Memorandum submited by Mr Phillip Bratby (NPS 14)

 

Draft National Policy Statement (NPS) for Nuclear Power Generation (EN-6)

 

Executive Summary

 

The current regime for the licensing of nuclear power stations is briefly described. The procedure has been successfully developed over many years. The applicant submits a safety case to the Nuclear Installations Inspectorate (NII), which grants a licence if it is satisfied that the risks to the general public and workers are as low as reasonably practicable. EN-6 is proposing the addition of a dangerous prescriptive element to the licensing regime. This interference in the licensing process must be resisted and the relevant sections of EN-6 should be deleted.

 

The effect of a new fleet of nuclear power stations upon the needs to store higher level waste is minor and it is expected that technological developments will be such that the safe long term storage of the wastes will be available when needed.

 

Introduction

 

1. My name is Phillip Bratby. I have a first class honours degree in physics from the Imperial College of Science and Technology (London University) and a doctorate in physics from Sheffield University. I am a semi-retired energy consultant, being the sole director of my own consultancy company. I worked in the military and commercial nuclear power industry for over 33 years. My main areas of expertise are in the safety and operation of pressurised water reactors. I was involved in the Sizewell B project from its inception, including the Sizewell B public inquiry, the design, construction, commissioning and first ten years of operation.

 

Part 1 Nuclear Licensing

 

2. The license to operate a nuclear power plant in the UK requires the applicant (licensee) to submit a safety case to the regulator (Nuclear Installations Inspectorate (NII)) which decides, based on the safety case and use of the NII Safety Assessment Principles (SAPS[1]) and the guidance provided by the Technical Assessment Guides (TAGs[2]), whether to grant a nuclear site licence. The NII does not prescribe the contents of the safety case or the data or methods on which it should be based. The onus is upon the applicant to produce a safety case that the regulator finds acceptable in that the overall risk to workers and members of the public is broadly acceptable or tolerable and is as low as reasonably practicable (ALARP[3]). The tolerable level of risk (TOR) to the public and workers from nuclear power stations was developed by the Health and Safety Executive (HSE) following recommendations made at the Sizewell B Public Inquiry[4]. The NII SAPS have been developed over many years and contain best practices to ensure safe operation of nuclear power stations.

 

3. The NII SAPS state: NIIs inspectors use these Safety Assessment Principles (SAPs), together with the supporting Technical Assessment Guides (TAGs), to guide regulatory decision making in the nuclear permissioning process. Underpinning such decisions is the legal requirement on nuclear site licensees to reduce risks so far as is reasonably practicable, and the use of these SAPs should be seen in that context.

 

4. In addition, the NII states[5]: 1.13 The licence conditions provide the basis for regulation by HSE. They do not relieve the licensee of the responsibility for safety. They are non-prescriptive and set goals that the licensee is responsible for meeting, amongst other things by applying detailed safety standards and safe procedures for the facility.

 

5. Thus it can clearly be seen that the UK licensing process is non-prescriptive. The adoption of a prescriptive licensing regime in the USA was one of the factors relevant to the Three Mile Island Accident. The imposition of prescriptive licensing rules by the US Nuclear Regulatory Commission (NRC) led the vendors to concentrate on the large loss of coolant accident (LOCA) to the virtual exclusion of the higher risk small LOCA. The UK regulatory regime enables the applicant to make his own safety case, which, through the use of a probabilistic safety analysis (PSA), ensures that all envisaged hazards and risks are included in the safety case so that the risks are made as low as reasonably practicable (the ALARP principle).

 

6. However, section 3.7 of EN-6 "Climate change adaptation" appears to be imposing prescriptive licensing rules on applicants. EN-6 states:

 

3.7.6 In consultation with the EA and NII, applicants should use the latest set of UK Climate Projections[6] and the Government's latest national Climate Change Risk Assessment when available, to ensure that they have identified appropriate measures to adapt to the risks of climate change. Applicants should apply as a minimum, the emissions scenario that the independent Committee on Climate Change suggests the world is currently most closely following - and the 10%, 50% and 90% estimate ranges. These results should be considered by the applicant alongside relevant research which is based on the climate change projections.

 

3.7.7 In addition the applicant should apply the high-emissions scenario - high impact, low likelihood - to those elements of their application that are critical to the safe operation of the station.

 

3.7.8 Should a new set of UK Climate Projections become available after the preparation of the ES, the IPC should consider whether they need to request further information from the applicant.

 

7. It is noted that a projection is essentially meaningless - one can draw a straight line through any trend and call it a projection. As long as a projection is not considered to be a prediction or a forecast, then it is just speculation and no weight should ever be attached to it in terms of planning or risk assessment and mitigation.

 

8. With regard to the effect of climate on nuclear power stations, the NII SAPS state:

 

208 External hazards include earthquake, aircraft impact, extreme weather, electromagnetic interference (off-site cause) and flooding as a result of extreme weather/climate change (this list is not exhaustive).

 

226 The reasonably foreseeable effects of climate change over the lifetime of the facility should be taken into account.

 

703 The timing of decommissioning should be considered on a case-by-case basis. Factors to be considered for their relevance should include:

p) future uncertainties including climate change;

 

9. Thus use of the NII SAPS will ensure that an applicant's safety case is based on a proper risk assessment of all external hazards, which includes any hazards resulting from changes to the climate. The NII does not prescribe what climate model should be used in calculating the risk and in mitigating the effect of the risk to make it ALARP. It is the responsibility of the applicant to determine and justify the current and future climate hazards that it should mitigate by design and operation and justify in the safety case.

 

10. The safety case of the licensee is maintained during operation through the Station Safety Report (SSR). This is a living document, maintained up-to-date as the station and its environment change. Similarly, the risks are maintained up-to-date through use of a Living Probabilistic Safety Assessment (LPSA), which accounts for changes to the station and its environment. Furthermore, a Periodic Safety Review (PSR) is carried out by the licensee every 10 years and continued operation requires approval by the NII. Thus the safety of the station is maintained ALARP by these non-prescriptive processes which will of necessity include any environmental changes, regardless of the cause and will use the best available sources of data.

 

11. In addition, the safety analysis performed by applicants or vendors of nuclear power plants is performed using configured, quality controlled computer codes which have been verified and validated and which have acceptable documentation consisting of user manuals and quality assurance manuals. The UK climate model on which the UK Climate Projections are based does not appear to be of the required quality to be used in a safety case. It is stated[7] that "We've taken the Met Office Hadley Centre science as the basis for our projections and we've created 400 different models from that, representing all that we know about the uncertainty in our model. We've then, also, combined that information with information from 12 international known models from around the world, which have been in the Intergovernmental Panel on Climate Change". Combining information from different models is not a statistically valid procedure. Under no circumstances should nuclear licensing be based upon the projections from a combination of 13 different computer models with little in the way of validation, verification, user manuals and quality control.

 

12. Furthermore the UK Climate Projections do not model external climate forcing[8]: These scenarios assume no future changes in natural external forcing, apart from a prescribed repetition of the 11 year cycle of solar insolation based on past observations. It is evident from a study of the UK Climate Projections that many non-evidence-based assumptions are made and very little confidence can be placed in the projections. Indeed the IPPC states[9] Models continue to have significant limitations, such as in their representation of clouds, which lead to uncertainties in the magnitude and timing, as well as regional details, of predicted climate change and it is known that cloud processes are among the most difficult to simulate with models and cloud feedbacks remain the largest source of uncertainty in climate sensitivity estimates.

 

13. The revelations from the emails and data leaked from the Climatic Research Unit (CRU) of the University of East Anglia have cast considerable doubt upon the science behind the hypothesis of man-made climate change, further under-mining the validity of the climate projections.

 

14. Were applicants to follow the prescriptive method of EN-6 which states at section 3.7.3: Climate change is likely to mean that the UK will experience hotter, drier summers and warmer wetter winters. There is a likelihood of increased flooding, drought, heat waves, intense rainfall events and other extreme weather events such as storms, as well as rising sea levels and thereby ignore other potential changes to the climate, there is a danger of underestimating the risks from external climatic events. The ongoing extreme weather in the UK reinforces the message that it would indeed be foolish to assume for safety purposes that winters would be warmer and wetter.

 

15. For example, one area which the safety case addresses is ensuring that staff can get to the power station in extreme weather conditions, which includes snow storms, blizzards and ice conditions and that the power station continues to be operated within the boundaries of the safety case. The prescriptive nature of section 3.7.3 of EN-6 suggests that the applicant should ignore such winter conditions because we are going to experience warmer wetter winters. Furthermore a cooler climate could result in falling sea levels and the potential for a frozen sea leading to loss of cooling water. A range of ambient cooling water and air temperatures are justified within the safety case. The analysis of such hazards should be addressed as part of the risk assessment in the safety case as stated in the above SAPS and not ignored as section 3.7.3 of EN-6 would appear to be prescribing.

 

16. Section 3.4 of EN-6 correctly identifies that the IPC does not get involved in the regulatory process:

 

the IPC should make its decisions in relation to a development consent application on the basis that:

the relevant licensing and permitting regimes will be properly applied and enforced;

it does not need to consider matters that are within the remit of the nuclear regulators.

 

and

 

The IPC should not review or revisit any regulatory decision that has already been made in relation to the proposed development. This will help to ensure that there is clarity and clear division between the regimes for planning and regulation of the nuclear industry.

 

17. A National Policy Statement should not be used as vehicle to impose prescriptive licensing rules on applicants for nuclear power stations.

 

Part 1 - Conclusions and Recommendation

 

18. The current nuclear plant licensing regime ensures that the safety case includes all risks and ensures that the risks are maintained ALARP throughout the lifetime of the plant. It is a dangerous precedent for a NPS such as EN-6, to interfere prescriptively in the licensing process. The IPC does not consider matters that are within the remit of the NII as discussed in section 3.4 of EN-6. Section 3.7of EN-6 is irrelevant to the IPC and should be deleted from EN-6. All references to UK Climate Impacts Programme 2009(UKCIP) should be deleted from EN-6.

 

January 2010
Part2 - Radioactive Waste Management:

 

19. I am in agreement with section 3.8 of EN-6 concerning "higher level waste" (High Level Waste (HLW) and Intermediate Level waste (ILW)) for the following reasons:

 

The major concern is the storage and ultimate long term disposal of legacy waste. This is of no relevance to the issue of the waste from a new fleet of nuclear power stations.

The waste from a new fleet of new nuclear power stations will be a minor contributor to the total waste ultimately requiring long term disposal.

The waste from a new fleet of new nuclear power stations can be safely stored in on-site cooling water ponds until such time as long term disposal is available. The activity and heat load rapidly decay and the requirements in terms of cooling, chemistry and security are simple and straight-forward. The alternative to on-site ponds is transfer to on-site sealed casks in dry fuel stores after a few years in a pond. The sealed casks are cooled by natural air circulation. The casks have a design life of 100 years.

It is inconceivable to imagine that by the time ultimate long term storage of the waste from a new fleet of new nuclear power stations is required (~120 years from now for HLW), major technological advances will not have been made. Better solutions will inevitably be found.

 

Part 2 - Conclusions

 

20. The long term disposal of ILW and HLW from a new fleet of nuclear power stations is not a significant safety issue.

 



[1] http://www.hse.gov.uk/nuclear/saps/saps2006.pdf

[2] http://news.hse.gov.uk/2008/04/08/nuclear-technical-assessment-guides-tags/

[3] http://www.hse.gov.uk/risk/theory/alarp.htm

[4] http://www.hse.gov.uk/nuclear/tolerability.pdf

[5] http://www.hse.gov.uk/nuclear/notesforapplicants.pdf

[6] http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=163&Itemid=287

[7]http://www.metoffice.gov.uk/climatechange/guide/ukcp/dr_vicky_pope_talk_about_ukcp09_transcript.pdf

[8] http://ukclimateprojections.defra.gov.uk/content/view/2036/517/

[9] http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter8.pdf