The June 1896 earthquake of estimated magnitude 8.3 produced a tsunami with run-up height of 38 metres in Tohoku region, killing more than 27,000 people. In units 1, 2&4 there were cooling problems still evident on Tuesday 15th. (Japan Times 17/11/13) Another reported contrast from the Reconstruction Agency is that some $30 billion had been paid to 84,000 nuclear accident refugees but only some $20 billion to 300,000 tsunami survivors in the Tohoku region. Restrictions were placed on the distribution and consumption of food and the consumption of drinking water. In response, government officials designated a wider zone, extending to a radius of 30 km around the plant, within which residents were asked to remain indoors. restart. Also in November 2011 the Japan Nuclear Technology Institute published a 280-page report on the accident, with proposals to be addressed in the future. In addition it removed a lot of rubble with remote control front-end loaders, and this further reduced ambient radiation levels, halving them near unit 1. The Foreword to the Director General’s report in 2015 states: "A major factor that contributed to the accident was the widespread assumption in Japan that its nuclear power plants were so safe that an accident of this magnitude was simply unthinkable. Power was restored to instrumentation in all units except unit 3 by 25 March. By March 2016 total decay heat in units 1-3 had dropped to 1 MW for all three, about 1% of the original level, meaning that cooling water injection – then 100 m3/d – could be interrupted for up to two days. In recognizing that fact, each of us (every Japanese citizen) should reflect on our responsibility as individuals in a democratic society.". By the end of 2014, an Advanced ALPS of 500 m3/d had been added, making total capacity 2000 m3/d. A third explosion occurred on March 15 in the building surrounding reactor 2. Most of the release was by the end of March 2011. It also summarised radioactive releases and their effects. However, the radiation levels in most of the evacuated areas were not greater than the natural radiation levels in high background areas elsewhere in the world where no adverse health effect is evident, so maintaining the evacuation beyond a precautionary few days was evidently the main disaster in relation to human fatalities. This focuses on a number of questions which remained unexplained in the 2012 National Diet Investigation Commission report. 12 March
The Daiichi (first) and Daini (second) Fukushima plants are sited about 11 km apart on the coast, Daini to the south. The death toll directly due to the nuclear accident or radiation exposure remained zero, but stress and disruption due to the continuing evacuation remains high. http://www.reconstruction.go.jp/topics/20121102_sinsaikanrensi.pdf
The ponds hold some fresh fuel and some used fuel, the latter pending its transfer to the central used/spent fuel storage on site. 15:42 TEPCO made the first emergency report to the government. At that time the explosion was thought to have damaged the containment vessel housing the fuel rods. 20 mSv/yr was also the general limit set for children's dose rate related to outdoor activities, but there were calls to reduce this.In areas with 20-50 mSv/yr from April 2012 residency is restricted, with remediation action taken. There was some use of built-in plumbing for unit 2. In 2016 Kurion (now owned by Veolia) completed a demonstration project for tritium removal at low concentrations, with its new Modular Detritiation System (MDS),* in response to a JPY 1 billion commission from METI. The 2013 Japan trade deficit was JPY 11.5 trillion. In September 2017 the government updated the June 2015 decommissioning roadmap, with no changes to the framework, and confirming first removal of fuel debris from unit 1 in 2021. Initially cooling would have been maintained through the main steam circuit bypassing the turbine and going through the condensers. Before the fire pump could be used RPV pressure had to be relieved via the wetwell, which required power and nitrogen, hence the delay. In September 2013 Tepco commenced work to remove the fuel from unit 6. According to a survey released by the prefectural government in April 2017, the majority of people who voluntarily evacuated their homes after the accident and who are now living outside of Fukushima prefecture do not intend to return. Early in June 2011 the independent Investigation Committee on the Accident at the Fukushima Nuclear Power Stations (ICANPS), a panel of ten experts, mostly academics and appointed by the Japanese cabinet, began meeting. Fukushima accident, also called Fukushima nuclear accident or Fukushima Daiichi nuclear accident, accident in 2011 at the Fukushima Daiichi (“Number One”) plant in northern Japan, the second worst nuclear accident in the history of nuclear power generation. The 11 March earthquake measured magnitude 9.0 and involved substantial shifting of multiple sections of seabed over a source area of 200 x 400 km. Tepco wanted to include an electricity rate increase of 17% in the plan, to cover the additional annual fuel costs for thermal power generation to make up for lost capacity at idled nuclear power plants. People were promptly evacuated from the vicinity of the nuclear power plant, and later from a neighbouring area where radionuclides had accumulated. There were up to 200 workers on site each day. In October 2013 a 16-member IAEA mission reported on remediation and decontamination in the Special Decontamination Areas. (WHO drinking water guideline is 0.01 MBq/L tritium) The IAEA is reported to support release of tritiated water to the ocean, as does Dr Dale Klein, chairman of Tepco’s nuclear reform monitoring committee (NRMC) and former chairman of US Nuclear Regulatory Commission. Tritium is a weak beta-emitter which does not bio-accumulate (half-life 12 years), and its concentration has levelled off at about 1 MBq/L in the stored water, with dilution from groundwater balancing further release from the fuel debris. These submerged and damaged the seawater pumps for both the main condenser circuits and the auxiliary cooling circuits, notably the Residual Heat Removal (RHR) cooling system. It reported that 167 workers had received doses over 100 mSv. After examination of the inside of the reactors, states of the damaged fuel rods and reactor core internals, sampling will be done and the damaged core material will be removed from the RPVs as well as from the PCVs. In July 2015 the government approved Tepco’s recovery plan, including compensation payments of JPY 7075 billion ($57.2 billion), enabling it to receive JPY 950 billion more than the JPY 6125 billion estimated in April, according to METI. It allowed use of contaminated soil for embankments, where the activity was less then 8 kBq/kg, and unrestricted use if less than 100 Bq/kg. It is broadly positive regarding progress since 2013, but said that some challenging issues remain. However, Tepco’s latest roadmap shows fuel removal from the pond at unit 1 is now expected FY27-28, and from unit 2 FY24-FY26. They were restored to cold shutdown by the normal recirculating system on 20th, and mains power was restored on 21-22nd. It received JPY 7 billion ($91 million) in public funds as well as a total of JPY 7 billion from 12 nuclear plant operators, the Tepco share of JPY 2379 million ($30 million) being largest. Fukushima Daiichi Accident (Updated May 2020) Following a major earthquake, a 15-metre tsunami disabled the power supply and cooling of three Fukushima Daiichi reactors, causing a nuclear accident on 11 March 2011. The Director General said: "I am confident that the legacy of the Fukushima Daiichi accident will be a sharper focus on nuclear safety everywhere. After that, RPV temperatures decreased steadily. Staff laid and energised 8.8km of heavy-duty electric cables in 30 hours to supplement power. Ring in the new year with a Britannica Membership - Now 30% off. Tepco declared "cold shutdown condition" in mid-December 2011 when radioactive releases had reduced to minimal levels. It was not until the middle of December 2011 that Japanese Prime Minister Noda Yoshihiko declared the facility stable, after the cold shutdown of the reactors was completed. They were in 'cold shutdown' at the time, but still requiring pumped cooling. In May 2011 a team of 18 experts from 12 countries spent a week at the plant on behalf of the International Atomic Energy Agency (IAEA), and that mission's final report was presented to the IAEA Ministerial Conference in Vienna in June. In February 2015 the IAEA completed its third review mission (as follow-up to that of late 2013, and involving some 180 experts from 42 IAEA member states and other organizations over two years) and reported on decommissioning to METI. The concentrated tritiated water is fed through a ‘getter bed’ of dry metal hydrate, where the tritium replaces hydrogen, and the material is stored, being stable up to 500°C. A hardened emergency response centre on site was unable to be used in grappling with the situation, due to radioactive contamination. New cooling circuits with heat exchangers adjacent to the reactor buildings for all four ponds were commissioned after a few months, and each reduced the pool temperature from 70°C to normal in a few days. It concluded that "Radiation exposure following the nuclear accident at Fukushima Daiichi did not cause any immediate health effects. However, they also announced that radiation levels had declined enough in some towns located just beyond the original 20-km evacuation warning zone that residents could return to their homes there. However, this had not yet led to any major action by either the plant operator, Tepco, or government regulators, notably the Nuclear & Industrial Safety Agency (NISA). The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) is undertaking a 12-month study on the magnitude of radioactive releases to the atmosphere and ocean, and the range of radiation doses received by the public and workers. Fukushima Daiichi units 4, 5&6 were not operating at the time, but were affected. The tsunami countermeasures taken when Fukushima Daiichi was designed and sited in the 1960s were considered acceptable in relation to the scientific knowledge then, with low recorded run-up heights for that particular coastline. Temperatures are normal. In the event, tsunami heights coming ashore were about 15 metres, and the Daiichi turbine halls were under some 5 metres of seawater until levels subsided. Each module treats up to 7200 litres per day. The 770 PBq figure is about 15% of the Chernobyl release of 5200 PBq iodine-131 equivalent. During the initial response to the tsunami, this lack of readiness for station blackout was compounded by a lack of planning and training for severe accident mitigation. Reactors 1-3 came into commercial operation 1971-75. Run-off from the site into the sea was also carrying radionuclides well in excess of allowable levels. In January 2013 4.5 to 5.5 m3/hr was being added to each RPV via core spray and feed water systems, hence 370 m3 per day, and temperatures at the bottom of RPVs were 19°C in unit 1 and 32°C in units 2&3, at little above atmospheric pressure. The cover structure was fitted with internal monitoring cameras, radiation and hydrogen detectors, thermometers and a pipe for water injection. Instead of airborne surveys being the basis, personal dosimeters would be used, giving very much more accurate figures, often much less than airborne estimates. Pressure was vented on 13th and again on 15th, and meanwhile the blowout panel near the top of the building was opened to avoid a repetition of unit 1 hydrogen explosion. This is fed through a catalytic exchange column with a little water which preferentially takes up the tritium. The provision for contributions from other nuclear operators is similar to that in the USA. It has two technological advisers. The company used both US proprietary adsorbtion and French conventional technologies in the new 1200 m3/day treatment plant. TEPCO officials reported that the leak was the result of an open valve in the short barrier wall that surrounded several of the tanks used in radioactive water storage. NISA confirmed that there was no significant change in radioactivity levels in the sea as a result of the 0.15 TBq discharge. Read more Japan's Nuclear & Industrial Safety Agency originally declared the Fukushima Daiichi 1-3 accident as Level 5 on the International Nuclear Events Scale (INES) – an accident with wider consequences, the same level as Three Mile Island in 1979. Evacuation orders have been progressively lifted, apart from some 300 km2 designated areas with annual dose levels above 20 mSv with continuous occupation. All this put those reactors 1-3 in a dire situation and led the authorities to order, and subsequently extend, an evacuation while engineers worked to restore power and cooling. Those holes partially exposed the nuclear material in the cores. It lost circulation with the power outage, and temperature increased to 73°C by the time mains power and cooling were restored after two weeks. The area subject to high dose rates (over 166 mSv/yr) diminished from 27% of the 1117 km2 zone to 6% over 15 months to March 2013, and in the ‘no residence’ portion (originally 83-166 mSv/yr) no areas remained at this level and 70% was below 33 mSv/yr. In November 2011 the US Institute of Nuclear Power Operators (INPO) released its Special Report on the Nuclear Accident at the Fukushima Daiichi Nuclear Power Station, with timeline. Toshiba has built a 74-tonne fuel handling machine for transferring the 566 fuel assemblies into casks and to remove debris in the pool, and a crane for lifting the fuel transfer casks. The team's report calls on the Japanese authorities to "maintain their focus on remediation activities that bring best results in reducing the doses to the public.". Among hundreds of aftershocks, an earthquake with magnitude 7.1, closer to Fukushima than the 11 March one, was experienced on 7 April, but without further damage to the plant. Tepco has written off the four reactors damaged by the accident, and is decommissioning them. The highest radiation levels on site came from debris left on the ground after the explosions at units 3&4. Eight years on, the Olympics are set to arrive. This was effected at the end of July, so that Tepco then became government-controlled, at least temporarily. In mid-May 2011 the unit 1 core would still be producing 1.8 MW of heat, and units 2&3 would be producing about 3.0 MW each. Meanwhile a July 2011 report from MIT's Centre for Advanced Nuclear Energy Systems provided a useful series of observations, questions raised, and suggestions. Japan moved a few metres east and the local coastline subsided half a metre. Thereafter, many weeks of focused work centred on restoring heat removal from the reactors and coping with overheated spent fuel ponds. In 2011, a tsunami led to a catastrophic nuclear disaster on Japan's Fukushima coast. There was concern about structural strength of unit 4 building, so support for the pond was reinforced by the end of July. They were found to have no deformation or corrosion. Before the accident, there was a basic assumption in Japan that the design of nuclear power plants and the safety measures that had been put in place were sufficiently robust to withstand external events of low probability and high consequences. * In this, an electrolyser produces hydrogen and oxygen, with the tritium reporting in the hydrogen. The original design basis tsunami height was 3.1 m for Daiichi based on assessment of the 1960 Chile tsunami and so the plant had been built about 10 metres above sea level with the seawater pumps 4 m above sea level. In June 2013 Tepco requested a further JPY 666 billion ($6.7 billion) in government support through the Nuclear Damage Liability Facilitation Fund, bringing the total amount requested by Tepco to JPY 3.79 trillion ($38 billion). Japan has poured billions of dollars into recovery from the 2011 Fukushima nuclear disaster. Its preliminary report said that decontamination efforts were commendable but driven by unrealistic targets. It said that "In light of the lessons learned from the accident, Japan has recognized that a fundamental revision of its nuclear safety preparedness and response is inevitable.". In October 2013, about 84,000 evacuees received the payments. The Japanese government evacuated residents within a 20 km radiu… In December 2013 IRID called for innovative proposals for removing fuel debris from units 1-3 about 2020. The reactors... A man is checked for radiation exposure after having been evacuated from the quarantine area around a nuclear power station in Fukushima prefecture, Japan, that was damaged in the March 11, 2011, earthquake and tsunami. It clarified milestones to accomplish preventive and multilayered measures, involving the three principles of removing the source of the contamination, isolating groundwater from the contamination source, and preventing leakage of the contaminated water. As a result, Japan was not sufficiently prepared for a severe nuclear accident in March 2011." * effectively 6750, due to one rack of 90 having some damaged fuel. These figures are additional to the 19,000 that died in the actual tsunami. Nearly a decade later, the energy-poor country is grappling with how to … The panel set up four teams to undertake investigations on the causes of the accident and ensuing damage and on measures to prevent the further spread of damage caused by the accident, but not to pursue the question of responsibility for the accident. This was uneventful, and the task continued through 2014. At the same time all six external power supply sources were lost due to earthquake damage, so the emergency diesel generators located in the basements of the turbine buildings started up. The earthquake was centred 130 km offshore the city of Sendai in Miyagi prefecture on the eastern coast of Honshu Island (the main part of Japan), and was a rare and complex double quake giving a severe duration of about 3 minutes. Those efforts met with some success, which temporarily slowed the release of radiation; however, they were suspended several times after rising steam or smoke signaled an increased risk of radiation exposure. Some of the Tepco staff had lost homes, and even families, in the tsunami, and were initially living in temporary accommodation under great difficulties and privation, with some personal risk. In December 2013 the government raised the upper limit of its financial assistance to Tepco from JPY 5 trillion to JPY 9 trillion ($86 billion). Omissions? Tepco accepted the conditions imposed on the company as part of the package. There are fuel ponds near the top of all six reactor buildings at the Daiichi plant, adjacent to the top of each reactor so that the fuel can be unloaded under water when the top is off the reactor pressure vessel and it is flooded. Units 1-3: Water has been injected into each of the three reactor units more or less continuously, and in the absence of normal heat removal via external heat exchanger this water was boiling off for some months. On April 12 nuclear regulators elevated the severity level of the nuclear emergency from 5 to 7—the highest level on the scale created by the International Atomic Energy Agency—placing it in the same category as the Chernobyl accident, which had occurred in the Soviet Union in 1986. The figure is greater than for Iwate and Miyagi prefectures, with 434 and 879 respectively, though they had much higher loss of life in the earthquake and tsunami – about 14,200. It is proposed that they will be used for training. The other three, at Fukushima Daiichi, lost power at 3.42 pm, almost an hour after the earthquake, when the entire site was flooded by the 15-metre tsunami. Around 18,500 people died or disappeared in the quake and tsunami, and … UNSCEAR’s follow-up white paper in October 2015 said that none of the new information appraised after the 2013 report “materially affected the main findings in, or challenged the major assumptions of, the 2013 Fukushima report.". These comprised 783 spent fuel plus the full fuel load of 548. In July 2012 two of the 204 fresh fuel assemblies were removed from the unit 4 pool and transferred to the central spent fuel pool for detailed inspection to check damage, particularly corrosion. On 2 December 2011 Tepco released its interim investigation report on the accident (in Japanese). As pressure rose, attempts were made to vent the containment, and when external power and compressed air sources were harnessed this was successful, by about 2.30 pm Saturday, though some manual venting was apparently achieved at about 10.17 am. By 22 December 2014, all 1331 used as well as all 202 new fuel assemblies had been moved in 71 cask shuttles without incident, with weekly updates having been published. The companies planned to apply for a government subsidy to help defray costs. In unit 2, water injection using the steam-driven back-up water injection system failed on Monday 14th, and it was about six hours before a fire pump started injecting seawater into the RPV. The only exception are the 146 emergency workers that received radiation doses of over 100 mSv during the crisis. This operation was accomplished under water, using the new fuel handling machine (replacing the one destroyed by the hydrogen explosion) so that the used fuel could be transferred to the central storage on site. The scheme includes a new state-backed institution to expedite payments to those affected by the Fukushima Daiichi accident.