Office for Nuclear Regulation An agency of HSE Japanese earthquake and tsunami: Implications for the UK nuclear industry Final Report HM Chief Inspector of Nuclear Installations September 2011 Office for Nuclear Regulation An agency of HSE © Crown copyright 2011 ONR Report ONR‐FR‐REP‐11‐002 Revision 2 First published September 2011 You may reuse this information (excluding logos) free of charge in any format or medium, under the terms of the Open Government Licence. To view the licence visit www.nationalarchives.gov.uk/doc/open‐ government‐licence/, write to the Information Policy Team, The National Archives, Kew, London TW9 4DU, or email [email protected]. Some images and illustrations may not be owned by the Crown so cannot be reproduced without permission of the copyright owner. Enquiries should be sent to [email protected]. AP1000 is a registered trademark of Westinghouse Electric Company LLC in the United Kingdom and may be used or registered in other countries. Other names may be trademarks of their respective owners. For published documents, the electronic copy on the ONR website remains the most current publically available version and copying or printing renders this document uncontrolled. HM Chief Inspector’s Final Fukushima Report Office for Nuclear Regulation An agency of HSE Acknowledgements In preparing this report I am indebted to many colleagues in the Office for Nuclear Regulation (ONR), those outside of ONR who have taken the time to provide submissions of many types, and members of the Technical Advisory Panel that I set up to provide independent authoritative advice. I am also very grateful to many dedicated scientists and engineers of other agencies and Government bodies whose excellent work I have had access to. Mike Weightman HM Chief Inspector of Nuclear Installations September 2011 HM Chief Inspector’s Final Fukushima Report Office for Nuclear Regulation An agency of HSE Foreword On 11 March 2011 Japan suffered its worst recorded earthquake. The epicentre was 110 miles east north east from the of the Fukushima Dai‐ichi (Fukushima‐1) nuclear power site which has 6 Boiling Water Reactors. Reactor Units 1, 2 and 3 on this site were operating at power before thed event an on detection of the earthquake shut down safely. Initially 12 on‐site back diesel generators were used to provide the alternating (AC) electrical supplies to power essential post‐trip cooling. Within an hour a massive tsunami from the earthquake inundated the site. This resulted in the loss of all but one diesel generator, some direct current (DC) supplies and essential instrumentation, and created massive damage around the site. Despite the efforts of the operators eventually back‐up cooling was lost. With the loss of cooling systems, Reactor Units 1 to 3 overheated. This resulted in several explosions and what is predicted to be melting of the fuel in the reactors leading to major releases of radioactivity, initially to air but later by leakage of contaminated water to sea. It is clear that this was a serious nuclear accident, with an International Nuclear and Radiological Event Scale (INES) rating of Level 7 (the highest level). Tens of thousands of people were evacuated from a zone extending 20km from the site and remain so today. So far, the indications are that the public health effects from radiation exposure are not great. The Secretary of State (SoS) for Energy and Climate Change requested on 14 March 2011 that I examine the circumstances of the Fukushima accident to see what lessons could be learnt to enhance the safety of the UK nuclear industry. I was asked to provide an Interim Report by the middle of May 2011, which was published on 18 May 2011, and this final report within six months. At the time of writing, not everything is known about the detailed circumstances and contributory factors, and may never be, given the state of the site after the tsunami. However, many facts are available, useful information has been submitted to us, more information has been gleaned from the International Atomic Energy Agency (IAEA) and other nation's regulatory activities, further analysis has been undertaken, and the Japanese Government has provided an extensive report. I also gained insights from my leading an international mission of experts to Japan, during which I visited the Fukushima Dai‐ichi (Fukushima‐1), Fukushima Dai‐ni (Fukushima‐2) and Tokai sites. As indicated in my Interim Report, this Final Report is wider, covering all types of nuclear installations in the UK. Both reports link into other work underway or planned which seeks to learn lessons such as the European Council "Stress Tests" and the work of the Nuclear Energy Agency (NEA) of the Organisation for Economic Co‐operation and Development (OECD) and the IAEA. As with the Interim Report, this Final Report does not examine nuclear policy issues. These are rightly matters for others and outside my organisation’s competence and role. It looks at the evidence and facts, as far as they are known at this time, to establish technically based issues that relate to possible improvements in nuclear safety and its regulation in the UK. HM Chief Inspector’s Final Fukushima Report Office for Nuclear Regulation An agency of HSE From our work in bringing together this Final Report, having reviewed all the additional information and our further analysis, I am confident that the conclusion and recommendations of my Interim Report remain substantiated. Where appropriate, I have added to these with further clarification and some additional conclusions and recommendations. Mike Weightman HM Chief Inspector of Nuclear Installations September 2011 HM Chief Inspector’s Final Fukushima Report Office for Nuclear Regulation An agency of HSE Summary Introduction On the 14 March 2011 the Secretary of State (SoS) for Energy and Climate Change requested HM Chief Inspector of Nuclear Installations to examine the circumstances of the Fukushima accident to see what lessons could be learnt to enhance the safety of the UK nuclear industry. The aim of this report is to identify any implications for the UK nuclear industry, and in doing so co‐operate and co‐ordinate with international colleagues. The SoS requested that an Interim Report be produced by the middle of May 2011, with a Final Report six months later. The Interim Report was published in May 2011. This is the Final Report, referred to above. This report considers the implications for the UK nuclear industry, and has been expanded from focussing mainly on the nuclear power sector to cover all UK nuclear facilities. This report provides some background on radioactive hazards, and how people are protected against them. It also provides background on nuclear power technology, and the approach to nuclear safety in the UK, internationally and in Japan. It also describes how we have taken forward the work and how we expect to report on final responses to our recommendations. The report details who we have liaised with and describes the measures we have put in place to provide independent technical advice for our work. The detailed circumstances of the accident in Japan are not yet fully known and some may not be possible to determine given the loss of control and of certain instrumentation. Nevertheless, we consider that there is sufficient information to further develop lessons for the UK, and it is important to seek to draw early lessons wherever we can and to ensure those lessons are put into action in the UK as soon as possible. Sufficient was known by the time our Interim Report was finalised to enable us to draw key conclusions and recommendations. Additional information has become available since our Interim Report; in particular, the report of the International Atomic Energy Agency (IAEA) fact‐finding mission to Japan, and a large body of information in a report by the Japanese government. We have reviewed all of this information, and that of the many submissions to us, as well as conducting our own further analysis. This has enabled us to review our Interim Report recommendations and conclusions and undertake a review of the UK regulatory regime and our standards. As a result we have clarified and supplemented our Interim Report recommendations and made some new recommendations and conclusions. We have also set out our approach for taking the work forward. In taking the findings in this report forward, we should recognise that to achieve sustained high standards of nuclear safety we all need to adhere to the principle of “continuous improvement”. This principle is embedded in UK law, where there is a continuing requirement for nuclear designers and operators to reduce risks “so far as is reasonably practicable” (SFAIRP), which for assessment purposes is termed “as low as reasonably practicable” (ALARP). This is underpinned by the requirement for detailed periodic reviews of safety to seek further improvements. This means that, no matter how high the standards of nuclear design and subsequent operation are, the quest for improvement should never stop. Seeking to learn from events, new knowledge and experience, both nationally and internationally, must be a fundamental feature of the safety culture of the UK nuclear industry. The UK nuclear regulatory system is largely non-prescriptive. This means that the industry must demonstrate to the Regulator that it fully understands the hazards associated with its operations and knows how to control them. The Regulator challenges the safety and security of their designs and operations to ensure their provisions are robust and that they minimise any residual risks. So, we expect HM Chief Inspector’s Final Fukushima Report Page (i) Office for Nuclear Regulation An agency of HSE the industry to take the prime responsibility for learning lessons, rather than relying on the Regulator to tell it what to do.