In Russia, the Chernobyl trace was again found: radiation doses were increased in a number of areas

In Russia, there are still areas affected by the Chernobyl accident that need to be rehabilitated. Radioecologists from Obninsk near Moscow, who once carried out rehabilitation measures in the affected area from the Chernobyl accident, were entrusted to examine them and develop measures to reduce the radiation load on people. We talked to Acting Director of the Obninsk Institute of Atomic Energy (IATE NRNU MEPhI) Alexey Panov about how it happened then and which of the events of the 80–90s of the last century may be useful today for work in the south-west of Russia.

— Alexey Valeryevich, more than 36 years have passed since the Chernobyl accident, is the problem still relevant?

— Yes, strange as it may seem. The liquidation of the consequences of the accident at the Chernobyl nuclear power plant was long and large-scale, a lot of work was carried out in the 80s and early 90s. In Russia, settlements in four regions suffered the most from the accident: Bryansk, Kaluga, Tula and Oryol. After the accident, it was decided to zone these territories according to the degree of radioactive contamination.

And where did it get stronger?

– The southwestern regions of the Bryansk region were the most contaminated with radionuclides.

— What element of the periodic table prevailed in the contaminated territories?

“Specialists have identified the leading dose-forming radionuclide, which is cesium-137 (137Cs), because it was precisely this man-made radioisotope that turned out to be the most abundant in the environment after the accident.

— What measures have been taken to reduce the danger from radioactive contamination for people?

– Depending on the degree of pollution, scientists have developed rehabilitation measures. First, as you know, a 30-kilometer exclusion zone was allocated in the territories of Ukraine and Belarus. Radiation reserves were organized on them, where only scientists could be. On the territory of the Russian Federation there were also territories with a pollution level of more than 40 curies for 137Cs (the maximum permissible level for living. — Auth.), from which residents were also resettled. In the territories adjacent to these settlements, a gradation was introduced: from 15 to 40 curies, from 5 to 15 and from 1 to 5 curies. Remedial measures were taken depending on the level of pollution.

Can you give an example of such events?

– First of all, specialists reduced the dose of external radiation with the help of decontamination measures: they removed the upper part of the soil on household plots, changed roofs, washed the walls of houses with special compounds, changed contaminated asphalt. By the way, washing and replacing surfaces did not show high radiological efficiency: as soon as the wind blew from the neighboring contaminated area, a new portion of 137Cs covered them again. Someone left because of this from their homes, someone stayed, and they were paid compensation.

– What was the reason to pay attention to this problem now?

— Data on levels of radioactive contamination are periodically published by a number of scientific organizations. So every year they appear in the collections of NPO Typhoon of Roshydromet. As for information on radiation doses, the Research Institute of Radiation Hygiene of Rospotrebnadzor informs them every few years. So, according to the latest data, there are much more areas where contamination with radionuclides is recorded than places where the permissible doses of exposure to the population are exceeded. Thus, according to the latest published data of Rospotrebnadzor in 2017, the radiation situation in the above areas is generally assessed as favorable, with the exception of five districts in the south-west of the Bryansk region. Considering that we have 2023 on our doorstep, and cesium tends to decay over time, in these areas there are no more than 100 settlements with excess dose loads. These are the ones we will explore as part of our two-year project, for which we received a grant from the Russian Science Foundation.

– Tell us how your work will be built?

– First, we will need to collect and analyze radioecological data – these are measurements of the density of radioactive contamination of settlements and the levels of radionuclides in food products. Let us estimate the spatial distribution of radionuclides on the ground, since the pollution there is rather “spotty”. Then, having collected the entire array of necessary data, using computer decision support systems and geoinformation technologies, we will justify the optimal rehabilitation technologies individually for each settlement.

– Will you directly measure the radiation dose of the population?

– There are also methods in which the dose of internal radiation is measured using the so-called human radiation counters.

— By the way, are there any peculiarities in the accumulation of radionuclides depending on parts of the human body?

– I can only say that cesium accumulates most of all in the muscles, and strontium – in the bone tissue.

– Suppose you determine the increased radiation background, with what measures will you start rehabilitation work now?

– According to the Russian law on radiation safety, the level of additional exposure of the population should not exceed 1 millisievert per year. If in certain settlements we record increased dose loads on people, then, of course, we will recommend a number of measures. Now, after more than 30 years, there, most likely, it makes sense only to reduce the doses of the so-called internal exposure. Humans receive such exposure through local agricultural and natural foodstuffs.

– Tell us, in what ways does radioactivity in food products decrease?

– There are several of them. For example, the transfer of radionuclides from soil to plants (including animal feed) can be reduced through agro-technical and agro-chemical practices. This can be deep plowing of the soil or the introduction of complexes of mineral and organic fertilizers into it. You can sow crops that accumulate radionuclides to a lesser extent. As additional methods, various kinds of sorbents for livestock can be used. For example, complex salts (ferrocyanides), which absorb radionuclides from feed, and they pass into milk and meat to a lesser extent.

By the way, if in the 1990s the greatest role in the formation of internal exposure was played by agricultural products, now it is rather natural products – mushrooms, berries. Putting a high fence at the entrance to the forest will not work. Only one method remains: systematic explanatory work with the population about where to collect the gifts of the forest and how to process them to ensure the radiation safety of people.

Published in the newspaper “Moskovsky Komsomolets” No. 28943 dated December 29, 2022

Newspaper headline:
Chernobyl trace found again in Russia