M.V. Zheltonozhskaya1, N.V. Kuzmenkova2, I.E. Vlasova3, T.R. Polyakova4, V.V. Rozanov5, A.P. Chernyaev6

1–6 Lomonosov Moscow State University (Moscow, Russia)
 

Radiotoxic actinides have become permanent components of the biosphere as a result of nuclear weapons testing and accidents at nuclear facilities. The main form of finding transuranium radionuclides in the environment are radioactive microparticles (“hot” particles). Pollution of the earth's surface with hot particles has a different structure and radionuclide composition depending on the source of the release. Radionuclides from hot particles can accumulate as components of biogeocenoses and be included in food chains. The paper presents the results of studying the behavior of fuel fallout in soils with different levels of pollution in the near 10-km zone of the Chernobyl nuclear power plant. The studies were carried out using alpha, beta and gamma spectrometry methods. For gamma spectrometric measurements, semiconductor spectrometers with ultrapure germanium detectors of large volume with a thin entrance window were used. Detection of 90Sr in soil samples and hot particles was carried out using a NaI spectrometer with a thin input window. Radiochemical studies of individual particles were also carried out. As a result, new data were obtained on hot particles of Chernobyl origin, in which 241Am activity dominates. A new taxonomy of hot particles based on the ratio between the yield of KxU radiation and the 105 keV gamma line of 155Eu is proposed. In the alpha and gamma spectra, the activities of 243Cm and 244Cm are separated for the first time. The obtained data on the decrease in the size of hot particles, the migration of 90Sr, 137Cs and 241Am in soils in the form of compact structures demonstrate that leaching processes currently dominate for hot particles in the near zone of the Chernobyl nuclear power plant. An analysis of the experimental results using the convective-diffusion model of migration shows that the half-cleaning periods of the upper 5 cm soil layer for both strontium-90 and transuranium nuclides are approximately the same and are in the range of 30–50 years.

Zheltonozhskaya M.V., Kuzmenkova N.V., Vlasova I.E., Polyakova T.R., Rozanov V.V., Chernyaev A.P. Study of the behavior of fuel fallout in environment. Science Intensive Technologies. 2023. V. 24. № 1. P. 13−23. DOI: https://doi.org/10.18127/j19998465-202301-02 (in Russian)

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