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77-496: Fukushima Nuclear Power Plant can refer to: Fukushima Daiichi Nuclear Power Plant , Dai-ichi, 6 BWR units, operational from 1971, 4 damaged irrecoverably in March 2011. Fukushima Daini Nuclear Power Plant , Daini, 4 BWR units, operational from 1982, slightly damaged in March 2011. Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with

154-446: A Mark II type (over/under) containment structure. Unit 1 is a 460 MWe boiling water reactor ( BWR-3 ) constructed in July 1967. It commenced commercial electrical production on March 26, 1971, and was initially scheduled for shutdown in early 2011. In February 2011, Japanese regulators granted an extension of ten years for the continued operation of the reactor. It was damaged during

231-587: A possible uncovering of the Spent fuel pools in Units 1, 3 and 4. Units 5 & 6 were reported on March 19, by the station-wide alert log updates of the IAEA , to have gradually rising spent fuel pool temperatures as they had likewise lost offsite power, but onsite power provided by Unit 6's two diesel generators that had not been flooded, were configured to do double-duty and cool both Unit 5 and 6's spent fuel pools "and cores". As

308-440: A precautionary measure, vents in the roofs of these two units were also made to prevent the possibility of hydrogen gas pressurization and then ignition. Radiation releases from Units 1–4 forced the evacuation of 83,000 residents from towns around the plant. The triple meltdown also caused concerns about contamination of food and water supplies, including the 2011 rice harvest, and also the health effects of radiation on workers at

385-504: A small piece of melted fuel from Fukushima's reactor for radiation testing, a key step in its complex decommissioning process. Discharge of radioactive water of the Fukushima Daiichi Nuclear Power Plant Over 500,000 tonnes of untreated wastewater (including 10,000 tonnes released to free up storage space) escaped into the ocean shortly after the accident. In addition, persistent leakage into groundwater

462-560: A small sample of melted radioactive fuel from a damaged reactor. The sample will help improve future decommissioning strategies, though doubts persist about the long-term cleanup timeline. A glitch halted Telesco, the robot attempting to retrieve the sample, further delaying the mission. Concerns also remain over the impact on marine life as radioactive water is being released into the Pacific Ocean, despite government assurances that it meets safety standards. In November 2024,TEPCO has moved

539-610: A system to monitor the radionuclide concentration in ALPS-processed water in order to verify TEPCO's readings. An IAEA task force was dispatched to Japan in 2021, and they released their first report in February 2022. Among other findings, TEPCO has demonstrated to IAEA that their pump setup thoroughly mixes waters in tanks. In May 2023, 3 IAEA laboratories and 4 national laboratories participated in an interlaboratory comparison to verify TEPCO's testing of ALPS-treated water. Out of

616-658: A time for safety checks due to the TEPCO data falsification scandal . On February 28, 2011, TEPCO submitted a report to the Japanese Nuclear and Industrial Safety Agency admitting that the company had previously submitted fake inspection and repair reports. The report revealed that TEPCO failed to inspect more than 30 technical components of the six reactors, including power boards for the reactor's temperature control valves, as well as components of cooling systems such as water pump motors and emergency power diesel generators. In 2008,

693-508: Is a disabled nuclear power plant located on a 3.5-square-kilometre (860-acre) site in the towns of Ōkuma and Futaba in Fukushima Prefecture , Japan. The plant suffered major damage from the magnitude 9.1 earthquake and tsunami that hit Japan on March 11, 2011. The chain of events caused radiation leaks and permanently damaged several of its reactors, making them impossible to restart. The working reactors were not restarted after

770-516: Is a national decision by the Government of Japan and its report is neither a recommendation nor an endorsement of the decision. On 24 August 2023, the power plant started releasing the treated portion of its wastewater into the Pacific Ocean. At the time, its storage units held over a million tonnes of wastewater in total. Because new wastewater is constantly being formed and even treated water must be discharged slowly by diluting it with more sea water,

847-670: Is estimated at $ 71 billion. TEPCO will shoulder $ 143 billion of decommissioning and decontamination, while the Ministry of Finance of Japan will provide $ 17 billion. Other power companies will also contribute to the cost. On September 26, 2020, Prime Minister Yoshihide Suga visited the Daiichi Nuclear Power Plant to show that his cabinet prioritized the reconstruction of areas that were affected by natural and nuclear disasters. The three reactors host 880 tonnes of highly radioactive melted nuclear fuel. As of 2024–13 years after

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924-409: Is produced naturally in the atmosphere each year by cosmic rays. Other radionuclides present in the wastewater, like caesium-137 , are not normally released by nuclear power plants. However, the concentrations in the treated water is minuscule relative to regulation limits. "There is consensus among scientists that the impact on health is minuscule, still, it can't be said the risk is zero, which

1001-574: Is pumped out and combined into the reactor-cooling loop, which includes stronium–cesium removal (KURION, SURRY) and reverse osmosis desalination processes. In October 2012, TEPCO introduced the "Advanced Liquid Processing System" (ALPS, Japanese : 多核種除去設備 ), which is designed to remove radionuclides other than tritium and carbon-14 . ALPS works by first pre-processing the water by iron coprecipitation (removes alpha nuclides and organics) and carbonate coprecipitation (removes alkali earth metals including strontium elements). The water

1078-479: Is still radioactive immediately after treatment, the solution will be diluted by sea water to a lower concentration before being discharged. A review report by the International Atomic Energy Agency (IAEA) shows that the plan of discharging diluted ALPS-treated water into the sea is consistent with relevant international safety standards. It also emphasizes that the release of the treated water

1155-447: Is then passed through 16 absorbent columns to remove nuclides. Wastewater is pumped to ALPS along with the concentrated saltwater from desalination. As some tritium still remains, even treated water would require dilution to meet drinkable standards. Although carbon-14 is not removed, the content in pre-treatment water is low enough to meet drinkable standards without dilution. Japan's Nuclear Regulation Authority (NRA) approved

1232-529: Is what causes controversy", Michiaki Kai, a Japanese nuclear expert, told AFP . David Bailey, a physicist whose lab measures radioactivity, said that with tritium at diluted concentrations, "there is no issue with marine species, unless we see a severe decline in fish population". Ferenc Dalnoki-Veress, a scientist-in-residence at the Middlebury Institute of International Studies at Monterey , said regarding dilution that bringing in living creatures makes

1309-423: The 2011 Tōhoku earthquake and tsunami . Unit 1 was designed for a peak ground acceleration of 0.18  g (1.74 m/s ) and a response spectrum based on the 1952 Kern County earthquake , but rated for 0.498 g. The design basis for Units 3 and 6 were 0.45 g (4.41 m/s ) and 0.46 g (4.48 m/s ) respectively. All units were inspected after the 1978 Miyagi earthquake when the ground acceleration

1386-502: The Pacific Ocean in order to free up storage space for water that is even more radioactive. The untreated water was the least radioactively contaminated among the stored water, but still 100 times the legal limit. TEPCO estimated that a total of 520,000 tons of untreated radioactive water had escaped into the ocean before it could place silt fences to contain further spills. The UNSCEAR report in 2020 determined "direct releases in

1463-523: The moment magnitude scale occurred at 14:46 Japan Standard Time (JST) off the northeast coast of Japan, one of the most powerful earthquakes in history. Units 4, 5 and 6 had been "shut down" prior to the earthquake for planned maintenance. The remaining reactors were shut down/ SCRAMed automatically after the earthquake, and the remaining decay heat of the fuel was being cooled with power from emergency generators. The subsequent destructive tsunami with waves of up to 14 metres (46 ft) that over-topped

1540-508: The water column by 2020. The sediments may provide a long-term source of caesium-137 in the seawater. According to Buesseler, the release of strontium-90 could be more problematic because, unlike some of the other isotopes, it gets into a person's bones. Data on marine foods indicates their radioactive concentrations are falling towards initial levels. 41% of samples caught off the Fukushima coast in 2011 had caesium-137 concentrations above

1617-426: The 30 radionuclides TEPCO regularly tests for, 12 were found to be above detection limits. 52 out of 53 results were found to agree with the combined result; the only problematic result was of I-129, where Korea Institute of Nuclear Safety reported a value too low compared to the weighted average. TEPCO's methology was found to be fit for purpose: although it is less sensitive for actinides than some participating labs,

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1694-457: The ALPS process and were present in 71% of the tanks. Since the 2011 Fukushima Daiichi nuclear disaster , the nuclear plant has accumulated 1.25 million tonnes of waste water, stored in 1,061 tanks on the land of the nuclear plant, as of March 2021. It will run out of land for water tanks by 2022. It has been suggested the government could have solved the problem by allocating more land surrounding

1771-520: The Fukushima Daiichi nuclear power plant and to cancel plans to build units 7 and 8. It refused however to make a decision regarding units 5 and 6 of the station or units 1 to 4 of the Fukushima Daini nuclear power station until a detailed investigation is made. In December 2013 TEPCO decided to decommission the undamaged units 5 and 6; they may be used to test remote clean-up methods before use on

1848-578: The Fukushima Daini plant by the Tomioka Line (富岡線). Its major connection to the north is the Iwaki Line (いわき幹線), which is owned by Tohoku Electric Power . It has two connections to the south-west that connect it to the Shin-Iwaki substation (新いわき). The plant reactors came online one at a time beginning in 1970 and the last in 1979. From the end of 2002 through 2005, the reactors were among those shut down for

1925-532: The Fukushima disaster and the Chernobyl disaster worldwide the only Level 7 events up to date. Japanese wheelchair basketball player Akira Toyoshima revealed that he was working as an accountant at the Fukushima Daiichi Nuclear Power Plant when the 2011 Tōhoku earthquake and tsunami struck Japan and the tsunami eventually claimed the lives of thousands of people. Toyoshima insisted that he

2002-558: The IAEA warned Japan that the Fukushima plant was built using outdated safety guidelines, and could be a "serious problem" during a large earthquake. The warning led to the building of an emergency response center in 2010, used during the response to the 2011 nuclear accident. On April 5, 2011, TEPCO vice president Takashi Fujimoto announced that the company was canceling plans to build Reactors No. 7 and 8. On May 20 TEPCO's board of directors' officially voted to decommission Units 1 through 4 of

2079-486: The Japanese government approved the discharge of radioactive water , which has been treated to remove radionuclides other than tritium , into the Pacific Ocean over the course of 30 years. The reactors for Units 1, 2, and 6 were supplied by General Electric , those for Units 3 and 5 by Toshiba , and Unit 4 by Hitachi . All six reactors were designed by General Electric. Architectural design for General Electric's units

2156-454: The accident—attempts to remove highly radioactive material from the damaged reactor were halted. Tesco attempted to remove 3 grams (0.1 ounce) from an estimated 880 tons of lethally radioactive molten fuel. This sample will provide critical data for the development of future decommissioning methods, as well as the necessary technology and robots, according to experts. On 11 September 2024, a robotic mission at Fukushima Daiichi restarted to collect

2233-498: The caesium in groundwater, strontium and tritium can flow through more freely. At one time, nearly 400 tonnes of radioactive water was being formed every day (150,000 tonnes per year). TEPCO has since tried to stem or divert the inflow of groundwater to the damaged reactor sites and prevent contaminated water from escaping into the ocean. The UNSCEAR report in 2020 concluded "Direct release of about 60 T Bq [terabecquerel, 10  Bq] of caesium-137 in ground water draining from

2310-461: The creation of a structure to develop the technologies and processes necessary to dismantle the four reactors damaged in the Fukushima accident. To reduce the flow of contaminated water into the Pacific Ocean, TEPCO spent ¥34.5 billion (approx. $ 324 million) to build a 1.5 kilometer-long underground wall of frozen soil around the plant, constructed by Kajima Corporation. 1,500 one-hundred-foot long (thirty-metre), supercooled pipes were inserted into

2387-510: The damaged reactors. In 1990, the U.S. Nuclear Regulatory Commission (NRC) ranked the failure of the emergency electricity generators and subsequent failure of the cooling systems of plants in seismically very active regions one of the most likely risks. The Japanese Nuclear and Industrial Safety Agency (NISA) cited this report in 2004. According to Jun Tateno, a former NISA scientist, TEPCO did not react to these warnings and did not respond with any measures. Filmmaker Adam Curtis mentioned

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2464-495: The design of ALPS in March 2013. ALPS is to be run in three independent units and will be able to purify 250 tons of water per day. Unit "A" started operation in April. In June, unit A was found to be leaking water and shut down. In July, the cause was narrowed down to chloride and hypochlorite corrosion of water tanks; TEPCO responded by adding a rubber layer into the tanks. By August, all systems were shut down awaiting repair. One unit

2541-550: The detection limits were far enough from regulatory limits, and the alpha-emission screening test appears accurate enough. TEPCO's testing method for Am-141 may require additional review. The same sample was tested by Japan's NRA with no disagreements found. The tritium that is not filtered out has a radioactivity of 148,900 Bq/L, compared to 620,000 Bq/L before treatment. TEPCO intends to dilute it down to 1,500 Bq/L or less before release. On 22 August 2023, Japan announced that it would start releasing treated radioactive water from

2618-451: The entire process could take more than 30 years. The decision to release this water into the ocean has faced concerns and criticism from other countries and international organisations. As of the fourth round of discharge in March 2024, no abnormal tritium levels have been detected in nearby waters. Radioactive materials were dispersed into the atmosphere immediately after the disaster and account for most of all such materials leaked into

2695-454: The environment. 80% of the initial atmospheric release eventually deposited over rivers and the Pacific Ocean , according to a UNSCEAR report in 2020. Specifically, "the total releases to the atmosphere of Iodine-131 and Caesium-137 ranged generally between about 100 to about 500 P Bq [petabecquerel, 10  Bq] and 6 to 20 PBq, respectively. The ranges correspond to about 2% to 8% of the total inventory of Iodine-131 and about 1% to 3% of

2772-529: The events. First commissioned in 1971, the plant consists of six boiling water reactors . These light water reactors drove electrical generators with a combined power of 4.7 GWe, making Fukushima Daiichi one of the 15 largest nuclear power stations in the world . Fukushima was the first nuclear plant to be designed, constructed, and run in conjunction with General Electric and Tokyo Electric Power Company (TEPCO). The sister nuclear plant Fukushima Daini ( "number two" ), 12 km (7.5 mi) to

2849-531: The fact that they were still included in the supply plan for 2011, released in March 2011, after the accidents. The company stated that the plan had been drafted before the earthquake. The Fukushima Daiichi plant is connected to the power grid by four lines, the 500 kV Futaba Line (双葉線), the two 275 kV Ōkuma Lines (大熊線) and the 66 kV Yonomori Line (夜の森線) to the Shin-Fukushima (New Fukushima) substation. The Shin-Fukushima substation also connects to

2926-435: The first three months amounting to about 10 to 20 P Bq [petabecquerel, 10  Bq] of Iodine-131 and about 3 to 6 PBq of Caesium-137 ". About 82 percent having flowed into the sea before 8 April 2011. Scientists suspected that radioactive elements continued to leak into the ocean. High levels of caesium-134 were found in local fish, despite the isotope's comparatively shorter half-life. Meanwhile, radiation levels in

3003-405: The generators and batteries in that location, but mid-level engineers working on the construction of the plant were concerned that this made the backup power systems vulnerable to flooding. TEPCO elected to strictly follow General Electric's design in the construction of the reactors. The plant is on a bluff which was originally 35 meters above sea level. During construction, however, TEPCO lowered

3080-434: The ground in order to freeze the surrounding groundwater and soil. The wall ultimately failed to significantly decrease the groundwater flowing into the site. The cost of decommissioning and decontamination of the Fukushima Daiichi nuclear power plant has been estimated at $ 195 billion, which includes compensation payouts to victims of the disaster. The amount also includes decommissioning of Fukushima Daiichi reactors, which

3157-403: The height of the bluff by 25 meters. One reason for lowering the bluff was to allow the base of the reactors to be constructed on solid bedrock in order to mitigate the threat posed by earthquakes. Another reason was the lowered height would keep the running costs of the seawater pumps low. TEPCO's analysis of the tsunami risk when planning the site's construction determined that the lower elevation

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3234-450: The incident, as TEPCO had covered it up; interviews of two former workers in 2007 led to its discovery by TEPCO management. A manual shutdown was initiated during the middle of a start-up operation. The cause was a high pressure alarm that was caused by the shutting of a turbine bypass valve. The reactor was at 12% of full power when the alarm occurred at 4:03 am (local time) due to a pressure increase to 1,030 psi (7,100 kPa), exceeding

3311-401: The leaks came from the storage tanks for wastewater. Since then, TEPCO has had a record of being dishonest on its figures and has lost the public trust. For instance, in 2014, TEPCO blamed its own measuring method and revised the strontium in a groundwater well in July 2013 from 900,000 Bq/L to 5,000,000 Bq/L, which is 160,000 times the standard for discharge. While soil naturally absorbs

3388-442: The legal limit (100 becquerels per kilogram), and this had declined to 0.05% in 2015. United States Food and Drug Administration stated in 2021 that "FDA has no evidence that radionuclides from the Fukushima incident are present in the U.S. food supply at levels that are unsafe". Yet, presenting the science alone has not helped customers to regain their trust on eating Fukushima fishery products. The most prevalent radionuclide in

3465-419: The nearby sea water did not fall as expected. After repeated denials, the operator of the nuclear plant, Tokyo Electric Power Company (TEPCO), finally admitted on 22 July 2013 that leaks to groundwater had been happening. Some groundwater samples contained 310 Bq/L of cesium-134 and 650 Bq/L of cesium-137, exceeding WHO's maximum guideline of 10 Bq/L for drinking water. It was later determined that some of

3542-495: The next thirty years as per the plan. On August 25, TEPCO reported that the amount of tritium in seawater around Fukushima has remained below the detection limit of 10 Bq/L. The Japanese Fishery Agency reported that fish caught 4 km away from the discharge pipe contained no detectable amounts of tritium. In March 2024, the discharge was suspended temporarily after the Fukushima coastal region experienced another 5.8-magnitude earthquake. No abnormalities were detected with

3619-498: The ocean – contains the newer units 5 and 6, respectively, the positions from left to right. A set of seawalls protrude into the ocean, with the water intake in the middle and water discharge outlets on either side. Units 7 and 8 were planned to start construction in April 2012 and 2013 and to come into operation in October 2016 and 2017 respectively. The project was formally canceled by TEPCO in April 2011 after local authorities questioned

3696-506: The plant, and TEPCO announced plans to filter radioactive particles and discharge purified water. In August, Japanese officials said highly radioactive water was leaking from Fukushima Daiichi into the Pacific Ocean at a rate of 300 tons (about 272 metric tons) per day. Japanese Prime Minister Shinzo Abe ordered government officials to step in. By September 2019, one million tons of contaminated cooling water had been collected in tall steel tanks. Large filtration systems were used to clean

3773-637: The plant. Scientists estimate that the accident released 18 quadrillion becquerels of caesium-137 into the Pacific Ocean, contaminating 150 square miles (390 km ) of the ocean floor. The events at units 1, 2 and 3 have been rated at Level 5 each on the International Nuclear Event Scale , and those at unit 4 as Level 3 (Serious Incident) events, with the overall plant rating at Level 7 (major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasures), making

3850-470: The plant; the releases continue to this day. On April 20, 2011, the Japanese authorities declared the 20 km (12 mi) evacuation zone a no-go area which may only be entered under government supervision. In November 2011, the first journalists were allowed to visit the plant. They described a scene of devastation in which three of the reactor buildings were destroyed; the grounds were covered with mangled trucks, crumpled water tanks and other debris left by

3927-475: The power plant for water tanks, since the surrounding area had been designated as unsuitable for humans. Regardless, the government was reluctant to act. Mainichi Shimbun criticized the government for showing "no sincerity" in "unilaterally push[ing] through with the logic that there will no longer be enough storage space" On 13 April 2021, the Cabinet of Prime Minister Suga unanimously approved that TEPCO dump

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4004-405: The regulatory limit of 1,002 psi (6,910 kPa). The reactor was reduced to 0% power, which exceeded the 5% threshold that requires event reporting, and pressure dropped back under the regulatory limit at 4:25 am. Later, at 8:49 am the control blades were completely inserted, constituting a manual reactor shutdown. An inspection then confirmed that one of the 8 bypass valves had closed and that

4081-567: The regulatory standards set by the International Atomic Energy Agency. This plan has been approved by the International Atomic Energy Agency. But critics contend that more studies need to be done and the release should be halted. On 24 August, Japan began the discharge of treated waste water into the Pacific Ocean, sparking protests in the region and China to expand its ban to all aquatic imports from Japan. Over 1 million tonnes of treated wastewater will be released by Japan over

4158-457: The risks of the type of boiling water reactors cooling systems such as those in Fukushima I, and claimed the risks were known since 1971 in a series of documentaries in the BBC in 1992 and advised that PWR type reactors should have been used. Tokyo Electric Power Company (TEPCO) operated the station and was warned their seawall was insufficient to withstand a powerful tsunami, but did not increase

4235-402: The seawall height in response. The Onagawa Nuclear Power Plant , operated by Tohoku Electric Power , ran closer to the epicenter of the earthquake, but had much more robust seawalls of greater height and avoided severe accident. Fuel rods fell in reactor No. 3, causing a nuclear reaction. It took about seven and a half hours to place the rods back into proper positions. There was no record of

4312-444: The site up to October 2015, when measures were taken to reduce these releases, and about 0.5 TBq per year thereafter". In February 2024, a leak at the power plant was detected by a contractor and eventually repaired by TEPCO. The company estimated that 5.5 tonnes of water, which potentially contained 22 billion becquerels of radioactive materials such as caesium and strontium, had escaped from an air vent, pooled outside and seeped into

4389-641: The situation more complex. Robert Richmond, a biologist from the University of Hawaiʻi , told the BBC that the inadequate radiological and ecological assessment raises the concern that Japan would be unable to detect what enters the environment and "get the genie back in the bottle". Dalnoki-Veress, Richmond, and three other panelists consulting for the Pacific Islands Forum wrote that dilution may fail to account for bioaccumulation and exposure pathways that involve organically-bound tritium (OBT). Presenting

4466-471: The south, is also run by TEPCO. It also suffered serious damage during the tsunami, at the seawater intakes of all four units, but was successfully shut down and brought to a safe state. See the timeline of the Fukushima II nuclear accidents . The March 2011 disaster disabled the reactor cooling systems, leading to releases of radioactivity and triggering a 30 km (19 mi) evacuation zone surrounding

4543-400: The station, which had seawalls, disabled emergency generators required to cool the reactors and spent fuel pools in Units 1–5. Over the following three weeks there was evidence of partial nuclear meltdowns in units 1, 2 and 3: visible explosions, suspected to be caused by hydrogen gas, in units 1 and 3; a suspected explosion in unit 2, that may have damaged the primary containment vessel; and

4620-487: The stored water to the Pacific Ocean over a course of 30 years. The Cabinet asserted the dumped water will be treated and diluted to drinkable standard . The idea of dumping had been floated by Japanese experts and officials as early as June 2016. In April 2023, Japan's NRA announced a Comprehensive Radiation Monitoring Plan , in which the concentration of radionuclides in food (land and sea), soil, water, and air will be continually monitored across Japan. NRA also set up

4697-419: The surrounding soil, but did not leave the plant compound. It said this was caused by 10 out of 16 valves being left open when they should have been closed for flushing. To prevent the reactor meltdowns from worsening, a continuous supply of new water is necessary to cool the melted fuel debris . As of 2013, 400 metric tonnes of water was becoming radioactively contaminated each day. The contaminated water

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4774-663: The title Fukushima Nuclear Power Plant . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Fukushima_Nuclear_Power_Plant&oldid=709781270 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Fukushima Daiichi Nuclear Power Plant The Fukushima Daiichi Nuclear Power Plant ( 福島第一原子力発電所 , Fukushima Daiichi Genshiryoku Hatsudensho , Fukushima number 1 nuclear power plant)

4851-552: The total inventory of Caesium-137 in the three operating units (Units 1–3)". The indirect deposition to rivers come from the earlier direct discharge to the atmosphere. "Continuing indirect releases of about 5 to 10 T Bq [terabecquerel, 10  Bq] of Caesium-137 per year via rivers draining catchment areas", according to the UNSCEAR report in 2020. On 5 April 2011, the operator of the nuclear plant, Tokyo Electric Power Company (TEPCO), discharged 11,500 tons of untreated water into

4928-418: The tsunami-hit Fukushima nuclear plant into the Pacific Ocean in 48 hours, despite opposition from its neighbours. Japan says the water is safe after the use of Advanced Liquid Processing System (ALPS), which removes nearly all traces of radiation from the wastewater, with tritium being the primary exception to this. As a result, Japan has committed to diluting the water in order to bring levels of tritium below

5005-466: The tsunami; and radioactive levels were so high that visitors were only allowed to stay for a few hours. In April 2012, Units 1–4 were shut down. Units 2–4 were shut down on April 19, while Unit 1 was the last of these four units to be shut down on April 20 at midnight. In December 2013 TEPCO decided none of the undamaged units will reopen. Units 5 and 6 were shut down later in January 2014. In April 2021,

5082-436: The valve had a bad driving fluid connection. The reactor had been starting up following its 25th regular inspection, which had begun on October 18, 2008. Unit 3 had problems with over-insertion of control blades during outage. Repair work was being done on equipment that regulates the driving pressure for the control blades, and when a valve was opened at 2:23 pm a control blade drift alarm went off. On later inspection, it

5159-502: The wastewater is tritium. A total of 780 terabecquerels (TBq) will be released into the ocean at a rate of 22 TBq per year. Tritium is routinely released into the ocean from operating nuclear power plants, sometimes in much greater quantities. For comparison, the La Hague nuclear processing site in France released 11,400 TBq of tritium in the year of 2018. In addition, about 60,000 TBq of tritium

5236-407: The wastewater treatment. A large amount of caesium entered the sea from the initial atmospheric release (see above). By 2013, the concentrations of caesium-137 in the Fukushima coastal waters were around the level before the accident. However, concentrations in coastal sediments declined more slowly than in coastal waters, and the amount of caesium-137 stored in sediments most likely exceeded that in

5313-461: The water of its radioactive contaminants, but could not remove the estimated 14 grams of tritium , a radioactive isotope of hydrogen (Hydrogen-3) bonded into water molecules. TEPCO estimated the immediate site would run out of space by 2022, and planned to solve this problem by releasing the radioactive water into the Pacific Ocean . This proposed measure was criticised by environmental groups and several Asian governments, who claimed that storage area

5390-468: Was 0.125 g (1.22 m/s ) for 30 seconds, but no damage to the critical parts of the reactor was discovered. The design basis for tsunamis was 5.7 metres (18 ft 8 in). The reactor's emergency diesel generators and DC batteries, crucial components in helping keep the reactors cool in the event of a power loss, were located in the basements of the reactor turbine buildings. The reactor design plans provided by General Electric specified placing

5467-515: Was available in the exclusion zone around the reactor. Japan's government approved the release, beginning in 2023, over the course of an estimated 40 years. A note in the 2020 Tokyo Olympic Games opening speech referenced the disaster and how Japan has recovered from the disaster. The reactors will take 30–40 years to be decommissioned. On August 1, 2013, the Japanese Industry Minister Toshimitsu Motegi approved

5544-447: Was done by Ebasco . All construction was done by Kajima . Since September 2010, Unit 3 has been fueled by a small fraction (6%) of plutonium containing mixed-oxide (MOX) fuel , rather than the low enriched uranium (LEU) used in the other reactors. Units 1–5 were built with Mark I type (light bulb torus) containment structures . The Mark I containment structure was slightly increased in volume by Japanese engineers. Unit 6 has

5621-665: Was expected to come online by September, with full recovery planned by the end of 2013. By September 2018, TEPCO reports that 20% of the water had been treated to the required level. By 2020, the daily buildup of contaminated water was reduced to 170 metric tonnes thanks to groundwater isolation installations. TEPCO reports that 72% of the water in its tanks, some from early trials of ALPS, needed to be repurified. The portion of ready-to-discharge water raised to 34% by 2021, and to 35% by 2023. Some scientists expressed reservations due to potential bioaccumulation of ruthenium, cobalt, strontium, and plutonium, which sometimes slip through

5698-447: Was focused on organizing a set of important and urgent documents in the main office building of the Fukushima Daiichi Nuclear Power Plant as a member of the accounting team. In April 2013, TEPCO publicly admitted radionuclide contaminated water may have leaked from the storage units, possibly contaminating the soil and water nearby. The leak was controlled and stored in containment tanks. Contaminated water continued to accumulate at

5775-408: Was found that several of the rods had been unintentionally inserted. Unit 5 had an automatic SCRAM while an operator was conducting an adjustment to the control blade insertion pattern. The SCRAM was caused by a reactor low water level alarm. The turbine tripped along with the reactor and there was no radiation injury to workers. On March 11, 2011, an earthquake categorized as 9.1 M W on

5852-586: Was not admitted by the plant operator until 2013. The radioactivity from these sources exceeded legal limits. Since then, contaminated water has been pumped into storage units and gradually treated using the Advanced Liquid Processing System (ALPS) to eliminate most radionuclides , except notably tritium with a half-life of 12.32 years. In 2021, the Japanese cabinet approved the release of ALPS-treated water containing tritium. Because it

5929-442: Was safe because the sea wall would provide adequate protection for the maximum tsunami assumed by the design basis. However, the lower site elevation did increase the vulnerability for a tsunami larger than anticipated in design. The Fukushima Daiichi site is divided into two reactor groups, the leftmost group – when viewing from the ocean – contains units 4, 3, 2 and 1 going from left to right. The rightmost group – when viewing from

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