V. K. Shynkarenko, M. M. Talerko, A. M. Novikov, V. O. Krasnov, V. O. Kashpur, O. A. Svyryd, V. V. Augustov
Institute for Safety Problems of Nuclear Power Plants of the National Academy of Sciences of Ukraine, 12, Lysohirska st., Kyiv, 03028, Ukraine
DOI: doi.org/10.31717/2311-8253.25.2.7
Abstract
On February 14, 2025, at 1:54 a.m., a Russian combat UAV “Geran‑2” struck the New Safe Confinement (NSC) – the protective structure built over the destroyed Unit 4 of the Chornobyl NPP. The explosion damaged both layers of the NSC cladding and initiated a fire, followed by prolonged smoldering of the rubber filler layer. Although no fuel-containing objects were directly impacted, air monitoring under the NSC registered a notable increase in radionuclide activity. This paper presents the results of aerosol sampling using stationary filter-ventilation units (FVUs) and an impactor system. Analyses revealed elevated airborne 137Cs concentrations and the presence of radioactive aerosol particles, primarily with aerodynamic diameters under 40 µm. Autoradiographic and spectrometric studies confirmed low-activity hot particles consistent with irradiated nuclear fuel, as indicated by typical 137Cs/241Am ratios of 30−70. However, due to the lack of confirmed damage to radioactive material storage or fuel debris, the observed activity spike is most likely attributed to secondary resuspension of pre-existing contamination on surfaces within the NSC and Shelter structures, rather than new emissions. These findings underline the vulnerability of the NSC to external impacts and emphasize the need to enhance radiological monitoring strategies under conditions of military threat.
Keywords: Radioaerosols, Chornobyl zone, New Safe Confinement, 137Cs, 241Am, resuspension, monitoring, impactor, autoradiography, hot particle.
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