Stress often manifests in physical ailments, including behavioral changes such as poor dietary choices, lack of exercise, and sleep deprivation. Survivors, including some who lost homes, villages, and family members, were found likely to face mental health and physical challenges. Much of the stress came from lack of information and from relocation. Summarizing all responses to questions related to evacuees' current family status, one-third of all surveyed families live apart from their children, while 50.1% live away from other family members (including elderly parents) with whom they lived before the disaster. The survey also showed that 34.7% of the evacuees have suffered salary cuts of 50% or more since the outbreak of the nuclear disaster. A total of 36.8% reported a lack of sleep, while 17.9% reported smoking or drinking more than before they evacuated. Ein im Geographie-Unterricht der 10. Klasse erstelltes Kurzvideo, das Dir erklärt, wie es zum Reaktorunglück in Fukushima kam, welche Auswirkungen das Unglück hatte und was man tun kann, um zu.
500 PBq of iodine-131 was released, compared to approximately 1,760 PBq at Chernobyl. Iodine-131 has a half-life of 8.02 days, decaying into a stable nuclide. After ten half lives (80.2 days), 99.9% has decayed to xenon-131, a stable isotope. In June 2016 Tilman Ruff, co-president of the political advocacy group, the "International Physicians for the Prevention of Nuclear War" argues that 174,000 people have been unable to return to their homes and ecological diversity has decreased and malformations have been found in trees, birds, and mammals. Although physiological abnormalities have been reported within the vicinity of the accident zone, the scientific community has largely rejected any such findings of genetic or mutagenic damage caused by radiation, instead showing it can be attributed either to experimental error or other toxic effects. In the first half of September 2011, TEPCO estimated the radioactivity release at some 200 MBq (megabecquerels, 5.4 millicuries) per hour. This was approximately one four-millionth that of March. Traces of iodine-131 were detected in several Japanese prefectures in November and December 2011.
Release of Pu Isotopes from the Fukushima Daiichi Nuclear Power Plant Accident to the Marine Environment Was Negligible. Environmental Science & Technology 2014, 48 (16) , 9070-9078. DOI: 10.1021/es502480y. Junwen Wu. Sources and scavenging of plutonium in the East China Sea. Marine Pollution Bulletin 2018, 135, 808-818. DOI: 10.1016/j. Three investigations into the Fukushima disaster showed the man-made nature of the catastrophe and its roots in regulatory capture associated with a "network of corruption, collusion, and nepotism." Regulatory capture refers to the "situation where regulators charged with promoting the public interest defer to the wishes and advance the agenda of the industry or sector they ostensibly regulate." Those with a vested interest in specific policy or regulatory outcomes lobby regulators and influence their choices and actions. Regulatory capture explains why some of the risks of operating nuclear power reactors in Japan were systematically downplayed and mismanaged so as to compromise operational safety. Reactors 5 and 6 were also not operating when the earthquake struck. Unlike Reactor 4, their fuel rods remained in the reactor. The reactors had been closely monitored, as cooling processes were not functioning well. Both Unit 5 and Unit 6 shared a working generator and switchgear during the emergency and achieved a successful cold shutdown nine days later on 20 March. The plant's operators had to release 1,320 tons of low levels of radioactive waste that accumulated from the sub-drain pits into the ocean to prevent equipment from being damaged.  Fukushima nuclear crisis All the background info you need to understand the crisis at Japan's Fukushima Daiichi power station. 1. The Japan nuclear crisis. Coverage from Nature news with all the latest updates on the situation at Fukushima. 2. Fukushima explained
A survey by the Iitate local government obtained responses from approximately 1,743 evacuees within the evacuation zone. The survey showed that many residents are experiencing growing frustration, instability, and an inability to return to their earlier lives. Sixty percent of respondents stated that their health and the health of their families had deteriorated after evacuating, while 39.9% reported feeling more irritated compared to before the disaster. Read the latest articles of Nuclear Physics A at ScienceDirect.com, Elsevier's leading platform of peer-reviewed scholarly literatur During the core melt-down events at Fukushima, radioactivity was released as fine particulates that traveled in the air, sometime for distances of tens of kilometres, and settled onto the surrounding countryside.
In the reactor core, high-pressure systems cycle water between the reactor pressure vessel and heat exchangers. These systems transfer heat to a secondary heat exchanger via the essential service water system, using water pumped out to sea or an onsite cooling tower. Units 2 and 3 had steam turbine-driven emergency core cooling systems that could be directly operated by steam produced by decay heat and that could inject water directly into the reactor. Some electrical power was needed to operate valves and monitoring systems. On 10 September 2015, floodwaters driven by Typhoon Etau prompted mass evacuations in Japan and overwhelmed the drainage pumps at the stricken Fukushima nuclear plant. A TEPCO spokesperson said that hundreds of metric tons of radioactive water entered the ocean as a result. Plastic bags filled with contaminated soil and grass were also swept away by the flood waters.
The Fukushima Daiichi Nuclear Power Plant comprised six separate boiling water reactors originally designed by General Electric (GE) and maintained by the Tokyo Electric Power Company (TEPCO). At the time of the Tōhoku earthquake on 11 March 2011, Reactors 4, 5, and 6 were shut down in preparation for re-fueling. However, their spent fuel pools still required cooling . The report blamed Japan's central government as well as TEPCO, "depicting a scene of harried officials incapable of making decisions to stem radiation leaks as the situation at the coastal plant worsened in the days and weeks following the disaster". The report said poor planning worsened the disaster response, noting that authorities had "grossly underestimated tsunami risks" that followed the magnitude 9.0 earthquake. The 12.1-meter (40 ft) high tsunami that struck the plant was double the height of the highest wave predicted by officials. The erroneous assumption that the plant's cooling system would function after the tsunami worsened the disaster. "Plant workers had no clear instructions on how to respond to such a disaster, causing miscommunication, especially when the disaster destroyed backup generators." The Fukushima Nuclear Accident Independent Investigation Commission (NAIIC) was the first independent investigation commission by the National Diet in the 66-year history of Japan's constitutional government. To assuage fears, the government enacted an order to decontaminate over a hundred areas with a level contamination greater than or equivalent to one millisievert[clarification needed] of radiation. This is a much lower threshold than is necessary for protecting health. The government also sought to address the lack of education on the effects of radiation and the extent to which the average person was exposed.
According to the French Institute for Radiological Protection and Nuclear Safety, between 21 March and mid-July around 27 PBq of caesium-137 entered the ocean, about 82 percent before 8 April. This emission represents the most important individual oceanic emissions of artificial radioactivity ever observed. The Fukushima coast has one of the world's strongest currents (Kuroshio Current). It transported the contaminated waters far into the Pacific Ocean, dispersing the radioactivity. As of late 2011 measurements of both the seawater and the coastal sediments suggested that the consequences for marine life would be minor. Significant pollution along the coast near the plant might persist, because of the continuing arrival of radioactive material transported to the sea by surface water crossing contaminated soil. The possible presence of other radioactive substances, such as strontium-90 or plutonium, has not been sufficiently studied. Recent measurements show persistent contamination of some marine species (mostly fish) caught along the Fukushima coast. Chernobyl thyroid cancer incidence rates did not begin to increase above the prior baseline value of about 0.7 cases per 100,000 people per year until 1989 to 1991, 3–5 years after the incident in both adolescent and child age groups. The rate reached its highest point so far, of about 11 cases per 100,000 in the decade of the 2000s, approximately 14 years after the accident. From 1989 to 2005, an excess of 4,000 children and adolescent cases of thyroid cancer were observed. Nine of these had died as of 2005, a 99% survival rate.
Yukinobu Okamura of the Active Fault and Earthquake Research Center (replaced in 2014 by Research Institute of Earthquake and Volcano Geology (IEVG), Geological Survey of Japan (GSJ), AIST) urged TEPCO and NISA to revise their assumptions for possible tsunami heights upwards, based on his team's findings about the 869 Sanriku earthquake, but this was not seriously considered at the time. The nuclear plant closest to the epicenter of the earthquake, the Onagawa Nuclear Power Plant, successfully withstood the cataclysm. R said it may serve as a "trump card" for the nuclear lobby, providing evidence that it is possible for a correctly designed and operated nuclear facility to withstand such a cataclysm.
The International Atomic Energy Agency (IAEA) had expressed concern about the ability of Japan's nuclear plants to withstand earthquakes. At a 2008 meeting of the G8's Nuclear Safety and Security Group in Tokyo, an IAEA expert warned that a strong earthquake with a magnitude above 7.0 could pose a "serious problem" for Japan's nuclear power stations. The region had experienced three earthquakes of magnitude greater than 8, including the 869 Sanriku earthquake, the 1896 Sanriku earthquake, and the 1933 Sanriku earthquake. In 1967, when the plant was built, TEPCO levelled the sea coast to make it easier to bring in equipment. This put the new plant at 10 meters (33 ft) above sea level, rather than the original 30 meters (98 ft). In many cases, the Japanese government's reaction was judged to be less than adequate by many in Japan, especially those who were living in the region. Decontamination equipment was slow to be made available and then slow to be utilized. As late as June 2011, even rainfall continued to cause fear and uncertainty in eastern Japan because of its possibility of washing radioactivity from the sky back to earth.
Im März 2011 zerstörte ein Tsunami das Kernkraftwerk im japanischen Fukushima. Kein ausländisches Team durfte bislang in den Reaktoren filmen. Auch auf unsere Anfrage reagierte Tepco zunächst. On 22 August 2011, a government spokesman mentioned the possibility that some areas around the plant "could stay for some decades a forbidden zone". According to Yomiuri Shimbun the Japanese government was planning to buy some properties from civilians to store waste and materials that had become radioactive after the accidents. Chiaki Takahashi, Japan's foreign minister, criticized foreign media reports as excessive. He added that he could "understand the concerns of foreign countries over recent developments at the nuclear plant, including the radioactive contamination of seawater". A screening program a year later in 2012 found that more than a third (36%) of children in Fukushima Prefecture have abnormal growths in their thyroid glands. As of August 2013, there have been more than 40 children newly diagnosed with thyroid cancer and other cancers in Fukushima prefecture as a whole. In 2015, the number of thyroid cancers or detections of developing thyroid cancers numbered 137. However, whether these incidences of cancer are elevated above the rate in un-contaminated areas and therefore were due to exposure to nuclear radiation is unknown at this stage. Data from the Chernobyl accident showed that an unmistakable rise in thyroid cancer rates following the disaster in 1986 only began after a cancer incubation period of 3–5 years; however, whether this data can be directly compared to the Fukushima nuclear disaster is yet to be determined. Estimates of radioactivity released ranged from 10–40% of that of Chernobyl. The significantly contaminated area was 10-12% of that of Chernobyl. Unsuccessful attempts were made to connect portable generating equipment to power water pumps. The failure was attributed to flooding at the connection point in the Turbine Hall basement and the absence of suitable cables. TEPCO switched its efforts to installing new lines from the grid. One generator at unit 6 resumed operation on 17 March, while external power returned to units 5 and 6 only on March 20.
In November 2013, TEPCO began moving the 1533 fuel rods in the Unit 4 cooling pool to the central pool. This process was completed on 22 December 2014. The largest tsunami wave was 13–14 meters (43–46 feet) high and hit approximately 50 minutes after the initial earthquake, overwhelming the plant's seawall, which was 10 m (33 ft) high. The moment of impact was recorded by a camera. There was no MOX fuel in any of the cooling ponds at the time of the incident. The only MOX fuel was currently loaded in the Unit 3 reactor. According to a linear no-threshold model (LNT model), the accident would most likely cause 130 cancer deaths. However, radiation epidemiologist Roy Shore countered that estimating health effects from the LNT model "is not wise because of the uncertainties." Darshak Sanghavi noted that to obtain reliable evidence of the effect of low-level radiation would require an impractically large number of patients, Luckey reported that the body's own repair mechanisms can cope with small doses of radiation and Aurengo stated that “The LNT model cannot be used to estimate the effect of very low doses..." Two emergency diesel generators were available for each of Units 1–5 and three for Unit 6.
A 2012 analysis of the intermediate and long-lived radioactivity released found about 10–20% of that released from the Chernobyl disaster. Approximately 15 PBq of caesium-137 was released, compared with approximately 85 PBq of caesium-137 at Chernobyl, indicating the release of 26.5 kilograms (58 lb) of caesium-137. In 2011, scientists working for the Japan Atomic Energy Agency, Kyoto University and other institutes, recalculated the amount of radioactive material released into the ocean: between late March through April they found a total of 15 PBq for the combined amount of iodine-131 and caesium-137, more than triple the 4.72 PBq estimated by TEPCO. The company had calculated only the direct releases into the sea. The new calculations incorporated the portion of airborne radioactive substances that entered the ocean as rain. On 28 June 2012, Nuclear and Industrial Safety Agency officials apologized to mayor Yuko Endo of Kawauchi Village for NISA having failed to release the American-produced radiation maps in the first days after the meltdowns. All residents of this village were evacuated after the government designated it a no-entry zone. According to a Japanese government panel, authorities had shown no respect for the lives and dignity of village people. One NISA official apologized for the failure and added that the panel had stressed the importance of disclosure; however, the mayor said that the information would have prevented the evacuation into highly polluted areas, and that apologies a year too late had no meaning.
In the days after the accident, radiation released to the atmosphere forced the government to declare an ever larger evacuation zone around the plant, culminating in an evacuation zone with a 20-kilometer radius. All told, some 154,000 residents evacuated from the communities surrounding the plant due to the rising off-site levels of ambient ionizing radiation caused by airborne radioactive contamination from the damaged reactors. In the former Soviet Union, many patients with negligible radioactive exposure after the Chernobyl disaster displayed extreme anxiety about radiation exposure. They developed many psychosomatic problems, including radiophobia along with an increase in fatalistic alcoholism. As Japanese health and radiation specialist Shunichi Yamashita noted: Although people in the incident's worst affected areas have a slightly higher risk of developing certain cancers such as leukemia, solid cancers, thyroid cancer, and breast cancer, very few cancers would be expected as a result of accumulated radiation exposures. Estimated effective doses outside Japan are considered to be below (or far below) the levels regarded as very small by the international radiological protection community. Although there were no deaths from radiation exposure in the immediate aftermath of the incident, there were a number of (non-radiation related) deaths during the evacuation of the nearby population. As of September 2018, one cancer fatality was the subject of a financial settlement, to the family of a former station workman. while approximately 18,500 people died due to the earthquake and tsunami. The maximum predicted eventual cancer mortality and morbidity estimate according to the linear no-threshold theory is 1,500 and 1,800, respectively, but with the strongest weight of evidence producing an estimate much lower, in the range of a few hundred. In addition, the rates of psychological distress among evacuated people rose fivefold compared to the Japanese average due to the experience of the disaster and evacuation.
. Officials at that time were aware that 25–55% of the fuel had been damaged, and the threshold for which the term "meltdown" became appropriate (5%) had been greatly exceeded. TEPCO President Naomi Hirose told the media: "I would say it was a cover-up... It’s extremely regrettable.” The government initially set in place a four-stage evacuation process: a prohibited access area out to 3 km (1.9 mi), an on-alert area 3–20 km (1.9–12.4 mi) and an evacuation prepared area 20–30 km (12–19 mi). On day one, an estimated 170,000 people were evacuated from the prohibited access and on-alert areas. Prime Minister Kan instructed people within the on-alert area to leave and urged those in the prepared area to stay indoors. The latter groups were urged to evacuate on 25 March. The 20 km (12 mi) exclusion zone was guarded by roadblocks to ensure that fewer people would be affected by the radiation. During the evacuation of hospitals and nursing homes, 51 patients and elderly people died. Many of the internal components and fuel assembly cladding are made from zircaloy because it does not absorb neutrons. At normal operating temperatures of approximately 300 °C (572 °F), zircaloy is inert. However, above 1,200 degrees Celsius (2,190 °F), zirconium metal can react exothermically with water to form free hydrogen gas. The reaction between zirconium and the coolant produces more heat, accelerating the reaction. In addition, zircaloy can react with uranium dioxide to form zirconium dioxide and uranium metal. This exothermic reaction together with the reaction of boron carbide with stainless steel can release additional heat energy, thus contributing to the overheating of a reactor. Nuclear power station operators around the world began to install Passive Autocatalytic hydrogen Recombiners ("PARs"), which do not require electricity to operate. PARs work much like the catalytic converter on the exhaust of a car to turn potentially explosive gases such as hydrogen into water. Had such devices been positioned at the top of Fukushima I's reactor buildings, where hydrogen gas collected, the explosions would not have occurred and the releases of radioactive isotopes would arguably have been much less.
As of 2013, about 400 metric tons (390 long tons; 440 short tons) of water per day of cooling water was being pumped into the reactors. Another 400 metric tons (390 long tons; 440 short tons) of groundwater was seeping into the structure. Some 800 metric tons (790 long tons; 880 short tons) of water per day was removed for treatment, half of which was reused for cooling and half diverted to storage tanks. Ultimately the contaminated water, after treatment to remove radionuclides other than tritium, may have to be dumped into the Pacific. TEPCO decided to create an underground ice wall to block the flow of groundwater into the reactor buildings. A $300 million 7.8 MW cooling facility freezes the ground to a depth of 30 meter. As of 2019, the contaminated water generation had been reduced to 170 metric tons (170 long tons; 190 short tons) per day. On 22 July 2013, it was revealed by TEPCO that the plant continued to leak radioactive water into the Pacific Ocean, something long suspected by local fishermen and independent investigators. TEPCO had previously denied that this was happening. Japanese Prime Minister Shinzō Abe ordered the government to step in. Inventory at Fukushima via Stock 13 August 2014 http://nukeprofessional.blogspot.com/2014/08/total-radiation-inventory-at-fukushima.html
Migratory pelagic species are highly effective and rapid transporters of radioactivity throughout the ocean. Elevated levels of caesium-134 appeared in migratory species off the coast of California that were not seen pre-Fukushima. Scientists have also discovered increased traces of radioactive isotope Caesium-137 in wine grown in a vineyard in Napa Valley, California. The trace-level radioactivity was in dust blown across the Pacific Ocean. As of September 2012, the Los Angeles Times reported that "Prime Minister Yoshihiko Noda acknowledged that the vast majority of Japanese support the zero option on nuclear power", and Prime Minister Noda and the Japanese government announced plans to make the country nuclear-free by the 2030s. They announced the end to construction of nuclear power plants and a 40-year limit on existing nuclear plants. Nuclear plant restarts must meet safety standards of the new independent regulatory authority.
On 5 July 2012, the National Diet of Japan Fukushima Nuclear Accident Independent Investigation Commission (NAIIC) found that the causes of the accident had been foreseeable, and that the plant operator, Tokyo Electric Power Company (TEPCO), had failed to meet basic safety requirements such as risk assessment, preparing for containing collateral damage, and developing evacuation plans. At a meeting in Vienna three months after the disaster, the International Atomic Energy Agency faulted lax oversight by the Ministry of Economy, Trade and Industry, saying the ministry faced an inherent conflict of interest as the government agency in charge of both regulating and promoting the nuclear power industry. On 12 October 2012, TEPCO admitted for the first time that it had failed to take necessary measures for fear of inviting lawsuits or protests against its nuclear plants. Radiation deaths at Chernobyl were also statistically undetectable. Only 0.1% of the 110,645 Ukrainian cleanup workers, included in a 20-year study out of over 500,000 former Soviet clean up workers, had as of 2012 developed leukemia, although not all cases resulted from the accident. The amount of damage sustained by the reactor cores during the accident, and the location of molten nuclear fuel ("corium") within the containment buildings, is unknown; TEPCO has revised its estimates several times. On 16 March 2011, TEPCO estimated that 70% of the fuel in Unit 1 had melted and 33% in Unit 2, and that Unit 3's core might also be damaged. As of 2015 it can be assumed that most fuel melted through the reactor pressure vessel (RPV), commonly known as the "reactor core", and is resting on the bottom of the primary containment vessel (PCV), having been stopped by the PCV concrete. In July 2017 a remotely controlled robot filmed for the first time apparently melted fuel, just below the reactor pressure vessel of Unit 3.
From 17 to 19 March 2011, US military aircraft measured radiation within a 45 km (28 mi) radius of the site. The data recorded 125 microsieverts per hour of radiation as far as 25 km (15.5 mi) northwest of the plant. The US provided detailed maps to the Japanese Ministry of Economy, Trade and Industry (METI) on 18 March and to the Ministry of Education, Culture, Sports, Science and Technology (MEXT) two days later, but officials did not act on the information. At the time of the accident, the units and central storage facility contained the following numbers of fuel assemblies: Warnings by government committees, such as one in the Cabinet Office in 2004, that tsunamis taller than the maximum of 5.6 meters (18 ft) forecast by TEPCO and government officials were possible, were also ignored. Labels: Atomphysik, Energie, Fukushima, Physik. Keine Kommentare: Kommentar veröffentlichen. Beim Eingeben eines Kommentars kann Deine IP-Adresse von google gespeichert und verwendet werden. Kommentieren auf eigene Gefahr! Bevor Dein Kommentar im Blog erscheint, muss er erst freigeschaltet werden. Neuerer Post Älterer Post Startseite
-viele Menschen verloren ihr Leben -allgemeine Verwüstung -Stromversorgung Nordjapans brach zusamen - schwerwiegende Probleme und Folgen in dem Kernkraftwerk Fukushima Daiichi Ablauf : - Erdbeben - Probleme mit der Stromversorgung --> Notstromdieselgenaratoren A 2012 report in The Economist said: "The operating company was poorly regulated and did not know what was going on. The operators made mistakes. The representatives of the safety inspectorate fled. Some of the equipment failed. The establishment repeatedly played down the risks and suppressed information about the movement of the radioactive plume, so some people were evacuated from more lightly to more heavily contaminated places." This Cited by count includes citations to the following articles in Scholar. Helmut Satz Professor of Physics, Bielefeld University Verified email at physik.uni-bielefeld.de. K Fukushima, DE Kharzeev, HJ Warringa. Physical Review D 78 (7), 074033, 2008. 1664: 2008 The incident was rated 7 on the International Nuclear Event Scale (INES). This scale runs from 0, indicating an abnormal situation with no safety consequences, to 7, indicating an accident causing widespread contamination with serious health and environmental effects. Prior to Fukushima, the Chernobyl disaster was the only level 7 event on record, while the Three Mile Island accident was rated as level 5.
Immediately after the earthquake, the electricity-producing Reactors 1, 2, and 3 automatically shut down their sustained fission reactions by inserting control rods in a safety procedure referred to as a SCRAM, which ends the reactors' normal running conditions, by closing down the fission reaction in a controlled manner. As the reactors were now unable to generate power to run their own coolant pumps, emergency diesel generators came online, as designed, to power electronics and coolant systems. These operated normally until the tsunami destroyed the generators for Reactors 1–5. The two generators cooling Reactor 6 were undamaged and were sufficient to be pressed into service to cool the neighboring Reactor 5 along with their own reactor, averting the overheating issues the other reactors suffered. When the earthquake struck, units 1, 2, and 3 were operating, but units 4, 5, and 6 had been shut down for a scheduled inspection. One of the two connections to off-site power for units 1–3 also failed, so 13 on-site emergency diesel generators began providing power. A frozen soil barrier was constructed in an attempt to prevent further contamination of seeping groundwater by melted-down nuclear fuel, but in July 2016 TEPCO revealed that the ice wall had failed to stop groundwater from flowing in and mixing with highly radioactive water inside the wrecked reactor buildings, adding that "its ultimate goal has been to 'curtail' groundwater inflow, not halt it". By 2019, the ice wall had reduced the inflow of groundwater from 440 cubic meters per day in 2014 to 100 cubic meters per day, while contaminated water generation decreased to 170 cubic meters per day from 540 cubic meters per day in 2014.
As of October 2019, 1.17 million cubic meters of contaminated water was stored in the plant area. The water is being treated by a purification system that can remove radionuclides, except tritium, to a level that Japanese regulations allow to be discharged to the sea. As of December 2019, 28% of the water had been purified to the required level, while the remaining 72% needed additional purification. However, tritium cannot be separated from the water. As of October 2019, the total amount of tritium in the water was about 856 terabecquerels, and the average tritium concentration was about 0.73 megabecquerels per liter. A committee set up by the Japanese Government concluded that the purified water should be released to the sea or evaporated to the atmosphere. The committee calculated that discharging all the water to the sea in one year would cause a radiation dose of 0.81 microsieverts to the local people, whereas evaporation would cause 1.2 microsieverts. For comparison, Japanese people get 2100 microsieverts per year from natural radiation. IAEA considers that the dose calculation method is appropriate. Further, IAEA recommends that a decision on the water disposal must be made urgently. Despite the negligible doses, the Japanese committee is concerned that the water disposal may cause reputational damage to the prefecture, especially to the fishing industry and tourism. However, despite his paper being widely reported by the media, an undermining error, according to teams of other epidemiologists who point out Tsuda's remarks are fatally wrong, is that Tsuda did an apples and oranges comparison by comparing the Fukushima surveys, which uses advanced ultrasound devices that detect otherwise unnoticeable thyroid growths, with data from traditional non-advanced clinical examinations, to arrive at his "20 to 50 times what would be expected" conclusion. In the critical words of epidemiologist Richard Wakeford, “It is inappropriate to compare the data from the Fukushima screening program with cancer registry data from the rest of Japan where there is, in general, no such large-scale screening,”. Wakeford's criticism was one of seven other author's letters that were published criticizing Tsuda's paper. According to Takamura, another epidemiologist, who examined the results of small scale advanced ultrasound tests on Japanese children not near Fukushima, "The prevalence of thyroid cancer [using the same detection technology] does not differ meaningfully from that in Fukushima Prefecture,”. Many political activists have called for a phase-out of nuclear power in Japan, including Amory Lovins, who claimed, "Japan is poor in fuels, but is the richest of all major industrial countries in renewable energy that can meet the entire long-term energy needs of an energy-efficient Japan, at lower cost and risk than current plans. Japanese industry can do it faster than anyone – if Japanese policymakers acknowledge and allow it". Benjamin K. Sovacool asserted that Japan could have exploited instead its renewable energy base. Japan has a total of "324 GW of achievable potential in the form of onshore and offshore wind turbines (222 GW), geothermal power plants (70 GW), additional hydroelectric capacity (26.5 GW), solar energy (4.8 GW) and agricultural residue (1.1 GW)." Labels: Atomphysik, Energie, Fukushima, Physik 0 Kommentare. Dienstag, 22. März 2011. Die Strahlung geht weiter zurück. Labels: Atomphysik, Energie, Physik 0 Kommentare. Montag, 21. März 2011. Neuere Werte zur Strahlenbelastung. Aktualisierte Werte zur Strahlenbelastung rund um das japanische Kernkraftwerk Fukushima Daiishi gibt es hier
Map of Japan's electricity distribution network, showing incompatible systems between regions. Fukushima is in the 50 hertz Tohoku region. Data from Chernobyl showed that there was a steady but sharp increase in thyroid cancer rates following the disaster in 1986, but whether this data can be directly compared to Fukushima is yet to be determined.
In February 2015, TEPCO started the muon scanning process for Units 1, 2, and 3. With this scanning setup it will be possible to determine the approximate amount and location of the remaining nuclear fuel within the RPV, but not the amount and resting place of the corium in the PCV. In March 2015 TEPCO released the result of the muon scan for Unit 1 which showed that no fuel was visible in the RPV, which would suggest that most if not all of the molten fuel had dropped onto the bottom of the PCV – this will change the plan for the removal of the fuel from Unit 1. In contrast, others have said that the zero mortality rate from the Fukushima incident confirms their opinion that nuclear fission is the only viable option available to replace fossil fuels. Journalist George Monbiot wrote "Why Fukushima made me stop worrying and love nuclear power." In it he said, "As a result of the disaster at Fukushima, I am no longer nuclear-neutral. I now support the technology." He continued, "A crappy old plant with inadequate safety features was hit by a monster earthquake and a vast tsunami. The electricity supply failed, knocking out the cooling system. The reactors began to explode and melt down. The disaster exposed a familiar legacy of poor design and corner-cutting. Yet, as far as we know, no one has yet received a lethal dose of radiation." Responses to Monbiot noted his "false calculation that [nuclear powered electricity] is needed, that it can work economically, and that it can solve its horrific waste, decommissioning and proliferation-security pitfalls ... [along with human] safety, health and indeed human psychology issues." Nuclear reactors generate electricity by using the heat of the fission reaction to produce steam, which drives turbines that generate electricity. When the reactor stops operating, the radioactive decay of unstable isotopes in the fuel continues to generate heat (decay heat) for a time, and so requires continued cooling. This decay heat amounts to approximately 6.5% of the amount produced by fission at first, then decreases over several days before reaching shutdown levels. Afterwards, spent fuel rods typically require several years in a spent fuel pool before they can be safely transferred to dry cask storage vessels. The decay heat in the Unit 4 spent fuel pool had the capacity to boil about 70 metric tons (69 long tons; 77 short tons) of water per day. In 2012 researchers from the Institute of Problems in the Safe Development of Nuclear Energy, Russian Academy of Sciences, and the Hydrometeorological Center of Russia concluded that "on March 15, 2011, ~400 PBq iodine, ~100 PBq caesium, and ~400 PBq inert gases entered the atmosphere" on that day alone. The Japanese government did not keep records of key meetings during the crisis. Data from the SPEEDI network were emailed to the prefectural government, but not shared with others. Emails from NISA to Fukushima, covering 12 March 11:54 PM to 16 March 9 AM and holding vital information for evacuation and health advisories, went unread and were deleted. The data was not used because the disaster countermeasure office regarded the data as "useless because the predicted amount of released radiation is unrealistic." On 14 March 2011 TEPCO officials were instructed not to use the phrase "core meltdown" at press conferences.
On 24 August 2011, the Nuclear Safety Commission (NSC) of Japan published the results of its recalculation of the total amount of radioactive materials released into the air during the accident at the Fukushima Daiichi Nuclear Power Station. The total amounts released between 11 March and 5 April were revised downwards to 130 PBq (petabecquerels, 3.5 megacuries) for iodine-131 and 11 PBq for caesium-137, which is about 11% of Chernobyl emissions. Earlier estimations were 150 PBq and 12 PBq. Cross-section of a typical BWR Mark I containment as used in units 1 to 5.RPV: reactor pressure vesselDW: dry well enclosing reactor pressure vessel.WW: wet well – torus-shaped all around the base enclosing steam suppression pool. Excess steam from the dry well enters the wet well water pool via downcomer pipes.SFP: spent fuel pool areaSCSW: secondary concrete shield wall Unlike Chernobyl, all Japanese reactors were in concrete containment vessels, which limited the release of strontium-90, americium-241, and plutonium, which were among the radioisotopes released by the earlier incident. The accident was started by the Tōhoku earthquake and tsunami on Friday, 11 March 2011. On detecting the earthquake, the active reactors automatically shut down their fission reactions. Because of the reactor trips and other grid problems, the electricity supply failed, and the reactors' emergency diesel generators automatically started. Critically, they were powering the pumps that circulated coolant through the reactors' cores to remove decay heat, which continues to be produced after fission has ceased. The earthquake generated a 14-meter-high tsunami that swept over the plant's seawall and flooded the plant's lower grounds around the Units 1–4 reactor buildings with sea water, filling the basements and knocking out the emergency generators. The resultant loss-of-coolant accidents led to three nuclear meltdowns, three hydrogen explosions, and the release of radioactive contamination in Units 1, 2 and 3 between 12 and 15 March. The spent fuel pool of previously shut-down Reactor 4 increased in temperature on 15 March due to decay heat from newly added spent fuel rods, but did not boil down sufficiently to expose the fuel.
In March 2017, a Japanese court ruled that negligence by the Japanese government had led to the Fukushima disaster by failing to use its regulatory powers to force TEPCO to take preventive measures. The Maebashi district court near Tokyo awarded ¥39 million (US$345,000) to 137 people who were forced to flee their homes following the accident. The atmosphere was not affected on a noticeable scale, as the overwhelming majority of the particulates settled either within the water system or soil surrounding the plant. TEPCO admitted for the first time on 12 October 2012 that it had failed to take stronger measures to prevent disasters for fear of inviting lawsuits or protests against its nuclear plants. There are no clear plans for decommissioning the plant, but the plant management estimate is thirty or forty years.
In May 2011, UK chief inspector of nuclear installations Mike Weightman traveled to Japan as the lead of an International Atomic Energy Agency (IAEA) expert mission. The main finding of this mission, as reported to the IAEA ministerial conference that month, was that risks associated with tsunamis in several sites in Japan had been underestimated. Present and discuss observations of earth as may be related to Fukushima Daiichi and earth's biosphere.In February 2014, NHK reported that TEPCO was reviewing its radioactivity data, after finding much higher levels of radioactivity than was reported earlier. TEPCO now says that levels of 5 MBq (0.12 millicuries) of strontium per liter (23 MBq/imp gal; 19 MBq/U.S. gal; 610 μCi/imp gal; 510 μCi/U.S. gal) were detected in groundwater collected in July 2013 and not the 900 kBq (0.02 millicuries) (4.1 MBq/imp gal; 3.4 MBq/U.S. gal; 110 μCi/imp gal; 92 μCi/U.S. gal) that were initially reported. Thyroid cancer is one of the most survivable cancers, with an approximate 94% survival rate after first diagnosis. That rate increases to a nearly 100% survival rate if caught early. In February 2017, TEPCO released images taken inside Reactor 2 by a remote-controlled camera that show a 2-meter (6.5 ft) wide hole in the metal grating under the pressure vessel in the reactor's primary containment vessel, which could have been caused by fuel escaping the pressure vessel, indicating a meltdown/melt-through had occurred, through this layer of containment. Ionizing radiation levels of about 210 sieverts (Sv) per hour were subsequently detected inside the Unit 2 containment vessel. Undamaged spent fuel typically has values of 270 Sv/h, after ten years of cold shutdown with no shielding.
In the wake of the disaster, the Senate Appropriations Committee requested the United States Department of Energy “to give priority to developing enhanced fuels and cladding for light water reactors to improve safety in the event of accidents in the reactor or spent fuel pools”. This brief has led to ongoing research and development of Accident Tolerant Fuels, which are specifically designed to withstand the loss of cooling for an extended period, increase time to failure, and increase fuel efficiency.. This is accomplished by incorporating specially designed additives to standard fuel pellets and replacing or altering the fuel cladding in order to reduce corrosion, decrease wear, and reduce hydrogen generation during accident conditions.. While research is still ongoing, on 4 March 2018, the Edwin I. Hatch Nuclear Power Plant near Baxley, Georgia has implemented “IronClad” and “ARMOR” (Fe-Cr-Al and coated Zr claddings, respectively) for testing. A monitoring system operated by the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) tracked the spread of radioactivity on a global scale. Radioactive isotopes were picked up by over 40 monitoring stations. Fukushima II was also struck by the tsunami. However, it had incorporated design changes that improved its resistance to flooding, reducing flood damage. Generators and related electrical distribution equipment were located in the watertight reactor building, so that power from the electricity grid was being used by midnight. Seawater pumps for cooling were protected from flooding, and although 3 of 4 initially failed, they were restored to operation.
Unpowered filtering systems on containment building vent lines, known as Filtered Containment Venting Systems (FCVS), can safely catch radioactive materials and thereby allow reactor core depressurization, with steam and hydrogen venting with minimal radioactivity emissions. Filtration using an external water tank system is the most common established system in European countries, with the water tank positioned outside the containment building. In October 2013, the owners of Kashiwazaki-Kariwa nuclear power station began installing wet filters and other safety systems, with completion anticipated in 2014. The loss of 30% of the country's generating capacity led to much greater reliance on liquified natural gas and coal. Unusual conservation measures were undertaken. In the immediate aftermath, nine prefectures served by TEPCO experienced power rationing. The government asked major companies to reduce power consumption by 15%, and some shifted their weekends to weekdays to smooth power demand. Converting to a nuclear-free gas and oil energy economy would cost tens of billions of dollars in annual fees. One estimate is that even including the disaster, more years of life would have been lost in 2011 if Japan had used coal or gas plants instead of nuclear.
On 5 July 2012, the Japanese National Diet-appointed Fukushima Nuclear Accident Independent Investigation Commission (NAIIC) submitted its inquiry report to the Japanese Diet. The Commission found the nuclear disaster was "manmade", that the direct causes of the accident were all foreseeable prior to 11 March 2011. The report also found that the Fukushima Daiichi Nuclear Power Plant was incapable of withstanding the earthquake and tsunami. TEPCO, the regulatory bodies (NISA and NSC) and the government body promoting the nuclear power industry (METI), all failed to correctly develop the most basic safety requirements – such as assessing the probability of damage, preparing for containing collateral damage from such a disaster, and developing evacuation plans for the public in the case of a serious radiation release. Meanwhile, the government-appointed Investigation Committee on the Accident at the Fukushima Nuclear Power Stations of Tokyo Electric Power Company submitted its final report to the Japanese government on 23 July 2012. A separate study by Stanford researchers found that Japanese plants operated by the largest utility companies were particularly unprotected against potential tsunami. On 26 August, the government took charge of emergency measures to prevent further radioactive water leaks, reflecting their lack of confidence in TEPCO. In the late 1990s, three additional backup generators for Units 2 and 4 were placed in new buildings located higher on the hillside, to comply with new regulatory requirements. All six units were given access to these generators, but the switching stations that sent power from these backup generators to the reactors' cooling systems for Units 1 through 5 were still in the poorly protected turbine buildings. The switching station for Unit 6 was protected inside the only GE Mark II reactor building and continued to function. All three of the generators added in the late 1990s were operational after the tsunami. If the switching stations had been moved to inside the reactor buildings or to other flood-proof locations, power would have been provided by these generators to the reactors' cooling systems. Unit 1 had a different, entirely passive cooling system, the Isolation Condenser (IC). It consisted of a series of pipes run from the reactor core to the inside of a large tank of water. When the valves were opened, steam flowed upward to the IC, where the cool water in the tank condenses the steam back to water that runs under gravity back to the reactor core. For unknown reasons, Unit 1's IC was operated only intermittently during the emergency. However, during a 25 March 2014 presentation to the TVA, Takeyuki Inagaki explained that the IC was being operated intermittently to maintain reactor vessel level and to prevent the core from cooling too quickly, which can increase reactor power. As the tsunami engulfed the station, the IC valves were closed and could not be reopened automatically due to the loss of electrical power, but could have been opened manually. On 16 April 2011, TEPCO declared that cooling systems for Units 1–4 were beyond repair. A 2018 publication by Yamashita et al. also concluded that Thyroid cancer rate differences can be attributed to the screening effect. They noted that the mean age of the patients at the time of the accident was 10–15 years, while no cases were found in children from the ages of 0-5 who would have been most susceptible. Yamashita et al. thus conclude that "In any case, the individual prognosis cannot be accurately determined at the time of FNAC at present. It is therefore urgent to search not only for intraoperative and postoperative prognostic factors but also for predictive prognostic factors at the FNAC/preoperative stage."
In October 2012, the former Japanese Ambassador to Switzerland and Senegal, Mitsuhei Murata, said that the ground under Fukushima Unit 4 was sinking, and the structure may collapse. Upon a station blackout, similar to the one that occurred after Fukushima's back-up battery supply was exhausted, many constructed Generation III reactors adopt the principle of passive nuclear safety. They take advantage of convection (hot water tends to rise) and gravity (water tends to fall) to ensure an adequate supply of cooling water to handle the decay heat, without the use of pumps.
Government agencies and TEPCO were unprepared for the "cascading nuclear disaster". The tsunami that "began the nuclear disaster could and should have been anticipated and that ambiguity about the roles of public and private institutions in such a crisis was a factor in the poor response at Fukushima". In March 2012, Prime Minister Yoshihiko Noda said that the government shared the blame for the Fukushima disaster, saying that officials had been blinded by a false belief in the country's "technological infallibility", and were taken in by a "safety myth". Noda said "Everybody must share the pain of responsibility." On 21 March, temperatures in the fuel pond had risen slightly, to 61 °C (142 °F) and water was sprayed over the pool. Power was restored to cooling systems on 24 March and by 28 March, temperatures were reported down to 35 °C (95 °F). According to reinsurer Munich Re, the private insurance industry will not be significantly affected by the disaster. Swiss Re similarly stated, "Coverage for nuclear facilities in Japan excludes earthquake shock, fire following earthquake and tsunami, for both physical damage and liability. Swiss Re believes that the incident at the Fukushima nuclear power plant is unlikely to result in a significant direct loss for the property & casualty insurance industry."[failed verification] Large amounts of water contaminated with radioactive isotopes were released into the Pacific Ocean during and after the disaster. Michio Aoyama, a professor of radioisotope geoscience at the Institute of Environmental Radioactivity, has estimated that 18,000 terabecquerel (TBq) of radioactive caesium 137 were released into the Pacific during the accident, and in 2013, 30 gigabecquerel (GBq) of caesium 137 were still flowing into the ocean every day. The plant's operator has since built new walls along the coast and also created a 1.5-kilometer-long "ice wall" of frozen earth to stop the flow of contaminated water.
The World Health Organization stated that a 2013 thyroid ultrasound screening program was, due to the screening effect, likely to lead to an increase in recorded thyroid cases due to early detection of non-symptomatic disease cases. The overwhelming majority of thyroid growths are benign growths that will never cause symptoms, illness, or death, even if nothing is ever done about the growth. Autopsy studies on people who died from other causes show that more than one third of adults technically have a thyroid growth/cancer. As a precedent, in 1999 in South Korea, the introduction of advanced ultrasound thyroid examinations resulted in an explosion in the rate of benign thyroid cancers being detected and needless surgeries occurring. Despite this, the death rate from thyroid cancer has remained the same. The original plans separated the piping systems for two reactors in the isolation condenser from each other. However, the application for approval of the construction plan showed the two piping systems connected outside the reactor. The changes were not noted, in violation of regulations. A 2019 investigation by Yamamoto et al. evaluated the first and the second screening rounds separately as well as combined covering 184 confirmed cancer cases in 1.080 million observed person years subject to additional radiation exposure due to the nuclear accidents. The authors concluded "A significant association between the external effective dose-rate and the thyroid cancer detection rate exists: detection rate ratio (DRR) per μSv/h 1.065 (1.013, 1.119). Restricting the analysis to the 53 municipalities that received less than 2 μSv/h, and which represent 176 of the total 184 cancer cases, the association appears to be considerably stronger: DRR per μSv/h 1.555 (1.096, 2.206). The average radiation dose-rates in the 59 municipalities of the Fukushima prefecture in June 2011 and the corresponding thyroid cancer detection rates in the period October 2011 to March 2016 show statistically significant relationships. This corroborates previous studies providing evidence for a causal relation between nuclear accidents and the subsequent occurrence of thyroid cancer." Many reports say that the government shares blame with the regulatory agency for not heeding warnings and for not ensuring the independence of the oversight function. The New York Times said that the Japanese nuclear regulatory system sided with and promoted the nuclear industry because of amakudari ('descent from heaven') in which senior regulators accepted high paying jobs at companies they once oversaw. To protect their potential future position in the industry, regulators sought to avoid taking positions that upset or embarrass the companies. TEPCO's position as the largest electrical utility in Japan made it the most desirable position for retiring regulators. Typically the "most senior officials went to work at TEPCO, while those of lower ranks ended up at smaller utilities." In September 2011, IAEA Director General Yukiya Amano said the Japanese nuclear disaster "caused deep public anxiety throughout the world and damaged confidence in nuclear power". Following the disaster, it was reported in The Economist that the IAEA halved its estimate of additional nuclear generating capacity to be built by 2035.
While there has been ongoing controversy over the health effects of the disaster, a 2014 report by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR)  and World Health Organization projected no increase in miscarriages, stillbirths or physical and mental disorders in babies born after the accident. An ongoing intensive cleanup program to both decontaminate affected areas and decommission the plant will take 30 to 40 years, plant management estimate. Doku 2015 Kernfusion - Fukushima : Atomkatastrophe in Japan [Deutsch] Dokumentation 2015 Kernfusion - Fukushima : Atomkatastrophe in Japan [Deutsch] Im März 2011 erschüttert ein starkes Erdbeben. The reactor's emergency diesel generators and DC batteries, crucial components in powering cooling systems after a power loss, were located in the basements of the reactor turbine buildings, in accordance with GE's specifications. Mid-level GE engineers expressed concerns, relayed to TEPCO, that this left them vulnerable to flooding. In July 2018, a robotic probe has found that radiation levels remain too high for humans to work inside one of the reactor buildings. GFS Physik 2012/13. Blog. 13 May 2020. Stay connected to your students with Prezi Video, now in Microsoft Team
Im März 2011 wird Japan von einem Erdbeben der Stärke 9,0 und einem nachfolgenden Tsunami getroffen - zwei Ereignisse, die die atomare Katastrophe in Fukushima auslösten. Alle vier Reaktoren. Physicist and environmentalist Amory Lovins said that Japan's "rigid bureaucratic structures, reluctance to send bad news upwards, need to save face, weak development of policy alternatives, eagerness to preserve nuclear power's public acceptance, and politically fragile government, along with TEPCO's very hierarchical management culture, also contributed to the way the accident unfolded. Moreover, the information Japanese people receive about nuclear energy and its alternatives has long been tightly controlled by both TEPCO and the government." Reactor 4 was not operating when the earthquake struck. All fuel rods from Unit 4 had been transferred to the spent fuel pool on an upper floor of the reactor building prior to the tsunami. On 15 March, an explosion damaged the fourth floor rooftop area of Unit 4, creating two large holes in a wall of the outer building. It was reported that water in the spent fuel pool might be boiling. The explosion was later found to be caused by hydrogen passing to unit 4 from unit 3 through shared pipes. As a result from the explosion, a fire broke out and caused the temperature to in the fuel pool to increase to 84 °C (183 °F).  Radiation inside the Unit 4 control room prevented workers from staying there for long periods. Visual inspection of the spent fuel pool on 30 April revealed no significant damage to the rods. A radiochemical examination of the pond water confirmed that little of the fuel had been damaged. HAARP And How Fukushima Radiation Beamed Down To Australia By Yoichi Shimatsu During the war years, the Greek elevator engineer focused on the German theories on particle physics or Deutsche Physik, presumably based on the papers of Werner Heisenberg, Paul Harteck and Erik Schumann. Much of this strategic field was, however, a well. The Fukushima reactors were not designed for such a large tsunami, nor had the reactors been modified when concerns were raised in Japan and by the IAEA.
On 16 December 2012, Japan held its general election. The Liberal Democratic Party (LDP) had a clear victory, with Shinzō Abe as the new Prime Minister. Abe supported nuclear power, saying that leaving the plants closed was costing the country 4 trillion yen per year in higher costs. The comment came after Junichiro Koizumi, who chose Abe to succeed him as premier, made a recent statement to urge the government to take a stance against using nuclear power. A survey on local mayors by the Yomiuri Shimbun newspaper in January 2013 found that most of them from cities hosting nuclear plants would agree to restarting the reactors, provided the government could guarantee their safety. More than 30,000 people marched on 2 June 2013, in Tokyo against restarting nuclear power plants. Marchers had gathered more than 8 million petition signatures opposing nuclear power. When a reactor is not producing electricity, its cooling pumps can be powered by other reactor units, the grid, diesel generators, or batteries.
Fukushima Information. In 2011, the Japanese experienced the worst earthquake in their history, followed by a devastating tsunami. These natural disasters have had a serious impact on several Japanese nuclear reactors, principally those at the Fukushima Daiichi site The World Nuclear Association reports that the radiation exposure to those living in proximity to Fukushima is expected to be below 10 mSv, over the course of a lifetime. In comparison, the dosage of background radiation received over a lifetime is 170 mSv. The Commission recognized that the affected residents were still struggling and facing grave concerns, including the "health effects of radiation exposure, displacement, the dissolution of families, disruption of their lives and lifestyles and the contamination of vast areas of the environment".
The Fukushima Daiichi Nuclear Power Plant comprised six separate boiling water reactors originally designed by General Electric (GE) and maintained by the Tokyo Electric Power Company (TEPCO). At the time of the Tōhoku earthquake on 11 March 2011, Reactors 4, 5, and 6 were shut down in preparation for re-fueling. However, their spent fuel pools still required cooling. The 9.0 MW earthquake occurred at 14:46 on Friday, 11 March 2011, with the epicenter near Honshu, the largest island of Japan. It produced maximum ground g-forces of 0.56, 0.52, 0.56 at units 2, 3, and 5 respectively. This exceeded the seismic reactor design tolerances of 0.45, 0.45, and 0.46 g for continued operation, but the seismic values were within the design tolerances at units 1, 4, and 6. Physik & Mehr Archäologie & Altertum Geist & Soziales Forschung & Politik Wenn Menschen wie jetzt die Mannschaft in Fukushima nach einem Unglück an Stellen arbeiten, an denen sie extremen.
In a 2017 risk analysis, relying on the metric of potential months of life lost, it determined that unlike Chernobyl, "relocation was unjustified for the 160,000 people relocated after Fukushima", when the potential future deaths from exposure to radiation around Fukushima, would have been much less, if the alternative of the shelter in place protocol had instead been deployed. Fukushima Riskanter Kampf gegen die Strahlung in der Atomruine . Tausende Menschen arbeiten in der 2011 havarierten Atomanlage Fukushima Daiichi in Japan daran, eine Art Normalzustand herzustellen The Fukushima Daiichi Nuclear Power Plant consisted of six GE light water boiling water reactors (BWRs) with a combined power of 4.7 gigawatts, making it one of the world's 25 largest nuclear power stations. It was the first GE-designed nuclear plant to be constructed and run entirely by the Tokyo Electric Power Company (TEPCO). Reactor 1 was a 439 MWe type (BWR-3) reactor constructed in July 1967, and commenced operation on 26 March 1971. It was designed to withstand an earthquake with a peak ground acceleration of 0.18 g (1.4 m/s2, 4.6 ft/s2) and a response spectrum based on the 1952 Kern County earthquake. Reactors 2 and 3 were both 784 MWe type BWR-4s. Reactor 2 commenced operation in July 1974, and Reactor 3 in March 1976. The earthquake design basis for all units ranged from 0.42 g (4.12 m/s2, 13.5 ft/s2) to 0.46 g (4.52 m/s2, 14.8 ft/s2). After the 1978 Miyagi earthquake, when the ground acceleration reached 0.125 g (1.22 m/s2, 4.0 ft/s2) for 30 seconds, no damage to the critical parts of the reactor was found. Units 1–5 have a Mark-1 type (light bulb torus) containment structure; unit 6 has Mark 2-type (over/under) containment structure. In September 2010, Reactor 3 was partially fueled by mixed-oxides (MOX). On 12 March, radioactive releases first reached a CTBTO monitoring station in Takasaki, Japan, around 200 km (120 mi) away. The radioactive isotopes appeared in eastern Russia on 14 March and the west coast of the United States two days later. By day 15, traces of radioactivity were detectable all across the northern hemisphere. Within one month, radioactive particles were noted by CTBTO stations in the southern hemisphere.