Confidence in Nuclear Safety under Uncertainties and Unknowns

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1 Presented at PSA2017 September 25-28, 2017 Confidence in Nuclear Safety under Uncertainties and Unknowns September 25, 2017 Akira Yamaguchi University of Tokyo, JAPAN 1

2 Fukushima Dai-ichi Accident Lessons-learned have delivered strong message that uncertainties and unknowns exist no matter that we achieve the best safety Nuclear community may have lost confidence in reaction to sharp criticism The accident was manmade Regulatory capture Stopgap measure The disaster was made in Japan The National Diet of Japan, Fukushima Nuclear Accident Independent Investigation Commission, 2

3 Independent and Unified Regulatory Before Authority, Established in Sep After regulatory promotional MOE AEC Security NSC 2nd Check METI Promotion of nuclear energy NISA Regulation on Commercial facilities MEXT R&D of nuclear Regulation on RR, RI, Safeguards, Monitoring MOE NRA Safety, Security, Safeguards, RI, Monitoring, etc. AEC METI MEXT AEC : Atomic Energy Commission METI : Ministry of Economy, Trade and Industry MEXT : Ministry of Education, Culture, Sports, Science and Technology MOE : Ministry of the Environment NISA : Nuclear and Industrial Safety Agency (abolished) NSC : Nuclear Safety Commission (abolished) Regulatory promotional Source: Presentation by Mr. Shimizu, NRA Secretary-General, at the International Conference on Effective Nuclear Regulatory Systems on April 12, 2016, 6 3

4 Drastic Regulatory Reform Nuclear Regulation Authority Is Established Independence of promotional ministry (METI) Unified regulatory administration (METI, MEXT, Cabinet Office) Commercial reactor/research reactor/security Strict Regulatory Rules Are Established Severe accident prevention/progression/mitigation Extended external events consideration PRA is mandatory in safety analysis report Backfit rule is applied to all the nuclear facilities 4

5 Industry Initiative for Voluntary and Continuous Safety Enhancement Immediately safety enhancement measures were taken Recommendation of METI WG on Industry Voluntary Initiative of Reactor Safety Improvement (May, 2014) Risk management under the adequate framework Leadershipoftop management Peer review by JANSI Reciprocal and cooperative industry s activity based on technical insights Reflection of lessons-learned from Fukushima Dai-ichi accident Comprehensive PRA (plant-specific) Control of residual risk (Defense-in-depth and PRA) Safety research and its coordination Attitude to ingrain good practices in organizations and individuals Safety culture based on and supported by questioning attitude Operationalexperience andnewfindings Involvement ofstakeholders Strategic human resource development Overall optimization of safety-related activity 5

6 Strategic Energy Plan (April 2014) Nuclear power is an important base-load power source on the major premise of ensuring safety Restart nuclear power plants only if they are in conformity with the new regulatory requirements out of respect for the regulators Dependence on nuclear power generation will be lessened to the lowest possible. The dependence on nuclear energy will be carefully examined Agency for Natural Resources and Energy, Cabinet Decision on the New Strategic Energy Plan, 6

7 Long Term Perspective of Energy (July 2015) Perspective In 2030 Dependency on nuclear energy is to be 20-22% ~30% before 2011 Fraction of the base-load power source will be 56% Fraction of zero-emission energy will be 44% Agency for Natural Resources and Energy Long-term Energy Supply and Demand Outlook, 7

8 Timeline after Fukushima Dai-ichi Accident 03/11, 2011 Fukushima Dai-ichi Accident Immediate Safety Enhancement by Utilities 09/19, 2012 Establishment of Nuclear Regulation Authority 07/08, 2013 Enforcement of New Regulatory Requirement 04/11, 2014 Strategic Energy Policy (GOJ, Cabinet Office) 07/16, 2015 Long Term Energy Perspective (GOJ,Cabinet Office) 09/10, 2015 Restart Sendai NPP Unit 1 03/09, 2016 Injunction of Takahama 3 & 4 operation (Ohtsu Dist. Court) 03/28/2017 Disaffirmance (Osaka High Court) 06/20/ Year Life Extension of Takahama 1 & 2 Approved 08/09, 2017 Strategic Energy Policy Update Start (GOJ) Long term National Vision Looking at

9 Current NPP Operational Status 5 Units in Operation out of 60 Units In operation 5 (5/0) Operation approved by the NRA 7 (7/0) Under regulatory review 14(4/10) In preparation for application 19(5/15) Decommissioning 15(5/9/1) Total 60(26/34/1) 4 Units are younger than 20 Years Old Total (PWR/BWR/GCR) July 31,

10 Views of Government, Nuclear Regulation Authority and Electric Power Companies Japanese Government (Cabinet) GOJ restarts nuclear power plants, giving the highest priority on safety, and lessens dependence on nuclear power to the lowest possible Nuclear Regulation Authority Chairman I do not say an NPP is definitely safe even though it is in conformity of the new regulatory requirements Federation of Electric Power Companies We recognize risks of nuclear power and continuously eliminate/reduce the risks, continue to reduce the risk 10

11 If Safe Enough, Restart NPP NRA: I do not say an NPP is definitely safe Regulatory Initiative Industry Initiative Safe Enough? When is NPP Safe Enough? Restart NPP Industry: Residual risk exists. We continue to reduce risk 11

12 Questions on Nuclear Safety An NPP is in conformity of the regulatory requirement Is an NPP safe enough to restart? Why voluntary safety enhancement is necessary for an NPP already safe enough? There exists residual risk in an NPP Is it small enough to accept (not zero risk)? Why the NPP can restart with risk remains 12

13 Risk Management: To Understand and To Manage Knowns and Unknowns Risk Unknowns 13

14 ALARP: Individual Risks and Societal Concerns Make a judgement if tolerable? Risk Assessment Best available scientific knowledge Best available scientific advice Residual risk management by ALARP Periodical check if ALARP is appropriate Reducing risks, protecting people, HSE s decision making process (2001) 14

15 Restart of Sendai Nuclear Power Station, Unit 1 and Unit 2 Dismissal of Petition for Temporary Injunction The Fukuoka High Court, April 6, 2016 However, it is impossible under the current level of science and technology to ensure the perfect safety such that radioactive materials are released under no circumstances. We have no option but to make a judgement with regard to the safety to be achieved and ensured on the basis of conventional wisdom, in other words, the acceptable safety level or acceptable risk level. Conventional Wisdom on Acceptable Risk Level 15

16 Answer to the 1 st Question: ALARP As Low As Reasonably Practicable (ALARP) Risk assessment and risk management Best available knowledge and advice Periodical check if it is appropriate (reasonably practicable) We might be possessed by false assumption/obsession We must pursue low risk and are forced to do everything we can regardless of its effectiveness and cost We restart NPPs because we follow ALARP Voluntary safety enhancement ensures good ALARP 16

17 Role of Nuclear Energy (April, 2014) Nuclear power is an important base-load power source as a low carbon and quasidomestic energy source, contributing to stability of energy supply-demand structure, on the major premise of ensuring of its safety, because of the perspectives; 1) superiority in stability of energy supply and efficiency, 2) low and stable operational cost and 3) free from GHG emissions during operation.* *Strategic Energy Plan, Cabinet Office of Japan, April 2014, (Provisional Translation ) 17

18 Energy Policy Toward , Present and 2030 Target Unit Zero-Emission Power % Energy Saving Gl-Oil Carbon Dioxide Emission G-ton Electric Power Cost* T-JYen Self-Sufficiency Ratio % * Note Oil Price is low 1.00:1.31:0.57 (2010:2011:2017) In 2030, FIT (Feed-in Tariff) will be Target in 2050: 80% reduction of Greenhouse gas emission 18

19 The Fundamental Safety Objective Principle 4: Justification To protect people and the environment from harmful effects of ionizing radiation. This fundamental safety objective has to be achieved without unduly limiting the operation of facilities or the conduct of activities that give rise to radiation risks. Principle 4: Justification of facilities and activities Facilities and activities that give rise to radiation risks must yield an overall benefit. For facilities and activities to be considered justified, the benefits that they yield must outweigh the radiation risks to which they give rise. 19

20 Definition: What is Risk? Risk is an uncertain (generally adverse) consequence of an event or activity with respect to something that human beings value. Risks are often taken for opportunities associated with initiating activities or applying technologies. An introduction to the IRGC Risk Governance Framework, International Risk Governance Council, 2012 ISBN

21 How Safe Is Safe Enough? Target of Safety Enhancement Risk Eliminate Danger Control Uncertainty Uncertainty Unknown Safety Design Risk Management Safety Enhancement 21

22 Safety System Killed Driver April 22, 2017, in Saitama Prefecture A compact car fell down under the 15 meter cliff. The driver, 18 years old, was killed by the accident. Fellow passengers told that the car hit a rock of about 0.5x0.3x0.2 m on the road. The impact activated the air bag in the driver seat. The driver was unable to see front. The car was out of control and fell under the cliffs. 22

23 Target of Safety Enhancement: To Pour Water But Not Be Flooded Safe Enough? How safe is safe enough? 23

24 Answer to the 2 nd Question: Value Nuclear energy is something that we value. Usage of nuclear energy is justified Risks or uncertain consequences are managed at or around an appropriate level Therefore, risk is small enough to be worth an NPP be restarted 24

25 Restart of Sendai Nuclear Power Station, Unit 1 and Unit 2 Dismissal of Petition for Temporary Injunction The Fukuoka High Court, April 6, 2016 New regulatory requirements on seismic ground motion, seismic safety design, severe accident management: Judging the concepts, guides and standards separately, some risks remain. One can not deny that a better guides or standards exist. The regulatory requirements should be improved reflecting the most recent scientific and technical knowledge. Understanding those collectively from the viewpoint of ensuring seismic safety, they make highly rational systematic framework for ensuring overall safety. Risk remains but safe in aggregate 25

26 Open Issues (Lessons-Learned) Category 4: Reinforcement of safety infrastructure 27. Effective use of probabilistic safety assessment (PSA) in risk management Category 5: Safety Culture 28. Thoroughly instill a safety culture The decision by Fukuoka High Court implies No undue risk in comparison to other risks Social receptiveness of safety target, and ALARP principle works (1) Report of Japanese Government to the IAEA Ministerial Conference on Nuclear Safety, The Accident at TEPCO's Fukushima Nuclear Power Stations, June 2011.

27 Feasibility of Energy Policy Target at 2030 Dependency on nuclear energy is to be 20-22% NPPs in operation (5 units), operation approved (7 units) and under regulatory review (14 units) sum up to 17.9 % NPPs (26units) younger than 40 years at 2030 sum up to 17.2 % 3 or more units of 1,200MWe and life extension are needed to achieve the energy policy target at 2030 (20-22 % from nuclear) 27

28 Conclusions NPPs are safe enough and can be restarted because we value NPPs and we believe risks are managed Understanding the risk (PRA) Control and management of the risk Voluntary safety enhancement is necessary to achieve ALARP and to assure the residual risk is expected to be kept below enough an tolerable level Awareness of risk will reduce risk Voluntary safety initiative. The activities will be supported by a safety culture Risk insights work 28