Radionuclides deposition on sea surface following hypothetical accidental releases at Korean nuclear power plant

Abstract

The scenarios of deposition on the sea surface around the Korean Peninsula following hypothetical release at Kori NPP were studied by application of the atmospheric transport model FLEXPART. The series of 1460 dispersion scenarios was calculated, covering the time period of 1 year. The total depositions on the surfaces of the East/Japan Sea (EJS), Yellow Sea (YS), East China Sea (ECS), and near-coast zone of 200-km vicinity around the Korean Peninsula, normalized on the total emission inventory were analyzed. The normalized deposition on the total area of 3 seas varied by more than 2 orders of magnitude from 0.003 to 0.59. The fraction of wet deposition in total deposition varied from 0 to 0.99. The selected most heavy deposition scenarios were divided into those dominated by dry deposition and wet deposition. The most conservative release scenarios (7 August 2020 and 2 September 2020) were dominated by wet deposition and were caused by the monsoon rainband and passage of the typhoon. In the scenario of 7 August 2020, 96% of deposition appeared in the near-coast zone. Cluster analysis of dispersion scenarios confirmed strong seasonal dependence of deposition patterns. For EJS and YS, the maximum average deposition was reached in the ‘Summer’ cluster. For ECS the maximum average normalized deposition was reached in the ‘Spring + Fall’ cluster (Dr=0.055). Minimum average deposition on all seas was obtained for the ‘Winter’ cluster.