Stages of radiation monitoring on the territory of the Tula region affected in consequence of the Chernobyl NPP accident

More than half of the Tula oblast territory was contaminated following the accident at the Chernobyl nuclear power plant. This article describes the stages of radiation hygiene monitoring of objects in the habitat in the Tula region impacted by radioactive contamination. Information is given on changes in radioactively contaminated areas at different periods after the accident. An assessment is made of the radiological situation at the initial “iodic” period of the accident, the subsequent “cesium” period, and at the current stage. A description is given of work done by the oblast’s state sanitary and epidemiological service based on radiation monitoring results for reducing the radiation exposure of the population at different stages of supervision. Information is supplied on high levels of gamma background up to 35 mkSv/h during the “iodic” period. Tabulated data are supplied on exceeding the tentative maximum permissible level of iodine-131 content in dairy products produced in Plavski district, the most contaminated area in the region. Data are given on laboratory tests on food products for total beta activity in 1986-87 and the frequency of exceeding the permissible level of cesium-137 content during 1986. The above permissible content of radionuclides in food products was registered only in 1986 due to surface contamination of plants, while in wild mushrooms this took place as late as 2004. Currently, the proved content of cesium-137 and strontium-90 in food products is determined only by the radio-chemical method. A table is supplied showing results of radio-chemical research on major dose contributing food products from 2010 to 2021. The article supplies a table with numeric values of annual average effective doses of radiation sustained by the population of settlements located in the Chernobyl radioactively contaminated zone during 1986 through 2021. The dose of the population’s exposure to the Chernobyl radiation since 1994 does not exceed 1 mSv/year. In 2021, the population’s annual effective dose in 98.3% of settlements amounted to less than 0.2 mSv/year.

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