<P> The Russian founder of that region's chapter of Greenpeace authored a book titled Chernobyl: Consequences of the Catastrophe for People and the Environment, which suggests 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 . Greenpeace itself advocates a figure of at least 200,000 or more . The book was not peer reviewed prior to its publication, and it has been heavily criticized; of the five reviews published in the academic press, four considered the book severely flawed and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 . </P> <P> On 26 April 1986, at 01: 23 (UTC + 3), reactor four suffered a catastrophic power increase, leading to explosions in its core . This dispersed large quantities of radioactive isotopes into the atmosphere and caused an open - air fire . The fire increased the emission of radioactive particles, carried by the smoke, as the reactor had not been encased by any kind of hard containment vessel . The accident occurred during an experiment scheduled to test a potential safety emergency core cooling feature, which took place during a normal shutdown procedure . </P> <P> In steady state operation, a significant fraction (over 6%) of the power from a nuclear reactor is derived not from fission but from the decay heat of its accumulated fission products . This heat continues for some time after the chain reaction is stopped (e.g., following an emergency SCRAM) and active cooling may be required to prevent core damage . RBMK reactors like those at Chernobyl use water as a coolant . Reactor 4 at Chernobyl consisted of about 1,600 individual fuel channels; each required a coolant flow of 28 metric tons (28,000 litres or 7,400 US gallons) per hour . </P> <P> Since cooling pumps require electricity to cool a reactor after a SCRAM, in the event of a power grid failure, Chernobyl's reactors had three backup diesel generators; these could start up in 15 seconds, but took 60--75 seconds to attain full speed and reach the 5.5 ‐ megawatt (MW) output required to run one main pump . </P>

Who was involved in the chernobyl nuclear disaster