Research and analysis

Nuclear power station cooling waters evidence on 3 aspects: summary

Published 17 April 2019

Applies to England

1. Chief Scientist’s Group research summary

Nuclear power stations require large volumes of water from coasts or estuaries for cooling. The abstraction and discharge of this water can damage the environment. This study reviews the evidence on 3 aspects of cooling water abstraction and discharge that are particularly relevant to the protection of animal and plant life (biota):

• information on fish deterrent systems
• the regulatory approach taken by other countries
• modelling methods used to assess the impact of cooling water systems on fish and other biota

These aspects were identified through a previous scoping study ‘Protecting biota from cooling water intakes at nuclear power stations - SC160009/R’. They are of particular importance in the regulation of new-build nuclear power stations in the UK.

The Environment Agency wants to minimise the environmental impact of cooling water abstractions and discharges at these power stations.

The rigorous approach used to assess the scientific evidence provides confidence that the review was comprehensive.

The information assessed in this report may have relevance to other large-scale water intakes and discharges such as those for existing nuclear and conventional power stations, and tidal hydropower.

1.1 Background

New-build nuclear power stations in the UK will require large volume intakes of cooling waters from estuarine or coastal sites. A 2010 Environment Agency report (SC070015/SR3) included some evidence on methods to reduce the impact on biota from cooling water intakes. A brief scoping study in 2018 for the Environment Agency (SC160009/R) summarised recent advances in methods and technologies for biota protection in cooling water systems.

Following the 2018 scoping study, the 3 aspects listed above were considered to be of high importance to the regulation of cooling water systems. This current study reviews the recent available information on these 3 subjects.

1.2 Results

Fish deterrent systems

Some fish deterrent technologies are suitable for the large cooling water intakes needed for nuclear power stations. The majority of studies into these technologies are for on-shore intakes at coastal, riverine or lake environments. Few studies cover off-shore intakes at coastal or estuarine environments similar to UK nuclear power station requirements. Information on maintenance and reliability of the technologies is limited.

Different deterrent methods are more suitable for some species, but none is likely to effectively protect all species or age ranges. The effect of impingement (contact with the cooling water equipment) and entrainment (unwanted uptake into the cooling water system) on biota at population levels is not well understood.

Regulatory approach taken by other countries

A review of international policy and practice for cooling waters intake systems at coastal and estuarine power plants was undertaken. In most cases, information was suitable for comparison with the new build nuclear power stations in the UK. There is little evidence on the implications and effectiveness for biota protection of decisions taken by regulators in other countries.

Regulation and practice in the USA was particularly considered because in 2014, following a long legal review process, the US Environmental Protection Agency issued a rule that requires the minimisation of cooling water intake volumes to protect biota. Although the US regulatory regime is not directly comparable with that in the UK, there is some information available which is important to consider for the site-specific permitting approach of the UK.

Assessing the impact on fish and other aquatic life

There have been recent advances in modelling approaches which can assess the impact of cooling water systems on fish populations. Losses of fish across the population age range can be compared to an estimate of:

• adults lost in a population (equivalent adult value)
• the impact on a fish stock (equivalent area of lost production)

Impacts from both impingement on the screening equipment and entrainment through the cooling water system can be modelled.

Several models are available which assess impacts from cooling water systems on fish populations, or which assess long term stock and ecosystem implications. There are large uncertainties in the input data used for modelling, and there is little observed data on which to base modelling predictions. Therefore uncertainty in the model predictions is high. These modelling approaches are limited to considering fish populations rather than other biota.

1.3 Publishing details

This summary relates to information from project SC170021, reported in detail in the following output:

Report:

SC170021/R1 Nuclear_power_station_cooling_waters_evidence_on_3_aspects_SC170021

Title:

Nuclear power station cooling waters: evidence on 3 aspects

April 2019

Project manager:

Louise Paul

Research Contractor:

APEM Ltd
First Floor
7 Old Field Road
Bocam Park
Pencoed
CF35 5LJ

Tel: 01443 239205

This project was commissioned by the Environment Agency’s Research, Analysis and Evaluation group, which provides scientific knowledge, tools and techniques to enable us to protect and manage the environment as effectively as possible.

If you have any questions about this report please email research@environment-agency.gov.uk.