Units 4, 5 and 6
When the Fukushima Daiichi nuclear disaster began on 11 March 2011, reactor unit 4 was shut down and all fuel rods had been transferred to the spent fuel pool on an upper floor of the reactor building. On 15 March, an explosion damaged the fourth floor rooftop area of the unit 4 reactor. Japan's nuclear safety agency NISA reported two large holes in a wall of the outer building of unit 4 after the explosion. It was reported that water in the spent fuel pool might be boiling. Radiation inside the unit 4 control room prevented workers from staying there permanently. Visual inspection of the spent fuel pool of reactor 4 on 30 April showed that there was no significant visible damage to the fuel rods in the pool. A radiochemical examination of the water from the pond confirms that little of the fuel in the pond has been damaged.
Reactors 5 and 6 were also not operating when the earthquake struck although, unlike reactor 4, they were still fueled. The reactors have been closely monitored, as cooling processes were not functioning well.
Central fuel storage areas
Used fuel assemblies taken from reactors are initially stored for at least 18 months in the pools adjacent to their reactors. They can then be transferred to the central fuel storage pond. This contains 6375 fuel assemblies and was reported "secured" with a temperature of 55 °C. After further cooling, fuel can be transferred to dry cask storage, which has shown no signs of abnormalities. On 21 March, temperatures in the fuel pond had risen slightly, to 61 °C 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.
Cascade of failures
Government agencies and Tepco were thoroughly unprepared for the "cascading nuclear disaster" which was largely caused by a public myth of "absolute safety" that nuclear power proponents had nurtured over decades. 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". Mr. Noda said "Everybody must share the pain of responsibility".
According to Naoto Kan, Japan's former prime minister, the country was totally unprepared for the Fukushima disaster, and the crippled Fukushima plant should not have been built so close to the ocean on a tsunami-prone coast. Kan has acknowledged flaws in authorities' handling of the crisis, including poor communication and coordination between nuclear regulators, utility officials and the government. He said the disaster "laid bare a host of an even bigger man-made vulnerabilities in Japan's nuclear industry and regulation, from inadequate safety guidelines to crisis management, all of which he said need to be overhauled".
A national program to develop robots for use in nuclear emergencies was terminated in midstream because it "smacked too much of underlying danger". Japan, supposedly a leader in robotics, had none to send in to Fukushima when the crisis began. Similarly, Japan’s Nuclear Safety Commission said in its safety guidelines for light-water nuclear facilities that "the potential for extended loss of power need not be considered." But just such an extended loss of power contributed to the Fukushima meltdowns.
Physicist Amory Lovins has said: 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".
Poor communication and delays
The Japanese government has admitted it did not keep records of key meetings during the Fukushima nuclear crisis, even though such detailed notes are considered a key component of disaster management. Data from SPEEDI (System for Prediction of Environmental Emergency Dose Information) were sent by email to the government of the Fukushima prefecture, but not shared with others. The data of five crucial days, from 12 March 2011 11:54 p.m. tp 16 March 9 a.m – holding vital information for evacuation and health advisories – the emails from NISA to Fukushima stayed unread and were deleted afterwards. All was revealed more than a year later, on 21 March 2012. The data were not used, because the disaster countermeasure office did regard the data "useless because the predicted amount of released radiation is unrealistic." 
Japan's response to the crisis at Fukushima Daiichi was flawed by "poor communication and delays in releasing data on dangerous radiation leaks at the facility", a government-appointed investigative panel has found. The panel was led by University of Tokyo Professor Yotaro Hatamura and the panel's Investigation Committee on the Accident at the Fukushima Nuclear Power Stations of Tokyo Electric Power Company report attaches blame to Japan's central government as well as Tokyo Electric Power Co., "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 507-page interim report, which resulted from hundreds of interviews with utility workers and government officials, said poor planning also worsened the disaster response, noting that authorities had "grossly underestimated tsunami risks" that followed the magnitude 9.0 earthquake. The 40-foot-high tsunami that struck the plant was twice as tall as the highest wave predicted by officials, and the erroneous assumption that the plant's cooling system continued to work after the tsunami struck 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. Ultimately, the series of failures led to the worst nuclear catastrophe since Chernobyl".
In February 2012, an independent investigation into the accident by the Rebuild Japan Initiative Foundation described how Japan's response was hindered at times by a loss of trust between the major actors: Naoto Kan, the Tokyo headquarters of Tepco, and the manager at the stricken plant. The report said that these conflicts "produced confused flows of sometimes contradictory information in the early days of the crisis". According to the report, Kan delayed the cooling of the reactors by questioning the use of seawater instead of fresh water. Kan further hindered the response to the crisis by micromanaging disaster management efforts and appointing his own nominees to a small, closed, decision-making staff. The report stated that the Japanese government was also slow to accept assistance from U.S. nuclear experts.
A 2012 report in The Economist said: "The reactors at Fukushima were of an old design. The risks they faced had not been well analysed. 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".
From 17 to 19 March 2011, US military aircraft, on behalf of the US Department of Energy, measured the radiation within a 45-km radius of the reactors. The data recorded 125 microsieverts per hour of radiation as far as 25 km northwest of the plant. The US provided the data, illustrated on detailed maps, to the Japanese Ministry of Economy, Trade, and Industry on 18 March and to the Ministry of Education, Culture, Sports, Science, and Technology two days later. Japanese government officials did not act on the information provided by the maps.
The data were not forwarded to the prime minister's office and the Nuclear Safety Commission, and subsequently not used to direct the evacuation of the people living around the plant. Because a substantial portion of radioactive materials released from the plant went northwest and was fallen onto the ground, and some residents were "evacuated" into this direction, these people could have avoided unnecessary exposure to radiation when the data would have been published directly. According to Tetsuya Yamamoto, chief nuclear safety officer of the Nuclear Safety Agency, "It was very regrettable that we didn't share and utilize the information." But an official of the Science and Technology Policy Bureau of the technology ministry, Itaru Watanabe, said it was not Japan, but more appropriate for the United States to release the data.
After the Americans had published their map on 23 March, Japan felt itself forced to publish, and the fallout-maps, compiled from measurents on the ground and the predictions of the computer-simulations of SPEEDI, were released the same day. On 19 June 2012 science minister Hirofumi Hirano defended the decision not to publish, with the remark, that his "job was only to measure radiation levels on land", and that the government would study whether disclosure of the maps could have helped in the evacuation efforts.
Regulatory capture may have contributed to the cascade of failures which were revealed after the tsunami receded. Regulatory capture may have also contributed to the current situation. Critics argue that the government shares blame with regulatory agency for not heeding warnings, for not ensuring the independence of the nuclear industry's oversight while encouraging the expansion of nuclear energy domestically and internationally. World media have argued that the Japanese nuclear regulatory system tends to side with and promote the nuclear industry because of amakudari (roughly translated as descent from heaven), in which senior regulators accept high paying jobs at the companies they once oversaw. To protect their potential future position in the industry, regulators seek to avoid taking positions that upset or embarrass the utilities they regulate. TEPCO's position as the largest electrical utility in Japan led it to be 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" according to the New York Times.
In August 2011, several top energy officials were fired by the Japanese government; affected positions included the Vice-minister for Economy, Trade and Industry; the head of the Nuclear and Industrial Safety Agency, and the head of the Agency for Natural Resources and Energy.
The severity of the nuclear accident is provisionally 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 accident on record, while theThree Mile Island accident was a level 5 accident. Arnold Gundersen, a former nuclear power industry executive who served as an expert witness in the investigation of the Three Mile Island accident, said that "Fukushima is the biggest industrial catastrophe in the history of mankind,"[neutrality is disputed] although current estimates of the total amount of radioactivity released from the 3 Fukushima Daiichi reactors is only 10% that from Chernobyl.
The Japan Atomic Energy Agency initially rated the situation at Unit 1 below both of these previous accidents; on 13 March it announced it was classifying the event at level 4, an "accident with local consequences". On 18 March it raised its rating on Units 1, 2 and 3 to Level 5, an "accident with wider consequences". It classified the situation at Unit 4 as a level 3 "serious incident".
Several parties disputed the Japanese classifications, arguing that the situation was more severe than they were admitting at the time. On 14 March, three Russian experts stated that the nuclear accident should be classified at Level 5, perhaps even Level 6. One day later, the French nuclear safety authority ASN said that the Fukushima plant could be classified as a Level 6. as of 18 March, the French nuclear authority—and as of 15 March, the Finnish nuclear safety authority—estimated the accidents at Fukushima to be at Level 6 on the INES. On 24 March, a scientific consultant for noted anti-nuclear environmental group Greenpeace, working with data from the Austrian ZAMG and French IRSN, prepared an analysis in which he rated the total Fukushima accident at INES level 7.
The Asahi Shimbun newspaper reported on 26 March that the accident might warrant level 6, based on its calculations. The Wall Street Journal stated that Japan's NISA would make any decision on raising the level. INES level 6, or "serious accident", had only been applied to the Kyshtym disaster (Soviet Union, 1957), while the only level 7 was Chernobyl (Soviet Union, 1986). Previous level 5 accidents included the Windscale fire (United Kingdom, 1957); the Lucens reactor (Switzerland, 1969); Three Mile Island (United States, 1979); and the Goiânia accident (Brazil, 1987).
Assessing "seriousness" as partial or full meltdown at a civilian plant, The New York Times reported on 3 April that based on remote sensing, computer "simulations suggest that the number of serious accidents has suddenly doubled, with three of the reactors at the Fukushima Daiichi complex in some stage of meltdown." The Times counted three previous civilian meltdowns, from World Nuclear Association information: Three Mile Island; Saint-Laurent Nuclear Power Plant (France, 1980, INES level 4); and Chernobyl.
On 11 April, the Japanese Nuclear and Industrial Safety Agency (NISA) temporarily raised the disaster at Fukushima Daiichi to Level 7 on the INES scale, by considering the whole event and not considering each reactor as an individual event per se (rated between 3 and 5). This would make Fukushima the second Level 7 "major accident" in the history of the nuclear industry; having said that, radiation released as a result of the events at Fukushima was, as of 12 April, only approximately 10% of that released as a result of the accident at Chernobyl (1986), also rated as INES Level 7. The largest study, as of 21 October 2011, on Fukushima fallout concludes that Fukushima was "the largest radioactive noble gas release in history not related to nuclear bomb testing. The release is a factor of 2.5 higher than the Chernobyl 133Xe source term.", although the "Xenon-133 [main noble gas] does not pose serious health risks because it is not absorbed by the body or the environment." Arnold Gundersen said Fukushima has 20 times the potential to be released than Chernobyl. Hot spots are being found 60 to 70 kilometres away from the reactor (further away than they were found from Chernobyl), and the amount of radiation in many of them is the amount that caused areas to be declared no-man's-land for Chernobyl.
In off-the-record-interviews with Japanese newspapers like the Tokyo Shimbun, Naoto Kan, former premier minister of Japan, revealed that there were moments he believed the disaster could have surpassed Chernobyl, many times. At first Tepco denied that fuel-cores were melted, after all cooling functions were lost. Trade minister, Banri Kaieda, mentioned that Tepco seriously considered pulling away all staff-members from the plant and leaving it abandoned. Kan could not accept this: "Withdrawing from the plant was out of the question, If that had happened, Tokyo would be deserted by now. It was a critical moment for Japan's survival. It could have been a led to leaks of dozens of times more radiation than Chernobyl." That might have "compromised the very existence of the Japanese nation".
Tepco's president at that time, Masataka Shimizu, was never clear in his answers, and TEPCO failed to obey the orders to vent one of the overheating reactors, In an interview to the Asahi Shimbun newspaper. Kan revealed, that he went to the plant itself and inspected the plant from above in a helicopter because: "I felt I had to go there in person and speak to the people in charge or I would never have known what was going on." The American Government was seriously concerned about the Japanese response to the accident: Kan said: "We were not told straight out, but it was obvious that they questioned whether we were really taking this seriously."
Kan did defend his changed attitude to a non-nuclear energy policy with the following remarks: "If there is a risk of accidents that could make half the land mass of our country uninhabitable, then we cannot afford to take that risk."
Major news source reporting at least 2 TEPCO employees confirmed dead from "disaster conditions" following the earthquake. "The two workers, aged 21 and 24, sustained multiple external injuries and were believed to have died from blood loss, TEPCO said. Their bodies were decontaminated as radiation has been spewing from the plant for three weeks."
45 patients were reported dead after the evacuation of a hospital in Futaba due to lack of food, water and medical care as evacuation was delayed by three days.
The Associated Press reported that fourteen senior citizens died after being moved from their hospital which was in the Fukushima plant evacuation zone.
On 14 April 2011, it was reported that the oldest resident of Iitate, a 102-year-old, committed suicide rather than to leave following the announcement of his village's evacuation.
According to the Japanese Government, over 160,000 people in the general population were screened in March 2011 for radiation exposure and no case was found which affects health. Thirty workers conducting operations at the plant had exposure levels greater than 100 mSv.
In April 2011, the United States Department of Energy published projections of the radiation risks over the next year for people living in the neighborhood of the plant. Potential exposure could exceed 20 mSv/year (2 rems/year) in some areas up to 50 kilometers from the plant. That is the level at which relocation would be considered in the USA, and it is a level that could cause roughly one extra cancer case in 500 young adults. Natural radiation levels are higher in some part of the world than the projected level mentioned above, and about 4 people out of 10 can be expected to develop cancer without exposure to radiation. Further, the radiation exposure resulting from the accident for most people living in Fukushima is so small compared to background radiation that it may be impossible to find statistically significant evidence of increases in cancer.
As of September 2011, six workers at the Fukushima Daiichi site have exceeded lifetime legal limits for radiation and more than 300 have received significant radiation doses.
Workers on-site now wear full-body radiation protection gear, including masks and helmets covering their entire heads, but it means they have another enemy: heat. As of 19 July 2011, 33 cases of heat stroke had been recorded. In these harsh working conditions, two workers in their 60s have died from heart failure.
Two other worker deaths have been reported to date. By mid-August 2011, a man in his forties who had worked for a week on the Fukushima Daiichi site was hospitalized and died of acute leukemia not long after passing a physical test. It was not caused by occupational exposure, according to Tepco officials, as "it is medically impossible for symptoms of acute leukemia to manifest from occupational radiation exposure from a few weeks ago." In October 2011, another worker died in his 50s for an undisclosed reason which, according to TEPCO, "had nothing to do with exposure to radiation."
As of September 2011, there were no deaths or serious injuries due to direct radiation exposures. Cancer deaths due to accumulated radiation exposures cannot be ruled out, and according to one expert, might be in the order of 100 cases. A May 2012 United Nations committee report stated that none of the six Fukushima workers who had died since the tsunami had died from radiation exposure.
Frank N. von Hippel, a U.S. scientist, has estimated that "on the order of 1,000" people will die from cancer as a result of their exposure to radiation from the Fukushima Daiichi disaster, that is, an increase of 0.1% in the incidence of cancer, and much less than the approximately 20,000 people killed directly by the earthquake and tsunami. Because contaminated milk was "interdicted in Japan" the number of (mostly non-fatal) thyroid cancer cases will probably be less than 1% of similar cases at Chernobyl. Von Hippel added that "fear of ionizing radiation could have long-term psychological effects on a large portion of the population in the contaminated areas".
According to a 2012 Yomiuri Shimbun survey, 573 deaths have been certified as "disaster-related" by 13 municipalities affected by the Fukushima nuclear disaster. These municipalities are in the no-entry, emergency evacuation preparation or expanded evacuation zones around the crippled Fukushima nuclear plant. A disaster-related death certificate is issued when a death is not directly caused by a tragedy, but by "fatigue or the aggravation of a chronic disease due to the disaster".
Plight of evacuees
A survey by the Iitate, Fukushima local government obtained responses from approximately 1,743 people who have evacuated from the village, which lies within the emergency evacuation zone around the crippled Fukushima Daiichi Plant. It shows that many residents are experiencing growing frustration and instability due to the nuclear crisis and an inability to return to the lives they were living before the disaster. 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.
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.
On 7 June 2011 a government-appointed committee of 10 people convened to investigate the accident. The panel was headed by Yotaro Hatamura, professor emeritus of the University of Tokyo, and included Yukio Takasu, Michio Furukawa, the mayor of Kawamata, Fukushima, and author Kunio Yanagida, considered an expert on crisis management.
As part of the government inquiry, the House of Representatives of Japan's special science committee directed TEPCO to submit to them its manuals and procedures for dealing with reactor accidents. TEPCO responded by submitting manuals with most of the text blotted out. In response, the Nuclear and Industrial Safety Agency ordered TEPCO to resubmit the manuals by 28 September 2011 without hiding any of the content. TEPCO replied that it would comply with the order.
On 24 October NISA published a large portion of Tokyo Electric Power Company's procedural manuals for nuclear accidents. These were the manuals that the operator of the Fukushima Daiichi nuclear power plant earlier did send to the Lower House with most of the contents blacked out, saying that this information should be kept secret to protect its intellectual property rights, and that disclosure would offer information to possible terrorists. NISA ordered TEPCO to send the manuals without any redaction, as the law orders. 200 pages were released from the accident procedural manuals used for Fukushima Daiichi nuclear power plant. All their contents were published, only the names of individuals were left out.
From these documents could be concluded:
- TEPCO did not make sufficient preparations to cope with critical nuclear accidents.
- After the batteries and power supply boards were inundated on 11 March, almost all electricity sources were lost
- TEPCO did not envision such a power failure or any kind of prolonged power loss.
- TEPCO thought that in a serious incident, venting pressure in the reactor containment vessels or carrying out other safety procedures would still be possible, because emergency power sources would still be available.
The agency said, the decision to publish the manuals was taken, for transparency in the search what caused the nuclear accident in Fukushima and also to establish better safety measures for the future.
On 24 October 2011 the first meeting was held by a group of 6 nuclear energy specialists invited by NISA to discuss the lessons to be learned from the accidents in Fukushima. Their first remarks were:
- Japanese nuclear power plants should have multiple power sources
- plants should be able to maintain electricity during an earthquake or other emergencies
- TEPCO should examine why the equipment failed to work and should take appropriate actions to prevent such failures in the future
According to professor Tadashi Narabayashi of the Hokkaido University Graduate School, plant operators should arrange emergency power supplies with other utilities. These discussion should be completed in March 2012, to be able to implement their conclusions into the new safety-regulations by the new nuclear safety agency to be launched in April 2012.
The Investigation Committee on the Accident at the Fukushima Nuclear Power Stations of Tokyo Electric Power Company was formed 7 June 2011 by the Japanese government as an independent body to investigate the Fukushima Daiichi disaster. The Investigation Committee issued an interim report in December 2011, and is expected to issue its final report summer, 2012. The interim report was "a scathing assessment of the response to the Fukushima disaster", in which the investigative panel "blamed the central government and the Tokyo Electric Power Co., saying both seemed incapable of making decisions to stem radiation leaks as the situation at the coastal plant worsened in the days and weeks after the disaster".
In February 2012, an independent investigation into the accident by the Rebuild Japan Initiative Foundation said that "In the darkest moments of last year's nuclear accident, Japanese leaders did not know the actual extent of damage at the plant and secretly considered the possibility of evacuating Tokyo, even as they tried to play down the risks in public". The government was preparing for the possibility of having to evacuate Tokyo while assuring its millions of residents that everything was under control.
Officials revealed in interviews that they were grappling the possibility of a "demonic chain reaction": If Fukushima collapsed and released enough radiation, it was possible that other nearby nuclear power plants would have to be abandoned and could also collapse, thereby necessitating the evacuation of one of the world's largest cities.
A 2012 report in The Economist said that the response to Fukushima has, so far, been inadequate, as many questions remain. One of the more worrying is how much damage the earthquake did to the reactors:
It is claimed that they weathered the quake, but some experts, such as Masashi Goto, a retired nuclear engineer, argue that there is evidence of significant damage that speeded up the subsequent meltdown. Analysis of the spread of fallout suggests that the first releases came very soon after the tsunami hit, if not before. With quakes a more constant threat than monster tsunamis, these are the sort of lessons that Japan’s "nuclear village" needs to learn.
Oregon's United States Senator Ron Wyden toured the plant and issued a statement that the situation was "worse than reported." He sent a letter to Japanese Ambassador Ichiro Fujisaki urging Japan to seek international help to relocate spent fuel rods stored in unsound structures and prevent leakage of dangerous nuclear material.
TEPCO released its final internal investigation report on 20 June 2012. In the report, TEPCO complained that top politicians, including the prime minister, interfered with recovery efforts during the initial stages of the disaster by making specific requests that were out of touch with what was actually taking place at the plant. TEPCO concluded that the direct cause of the accident was the tsunami which knocked out the reactors' cooling system. TEPCO also admitted that it was at fault in not being prepared for the situation, but said that its workers did the best they could "amid unprecedented circumstances."
On July 5, 2012, the National Diet of Japan Fukushima Nuclear Accident Independent Investigation Commission released an executive summary report of The Fukushima Nuclear Accident. The report "blames Japanese culture for the fundamental causes of the disaster." The panel is due to deliver its final report at the end of July.
According to Munich Re, a major reinsurer, the private insurance industry will not be significantly affected by the accidents at the Fukushima nuclear power plant. Swiss Resimilarly states "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."
Radioactive material has been released from the Fukushima containment vessels as the result of deliberate venting to reduce gaseous pressure, deliberate discharge of coolant water into the sea, and accidental or uncontrolled events. Concerns about the possibility of a large scale radiation leak resulted in 20 km exclusion zone being set up around the power plant and people within the 20–30 km zone being advised to stay indoors. Later, the UK, France and some other countries told their nationals to consider leaving Tokyo, in response to fears of spreading radioactive contamination. The Fukushima accident has led to trace amounts of radiation, including iodine-131,caesium-134 and caesium-137, being observed around the world (New York State, Alaska, Hawaii, Oregon, California, Montreal, and Austria). Large amounts of radioactive isotopes have also been released into the Pacific Ocean.
A monitoring system designed to detect nuclear explosions, operated by the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), tracked the dispersion of radioactivity from the crippled nuclear reactor on a global scale. Radioactive isotopes originating from Fukushima were picked up by over 40 CTBTO radionuclide monitoring stations. The CTBTO makes its monitoring data and analysis results available to all its 183 Member States. Around 1,200 scientific and academic institutions in 120 countries currently make use of this offer.
On 12 March, radioactive releases first reached a CTBTO monitoring station in Takasaki, Japan, around 200 km away from the troubled power plant. The dispersion of the radioactive isotopes could then be followed to eastern Russia on 14 March and to 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 also picked up by CTBTO stations in the southern hemisphere, located for example in Australia, Fiji, Malaysia and Papua New Guinea.
According to one expert, the release of radioactivity is about one-tenth that from the Chernobyl disaster and the contaminated area is also about one-tenth that that of Chernobyl. A March 2012 report by the Ministry of Education, Culture, Sports, Science and Technology agreed that radioactive debris from the damaged reactors had dispersed about one-eighth to one-tenth of the distance as those in the Chernobyl disaster. But according to a study conducted by Norwegian Institute for Air Research, the release of caesium-137 was about 40 percent of the total from Chernobyl.
In March 2011, Japanese officials announced that "radioactive iodine-131 exceeding safety limits for infants had been detected at 18 water-purification plants in Tokyo and five other prefectures". As of July 2011, the Japanese government has been unable to control the spread of radioactive material into the nation's food. Radioactive material has been detected in a range of produce, including spinach, tea leaves, milk, fish and beef, up to 200 miles from the nuclear plant. Inside the 12-mile evacuation zone around the plant, all farming has been abandoned.
As of August 2011, the crippled Fukushima nuclear plant is still leaking low levels of radiation and areas surrounding it could remain uninhabitable for decades due to high radiation. It could take "more than 20 years before residents could safely return to areas with current radiation readings of 200 millisieverts per year, and a decade for areas at 100 millisieverts per year".
On 24 August 2011, the Nuclear Safety Commission (NSC) of Japan published the results of the 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 1.3 × 1017 Bq for iodine-131 and 1.1 × 1016 Bq for caesium-137, which is about 11% of Chernobyl emissions. Earlier estimations were 1.5 × 1017 Bq and 1.2 × 1016 Bq.
On 8 September 2011 a group of Japanese scientists working for the Japan Atomic Energy Agency, the Kyoto University and other institutes, published the results of a recalculation of the total amount of radioactive material released into the ocean: between late March through April they found a total of 15,000 TBq for the combined amount of iodine-131 and caesium-137. This was more than triple the figure of 4,720 TBq estimated by the plant-owner. TEPCO made only a calculation about the releases from the plant in April and May into the sea. The new calculations were needed because a large portion of the airborne radioactive substances would enter the seawater when it came down as rain.
In the first half of September 2011 the amount of radioactive substances released from the plant was about 200 million becquerels per hour, according to TEPCO, this was approximately one four-millionth of the level of the initial stages of the accident in March. Traces of iodine-131 are still detected in several Japanese prefectures in the months of November and December 2011.
According to a report published in October 2011 by the French Institute for Radiological Protection and Nuclear Safety, between 21 March and mid-July around 2.7 × 1016 Bq of caesium-137 entered the ocean, about 82 percent having flowed into the sea before 8 April. This emission of radioactivity into the sea represents the most important individual emissions of artificial radioactivity into the sea ever observed. The Fukushima coast has one of the world's strongest currents and this transported the contaminated waters far into the Pacific Ocean, causing a high dispersion of the radioactive elements. The results of measurements of both the seawater and the coastal sediments lead to suppose that the consequences of the accident, for what concerns radioactivity, will be minor for marine life as of late 2011 (weak concentration of radioactivity in the water and limited accumulation in sediments). On the other hand, significant pollution of sea water along the coast near the nuclear plant might persist, because of the continuing arrival of radioactive material transported towards the sea by surface water running over contaminated soil. Further, some coastal areas might have less favorable dilution or sedimentation characteristics than those observed so far. Finally, the possible presence of other persistent 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 coast of Fukushima district. Organisms that filter water and fish at the top of the food chain are, over time, the most sensitive to caesium pollution. It is thus justified to maintain surveillance of marine life that is fished in the coastal waters off Fukushima.
As of March 2012, there had been no reported cases of Fukushima residents suffering ailments related to radiation exposure. Experts cautioned that insufficient data was available so far to make conclusions on the impact on residents' health. Nevertheless, Michiaki Kai, professor of radiation protection at Oita University of Nursing and Health Sciences, stated, "If the current radiation dose estimates are correct, (cancer-related deaths) likely won't increase."
On 24 May 2012, TEPCO released their estimate of radiation releases due to the Fukushima Daiichi Nuclear Disaster. An estimated 538,100 terabecquerels (TBq) of iodine-131, caesium-134 and caesium-137 was released. 520,000 TBq was released into the atmosphere between March 12 to March 31, 2011 and 18,100 TBq into the ocean from March 26 to September 30, 2011. A total of 511,000 TBq of iodine-131 was released into both the atmosphere and the ocean, 13,500 TBq of caesium-134 and 13,600 TBq of caesium-137.
In May 2012, TEPCO reported that at least 900 PBq had been released "into the atmosphere in March last year  alone".
Reaction in Japan and evacuation measures
A nuclear emergency was declared by the government of Japan on 11 March 2011. Later Prime Minister Naoto Kan issued instructions that people within a 20 km (12 mi) zone around the Fukushima Daiichi nuclear plant must leave, and urged that those living between 20 km and 30 km from the site to stay indoors. The latter groups were also urged to evacuate on 25 March.
Japanese authorities have admitted that lax standards and poor oversight contributed to the nuclear disaster. They have come under fire for their handling of the emergency, and have engaged in a pattern of withholding damaging information and denying facts of the accident. Authorities apparently wanted to "limit the size of costly and disruptive evacuations in land-scarce Japan and to avoid public questioning of the politically powerful nuclear industry". There has been public anger about an "official campaign to play down the scope of the accident and the potential health risks". The accident is the second biggest nuclear accident after the Chernobyl disaster, but more complex as all reactors are involved.
Once a proponent of building more reactors, Prime Minister Naoto Kan took an increasingly anti-nuclear stance in the months following the Fukushima disaster. In May, he ordered the aging Hamaoka Nuclear Power Plant be closed over earthquake and tsunami fears, and said he would freeze plans to build new reactors. In July 2011, Mr. Kan said that "Japan should reduce and eventually eliminate its dependence on nuclear energy ... saying that the Fukushima accident had demonstrated the dangers of the technology".
On 22 August 2011 a spokesman of the Japanese Government mentioned the possibility, that some areas of the evacuation zone around the nuclear plant for "could stay for some decades a forbidden zone". According to the Japanese newspaper Yomiuri Shimbun the Japanese government was planning to buy some properties from civilians to store radioactive waste and materials that had become radioactive after the accidents. Chiaki Takahashi, Japan's foreign minister, criticised foreign medias reports over accidents in Fukushima Daichii as overdone and excessive. But Takahashi added that "he can understand the concerns of foreign countries over recent developments at the nuclear plant, including the radioactive contamination of seawater".
Due to frustration with Tokyo Electric Power Company (TEPCO) and the Japanese government "providing differing, confusing, and at times contradictory, information on critical health issues" a citizen's group called "Safecast" has been recording detailed radiation level data in Japan. The Japanese government "does not consider non-government readings to be authentic". The group uses off-the-shelf Geiger counter equipment. It is important to note that a simple geiger counter is a contamination meter and not a dose rate meter, as the response differs so much between different radioisotopes it is not possible to use a simple GM tube for dose rate measureemnts when more than one radioisotope is present. A thin metal shield is needed around a GM tube to provide energy compensation to enable it to be used for dose rate measurements. For measurements of dose rates due to gamma emitters either an ionization chamber, a gamma spectrometer or an energy compensated GM tube should be used. Members of the Air Monitoring station facility at the Department of Nuclear Engineering at the University of Berkeley, California have been doing extensive tests of environmental samples in Northern California.
The international reaction to the 2011 Fukushima Daiichi nuclear disaster has been diverse and widespread. Many inter-governmental agencies are responding to the Fukushima Daiichi nuclear disaster, often on an ad hoc basis. Responders include International Atomic Energy Agency, World Meteorological Organization and the Preparatory Commission for the Comprehensive Nuclear Test Ban Treaty Organization, which has radiation detection equipment deployed around the world.
Many countries have advised their nationals to leave Tokyo, citing the risk associated with the nuclear plants' ongoing accident. International experts have said that a workforce in the hundreds or even thousands would take years or decades to clean up the area. Stock prices of many energy companies reliant on nuclear sources have dropped.
There has been a significant re-evaluation of existing nuclear power programs in many countries. One poll found that what had been growing acceptance of nuclear power in the United States was eroded sharply following the 2011 Japanese nuclear accidents, with 43% approving and 50% disapproving of building new plants. Worldwide, a study byUBS, reported on 12 April 2011, suggests that around 30 nuclear plants may be closed as a result of Fukushima, with those located in seismic zones or close to national boundaries being the most likely to shut. Events at Fukushima "cast doubt on the idea that even an advanced economy can master nuclear safety". Increased anti-nuclearsentiment has been evident in India, Italy, Germany, Spain, Switzerland, Taiwan, and the United States.
Much of the help and decontamination work could be done by AREVA France with boron acid, shutting down one reactor, protection suits, measurement equipment, generators, filters; by more than 1000 men with own first-hand help and information offered.
|29 June||6380||76 %|
|6 July||6130||73 %|
|13 July||4510||54 %|
|20 July||4870||58 %|
|27 July||6190||74 %|
|3 August||6720||80 %|
|10 August||7420||88 %|