Radiation environment and monitoring results within the 30 km zone of the Rostov NPP

Abstract

The relevance of this study is determined by the need to verify radiation monitoring data and to provide an objective assessment of radiation safety of the population residing within the 30-km surveillance zone of the Rostov Nuclear Power Plant (RoNPP). The objective is to analyze interannual dynamics of the radiation situation based on systematic measurements performed during 2021-2025. The study objects include atmospheric fallout, soil, and surface water (the RoNPP cooling pond and Tsimlyansk Reservoir) sampled at control points in Volgodonsk and Tsimlyansk. Gamma spectrometry and radiochemical analysis are applied to determine total β-activity and specific activity of technogenic (¹³⁷Cs, ¹³⁴Cs, ⁶⁰Co, ¹³¹I) and natural (⁴⁰K, ²³²Th, ²²⁶Ra) radionuclides. Statistical processing employs the non-parametric Mann-Kendall test, Sen's slope estimation, correlation analysis (Pearson/Spearman), paired Wilcoxon signed-rank test, and cross-correlation with temporal lags. Average annual values of radionuclide specific activity in atmospheric fallout (∑β, ¹³⁷Cs) consistently remain within background ranges typical for the European part of Russia (43-47% of the upper regional background boundary). ¹³⁷Cs content in soil (1-6 Bq/kg) and water (0.3-0.7 Bq/kg) do not exceed levels attributable to global fallout and is 1–2 orders of magnitude below drinking water standards. Statistical analysis reveals no significant monotonic trends for any monitored parameter (all p > 0.10) and no significant differences between sampling locations. In conclusion, the obtained data indicate the absence of a significant technogenic contribution from the RoNPP to the radiation situation in the surveillance zone. A continuous five-year measurement series is presented with application of modern non-parametric statistical methods for the first time in this region, enabling a transition from descriptive monitoring to quantitative assessment of radiation background stability.