identifying BAT and making sure it is used in the design

Holtec Britain Limited has developed an approach and application of BAT demonstration during Step 1 which will be implemented at the start of Step 2 and a BAT TEP (Holtec Britain Limited, Topic Engagement Plan – Best Available Techniques, HI-2240516, Revision 1, June 2024). The BAT TEP initial scope was narrow and was revised in Step 1 to broaden its scope and support the other environmentally facing TEPs. In Step 2, we need to follow up on the undertakings made and corrective actions set out by Holtec Britain Limited to demonstrate the extent to which BAT requirements are met by the design, and set out meaningful commitments by the end of Step 2.

Producing and maintaining the submission

Holtec Britain Limited provided submissions for the SSEC structure (Holtec Britain Limited, SMR-300 GDA Safety, Security and Environmental Case Structure, HI-2240064, Revision 0, January 2024) and its procedure for scoping, drafting, reviewing and updating the SSEC (Holtec Britain Limited, Holtec SMR-300 GDA Management of Safety, Security and Environmental Cases, HPP-3295-0012, Revision 0, April 2024). The procedure describes the roles of SSEC managers, authors and reviewers. A procedure on controlling the quality of GDA submissions is in draft. We had sight of this draft and of some of the records produced during our evaluation visit. We do not have concerns at present about the process for producing and managing the GDA submissions.

Ongoing communications with the regulators and matters raised by them during GDA

Holtec Britain Limited has agreed interface arrangements with the regulators and produced procedures to supply information in response to RQs, ROs and RIs (Holtec Britain Limited, Managing Regulators’ RQs, RIs & ROs, HPP-3295-0015, Revision 0, April 2024). It has also produced a procedure for the reference design process and GDA prospective design change register (Holtec Britain Limited, Holtec SMR-300 Generic Design Assessment Reference Design Process and GDA Prospective Design Change Register, HPP-3295-0017, Revision 0, May 2024) to manage design change proposals after the SMR-300 design freeze has been declared through stated commitment to implement design changes (or supply information) required to meet UK requirements.

Holtec Britain Limited has responded to several RQs during Step 1, and Step 2 engagement plans have been developed via the TEPs for each topic area. We do not have any concerns with Holtec Britain Limited’s communication with regulators or with the company’s response to matters raised by regulators during GDA.

Maintaining records of design and construction

Design requirements of the systems comprising the SMR-300 plant are set out in Holtec International’s System Design Description Procedure (Holtec International, SMR-160 System Design Description Procedure, HPP-160-3001, Revision 4, January 2023). The records to be kept are laid out in Holtec International’s System Requirements Notebook Development (Holtec International, System Requirements Notebook Development, HPP-160-3033, Revision 0, October 2022) and include diagrams and models. Design requirements and records are captured in documents stored in the Holtec International Document Organization and Control (HIDOC) database application. During our evaluation visit, we viewed the system design description and system requirements for the spent fuel pond. Over 80 design requirements were listed, and the design specification was thorough.

We do not have any concerns about the control of design process from the high-level Step 1 review. However, how BAT has been applied to demonstrate that exposures from disposals are as low as reasonably achievable (ALARA) (taking into account economic and social factors) have generally not been considered in the lead up to the design freeze, so we will need to assess Holtec Britain Limited’s identification of gaps and commitments during Step 2.

Controlling and documenting design modifications, both during and after completion of GDA

The design evolution and freeze process for SMR-300 development submission (Holtec International, Design Evolution and Freeze Process for SMR-300, HPP-160-3037, Revision 2, February 2024) sets out the steps necessary to complete the conceptual design of the SMR-300 subsystems. It describes the responsibilities and process for achieving the design freeze. This is a staged process of defining and enforcing the freeze or justifying design changes where needed. The System Requirements Notebook Development submission describes the design decision process. Guidance on identifying, tracking and resolving design decisions and project risks is provided in the Design Decision and Risk Management Procedure submission, which also lays out the responsibilities of decision makers, guidance on risk categorisation and resolution procedures, and requirements for decision records.

The SMR-300 Generic Design Assessment Reference Design Process and GDA Prospective Design Change Register submission cover all design changes proposed during the GDA project. Actions to be taken depend on the significance of the proposed design changes.

The SMR-300 Generic Design Assessment Capturing and Managing Commitments, Assumptions (and Requirements) submission (Holtec Britain Limited, Holtec SMR-300 Generic Design Assessment Capturing and Managing Commitments, Assumptions and Requirements, HPP-3295-0013, Revision 0, April 2024) describes the process of maintaining and reviewing commitments and assumptions (CARs) made by Holtec Britain Limited. The 8-step process includes categorisation and documentation (by topic lead) and maintenance and review of the register by the project manager. At the end of Step 2, Holtec Britain Limited intends to carry out a complete review of the SSEC, as well as resolution plans and design changes to ensure that all applicable CARs have been captured and taken forward into future iterations of the SSEC and SMR-300 design baseline.

Transferring information to prospective operators and providing ongoing support to them throughout the nuclear power plant reactor’s lifecycle

Providing information to prospective operators has not been addressed in current arrangements and should be addressed formally in Step 2.

The environment case

Our guidance expects the Requesting Party for GDA to agree with us the scope, structure and format of its environment case submission. 

Full engineering details of the reactor may not be available at the GDA stage. It is normal to finalise engineering details once the site-specific requirements are known and during the procurement and construction programme. However, the Requesting Party is expected to provide enough functional specifications for its design so that a meaningful GDA can be carried out.

A sufficiently detailed environment case needs to be developed. Our guidance expects the Requesting Party to provide relevant plant and process descriptions, including engineering drawings, process flow diagrams and other information that will help us understand the nuclear power plant design, its underpinning design philosophy and its environmental protection features.

We submitted an RQ on 2 April 2024, concerning Holtec Britain Limited’s GDA Scope submission (Environment Agency, Environment comments on SMR-300 UK Generic Design Assessment Scope, RQ01311, April 2024) to query the environmental relevant SSCs included in GDA scope and how the TEPs support the GDA scope. Holtec Britain Limited’s response to the RQ confirmed that the environmentally relevant SSCs, where an impact on the public or environment may be seen, are included in the GDA scope, and this detail is provided in the individual TEPs.

Environment case structure and content

Holtec Britain Limited provided a SSEC structure document which detailed the objective and content of each part of the SSEC. The SSEC is made up of the:

• preliminary safety report (PSR)
• preliminary environment report (PER)
• generic security report (GSR)
• preliminary safeguards report (PSgR)

Holtec Britain Limited stated that the objective of the PER is to present the environmental standards, criteria and management arrangements. This provides confidence that the design, construction, operation and decommissioning of the SMR-300 not only protects people and the environment from harm, but also applies BAT, by incorporating relevant good practice and operating experience. At entry to Step 2, the PER consists of four separate chapters, with an additional introduction, and generic aspects and site characteristics shared with the PSR:

• PER Chapter 1: Radioactive waste management arrangements
• PER Chapter 2: Quantification of effluent discharges and limits
• PER Chapter 3: Radiological impact assessment
• PER Chapter 4: Conventional impact assessment

A separate ‘Approach and Application of BAT’ document has been produced which discusses the Holtec Britain Limited approach to the application of BAT to the SMR-300.  During Step 2 the BAT PER chapter will be developed using the Claims, Arguments Evidence format to demonstrate BAT for the design and operation of SMR-300, responding to the specific GDA guidance on best available technique demonstration.

The SSEC will be supported by strategy, methodology and optioneering documents to make up the environment case.

During Step 1, we provided advice to Holtec Britain Limited on our expectations for the environment case in readiness for Step 2. We have not carried out a formal technical assessment of any of the documents received during Step 1 that make up the environment case. Our technical assessment will begin in Step 2.

Best available techniques (BAT)

During GDA, the Requesting Party must provide its approach for determining BAT to prevent or minimise the generation of radioactive waste and its environmental impact during the lifecycle of the plant, including design, construction, commissioning, operation and decommissioning.

Holtec Britain Limited provided a TEP on the scope and submissions plan for BAT assessment (BAT Demonstration Topic Engagement Plan, HI-2240516, Revision 0, April 2024). The initial version of the TEP did not meet our expectations to enable a fundamental assessment due to the number of fundamental gaps in the application of BAT for the reactor design. The other environmental TEPs referred out to the BAT TEP for claims and argument details, but the BAT TEP did not fulfil this role. We provided advice and guidance to Holtec Britain Limited and the BAT TEP was revised in Step 1 to broaden its scope and increase the level of detail shared with us (BAT Demonstration Topic Engagement Plan, HI-2240516, Revision 1, June 2024). Like other TEPs, it will be further developed during Step 2.

We submitted an RQ on 6 March 2024, concerning the consideration of environmental impacts and BAT assessment in reactor design decisions to understand how the best available techniques will be identified by a methodology that is timely, transparent, inclusive, based on good quality data, and properly documented. Holtec Britain Limited’s response to the RQ included noting that it will develop an optioneering methodology to support Step 2, that will describe how BAT and ALARP are to be considered in an optioneering process.

We submitted an RQ on 2 April 2024, concerning queries on 5 Step 1 submissions from Holtec Britain Limited, including the Step 1 – Codes and Standards Report (Environment Agency, Environment topic feedback on five Step 1 submissions, RQ01312, April 2024). We note that environmental codes and standards were excluded from the report, and we queried whether there will be a separate environmental codes and standards submission for Step 2, or whether it will be included in the PER. Holtec Britain Limited shared the relevant environmental codes and standards in a technical meeting with the regulators and confirmed more details are planned to be included in the PER chapters.

Discharges

Our GDA guidance expects the Requesting Party to present information on the quantities and types of radioactive waste (gaseous, liquid and solid) and spent fuel that are likely to arise from the reactor design.

Holtec Britain Limited provided a TEP on the scope and submission plan for the quantification of effluent discharges and limits assessment​ (Quantification of Effluent Discharges and Limits Topic Engagement Plan, HI-2240518, Revision 1, June 2024). The TEP was clear on the principles relevant to discharges and identification of risks and gaps. Our preliminary review of the TEP initially indicated that anticipated operational occurrences and headroom factors for limit setting appeared to be missing from the scope of the GDA, and Holtec Britain Limited clarified that these were in the GDA scope.

Assessment of this topic area, like other environmental topics, depends on a detailed source term being provided to demonstrate the minimisation of waste arisings and the calculation of discharges and limits. Holtec Britian Limited has confirmed that the normal operation source term will be available in Step 2, but later than previously planned. This means that some of the revised PER chapters will now be provided later in Step 2, and the schedule has, therefore, been revised accordingly.

Generic site and radiological impact assessment (RIA)

During GDA, the Requesting Party must provide information on the likely impact on people and the environment of any proposed discharges of gaseous and liquid radioactive waste.

Holtec Britain Limited provided a TEP on the scope and submission plan, which included provisional information on the methods it will use to assess these aspects (Holtec Britain Limited, Topic Engagement plan – Radiological Impact Assessment and Generic Site Description, HI-2240520, Revision 1, May 2024) and an outline of the expected impact on people and the environment, taking into account the characteristics of the generic site (Holtec Britain Limited, Generic Site Envelope Report for SMR-300 UK GDA, HI-2240069, Revision 1, February 2024). The generic site is a description of the type of site where the power plant could be built. The assessment will be based on estimated discharges to the environment. Discharges will be derived from existing PWR data until specific information on discharges from the SMR-300 becomes available.

We expect a description of the type of site where the power plant could be built (the generic site). This description should include the environmental characteristics and constraints, such as protected habitats. The generic site description will be an input to the assessment of the radiological impact on people and the environment.

Two generic sites have been selected to provide bounding radiological impact assessments, considering liquid effluent discharges to a coastal site and to a lake.

Solid waste, spent fuel and disposability

During GDA, the Requesting Party must provide information on the disposability of any solid radioactive waste arisings. We assess the solid waste, spent fuel and disposability topic jointly with ONR.

Holtec Britain Limited provided a TEP on the scope and submission plan for the radioactive waste management arrangements (Holtec Britain Limited, Topic Engagement Plan – Radioactive Waste Management Arrangements, HI-2240521, Revision 1, June 2024), including an outline of the disposability assessment during the GDA Step 2. Holtec Britain Limited has stated that it will share its plans and intentions with Nuclear Waste Services (NWS) early in the GDA process. NWS is part of the UK’s Nuclear Decommissioning Authority (NDA), brings together the leading nuclear waste management capabilities and will be the developer of the UK’s Geological Disposal Facility. NWS will provide an expert view to advise whether the RP’s proposals would result in radioactive waste and spent fuel that is compatible with NWS’s disposal facilities’ waste acceptance criteria (for low level waste [LLW] to the Low Level Waste Repository [LLWR]) or generic disposal system specification (for higher activity waste [HAW] destined for a geological disposal facility [GDF]). Holtec Britain Limited will obtain disposal advice from NWS on higher activity waste (HAW) from both operational and decommissioning wastes arisings and operational low-level waste (LLW). We are supportive of Holtec Britain Limited’s early engagement with NWS. We note that the complete information on radioactive waste will be in the PSR and PER parts of the SSEC. Therefore, Holtec Britain Limited will need to provide appropriate mapping to the information.

During GDA, the Requesting Party must provide information on the strategic considerations for radioactive waste management which underpin the design. It must also provide a description of all radioactive wastes and spent fuel arising throughout the nuclear power plant’s lifecycle, and the proposals for its management and disposal.

Holtec Britain Limited provided TEPs on the scope and submission plans for the spent fuel management (Holtec Britain Limited, Topic Engagement Plan – Spent Fuel Management, HI-2240526, Revision 1, June 2024) and decommissioning approach (Topic Engagement Plan – Decommissioning Approach, HI-2240500, Revision 1, June 2024), which included noting the provision of an integrated waste strategy (IWS) in Step 2, which will identify the expected radioactive waste and spent fuel arisings, as well as proposed management and disposal strategies. Other notable submissions include a spent fuel management strategy and a safety and environmental review of the HI-STORM UMAX system (an underground storage system for spent fuel that has not yet been permitted in UK). Holtec Britain Limited will provide a radioactive waste inventory submission in Step 2 to present the waste streams due to arise from the operational and decommissioning lifecycle phases of an SMR-300 and describe relevant radioactive and non-radiological characteristics.

The SMR-300 design does not currently include an intermediate level waste (ILW) store as waste is handled differently in the USA compared to the UK. The optioneering for the interim storage of ILW will be an area of interest for our assessment in Step 2 to ensure the wastes are ultimately disposable. Also, the radiological waste systems are contracted by Holtec International to be designed by a USA based contractor. In Step 2, we will seek to understand how UK and International Atomic Energy Agency (IAEA) requirements will be incorporated into the design of the systems.

Sampling and monitoring

Requesting Parties must provide appropriate information on sampling arrangements, techniques and systems for measuring and assessing discharges and disposals of radioactive waste. These must cover in-process monitoring and the monitoring of final discharges and disposals. Information is not required until later in Step 2, but can be developed and provided earlier in GDA.

During Step 1, Holtec Britain Limited provided a TEP on the scope and submission plan for its approach to radioactive discharge sampling and monitoring as a PER chapter to be developed in Step 2 (Sampling and Monitoring Topic Engagement Plan, HI-2240523, Revision 1, June 2024). The TEP showed it had adequately considered what will be required for sampling and monitoring discharges, provision for in-process monitoring, and that it will consider monitoring of non-aqueous liquids and solid wastes.

Conventional impact assessment (CIA)

In our guidance, the Requesting Party is expected to provide information about conventional aspects of the design, including potential impacts on people and the environment of discharges from back-up diesel generators, cooling and process water discharges, other waste disposals, and information about its approach to applying BAT (where applicable).

Holtec Britain Limited provided a TEP on the scope and submission plan covering the requirements in the guidance to Requesting Parties (Conventional Impact Assessment Topic Engagement Plan, HI-2240517, Revision 1, June 2024). During the GDA Step 1, we provided advice and guidance to help the Requesting Party produce a sufficiently detailed environment case. We reviewed documents submitted in Step 1 of GDA and provided feedback, but did not make an assessment. During the TEP review, we noted intentions to consider possible use of waste heat and reuse water which are good practices. We also noted that the options for cooling water arrangements are still open.

Sustainability of a design is not a formal area for assessment in GDA. We have agreed that it will be included as a cross-cutting topic throughout the GDA documents.

Holtec Britain Limited recognises the importance of sustainable development and, in support of its own activities, has agreed to incorporate sustainability into the CIA topic area for discussion during GDA. Several initial discussions took place on sustainability, and Holtec Britain Limited includes reference to sustainability assessment in the CIA TEP. Main areas of interest include understanding how sustainability has been considered in decision-making during the design process, with resulting impacts on the sustainability of the design, benchmarking within the nuclear and other industries, and understanding how sustainability-related factors will be monitored through performance indicators or metrics.

Standards and guidance

The Requesting Party is expected to show how it will take account of Environment Agency guidance, in particular our Radioactive substances regulation (RSR) objective and principles and the RSR generic developed principles for regulatory assessment.

Holtec Britain Limited identified the main generic developed principles related to each topic area in the associated TEP and stated that it will consider Environment Agency guidance when developing its environment case within Step 2.

Document submission

We agreed with the Requesting Party a schedule for submitting the environment case information at the end of Step 1 and during Step 2.

Holtec Britain Limited has provided a schedule for the submission of the environment case information at the end of Step 1, and during Step 2 for the SSEC and supporting documents. We have discussed the proposed schedule with Holtec Britain Limited and the submission schedule is acceptable.

The format of the SSEC will be as a portable document format (PDF).

Gap analysis and readiness review

Holtec International’s readiness review

Holtec International carried out a readiness review during May and June 2024 for entry into Step 2 (Holtec Britain Limited, SMR-300 GDA Step 2 Readiness Review, HI-2240809, Revision 0, June 2024). The readiness review involved representatives from Holtec Britain, Holtec International and an independent technical assessment (ITA) panel. The 4 ITA panel members’ experience spanned the GDA topic areas. The panel provided an independent view for determining the project’s readiness for Step 2 and fed the results back to Holtec.

The readiness review process involved the ITA panel reviewing evidence from Holtec Britain Limited, including the TEPs and draft SSEC chapters followed by a workshop. The sessions in the workshop included reviewing technical and organisational readiness, Step 1 expectations, ITA panel feedback and readiness scoring. The risks identified during the readiness review were included within Holtec International’s project risk register. There were 21 risks identified during the readiness review with a plan to mitigate, including availability of source term data and parts of the design being novel, and further analysis required for parts that may not align with UK expectations.

Following the Requesting Party’s self-assessment in its readiness review, Holtec International declared that it is ready to enter Step 2 of the GDA.

Our readiness review

Our GDA guidance for Requesting Parties requires that we should be ready to enter Step 2. To meet this requirement, we carried out a review of our readiness. As part of our engagement in Step 1, we have reviewed the submission schedules Holtec Britain Limited provided for the relevant parts of the SSEC case. We have agreed that there will be enough time after the submissions in Step 2 for our assessment. We have developed an assessment schedule for Step 2 that will match the submission schedules Holtec Britain Limited provided.

We have agreed that there will be enough content in the submissions for us to assess during Step 2. We considered if we have enough resources to carry out the assessment during Step 2 and suitable guidance to support the assessment process. 

We have joint regulator GDA webpages, hosted by ONR. The environment agencies also publish reports and GDA information on their own websites. The webpages are one of several communication channels used by the regulators to share information with the public.

We reviewed the progress of Holtec Britain Limited in Step 1 against the requirements in our guidance and the requirements in Appendix 2 in the ONR GDA Guidance to Requesting Parties, which we consider were met.

Our readiness to proceed into Step 2 was agreed by our New Reactors Programme Board.

Public comments and communication

The Requesting Party must put processes in place that allow the public to interact with it throughout Step 2 of the GDA process.

The Requesting Party should provide information on a public website about the proposed design and how it will meet standards for environmental protection, safety, security and safeguards. The website should enable the public to see the information the Requesting Party has provided to the regulators as part of GDA, make comments and ask questions. The Requesting Party must agree with the regulators the information that it will publish on its website. It will be expected to update this public information whenever it makes any significant changes to the information it submits to the regulators. The Requesting Party must also agree with the regulators the process and timescales it will use to respond to comments from the public. It must provide the comments and questions raised by the public to the regulators, as well as its responses.

Holtec Britain Limited has developed a website and identified materials to be published at the start of Step 2. This will include a process for managing and responding to public comments. The website and the comments process are on track to go live at the start of Step 2 of GDA.

5. Conclusions from Step 1 (initiation) assessment

The scope indicates that Holtec International is intending to progress to the end of GDA Step 2 (fundamental assessment), seeking a Step 2 Statement. This means that a SoDA will not be issued at the end of the GDA and further detailed design assessment work will need to take place before any future site-specific permissioning phase.

Interface agreements are in place which set out how Holtec Britain Limited will submit information and how we will track it. Also in place are arrangements for correspondence and meetings, and how regulatory questions (RQs, ROs, and RIs) will be raised and tracked. We have agreed with Holtec Britain Limited how it will publish the GDA information, how it will manage public comments, and when it will place documents on its website. Holtec Britain Limited currently plans to issue and publish the GDA submissions relevant to the environment at the start of Step 2 of GDA.

With ONR, we jointly carried out an assessment of Holtec Britain Limited’s management arrangements for GDA. Overall, based on our sampling, we consider that Holtec Britain Limited’s management arrangements are satisfactory for this stage of the GDA process. We have used our Step 1 assessment and review of our findings to develop an appropriate assessment plan for management arrangements in Step 2 of GDA. This includes assessment of Holtec Britain Limited’s progress in addressing the areas identified as gaps.

Holtec International carried out a readiness review for entry into Step 2 of GDA. It declared that it is ready to enter Step 2 of GDA, and identified 21 risks with a mitigation plan captured in a project risk register.

The environment agencies have carried out a review of Holtec Britain Limited’s progress in Step 1 and of its readiness reviews. We have determined that the arrangements and resources Holtec Britain Limited has put in place to carry out the GDA are adequate to progress to Step 2.

We have agreed a schedule for submitting the environment case information during Step 2. We have also agreed how any outstanding information from Step 1 will be dealt with in Step 2 of GDA.

The documentation Holtec Britain Limited provided addresses our information requirements for Step 1 of GDA as set out in our GDA guidance for Requesting Parties.

We have concluded that we can progress to Step 2 of GDA.

Our next steps will be to finalise our schedule of work and plans for Step 2, and then begin to review and assess the submissions that Holtec Britain Limited will provide during Step 2.