Fukushima 1 Facts

After a terrible 9.0 magnitude earthquake in Japan the Tokyo Electric Power Co. (TEPCO) has been clambering to prevent a nuclear catastrophe. The Fukushima Daiichi nuclear power station, with six nuclear reactors in it, experienced explosions at three reactors and a fire in a spent-fuel pool at a fourth. At two reactors, unit Nos. 2 and 3, the vessels containing the nuclear matter are suspected to be in danger.

A small group of Fukushima 1 workers remained on the site, implementing emergency cooling activities at the damaged, overheated reactors. Radiation amounts have increased considerably after disaster, and the extent to which the workers' health has been threatened may not become broken for years. 

Below you will find some facts and numbers about the radiation  danger generated by the Fukushima fallout and how it compares with other nuclear catastrophes in history. Radiation is measured in millisieverts, an international unit of radiation dosage. (One sievert is equal to 100 rems, which is a dosage unit of x-ray and gamma-ray radiation exposure; one millisievert is 0.1 rem.)

Peak radiation dose measured inside Fukushima Daiichi on March 15:400 mSv per hour


Radiation dose at the boundary of the Fukushima Daiichi nuclear  station on March 16, 2011: 1.9 millisieverts (mSv) per hour

Approximate amount of nuclear fuel in each crippled Fukushima Daiichi reactor: 70 to 100 metric tons

Maximum allowable exposure for American radiation specialists and amployees: 50 mSv per year

Average exposure of American workers from natural and man-made radiation sources: 6.2 mSv per year

Total estimated exposure at the boundary of the Three Mile Island site in Pennsylvania during the 1979 accident there: one mSv or less

Average total radiation dose to the 114,500 people evacuated during the 1986 Chernobyl catastrophe: 31 mSv 

Half-life of iodine 131, a dangerous radioactive isotope released in nuclear disaster: 8 days

Half-life of cesium 137, another major radionuclide released in nuclear accidents: thirty years

Decay products of iodine 131 and cesium 137: both emit gamma rays and beta particles (electrons or positrons)

Amount of nuclear fuel in 4th Chernobyl`s reactor 4 that exploded in 1986:190 metric tons

Amount of nuclear fuel and by-products уьшееув into the atmosphere during Chernobyl disaster: 25 to 57 metric tons