241Am and 137Сs in the Khoiniki district of Belarus: updated radiological assessment of the local existing exposure situation

The results covered in this paper relate to the “Khoiniki” research sub-unit of a larger-scale sequence of studies focused on the local assessments of the present-day ²⁴¹Am and ¹³⁷Cs concentrations in the soils and locally produced foods, with the estimation of the public internal radiation doses in the residential areas of the Gomel region of the Republic of Belarus most closely adjacent to the ChNPP resettlement zone. The objective was to make a conservative estimate of a committed annual dose of internal exposure from ²⁴¹Am and ¹³⁷Сs received by the villagers of 96 farmsteads in 30 settlements of the private sector of Khoiniki countryside through both, inhalation and consumption of local foodstuffs. The results obtained in this study include an update of the existing contamination levels of ²⁴¹Am and ¹³⁷Сs present in the local soils and foods grown or produced in private backyards and households. ²⁴¹Am in food samples was determined by alpha-spectroscopy radiochemical analysis with the use of selective extraction-chromatographic resins. Gamma-spectrometry techniques were used to measure ²⁴¹Am in soil samples and ¹³⁷Сs in soil and food samples. Based on our findings, the present-day deposition density of ²⁴¹Am in the soils does not exceed 4 kBq/m² , while the values of ¹³⁷Cs contamination are by one to two orders of magnitude higher than that of ²⁴¹Am and vary between 30 and 500 kBq/m² . Generally, the values of activity concentration of ²⁴¹Am detected in local soils are well within 10 Bq/kg in the majority of inspected villages, with the exception of three sites where higher levels of ²⁴¹Am contamination is soils were detected ranging from 14 to 16 Bq/kg. The ambient dose rates in the countryside range from 0.05 to 0.38 μSv/hour, with the average of 0.15 μSv/hour. No cases of ¹³⁷Сs contamination above the established reference levels of 80, 100 and 90 Bq/ kg have been found in the local food samples of, respectively, potatoes, vegetables (incl. roots and tubers) and grains. The content of ²⁴¹Am in the staple foods produced in the area varies from single digits to tenths of mBq/ kg, which is less by three orders of magnitude than ¹³⁷Сs activities concentrationd found in the same staples. Of the two pathways contributing to the local committed internal exposure from ²⁴¹Am, the dominant one is through inhalation (0.006–0.038 mSv/year) prevailing over the consumption pathway of this same radioisotope by at least one order of magnitude. At the time of gardening and other household field works, the existing levels of ²⁴¹Am contamination in soils are estimated to produce from 85 to 98% of the internal radiation dose received by individuals from inhaling the total of ²⁴¹Am and ¹³⁷Сs. The maximum committed annual doses of internal exposure from ¹³⁷Сs are estimated to be above 1 mSv/year in 6 out of 30 villages engaged in our study. At the same time, the estimated internal radiation dose due to ²⁴¹Am does not surpass 0.04 mSv/year. The ¹³⁷Сs major contribution to the internal exposure of villages in the Khoiniki countryside is through food consumption.

1. Onischenko GG, Popova AYu, Romanovich IK. Radiological consequences and lessons of the Chernobyl NPP and “Fukushima-1” NPP radiation accidents. Radiatsionnaya Gygiena = Radiation Hygiene. 2021;14(1): 6-16. (In Russian). DOI: 10.21514/1998-426X-2021-14-1-6-16.

2. Atlas of current and future effects of the Chernobyl accident on affected parts of the Russian Federation and Belarus (ACFE Russia-Belarus). Eds.: Israel YuA, Bogdevich IM. MoscowMinsk: Foundation «Infosfera», NIA Priroda; 2009. 140 p. (In Russian).

3. 35 years after the Chernobyl disaster: results and prospects of overcoming its consequences: national report of the Republic of Belarus. Department for elimination of consequences of the Chernobyl disaster of the Ministry of emergency situations of the Republic of Belarus. Minsk: IVC Minfina; 2020. 152 p. (In Russian).

4. Aleksakhin RM, Sanzharova NI, Fesenko SV. Radioecology and the accident at the Chernobyl nuclear power plant. Atomnaya energiya = Atomic. Energy. 2006;100(4): 267-276. (In Russian).

5. Konoplya EF, Kudryashov VP, Mironov VP. Radiation and Chernobyl: Transuranic elements on the Belarus territory, Gomel: RNIUP «Institute Radiologii»; 2007. 128 p. (In Russian).

6. UNSCEAR 2008. Effects of Ionizing Radiation. Volume II: Report to the General Assembly, Scientific Annexes C, D and E. United Nations Scientific Committee on the Effects of Atomic Radiation. New York: United Nations; 2011. 219 p.

7. Nilova EK, Bortnovsky EV, Tagai SA, Dudareva NV, Zhukova LV. 241Am on the territories adjacent to the Belarusian sector of the Chernobyl NPP resettlement zone: soil contamination, foodstuffs and population internal dose assessment. Radiatsionnaya Gygiena = Radiation Hygiene. 2019;12 (2 (special issue)): 75-82. (In Russian) DOI: 10.21514/1998-426х-2019-12-2s-75-82.

8. Nilova EK, Bortnovsky VN, Tagai SA, Dudareva NV, Nikitin AN. Assessment of the current levels of 241Am and 137Сs in soils and foodstuff, as well as of public internal exposure to ionizing radiation in populated areas adjacent to the Chernobyl NPP exclusion zone (case study: the Bragin district of the Gomel region, Belarus). Radiatsionnaya Gygiena = Radiation Hygiene. 2020;13(3): 25-37. (In Russian). DOI: 10.21514/1998-426X-2020-13-3-25-37.

9. Bulavik IM, Perevolotskiy AN, Dudareva NV, Tagai SA. Inventors; Institute of Radiology, assignee. Republic of Belarus patent BY 3793; 2007. P. 231-232. (In Russian).

10. Food consumption in households. National statistical Committee of the Republic of Belarus. Available from: https://www.belstat.gov.by/ofitsialnaya-statistika/solialnaya-sfera/uroven-zhizni-naseleniya/dokhody-i-potreblenie-domashnikh-khozyaystv/operativnye-dannye/ potreblenie-osnovnykh-produktov-pitaniya-v-domashnikhkhozyaystvakh. [Accessed 30 June 2021] (In Russian).

11. Ramzaev VP, Barkovsky AN, Bratilova AA. Evaluation of the contribution of natural and technogenic components to the capacity of the ambient dose equivalent in vegetable gardens in the settlements of the Bryansk region. Radiation-hygienic consequences and lessons of the accident at the Chernobyl Nuclear Power Plant and the Fukushima-1 nuclear power Plant: Proceedings of the international scientific-practical conference. St-Petersburg; 2021. P. 174-175 (In Russian).

12. Ramzaev V, Barkovsky A, Bernhardsson C, Mattsson S. Calibration and testing of a portable NaI(Tl) gamma-ray spectrometer-dosimeter for evaluation of terrestrial radionuclides and 137Cs contributions to ambient dose equivalent rate outdoors. Radiatsionnaya Gygiena = Radiation Hygiene. 2017;10(1): 18–29.

13. Ramzaev VP, Barkovsky AN. Dynamics of decrease of the gamma dose rate in air in rural settlements of the Bryansk region (Russia) in the remote period after the Chernobyl accident. Radiatsionnaya Gygiena = Radiation Hygiene. 2020;13(1): 38-46. (In Russian). DOI: 10.21514/1998-426X-2020-13-1-38-46.

14. Pavlotskaya FI, Pospelov YuI, Myasoyedov BF, Kuznetsov YuV, Legin VK. The behavior of transplutonium elements in the environment. Radiokhimiya = Radiochemistry. 1991;5: 112–119. (In Russian).

15. Averin VS, Podolyak AG, Tagai SA, Kukhtevich AB, Buzdalkin KN, Tsarenok AA, et al. Americium and plutonium in agroecosystems. 1986 Chernobyl disaster. Gomel: RNIUP «Institute Radiologii»; 2014. 176 p. (In Russian).

16. Romney EM, Wallace A, Schulz RK, et al. Plant uptake of 237Np, 239,240Pu, 241Am, and 244Cm from soils representing major food production areas of the United States. Soil Science. 1981; 132(1): 40-59. DOI: 10.1097/00010694-198107000-00007

17. Bunzl K, Kracke W. Soil to plant transfer of 239 + 240Pu, 238Pu, 241Am, 137Cs and 90Sr from global fallout in flour and bran from wheat, rye, barley and oats, as obtained by field measurements. Science of the Total Environment. 1987;63(C): 111-124. DOI: doi.org/10.1016/0048-9697(87)90040-4.

18. Applbi LDzh, et al. Ways of migration of artificial radionuclides in the environment. Radioecology after Chernobyl. Ed. by Warner F, Harrison RM. Moscow: «Mir»; 1999. 512 p. (In Russian).

19. Popplewell DS, Ham GJ, Johnson TE, Stather JW, Sumner SA. The uptake of plutonium-238, 239, 240, americium-241, strontium-90 and caesium-137 into potatoes. Science of the Total Environment. 1984;38: 173-181.

20. International Atomic Energy Agency (IAEA) Handbook of Parameter Values for the Prediction of Radionuclide Transfer in Terrestrial and Freshwater Environments/Technical Reports Series. TRS-472.Vienna: IAEA; 2010. 208 p.

21. International Atomic Energy Agency (IAEA) Quantification of Radionuclide Transfer in Terrestrial and Freshwater Environments for Radiological Assessments / IAEATECDOC-1616.Vienna: IAEA; 2009. 307 p.

22. International Atomic Energy Agency (IAEA) Radiation protection and safety of radiation sources: international basic safety standards: general safety requirements. Interim edition. Vienna: IAEA; 2011. 303 p.

23. International Atomic Energy Agency (IAEA) IAEATECDOC-1162. Generic procedures for assessment and response during a radiological emergency: updating IAEATECDOC-1162. Vienna: IAEA; 2000. 194 p.

24. International Atomic Energy Agency (IAEA) Safety Standards for protecting people and environment. Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards. General Safety Requirements. Part 3 No GSR Part 3. Vienna: IAEA; 2014. 436 p.

25. Podolyak AG, Tagai SA, Averin VS, Buzdalkin KN, Nilova EK. Radiation doses received by the workers involved in agricultural operations on the territories contaminated by radionuclides (137Cs, 241Am and 238,239+240Pu). Radiatsiya i risk = Radiation and risk. 2014;23(2): 85-93. (In Russian).

26. Podolyak А, Tagai S, Nilova E, Averin V. Assessment of committed doses received by agricultural workers in grain harvesting operations in the areas of radioactive contamination. Radioprotection. 2017; 52(1): 37-43.