The reason why in 32 years after the Chornobyl accident in the Exclusion Zone the radiation background decreased by 10,000 times
Today, the radiation state in the Exclusion Zone is determined mainly by radioactive 137Cs (cesium-137) and 90Sr (strontium-90). But this is not the only radionuclides that escaped in 1986 on this territory.
According to Oleh Nasvit, First Deputy Head of SAUEZM, a huge amount of radionuclides was thrown into the environment during the Chornobyl accident from the destroyed reactor. Some of them have very small half-lives, some have bigger ones, and some are much more bigger.
«Immediately after the accident, the radiation state was determined by short-lived radionuclides. For example, 131I (iodine-131), the same that accumulated in the thyroid gland and caused its irradiation, has a half-life of only 8.5 days. There were many other radionuclides with a half-life in the days, months, half a year, a year. They all disappeared as a result of the natural radioactive decay», – the First Deputy Head of SAUEZM, said.
Indeed, short-lived radionuclides now naturally disappeared from the territory of the Exclusion Zone, which led to a 10,000-fold reduction in the radiation background compared to the first weeks after the accident.
However, part of the land of the Exclusion Zone still remains unsuitable for permanent residence and human management, since these lands were contaminated not only by short-lived radionuclides. In this area also dangerous quantities and transuranium elements settled in, in particular, isotopes 239, 240 Pu (plutonium-239 and plutonium-240), half-life periods of which are 24 and 6,5 thousand years.
It is decided to declare this zone permanently unsuitable for the accommodation of the population and it is declared a territory of special industrial use.