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Fukushima Daiichi accident as a stress test for the national system for the protection of the public in event of severe accident at NPP
Available online at www.sciencedirect.com
Nuclear Energy and Technology 3 (2017) 38–42 www.elsevier.com/locate/nucet
Fukushima Daiichi accident as a stress test for the national system for the protection of the public in event of severe accident at NPP V.A. Kutkov a,b,∗, V.V. Tkachenko a b Obninsk
a NRC “Kurchatov Institute”, 1 Kurchatov Sq., Moscow 123182, Russia Institute for Nuclear Power Engineering, NRNU “MEPhI”, 1 Studgorodok Kaluga Region, Obninsk 249040, Russia
Available online 27 March 2017
Abstract It is proposed that the circumstances of the Fukushima Daiichi nuclear accident on 11 March 2011 in Japan should be used as the framework for the stress test of the national system for the protection of public in the beyond design extension conditions at NPP. Stress tests of the public protection strategy show to what extent the national system is stable under the most unfavorable NPP conditions and give an understanding of the potential vulnerabilities and the ways to resolve them. A definition of the Fukushima stress test model has been provided, and the actions undertaken by Japanese authorities under the conditions of the Fukushima Daiichi accident have been considered as the response to this stress test. The stress test has revealed major vulnerabilities in the strategy for the protection of public in the event of an accident at an NPP, which was successfully proven many times by over a hundred exercises at different levels. The stress test showed that the principal vulnerability of protection strategy being in use in Japan in 2011 was the reliance on computer systems in the assessment of the emergency exposure for decision-making during the emergency response phase. It is proposed, that the Fukushima stress test should be used to identify the vulnerabilities in the Russian Federation’s strategy for the protection of public in the event of a nuclear accident and to use the lessons learnt from the test results to perfect this strategy. Copyright © 2017, National Research Nuclear University MEPhI (Moscow Engineering Physics Institute). Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license. (http://creativecommons.org/licenses/by-nc-nd/4.0/) Keywords: Radiological accident; Public protection strategy; Nuclear power plant; Fukushima Daiichi accident; Stress test.
Introduction The Fukushima Daiichi accident in Japan began on 11 March 2011. It is the only of the severe nuclear accidents, the technical details of which has been available online and are accessible to the expert community thanks to the IAEA’s participation in dissemination of verified information on the disaster. The materials disclosing the accident development, the environmental and radiological effects, as well as the government’s mitigation and public protection activities have ∗
Corresponding author. E-mail addresses: [email protected] (V.A. Kutkov), tkachenko@iate. obninsk.ru (V.V. Tkachenko). Peer-review under responsibility of National Research Nuclear University MEPhI (Moscow Engineering Physics Institute). Russian text published: Izvestiya vuzov. Yadernaya Energetika (ISSN 0204-3327), 2016, n. 4, pp. 67–77.
been gathered in a publicly available database [1]. This data formed the basis for a detailed analysis into the accident developments, sources and consequences described, along with the accident lessons learnt, in the IAEA Director General’s Report on the Fukushima Daiichi accident [2]. The Fukushima lessons are reflected in Part 3 and Part 7 of the international General Safety Requirements, which establish the international safety requirements to the protection of people in the event of a radiation accident [3,4]. According to these requirements, based on the ICRP’s 2007 Recommendations, governments shall cause protection strategies to be developed, justified and generally optimized at the emergency preparedness phase and implemented as part of emergency response through the timely use of these strategies. The strategy selection defines the government’s capability to protect people in the event of a severe nuclear accident [5].
http://dx.doi.org/10.1016/j.nucet.2017.03.007 2452-3038/Copyright © 2017, National Research Nuclear University MEPhI (Moscow Engineering Physics Institute). Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license. (http://creativecommons.org/licenses/by-nc-nd/4.0/)
V.A. Kutkov, V.V. Tkachenko / Nuclear Energy and Technology 3 (2017) 38–42
Strategy of the public protection in the beyond design extension condition at NPP The strategy of the public protection suggests that emergency preparedness is ensured and protective measures are undertaken for the protection of people at the emergency response phase. We shall consider two basic types of public protection strategies. The strategy of Type 1 is based on detailed planning of the public protection actions for postulated classes of Beyond Design Extension Conditions at NPP (BDEC). The BDECs are classified depending on the state of critical safety functions of the NPP [6,7]. The framework for the strategy of pre-planned response actions (PP-type strategy) is formed by the following components: - postulated BDEC classes in accordance with the potential radiological effects; criteria for the BDEC classification in the form of Emergency Action Levels (EAL) reflecting the state of critical safety functions of the NPP or observations [3,8,9]; - off-site emergency planning zones and distances for timely implementation of protective actions in the event of BDEC of a given class to ensure that public exposure is kept below the generic criteria [3,9]; - Operational Intervention Levels (OIL), a set level of a measurable quantity that corresponds to a generic criterion. If OIL is exceeded, it is expected that the public exposure will exceed the certain generic criterion [3,8,9]. OILs are used to update the range for the pre-planned protective measures implemented in accordance with EALs with respect to the BDECs of a given class; - generally sound and optimized concepts of operations for precautionary urgent protective actions and urgent protective actions within the emergency planning zones or distances in a BDEC of a given class [9]. The PP-type strategy [3,9] suggests that the preplanned protective measures start to be implemented in the event of a BDEC, without waiting for the total failure of the NPP’s defense in depth and the subsequent release of fission products but depending on how the states of the NPP basic safety functions change. The NPP operator shall evaluate the facility state and initiate pre-planned public protection actions [3,9]. An example of a predominantly PP-type strategy is the strategy developed in accordance with the international requirements in [9]. The guidelines for this strategy are discussed in [5,10]. The strategy of Type 2 is based on a concept that capabilities for public protective actions are developed at preparedness phase and measures taken ad hoc in accordance to development of emergency. The framework for this strategy of contingency response actions (CG-type strategy) is based on the following components: - criteria for the BDEC classification as an emergency, reflecting the loss of critical safety functions [6,7,11,12];
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the emergency declaration is followed by activation of the authorities empowered to make decisions on ad hoc implementation of the public protective actions; - monitoring of the source term or the contamination of residential to predict the radiological effects in local residents due to BDEC and severe release of fission products in the environment; - generic action levels expressed in terms of avertable dose for initiation of individual protective measures to mitigate the radiological effects of the BDEC and their respective OILs for the assessment of the contamination of residential area to justify the protective actions [13]. The CG-type strategy suggests [12,14] the follows. - In the event of degradation of the NPP critical safety functions, preparations shall be started for taking and implementing decisions on the public protection actions in case the NPP defense in depth fails completely; - After fission products are released and off-site contamination is formed, contingency public protective measures shall be taken based on environmental monitoring and projection of emergency progressing. The authorities with decision-making powers shall initiate public protective actions after emergency notification [12,14]. An example of CG-type protection strategy is the strategy adopted in Japan before the Fukushima Daiichi accident began. The combination of CG-type and PP-type strategy is used in the Russian Federation. For instance, the new Russian NPP design [15] limits the implementation of PP-type strategy by emergency planning area up to 890 m from the reactor facility. No actions should be pre-planned in vicinity of that area as for BDEC in INES level 4 [16]. The GC-type strategy shall ensure the protection of the public in more severe BDEC [12,14]. Fukushima Daiichi accident as a stress test model Stress test is a test form used to determine the stability of a system under conditions when the normal operating limits are exceeded. Stress test models for the public protection strategy show to which extent the national system is stable in the most unfavorable NPP events and give an understanding of the potential vulnerabilities and the ways to resolve them. According to international requirements [3], preparedness for the public protection in the event of a beyond design basis accident at an NPP shall be ensured through an analysis of: - on-site events (including highly unlikely events) which are postulated as capable to lead to severe deterministic offsite effects; - the events recorded during earlier accidents. Each severe NPP accident serves as a stress test model for the public protection system. For instance, following the Three Miles Island accident in 1979 in the USA, the US
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Maximal ambient dose rate on the site boundary, µSv/h
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Date and time Fig. 1. Results of radiation monitoring on the Fukushima Daiichi site boundary.
National Regulatory Commission introduced extra stringent emergency preparedness and response requirements in its NPP regulations [6,17]. In the wake of the 1986 Chernobyl accident in the USSR, conventions were approved on the early notification of a nuclear accident and on the assistance in the event of a nuclear accident or a radiological emergency [18]. The INES scale was developed [19]. The Fukushima Daiichi accident is a new stress test for national emergency preparedness systems. The Fukushima Daiichi accident began at 14:46 (Japan Standard Time) on 11 March 2011 as the result of the 9.0 magnitude Great East Japan Earthquake causing heavy damage to the infrastructure in the NPP vicinity. All six power transmission lines that connected the Fukushima Daiichi NPP to the outside world broke down. All reactors on the site were shut down automatically. External ac power supply was lost, and the emergency diesel generators started to de-energize safety functions, including emergency core cooling. At 15:36 (+0:00) the earthquake was followed by а tsunami as the result of which the Fukushima-1 NPP site (units 1–4) turned out to be covered with an about 5 m water layer. The NPP’s emergency diesel generators, batteries and switchgears located below the site level were flooded. The NPP power supply system failed for an indefinite time and the loss of safety functions became irreversible. Just few of the process monitoring instruments remained serviceable and the accuracy of responses by some of them was doubtful. Operation was continued by 11 on-site and boundary ambient dose rate (ADR) monitors. As the emergency core cooling for units 1, 2, 3 and the irradiated reactor fuel cooling in the spent fuel pool of unit 4 was lost, fuel meltdown started leading to a non-controlled release of fission products into the atmosphere. After 04:00 on 12 March, the area in the vicinity of the NPP was heavily contaminated [20]. The dynamics of the release is shown in Fig. 1 which presents the maximum ADR monitor values (see Figs. 4.1- 4.4 in [20]). The dashed line shows the EALs (500 μSv/h) for an emergency (a nuclear accident) to be declared in Japan under [16]. For Russian NPPs, the buffer area boundary ADR level for an emergency (a nuclear accident) to be declared is equal to 200 μSv/h [11].
Protective measures were initiated by the Japanese government at 15:36. The Fukushima NPP events during the period of time from 14:46 to 15:36 form the basis for the stress test model. The Fukushima stress test suggests modeling and assessment of the actions by the NPP operator, the government and local authorities in response to a beyond design basis accident at an NPP with the development of events in the same manner as in the Fukushima scenario. The Fukushima stress test model: - NPP blackout for an indefinite time as the result of an external event leading to the reactor shutdown; - loss of the capability to monitor the reactor parameters; - loss of the reactor control capability; - limited life of the emergency core cooling system; - serviceability of the ADR monitors on the site boundary (monitoring data is as shown in the Fig. 1). Verification of Japan’s public protection strategy by fukushima stress test As of 31 December 2010, Japan had 20 NPPs with 54 effective units [21]. There was an average of about 18,200 km2 of land per NPP in Japan, which is equivalent to an area with a radius of about 76 km. With such a concentration of hazardous installations, major emphasis has always been placed in Japan on ensuring the emergency preparedness. An accident of September 1999 at a nuclear fuel fabrication facility in Tokaimura was another stress test followed by the adoption of a special law on preparedness to nuclear accidents [16]. The law and respective regulations defined the responsibilities of the licensee, the NPP operator, local authorities, the national government and the organizations involved in ensuring emergency preparedness and response. Criteria were defined for the BDEC classification as emergencies and the framework of the strategy for implementation of the public protective actions was established [22]. This strategy placed the Prime Minister in charge of decision-making on the public protection, and assigned two ministries, the Ministry
V.A. Kutkov, V.V. Tkachenko / Nuclear Energy and Technology 3 (2017) 38–42
for Economy, Trade and Industry (METI), along with its Nuclear and Industrial Safety Agency (NISA), and the Ministry of Education, Culture, Sports, Science and Technology (MEXT), to the key roles in the preparation of decisions. In 2000–2008, under the METI and MEXT auspices, twenty Remote Emergency Response Management Centers, one for each NPP, and four Regional Technical Support Centers were established [22]. Also in 2000–2008, 126 emergency exercises were conducted by local authorities (prefectures) jointly with NPPs. In the same period, 9 one- or two-day exercises were held by the METI also jointly with NPPs. Annually, beginning in 2000, large-scale emergency exercises are held by the Japanese government at one of each NPP [22]. The strategy for the protection of the public in the event of an accident at a Japanese NPP is described in detail in [22,23]. The licensee (the NPP operator) is responsible for the identification and prior classification of the BDEC and its on-site mitigation. The responsibilities of the central government led by the Prime Minister include the final BDEC classification, declaration of the emergency or nuclear accident at the NPP, activation of response to the emergency of all levels, prediction of the emergency development and decisionmaking on public protective actions. Local authorities are in charge of protective actions undertaken by a direct order or recommendation from the Prime Minister. This CG-type protection strategy, proven in the course of numerous emergency exercises, was tested by the Fukushima Daiichi accident. At 15:42 on 11 March (+0:06) the NPP operator, as required by Section 10 of [16], informed the national and local authorities of a special event (NPP blackout) [15]. At 16:45 (+1:03) the NPP Operator informed the government and local authorities that water could not be pumped into the emergency core cooling system for units 1 and 2 which, as defined in [16], was to be classified as a nuclear emergency (a nuclear accident). At 17:42 (+2:00) the METI and the NISA affirmed the initial BDEC classification by the NPP operator at 16:45. The METI minister informed forthwith so the Prime Minister and requested for the official declaration of a nuclear accident at the NPP. At 18:30 (+2:48) the Prime Minister approved the declaration of the emergency. At 19:03 (+3:27) the government declared an NPP nuclear accident and established the national- and local-level emergency response centers. Both were headed by the Prime Minister. In a real accident situation, the METI and the MEXT failed to perform the public exposure prediction functions they were in charge of. To this end, SPEEDI, a computer-based System for Prediction of Environmental Emergency Dose Information, was developed under the MEXT auspices [22,24]. The SPEEDI operation requires knowing the total amount of radioactive products in the environment as the result of the radioactive release, their approximate isotope composition and other release parameters, the weather conditions at the time of the release, etc. The METI and the NPP operator were re-
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sponsible for providing this information, but, because of the plant blackout, it was not possible to assess the NPP state, to predict its evolution and, more importantly, to predict the release (see the figure). The situation turned out to be extremely uncertain and promising no chance of improvement because of the loss of power for an indefinite time: no initial data – no predictive assessment – no protective measures. Therefore, the stress test showed that, acting fully in accordance with the requirements of [16] and the CG-type strategy, the government and the prime minister failed to make any decision to protect the public for the six initial hours after the critical safety functions were lost completely. At 20:50 (+5:14) the governor of Fukushima prefecture ordered the evacuation of residents within a 2 km area around the plant [23]. No central government reaction for many hours made the governor take a decision which was running counter to the requirements in [16] but was in line with the lessons learnt by local government from emergency exercises. In 2000–2008, there were six exercises conducted by the Fukushima prefecture authorities jointly with the Fukushima Daiichi NPP [22] and two more jointly with the FukushimaDaini NPP, so it was obvious to the local government that a delay in decision-making on the protection of the public in the event of a nuclear accident was only increasing the risk of adverse effects. This decision, which was fully in line with the PP-type strategy as to the preventive protection measures initiated before the release of fission products [9], triggered the government actions. At 21:23 (+5:47), following the actions by Fukushima prefecture’s governor, the government ordered the evacuation of residents within a 3 km area and the sheltering of residents within a 3 km to 10 km area [23], without having SPEEDIbased predictions for the development of the situation. A day later, on 12 March, the government was going on with making decisions in contradiction to [16] and the adopted strategy. At 18:25 on 12 March, 27 hours after the total loss of critical safety functions, the government ordered the evacuation of residents in a 20 km area around the NPP [15]. The emergency response planning area around the Fukushima Daiichi NPP, defined prior to the accident in the local government’s emergency plan, had a range of 10 km, which was equivalent to the shortest distance from the NPP to the city of Minamisoma with a population of about 350 thousand [23]. The consequences of the unplanned and ill-prepared protective actions were drastic. According to official data, several dozen patients died in the nonscheduled emergency evacuation of hospitals and elderly care centers within the 20 km area [23]. According to [25], the number of fatalities totaled 60. Therefore, the strategy for the protection of Japan’s population in the event of a nuclear accident at an NPP with more than a 10-year history of formation after the adoption of [16], failed the Fukushima stress test that has revealed vulnerabilities not identified in over a hundred drills during 10 years. All decisions on the measures for the protection of the public in the NPP vicinity had to be made by the Japanese
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V.A. Kutkov, V.V. Tkachenko / Nuclear Energy and Technology 3 (2017) 38–42
government before the NPP defense in depth failed and fission products were released, exactly as was recommended in [3,9]. Based on this experience, the Japan’s nuclear regulator made a decision to stop to use SPEEDI and other such codes for decision-making on the public protection in the event of a nuclear accident [24]. At the present time, the emergency preparedness and response system is being actively restructured in Japan for the practical introduction of the PP-type strategy for the public protection in the event of a severe nuclear accident. To accelerate this process, [9] has been translated into Japanese which is rather a rare event in the IAEA history. Conclusions The Fukushima stress test has provided a graphic demonstration of the fact that the public protection strategy adopted in Japan cannot protect the public in the event of a nuclear accident at an NPP. The use of a similar strategy adopted in the Russian Federation would obviously fail to prevent as well heavy public exposure beyond the NPP site and to provide for the sufficient protection. In a real situation of the Fukushima Daiichi accident on 11 March 2011, the Japanese government was successful in avoiding such development of events only thanks to following, in contradiction to national law and regulations, the international requirements on emergency preparedness and response, set forth in [3] and spontaneously acted in accordance with the respective IAEA recommendations in [9]. The Fukushima stress test has provided a clear indication as to where Japan’s basic regulatory requirements needed a revision as far as emergency preparedness and public protection in the event of a nuclear accident are concerned. The Russian Federation’s strategy for the protection of the public in the event of a nuclear accident is the result of the lessons learned from the Chernobyl NPP disaster. The fastest possible identification of the strategy’s vulnerabilities requires the use of the Fukushima stress test and the lessons learnt from the test results to be used for the strategy perfection. References [1] Countermeasures for the Great East Japan Earthquake. WARP Web Archiving Project. NISA, Nuclear and Industrial Safety Agency of Ministry of Economy, Trade and Industry (METI). Available at: http:// warp.ndl.go.jp/ info:ndljp/ pid/ 3531775/ www.nisa.meti.go. jp/ english/ (27.12.2015). [2] The Fukushima Daiichi accident. Report by the Director General, Vienna: IAEA, 2015. [3] General Safety Requirements Part 7: Safety Standard Series No. GSR Part 7, IAEA, Vienna, 2015, p. 146. [4] Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards, General Safety Requirements Part 3, Safety Standard Series No. GSR Part 3, IAEA, Vienna, 2014. [5] V.A. Kutkov, V.V. Tkachenko, S.P. Saakyan, Izvestiya vuzov. Yadernaya Energetika (4) (2015) 5–14 (in Russian). Kutkov V.A., Tkachenko V.V., Saakian S.P. Basic strategies of public protection in a nuclear power plant beyond—design basis accident. Nuclear Energy and Technology 2 (2016) 24–29.
[6] V.A. Ostreykovsky, Operation of Nuclear Power Plants, Energoatomizdat Publication, Moscow, 1999 (in Russian). [7] Practical Basis for the Development and Justification of the WWER, in: M.V. Kovalchuk, V.A. Sidorenko, Yu.V. Markov (Eds.), Reactor Unit Performance and Safety, NRC “Kurchatov Institute” Publication, Moscow, 2015 (in Russian). [8] Criteria for Use in Preparedness and Response for a Nuclear or Radiological Emergency, IAEA Safety Standards Series No. GSG-2, IAEA, Vienna, 2011. [9] Actions to Protect the Public in an Emergency due to Severe Conditions at a Light Water Reactor, Emergency Preparedness and Response Series EPR-NPP PUBLIC PROTECTIVE ACTIONS, IAEA, Vienna, 2013. [10] T. McKenna, P. Vilar-Welter, J. Callen, R. Martincic, B. Dodd, V. Kutkov, Health Phys. 108 (2015) 15–31. [11] Regulations on the Declaration of an Emergency, Fast Transmission of Information and Organization of Prompt Assistance to Nuclear Power Plants in the Event of a Radiological Emergency, Federal Standards and Regulations in the Field of the Use of Atomic Energy, Gosatomnadzor of Russia Publication, Moscow, 2016 (NP-005-16)(in Russian). [12] Model Content of a Plan of Measures for the Protection of Personnel in the Event of an Accident at a Nuclear Power Plant, Federal Standards and Regulations in the Field of the Use of Atomic Energy, Rostekhnadzor Publication, Moscow, 2012 (NP-015-12)(in Russian). [13] Derived Intervention Levels for Use in a Nuclear Accident. Guidelines MU 2.6.1. 047 -08. Moscow. Rospotrebnadzor Publ., 2008 (in Russian). [14] Action Plan of Sverdlovsk Oblast for the Protection of Citizens in the Event of an Emergency at Beloyarsk NPP. Yekaterinburg, Government of Sverdlovsk Oblast. Ref. No. 1263-PP, 1999 (in Russian). Available at: http://docs.pravo.ru/document/view/4722315/28592015/ (20.04.2015). [15] Description and Context of the Accident, The Fukushima Daiichi Accident, IAEA, Vienna, 2015 Technical Volume 1/5. [16] Act on Special Measures Concerning Nuclear Emergency Preparedness, Act No. 156 of 1999, as last amended by Act No. 118 of 2006 (Japan). Available at: http:// www.cas.go.jp/ jp/ seisaku/ hourei/ data/ ASMCNEP.pdf (19.06.2016). [17] Infrastructure and methodologies for the justification of nuclear power programmes. Woodhead Publishing Series in Energy No. 28/ Edited by Agustín Alonso. Oxford: Woodhead Publishing Limited, 2012. [18] Convention on early notification of a nuclear accident and Convention on assistance in the case of a nuclear accident or radiological emergency. IAEA Legal Series No. 14. Vienna: IAEA, 1987. [19] The International Nuclear and Radiological Event Scale User’s Manual. 2008 Edition, Vienna: IAEA, 2009. [20] Radiological Consequences, The Fukushima Daiichi Accident, IAEA, Vienna, 2015 Technical volume 4/5. [21] Nuclear Power Reactors in the World. IAEA Reference data series No. 2. 2011 Edition. Vienna: IAEA, 2011. [22] National Report of Japan for the third Review Meeting of Joint, Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste, Government of Japan, 2008. [23] Emergency Preparedness and Response, The Fukushima Daiichi Accident, IAEA, Vienna, 2015 Technical volume 3/5. [24] Hirano, M. New Framework for Emergency Preparedness and Response in Japan: International Experts Meeting on Assessment and Prognosis in Response to a Nuclear or Radiological Emergency. 20–24 April 2015. – Vienna: IAEA, 2015. IAEA-CN-256. Available at: http://www-pub. iaea.org/ iaeameetings/ IEM9p/ Opening/ Hirano.pdf (29.04.2016). [25] M.A Michio Ishikawa, Study of the Fukushima Daiichi Nuclear Accident Process. What caused the Core Melt and Hydrogen explosion?, Springer, Tokyo, 2015.
Nuclear Energy and Technology 3 (2017) 38–42 www.elsevier.com/locate/nucet
Fukushima Daiichi accident as a stress test for the national system for the protection of the public in event of severe accident at NPP V.A. Kutkov a,b,∗, V.V. Tkachenko a b Obninsk
a NRC “Kurchatov Institute”, 1 Kurchatov Sq., Moscow 123182, Russia Institute for Nuclear Power Engineering, NRNU “MEPhI”, 1 Studgorodok Kaluga Region, Obninsk 249040, Russia
Available online 27 March 2017
Abstract It is proposed that the circumstances of the Fukushima Daiichi nuclear accident on 11 March 2011 in Japan should be used as the framework for the stress test of the national system for the protection of public in the beyond design extension conditions at NPP. Stress tests of the public protection strategy show to what extent the national system is stable under the most unfavorable NPP conditions and give an understanding of the potential vulnerabilities and the ways to resolve them. A definition of the Fukushima stress test model has been provided, and the actions undertaken by Japanese authorities under the conditions of the Fukushima Daiichi accident have been considered as the response to this stress test. The stress test has revealed major vulnerabilities in the strategy for the protection of public in the event of an accident at an NPP, which was successfully proven many times by over a hundred exercises at different levels. The stress test showed that the principal vulnerability of protection strategy being in use in Japan in 2011 was the reliance on computer systems in the assessment of the emergency exposure for decision-making during the emergency response phase. It is proposed, that the Fukushima stress test should be used to identify the vulnerabilities in the Russian Federation’s strategy for the protection of public in the event of a nuclear accident and to use the lessons learnt from the test results to perfect this strategy. Copyright © 2017, National Research Nuclear University MEPhI (Moscow Engineering Physics Institute). Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license. (http://creativecommons.org/licenses/by-nc-nd/4.0/) Keywords: Radiological accident; Public protection strategy; Nuclear power plant; Fukushima Daiichi accident; Stress test.
Introduction The Fukushima Daiichi accident in Japan began on 11 March 2011. It is the only of the severe nuclear accidents, the technical details of which has been available online and are accessible to the expert community thanks to the IAEA’s participation in dissemination of verified information on the disaster. The materials disclosing the accident development, the environmental and radiological effects, as well as the government’s mitigation and public protection activities have ∗
Corresponding author. E-mail addresses: [email protected] (V.A. Kutkov), tkachenko@iate. obninsk.ru (V.V. Tkachenko). Peer-review under responsibility of National Research Nuclear University MEPhI (Moscow Engineering Physics Institute). Russian text published: Izvestiya vuzov. Yadernaya Energetika (ISSN 0204-3327), 2016, n. 4, pp. 67–77.
been gathered in a publicly available database [1]. This data formed the basis for a detailed analysis into the accident developments, sources and consequences described, along with the accident lessons learnt, in the IAEA Director General’s Report on the Fukushima Daiichi accident [2]. The Fukushima lessons are reflected in Part 3 and Part 7 of the international General Safety Requirements, which establish the international safety requirements to the protection of people in the event of a radiation accident [3,4]. According to these requirements, based on the ICRP’s 2007 Recommendations, governments shall cause protection strategies to be developed, justified and generally optimized at the emergency preparedness phase and implemented as part of emergency response through the timely use of these strategies. The strategy selection defines the government’s capability to protect people in the event of a severe nuclear accident [5].
http://dx.doi.org/10.1016/j.nucet.2017.03.007 2452-3038/Copyright © 2017, National Research Nuclear University MEPhI (Moscow Engineering Physics Institute). Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license. (http://creativecommons.org/licenses/by-nc-nd/4.0/)
V.A. Kutkov, V.V. Tkachenko / Nuclear Energy and Technology 3 (2017) 38–42
Strategy of the public protection in the beyond design extension condition at NPP The strategy of the public protection suggests that emergency preparedness is ensured and protective measures are undertaken for the protection of people at the emergency response phase. We shall consider two basic types of public protection strategies. The strategy of Type 1 is based on detailed planning of the public protection actions for postulated classes of Beyond Design Extension Conditions at NPP (BDEC). The BDECs are classified depending on the state of critical safety functions of the NPP [6,7]. The framework for the strategy of pre-planned response actions (PP-type strategy) is formed by the following components: - postulated BDEC classes in accordance with the potential radiological effects; criteria for the BDEC classification in the form of Emergency Action Levels (EAL) reflecting the state of critical safety functions of the NPP or observations [3,8,9]; - off-site emergency planning zones and distances for timely implementation of protective actions in the event of BDEC of a given class to ensure that public exposure is kept below the generic criteria [3,9]; - Operational Intervention Levels (OIL), a set level of a measurable quantity that corresponds to a generic criterion. If OIL is exceeded, it is expected that the public exposure will exceed the certain generic criterion [3,8,9]. OILs are used to update the range for the pre-planned protective measures implemented in accordance with EALs with respect to the BDECs of a given class; - generally sound and optimized concepts of operations for precautionary urgent protective actions and urgent protective actions within the emergency planning zones or distances in a BDEC of a given class [9]. The PP-type strategy [3,9] suggests that the preplanned protective measures start to be implemented in the event of a BDEC, without waiting for the total failure of the NPP’s defense in depth and the subsequent release of fission products but depending on how the states of the NPP basic safety functions change. The NPP operator shall evaluate the facility state and initiate pre-planned public protection actions [3,9]. An example of a predominantly PP-type strategy is the strategy developed in accordance with the international requirements in [9]. The guidelines for this strategy are discussed in [5,10]. The strategy of Type 2 is based on a concept that capabilities for public protective actions are developed at preparedness phase and measures taken ad hoc in accordance to development of emergency. The framework for this strategy of contingency response actions (CG-type strategy) is based on the following components: - criteria for the BDEC classification as an emergency, reflecting the loss of critical safety functions [6,7,11,12];
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the emergency declaration is followed by activation of the authorities empowered to make decisions on ad hoc implementation of the public protective actions; - monitoring of the source term or the contamination of residential to predict the radiological effects in local residents due to BDEC and severe release of fission products in the environment; - generic action levels expressed in terms of avertable dose for initiation of individual protective measures to mitigate the radiological effects of the BDEC and their respective OILs for the assessment of the contamination of residential area to justify the protective actions [13]. The CG-type strategy suggests [12,14] the follows. - In the event of degradation of the NPP critical safety functions, preparations shall be started for taking and implementing decisions on the public protection actions in case the NPP defense in depth fails completely; - After fission products are released and off-site contamination is formed, contingency public protective measures shall be taken based on environmental monitoring and projection of emergency progressing. The authorities with decision-making powers shall initiate public protective actions after emergency notification [12,14]. An example of CG-type protection strategy is the strategy adopted in Japan before the Fukushima Daiichi accident began. The combination of CG-type and PP-type strategy is used in the Russian Federation. For instance, the new Russian NPP design [15] limits the implementation of PP-type strategy by emergency planning area up to 890 m from the reactor facility. No actions should be pre-planned in vicinity of that area as for BDEC in INES level 4 [16]. The GC-type strategy shall ensure the protection of the public in more severe BDEC [12,14]. Fukushima Daiichi accident as a stress test model Stress test is a test form used to determine the stability of a system under conditions when the normal operating limits are exceeded. Stress test models for the public protection strategy show to which extent the national system is stable in the most unfavorable NPP events and give an understanding of the potential vulnerabilities and the ways to resolve them. According to international requirements [3], preparedness for the public protection in the event of a beyond design basis accident at an NPP shall be ensured through an analysis of: - on-site events (including highly unlikely events) which are postulated as capable to lead to severe deterministic offsite effects; - the events recorded during earlier accidents. Each severe NPP accident serves as a stress test model for the public protection system. For instance, following the Three Miles Island accident in 1979 in the USA, the US
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Maximal ambient dose rate on the site boundary, µSv/h
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Date and time Fig. 1. Results of radiation monitoring on the Fukushima Daiichi site boundary.
National Regulatory Commission introduced extra stringent emergency preparedness and response requirements in its NPP regulations [6,17]. In the wake of the 1986 Chernobyl accident in the USSR, conventions were approved on the early notification of a nuclear accident and on the assistance in the event of a nuclear accident or a radiological emergency [18]. The INES scale was developed [19]. The Fukushima Daiichi accident is a new stress test for national emergency preparedness systems. The Fukushima Daiichi accident began at 14:46 (Japan Standard Time) on 11 March 2011 as the result of the 9.0 magnitude Great East Japan Earthquake causing heavy damage to the infrastructure in the NPP vicinity. All six power transmission lines that connected the Fukushima Daiichi NPP to the outside world broke down. All reactors on the site were shut down automatically. External ac power supply was lost, and the emergency diesel generators started to de-energize safety functions, including emergency core cooling. At 15:36 (+0:00) the earthquake was followed by а tsunami as the result of which the Fukushima-1 NPP site (units 1–4) turned out to be covered with an about 5 m water layer. The NPP’s emergency diesel generators, batteries and switchgears located below the site level were flooded. The NPP power supply system failed for an indefinite time and the loss of safety functions became irreversible. Just few of the process monitoring instruments remained serviceable and the accuracy of responses by some of them was doubtful. Operation was continued by 11 on-site and boundary ambient dose rate (ADR) monitors. As the emergency core cooling for units 1, 2, 3 and the irradiated reactor fuel cooling in the spent fuel pool of unit 4 was lost, fuel meltdown started leading to a non-controlled release of fission products into the atmosphere. After 04:00 on 12 March, the area in the vicinity of the NPP was heavily contaminated [20]. The dynamics of the release is shown in Fig. 1 which presents the maximum ADR monitor values (see Figs. 4.1- 4.4 in [20]). The dashed line shows the EALs (500 μSv/h) for an emergency (a nuclear accident) to be declared in Japan under [16]. For Russian NPPs, the buffer area boundary ADR level for an emergency (a nuclear accident) to be declared is equal to 200 μSv/h [11].
Protective measures were initiated by the Japanese government at 15:36. The Fukushima NPP events during the period of time from 14:46 to 15:36 form the basis for the stress test model. The Fukushima stress test suggests modeling and assessment of the actions by the NPP operator, the government and local authorities in response to a beyond design basis accident at an NPP with the development of events in the same manner as in the Fukushima scenario. The Fukushima stress test model: - NPP blackout for an indefinite time as the result of an external event leading to the reactor shutdown; - loss of the capability to monitor the reactor parameters; - loss of the reactor control capability; - limited life of the emergency core cooling system; - serviceability of the ADR monitors on the site boundary (monitoring data is as shown in the Fig. 1). Verification of Japan’s public protection strategy by fukushima stress test As of 31 December 2010, Japan had 20 NPPs with 54 effective units [21]. There was an average of about 18,200 km2 of land per NPP in Japan, which is equivalent to an area with a radius of about 76 km. With such a concentration of hazardous installations, major emphasis has always been placed in Japan on ensuring the emergency preparedness. An accident of September 1999 at a nuclear fuel fabrication facility in Tokaimura was another stress test followed by the adoption of a special law on preparedness to nuclear accidents [16]. The law and respective regulations defined the responsibilities of the licensee, the NPP operator, local authorities, the national government and the organizations involved in ensuring emergency preparedness and response. Criteria were defined for the BDEC classification as emergencies and the framework of the strategy for implementation of the public protective actions was established [22]. This strategy placed the Prime Minister in charge of decision-making on the public protection, and assigned two ministries, the Ministry
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for Economy, Trade and Industry (METI), along with its Nuclear and Industrial Safety Agency (NISA), and the Ministry of Education, Culture, Sports, Science and Technology (MEXT), to the key roles in the preparation of decisions. In 2000–2008, under the METI and MEXT auspices, twenty Remote Emergency Response Management Centers, one for each NPP, and four Regional Technical Support Centers were established [22]. Also in 2000–2008, 126 emergency exercises were conducted by local authorities (prefectures) jointly with NPPs. In the same period, 9 one- or two-day exercises were held by the METI also jointly with NPPs. Annually, beginning in 2000, large-scale emergency exercises are held by the Japanese government at one of each NPP [22]. The strategy for the protection of the public in the event of an accident at a Japanese NPP is described in detail in [22,23]. The licensee (the NPP operator) is responsible for the identification and prior classification of the BDEC and its on-site mitigation. The responsibilities of the central government led by the Prime Minister include the final BDEC classification, declaration of the emergency or nuclear accident at the NPP, activation of response to the emergency of all levels, prediction of the emergency development and decisionmaking on public protective actions. Local authorities are in charge of protective actions undertaken by a direct order or recommendation from the Prime Minister. This CG-type protection strategy, proven in the course of numerous emergency exercises, was tested by the Fukushima Daiichi accident. At 15:42 on 11 March (+0:06) the NPP operator, as required by Section 10 of [16], informed the national and local authorities of a special event (NPP blackout) [15]. At 16:45 (+1:03) the NPP Operator informed the government and local authorities that water could not be pumped into the emergency core cooling system for units 1 and 2 which, as defined in [16], was to be classified as a nuclear emergency (a nuclear accident). At 17:42 (+2:00) the METI and the NISA affirmed the initial BDEC classification by the NPP operator at 16:45. The METI minister informed forthwith so the Prime Minister and requested for the official declaration of a nuclear accident at the NPP. At 18:30 (+2:48) the Prime Minister approved the declaration of the emergency. At 19:03 (+3:27) the government declared an NPP nuclear accident and established the national- and local-level emergency response centers. Both were headed by the Prime Minister. In a real accident situation, the METI and the MEXT failed to perform the public exposure prediction functions they were in charge of. To this end, SPEEDI, a computer-based System for Prediction of Environmental Emergency Dose Information, was developed under the MEXT auspices [22,24]. The SPEEDI operation requires knowing the total amount of radioactive products in the environment as the result of the radioactive release, their approximate isotope composition and other release parameters, the weather conditions at the time of the release, etc. The METI and the NPP operator were re-
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sponsible for providing this information, but, because of the plant blackout, it was not possible to assess the NPP state, to predict its evolution and, more importantly, to predict the release (see the figure). The situation turned out to be extremely uncertain and promising no chance of improvement because of the loss of power for an indefinite time: no initial data – no predictive assessment – no protective measures. Therefore, the stress test showed that, acting fully in accordance with the requirements of [16] and the CG-type strategy, the government and the prime minister failed to make any decision to protect the public for the six initial hours after the critical safety functions were lost completely. At 20:50 (+5:14) the governor of Fukushima prefecture ordered the evacuation of residents within a 2 km area around the plant [23]. No central government reaction for many hours made the governor take a decision which was running counter to the requirements in [16] but was in line with the lessons learnt by local government from emergency exercises. In 2000–2008, there were six exercises conducted by the Fukushima prefecture authorities jointly with the Fukushima Daiichi NPP [22] and two more jointly with the FukushimaDaini NPP, so it was obvious to the local government that a delay in decision-making on the protection of the public in the event of a nuclear accident was only increasing the risk of adverse effects. This decision, which was fully in line with the PP-type strategy as to the preventive protection measures initiated before the release of fission products [9], triggered the government actions. At 21:23 (+5:47), following the actions by Fukushima prefecture’s governor, the government ordered the evacuation of residents within a 3 km area and the sheltering of residents within a 3 km to 10 km area [23], without having SPEEDIbased predictions for the development of the situation. A day later, on 12 March, the government was going on with making decisions in contradiction to [16] and the adopted strategy. At 18:25 on 12 March, 27 hours after the total loss of critical safety functions, the government ordered the evacuation of residents in a 20 km area around the NPP [15]. The emergency response planning area around the Fukushima Daiichi NPP, defined prior to the accident in the local government’s emergency plan, had a range of 10 km, which was equivalent to the shortest distance from the NPP to the city of Minamisoma with a population of about 350 thousand [23]. The consequences of the unplanned and ill-prepared protective actions were drastic. According to official data, several dozen patients died in the nonscheduled emergency evacuation of hospitals and elderly care centers within the 20 km area [23]. According to [25], the number of fatalities totaled 60. Therefore, the strategy for the protection of Japan’s population in the event of a nuclear accident at an NPP with more than a 10-year history of formation after the adoption of [16], failed the Fukushima stress test that has revealed vulnerabilities not identified in over a hundred drills during 10 years. All decisions on the measures for the protection of the public in the NPP vicinity had to be made by the Japanese
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government before the NPP defense in depth failed and fission products were released, exactly as was recommended in [3,9]. Based on this experience, the Japan’s nuclear regulator made a decision to stop to use SPEEDI and other such codes for decision-making on the public protection in the event of a nuclear accident [24]. At the present time, the emergency preparedness and response system is being actively restructured in Japan for the practical introduction of the PP-type strategy for the public protection in the event of a severe nuclear accident. To accelerate this process, [9] has been translated into Japanese which is rather a rare event in the IAEA history. Conclusions The Fukushima stress test has provided a graphic demonstration of the fact that the public protection strategy adopted in Japan cannot protect the public in the event of a nuclear accident at an NPP. The use of a similar strategy adopted in the Russian Federation would obviously fail to prevent as well heavy public exposure beyond the NPP site and to provide for the sufficient protection. In a real situation of the Fukushima Daiichi accident on 11 March 2011, the Japanese government was successful in avoiding such development of events only thanks to following, in contradiction to national law and regulations, the international requirements on emergency preparedness and response, set forth in [3] and spontaneously acted in accordance with the respective IAEA recommendations in [9]. The Fukushima stress test has provided a clear indication as to where Japan’s basic regulatory requirements needed a revision as far as emergency preparedness and public protection in the event of a nuclear accident are concerned. The Russian Federation’s strategy for the protection of the public in the event of a nuclear accident is the result of the lessons learned from the Chernobyl NPP disaster. The fastest possible identification of the strategy’s vulnerabilities requires the use of the Fukushima stress test and the lessons learnt from the test results to be used for the strategy perfection. References [1] Countermeasures for the Great East Japan Earthquake. WARP Web Archiving Project. NISA, Nuclear and Industrial Safety Agency of Ministry of Economy, Trade and Industry (METI). Available at: http:// warp.ndl.go.jp/ info:ndljp/ pid/ 3531775/ www.nisa.meti.go. jp/ english/ (27.12.2015). [2] The Fukushima Daiichi accident. Report by the Director General, Vienna: IAEA, 2015. [3] General Safety Requirements Part 7: Safety Standard Series No. GSR Part 7, IAEA, Vienna, 2015, p. 146. [4] Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards, General Safety Requirements Part 3, Safety Standard Series No. GSR Part 3, IAEA, Vienna, 2014. [5] V.A. Kutkov, V.V. Tkachenko, S.P. Saakyan, Izvestiya vuzov. Yadernaya Energetika (4) (2015) 5–14 (in Russian). Kutkov V.A., Tkachenko V.V., Saakian S.P. Basic strategies of public protection in a nuclear power plant beyond—design basis accident. Nuclear Energy and Technology 2 (2016) 24–29.
[6] V.A. Ostreykovsky, Operation of Nuclear Power Plants, Energoatomizdat Publication, Moscow, 1999 (in Russian). [7] Practical Basis for the Development and Justification of the WWER, in: M.V. Kovalchuk, V.A. Sidorenko, Yu.V. Markov (Eds.), Reactor Unit Performance and Safety, NRC “Kurchatov Institute” Publication, Moscow, 2015 (in Russian). [8] Criteria for Use in Preparedness and Response for a Nuclear or Radiological Emergency, IAEA Safety Standards Series No. GSG-2, IAEA, Vienna, 2011. [9] Actions to Protect the Public in an Emergency due to Severe Conditions at a Light Water Reactor, Emergency Preparedness and Response Series EPR-NPP PUBLIC PROTECTIVE ACTIONS, IAEA, Vienna, 2013. [10] T. McKenna, P. Vilar-Welter, J. Callen, R. Martincic, B. Dodd, V. Kutkov, Health Phys. 108 (2015) 15–31. [11] Regulations on the Declaration of an Emergency, Fast Transmission of Information and Organization of Prompt Assistance to Nuclear Power Plants in the Event of a Radiological Emergency, Federal Standards and Regulations in the Field of the Use of Atomic Energy, Gosatomnadzor of Russia Publication, Moscow, 2016 (NP-005-16)(in Russian). [12] Model Content of a Plan of Measures for the Protection of Personnel in the Event of an Accident at a Nuclear Power Plant, Federal Standards and Regulations in the Field of the Use of Atomic Energy, Rostekhnadzor Publication, Moscow, 2012 (NP-015-12)(in Russian). [13] Derived Intervention Levels for Use in a Nuclear Accident. Guidelines MU 2.6.1. 047 -08. Moscow. Rospotrebnadzor Publ., 2008 (in Russian). [14] Action Plan of Sverdlovsk Oblast for the Protection of Citizens in the Event of an Emergency at Beloyarsk NPP. Yekaterinburg, Government of Sverdlovsk Oblast. Ref. No. 1263-PP, 1999 (in Russian). Available at: http://docs.pravo.ru/document/view/4722315/28592015/ (20.04.2015). [15] Description and Context of the Accident, The Fukushima Daiichi Accident, IAEA, Vienna, 2015 Technical Volume 1/5. [16] Act on Special Measures Concerning Nuclear Emergency Preparedness, Act No. 156 of 1999, as last amended by Act No. 118 of 2006 (Japan). Available at: http:// www.cas.go.jp/ jp/ seisaku/ hourei/ data/ ASMCNEP.pdf (19.06.2016). [17] Infrastructure and methodologies for the justification of nuclear power programmes. Woodhead Publishing Series in Energy No. 28/ Edited by Agustín Alonso. Oxford: Woodhead Publishing Limited, 2012. [18] Convention on early notification of a nuclear accident and Convention on assistance in the case of a nuclear accident or radiological emergency. IAEA Legal Series No. 14. Vienna: IAEA, 1987. [19] The International Nuclear and Radiological Event Scale User’s Manual. 2008 Edition, Vienna: IAEA, 2009. [20] Radiological Consequences, The Fukushima Daiichi Accident, IAEA, Vienna, 2015 Technical volume 4/5. [21] Nuclear Power Reactors in the World. IAEA Reference data series No. 2. 2011 Edition. Vienna: IAEA, 2011. [22] National Report of Japan for the third Review Meeting of Joint, Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste, Government of Japan, 2008. [23] Emergency Preparedness and Response, The Fukushima Daiichi Accident, IAEA, Vienna, 2015 Technical volume 3/5. [24] Hirano, M. New Framework for Emergency Preparedness and Response in Japan: International Experts Meeting on Assessment and Prognosis in Response to a Nuclear or Radiological Emergency. 20–24 April 2015. – Vienna: IAEA, 2015. IAEA-CN-256. Available at: http://www-pub. iaea.org/ iaeameetings/ IEM9p/ Opening/ Hirano.pdf (29.04.2016). [25] M.A Michio Ishikawa, Study of the Fukushima Daiichi Nuclear Accident Process. What caused the Core Melt and Hydrogen explosion?, Springer, Tokyo, 2015.