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The Chernobyl disaster (also referred to as Chernobyl or the Chernobyl accident) was a catastrophic nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in the town of Pripyat, in Ukraine (then officially the Ukrainian SSR), which was under the direct jurisdiction of the central authorities of the Soviet Union. An explosion and fire released large quantities of radioactive particles into the atmosphere, which spread over much of the western USSR and Europe. The Chernobyl disaster was the worst nuclear power plant accident in history in terms of cost and casualties.〔Nuclear and radiation accidents#Nuclear power plant accidents〕 It is one of only two classified as a level 7 event (the maximum classification) on the International Nuclear Event Scale, the other being the Fukushima Daiichi nuclear disaster in 2011. The battle to contain the contamination and avert a greater catastrophe ultimately involved over 500,000 workers and cost an estimated 18 billion rubles.〔Gorbachev, Mikhail (1996), interview in Johnson, Thomas, ', (), Discovery Channel, retrieved 19 February 2014.〕 During the accident itself, 31 people died, and long-term effects such as cancers are still being investigated. ==Overview== The disaster began during a systems test on 26 April 1986 at reactor number four of the Chernobyl plant, which is near the city of Pripyat and in proximity to the administrative border with Belarus and the Dnieper River. There was a sudden and unexpected power surge, and when an emergency shutdown was attempted, an exponentially larger spike in power output occurred, which led to a reactor vessel rupture and a series of steam explosions. These events exposed the graphite moderator of the reactor to air, causing it to ignite. The resulting fire sent a plume of highly radioactive fallout into the atmosphere and over an extensive geographical area, including Pripyat. The plume drifted over large parts of the western Soviet Union and Europe. From 1986 to 2000, 350,400 people were evacuated and resettled from the most severely contaminated areas of Belarus, Russia, and Ukraine. According to official post-Soviet data, about 60% of the fallout landed in Belarus. Russia, Ukraine, and Belarus have been burdened with the continuing and substantial decontamination and health care costs of the Chernobyl accident. A report by the International Atomic Energy Agency examines the environmental consequences of the accident.〔 Another UN agency, UNSCEAR, has estimated a global collective dose of radiation exposure from the accident "equivalent on average to 21 additional days of world exposure to natural background radiation"; individual doses were far higher than the global mean among those most exposed, including 530,000 local recovery workers who averaged an effective dose equivalent to an extra 50 years of typical natural background radiation exposure each.〔(【引用サイトリンク】title=Assessing the Chernobyl Consequences )〕〔(【引用サイトリンク】title=UNSCEAR 2008 Report to the General Assembly, Annex D )〕〔(【引用サイトリンク】title=UNSCEAR 2008 Report to the General Assembly )〕 Estimates of the number of deaths that will eventually result from the accident vary enormously; disparities reflect both the lack of solid scientific data and the different methodologies used to quantify mortality—whether the discussion is confined to specific geographical areas or extends worldwide, and whether the deaths are immediate, short term, or long term. Thirty-one deaths are directly attributed to the accident, all among the reactor staff and emergency workers. An UNSCEAR report places the total confirmed deaths from radiation at 64 as of 2008. The Chernobyl Forum predicts the eventual death toll could reach 4000 among those exposed to the highest levels of radiation (200,000 emergency workers, 116,000 evacuees and 270,000 residents of the most contaminated areas); this figure is a total causal death toll prediction, combining the deaths of approximately 50 emergency workers who died soon after the accident from acute radiation syndrome, nine children who have died of thyroid cancer and a future predicted total of 3940 deaths from radiation-induced cancer and leukemia.〔(【引用サイトリンク】url=http://www.who.int/mediacentre/news/releases/2005/pr38/en/index.html )〕 In a peer-reviewed publication in the ''International Journal of Cancer'' in 2006 the authors (following a different conclusion methodology to the Chernobyl forum study, which arrived at the total predicted death toll of 4000 after cancer survival rates were factored in) stated, without entering into a discussion on deaths, that in terms of total excess cancers attributed to the accident: Also based upon extrapolations from the linear no-threshold model of radiation induced damage, down to zero, the Union of Concerned Scientists estimates that, among the hundreds of millions of people living in broader geographical areas, there will be 50,000 excess cancer cases resulting in 25,000 excess cancer deaths.〔(Chernobyl Cancer Death Toll Estimate More Than Six Times Higher Than the 4000 Frequently Cited, According to a New UCS Analysis ) Note: ''"The UCS analysis is based on radiological data provided by UNSCEAR, and is consistent with the findings of the Chernobyl Forum and other researchers."''〕 For this broader group, the 2006 TORCH report, commissioned by the European Greens political party, predicts 30,000 to 60,000 excess cancer deaths. In terms of non-scientific publications, two affiliated with the anti-nuclear advocacy group Greenpeace, have been released, one of which reports the figure at 200,000 or more.〔(【引用サイトリンク】title=The Chernobyl Catastrophe. Consequences on Human Health )〕 The Russian founder of that region's chapter of Greenpeace also authored a book titled ''Chernobyl: Consequences of the Catastrophe for People and the Environment'', which concludes that among the billions of people worldwide who were exposed to radioactive contamination from the disaster, nearly a million premature cancer deaths occurred between 1986 and 2004. The book, however, has failed the peer review process.〔(Correspondence (see reference 17) ) to George Monbiot from Douglas Braaten, Director and Executive Editor, Annals of the New York Academy of Sciences, 2 April 2011: ''"In no sense did Annals of the New York Academy of Sciences or the New York Academy of Sciences commission this work; nor by its publication do we intend to independently validate the claims made in the translation or in the original publications cited in the work. The translated volume has not been peer-reviewed by the New York Academy of Sciences, or by anyone else."''〕 Of the five reviews published in the academic press, four considered the book severely flawed and contradictory, and one praised it while noting some shortcomings. The review by M. I. Balonov published by the New York Academy of Sciences concludes that the report is of negative value because it has very little scientific merit while being highly misleading to the lay reader. It characterized the estimate of nearly a million deaths as more in the realm of science fiction than science.〔 The accident raised concerns about nuclear power worldwide and slowed or reversed the expansion of nuclear power stations. The accident also raised concerns about the safety of the Soviet nuclear power industry, slowing its expansion for a number of years and forcing the Soviet government to become less secretive about its procedures.〔"No one believed the first newspaper reports, which patently understated the scale of the catastrophe and often contradicted one another. The confidence of readers was re-established only after the press was allowed to examine the events in detail without the original censorship restrictions. The policy of openness (glasnost) and 'uncompromising criticism' of outmoded arrangements had been proclaimed back at the 27th Congress (of KPSS), but it was only in the tragic days following the Chernobyl disaster that glasnost began to change from an official slogan into an everyday practice. The truth about Chernobyl that eventually hit the newspapers opened the way to a more truthful examination of other social problems. More and more articles were written about drug abuse, crime, corruption and the mistakes of leaders of various ranks. A wave of 'bad news' swept over the readers in 1986–87, shaking the consciousness of society. Many were horrified to find out about the numerous calamities of which they had previously had no idea. It often seemed to people that there were many more outrages in the epoch of perestroika than before although, in fact, they had simply not been informed about them previously." -Kagarlitsky pp. 333–334〕 The government coverup of the Chernobyl disaster was a "catalyst" for glasnost, which "paved the way for reforms leading to the Soviet collapse". 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Chernobyl disaster」の詳細全文を読む スポンサード リンク
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