II.-1. Major nuclear power facilities in Japan

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1 II.-1. Major nuclear power facilities in Japan In Japan, there are 50 operable nuclear reactors in nuclear power plants in 17 locations and 6 reactors which are under decommissioning. In addition to these reactors, eight reactors for research are owned by Japan Atomic Energy Agency in three locations. In Japan, there are also facilities for fuel processing/reprocessing and radioactive waste disposal facilities, etc. Data source: A webpage of the Nuclear Regulation Authority, as of April Tomari NPP Locations of major nuclear facilities NPP Fuel processing facilities, etc. Uranium enrichment facilities Fuel reprocessing facilities Low-level radioactive waste disposal facilities Higashidori NPP Vitrified waste storage facilities Shimane NPP Kashiwazaki Kariwa NPP Shika NPP Tsuruga NPP Mihama NPP Ohi NPP Takahama NPP Onagawa NPP Fukushima Daiichi NPP Fukushima Daini NPP Tokai Daini NPP Processing facilities Reprocessing facilities Genkai NPP Processing facilities Hamaoka NPP Processing facilities Sendai NPP Ikata NPP

2 II.- 2. Nuclear power facilities around the world Estimate of global nuclear power generation The right chart shows IAEA* s estimate of global nuclear power generation. The IAEA estimates that nuclear power generation will increase by about 2.4% at the minimum and about 68% at the maximum by This is equivalent of reactors of 1 million-kw level more than today. Particularly, the number is expected to sharply rise in East Asia. * International Atomic Energy Agency North America Western Europe Eastern Europe East Asia Unit: Gw(e) (1 million kw) 米国 Latin America Africa Middle East/South Asia Southeast Asia/Pacific 日本 region Data source: IAEA REFERENCE DATA SERIES No.1 (2006, 2011, 2014 Edition)

3 II.- 3. Past major nuclear accidents (1/4) Three Mile Island accident 1. Date: March 28, Accident site: Unit 2, Three Mile Island Nuclear Power Plant, Pennsylvania, USA 3. Accident type: Reactor core s meltdown accident due to loss of coolant (INES level: 5) 4. Overview of the accident: The accident occurred at Unit 2 which was a pressurized-water reactor. A combination of maintenance incident (near-accident incident), equipment malfunction and human errors is presumed to have caused the accident. On the accident day, transportation work was underway to wash a filter resin of a steam condenser. During the work, an air operated valve closed, which was unusual. This caused the shutdown of the main feed-water pump and turbine in the secondary cooling water system. This prevented the second cooling water from being pumped and the reactor core s pressure including the primary cooling system increased. Then a safety valve automatically opened and the reactor urgently shut down. (i.e. control rods were inserted and nuclear reaction was suspended.) An emergency core cooling system (ECCS) started running (i.e. incident). At that time, the safety valve was left open (i.e. equipment malfunction) when the pressure fell. The coolant was lost by turning into steam. In addition to the malfunction, a plant worker manually stopped the ECCS (i.e. human error). This combination resulted in loss of the coolant and led to the meltdown. 5. Damage caused by the accident The radioactive materials released by the accident were about 93,000 tera*-becquerels of radioactive noble gases such as helium, argon and xenon, etc. It is estimated that the radiation level which the residents in the surrounding area of the power plant were exposed to was up to about 1mSv. * The Three Mile Island accident site

4 II.- 3. Past major nuclear accidents (2/4) Chernobyl accident 1. Date: April 26, Accident site: Unit 4, Chernobyl Nuclear Power Plant, Ukraine (part of the former Soviet Union) 3. Accident type: Meltdown and explosion due to a runaway nuclear reactor (INES Level: 7) 4. Overview of the accident: The accident occurred at a unit which was an RBMK (a light water graphite-moderated reactor) developed by the former Soviet Union independently. While an experiment was being conducted during a test operation, the test plan was changed and procedures were violated many times. The characteristics of the reactor as well as the plan change and procedures violations caused the reactor temperature to rise in a very short time. Then steam and hydrogen were generated very quickly, which led to explosions and fires. The government of the Soviet Union neither disclosed the accident both at home and abroad nor took any step to evacuate the residents living near the power plant soon after the accident. As a result, the residents were exposed to high-level radioactive materials. 5. Damage caused by the accident The official number of people killed by this accident from acute radiation syndrome in 1986, the accident year, was 28 including the plant staff and firefighters who responded to the accident. In three countries of Ukraine, Belarus and Russia (then the Soviet Union), a huge amount of radioactive materials were released into the atmosphere in a wide area. Most of them were Iodine-131 (1.76 million tera-becquerels), Cesium-137 (85,000 tera-becquerels), Strontium-90 (10,000 tera-becquerels), etc. In these countries, more pediatric thyroid cancer cases have been observed due to the internal exposure effects of radioactive iodine. Furthermore, since the affected populations stress causes health injuries, the importance of taking measures against it has been emphasized. The Chernobyl accident site Accumulated amount of Cesium-137 on the soil surface by the Chernobyl accident (Source: UNSCEAR)

5 II.- 3. Past major nuclear accidents (3/4) Overview of the criticality accident in a JCO plant, Tokaimura, Ibaraki 1. Date: September 30, Accident site: Tokai Works, JCO Co., Ltd., Tokaimura, Ibaraki Prefecture 3. Accident type: Criticality accident which occurred during nuclear fuel processing (INES Level: 4) 4. Overview of the accident While nuclear fuel was being processed in the nuclear fuel processing facilities, uranium solution reached critical conditions. Three workers while at work were exposed to neutron ray at an extremely close range. The accident was caused by violation of the operating procedures set by the Japanese government to avoid to reach a critical state. 5. Damage caused by the accident Two of the three workers were exposed to the radiation exceeding a fatal dose and died despite hard efforts made by a special team dedicated to the treatment. They were the first victims of a radiological accident in Japan. It is estimated that the two workers were exposed to 16-20Sv of radiation and 6-10Sv, respectively. The other worker who recovered is estimated to have been exposed to 1-4.5Sv. Besides these three workers, more than 600 people were exposed to radiation in the facilities. Residents within a 350m radius of the accident site were requested to evacuate. Residents within a 500m radius of the site were recommended to evacuate. Recommendation for sheltering indoors was issued to residents within a 10km radius of the site. 6. Other Following the accident, the Act on Special Measures concerning Nuclear Emergency Preparedness was enacted in December 1999, the year of the accident. This accident, including making this Act, influenced the subsequent nuclear power safety measures in Japan. The site of the criticality accident in a JCO Plant, Tokaimura

6 Below scale Incident Accident II.- 3. Past major nuclear accidents (4/4) INES (International Nuclear Event Scale): A scale developed by the IAEA and OECD/NEA represents the degrees of nuclear incidents, accidents and events in seven levels. The International Nuclear and Radiological Event Scale (INES) Level Criteria1: People and the environment Criteria Criteria2: Radiological barriers and controls at facilities Criteria3: Defense in depth Examples 7 Major accident - Major release of radioactive material with widespread health and environmental effects. Chernobyl NPP, USSR (now in Ukraine), 1986 Fukushima Daiichi NPP, Japan, 2011 (Provisional rating) 6 Serious accident - Significant release of radioactive material. 5 Accident with wider consequences - Limited release of radioactive material. - Several deaths from radiation. - Severe damage to reactor core. - Release of large quantities of radioactive material within an installation with a high probability of significant public exposure. Three Mile Island NPP, USA, Accident with local consequences - Minor release of radioactive material. - At least one death from radiation. - Fuel melt or damage to fuel resulting in more than 0.1% release of core inventory. - Release of significant quantities of radioactive material within an installation with a high probability of significant public exposure. Tokaimura fuel processing facility, Japan, Serious incident - Exposure in excess of 10 times the statutory annual limit for workers. - Non-lethal deterministic health effect from radiation. - Exposure rates of more than 1Sv/hr in an operating area. - Severe contamination in an area not expected by design, with a low probability of significant public exposure. - Near accident at a nuclear power plant with no safety provision remaining. - Lost or stolen highly radioactive sealed source. 2 Incident - Exposure of a member of the public in excess of 10mSv. - Exposure of a worker in excess of the statutory annual limits. - Radiation levels in an operation area of more than 50mSv/hr. - Significant contamination within the facility into an area not expected by design. - Significant failures in safety provisions but with no actual consequences. Mihama NPP Unit 2, Japan, Anomaly - Overexposure of a member of the public in excess of statutory limits. - Low activity lost or stolen radioactive source. - Monju fast beeder reactor, Japan, Hamaoka NPP, Japan, Mihama NPP Unit 3, Japan, Below scale No safety significance Event that could possibly challenge safety requirements. Event that did not challenge safety requirements. Out of scale No safety relevance Note: Sievert (Sv) is a unit of effective dose of radiation. (1mSv = 1/1000 of a sievert) Translation of a table in Graphical Flip-chart of Nuclear & Energy Related Topics 2012 published by the Federation of Electric Power Companies of Japan