The disaster began during a systems test on Saturday, 26 April 1986 at reactor number four of the Chernobyl plant, which is near the city of Prypiat and in proximity to the administrative border with Belarus and Dnieper river. There was a sudden power output surge, and when an emergency shutdown was attempted, a more extreme spike in power output occurred, which led to a reactor vessel rupture and a series of explosions. These events exposed the graphite moderator of the reactor to air, causing it to ignite.[3] The resulting fire sent a plume of highly radioactive smoke 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.[4][5] According to official post-Soviet data,[6][7] about 60% of the fallout landed in Belarus. The accident raised concerns about the safety of the Soviet nuclear power industry, as well as nuclear power in general, slowing its expansion for a number of years and forcing the Soviet government to become less secretive about its procedures.[8][notes 1] The government coverup of the Chernobyl disaster was a "catalyst" for glasnost, which "paved the way for reforms leading to the Soviet collapse."[9] 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.[7] 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.[10][11][12] 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.[13] An UNSCEAR report places the total confirmed deaths from radiation at 64 as of 2008. The Chernobyl Forum estimates that the eventual death toll could reach 4,000 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 includes some 50 emergency workers who died of acute radiation syndrome, nine children who died of thyroid cancer and an estimated total of 3940 deaths from radiation-induced cancer and leukemia.[14] 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.[15] For this broader group, the 2006 TORCH report predicts 30,000 to 60,000 excess cancer deaths,[16] and a Greenpeace report puts the figure at 200,000 or more.[17] The Russian publication Chernobyl, which has received criticism for its methodology and sourcing, 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.[18]