Thirty years ago on April 26, 1986 a catastrophic nuclear accident at the Chernobyl Nuclear Power Plant happened. That was the worst nuclear power plant accident in the history. As a result of an accident, a radioactivity discharge occurred which included isotopes of uranium, plutonium, iodine-131. Iodine-131 is a radioactive nuclide of iodine. In addition, it is one of the main products of uranium and plutonium fission. It is the main contaminating radioactive component. Iodine- 131 causes mutation and death of cells it enters. Clouds containing these radioactive materials have spread over most of Europe. About 60% of the radioactive fall-out landed in Belarus. Heavy, black-colored rain fell on the city of Gomel, Belarus. Read More.