Office for Nuclear Regulation

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UK nuclear power station stress test report published

4 January 2012

European Council “Stress Tests” for UK nuclear power plants National Final Report December 2011

Safety reassessments undertaken at UK nuclear power stations in the light of events at Fukushima Dai-ichi have revealed no fundamental weaknesses.

A report published today by the Office for Nuclear Regulation, the UK's independent nuclear safety regulator, confirms that UK sites have identified and made improvements to enhance safety by learning from events in Japan.

The findings are contained in the UK national stress test report submitted to the European Council. It requested a targeted reassessment of safety at all European nuclear power plants based on the circumstances which occurred at Fukushima: extreme natural events challenging the plant safety functions and leading to a severe accident.

Licensees of the 33 operating or shutdown reactors in the UK within scope of the report have carried out the tests and the Office for Nuclear Regulation has reviewed the results. The UK national report has been published at

John Donald, a senior nuclear safety inspector at the Office for Nuclear Regulation, said:

“To date, no fundamental weaknesses in design and resilience have been identified at UK nuclear power plants, and lessons are being learnt from Fukushima to enhance safety, in line with our regulatory philosophy of continuous improvement.

“Fukushima provided the world a unique opportunity to learn from a serious nuclear accident. No matter how high our standards of safety, the quest for improvement must never stop. Work is already under way to improve safety at UK sites, such as bolstering flood defences and enhancing coolant supplies. We have also asked licensees of UK nuclear power stations to consider resilience against events that have only remote chances of happening in the UK.

“In line with the specifications of the stress tests, we now look forward to the UK's report being peer reviewed by colleagues from other European regulators. This may also identify further improvements that could be made.”


Notes to Editors:

1. The Office for Nuclear Regulation seeks to secure the protection of people and society from the hazards of the nuclear industry by ensuring compliance with relevant legislation and by influencing the nuclear industry to create an excellent health, safety and security culture.

2. The European Nuclear Safety Regulators Group (ENSREG) produced the criteria for the stress tests. The tests require licensees to evaluate the response of the power plant when facing a set of extreme conditions, as well as a verification of the preventative and mitigation measures adopted. This follows a defence in depth logic, i.e. multiple layers of defence should some layers fail.

3. All nations reports will be published on the ENSREG website

4. The UK has 18 operating nuclear reactors and 15 shutdown reactors which fall within the scope of the European stress tests. Shutdown reactors which no longer contain any fuel (for example Berkeley and Bradwell) are not in the scope.

5. The European stress tests cover only nuclear power plants. However, Mike Weightman, the UK's chief inspector of nuclear installations, is requiring all licensed nuclear installations in the UK to undertake a version of the stress tests. The report submitted to Europe includes stress test findings for nuclear power plants only. The Office for Nuclear Regulation intends to publish in Spring 2012 the findings of the stress tests covering all other licensed nuclear installations.