Research on Diffusion and Mitigation of Severe Accident Source Terms in Floating Nuclear Power Plant

Abstract ACP100S is a modular floating nuclear power plant independently developed by China National Nuclear Corporation (CNNC) with broad application prospects. At present, research on the source terms of severe accidents in floating nuclear power plants is not sufficient, and research is needed on the migration and distribution of source terms under severe accident conditions, as well as mitigation measures for source terms. Focusing on ACP100S, a severe accident source term analysis model for floating nuclear power plant reactor is established using the ISAA code in this paper. The accident process, release and migration of the source terms after the accident are studied. At the same time, the mitigation effect of containment spray on severe accident source terms is studied, as well. The results show that after the accident, the total amount of noble gases is about 99.7% in the containment and 0.254% in the primary circuit. The fraction of Cs is 80.1% in the containment, 19.1% in the primary circuit and 0.637% in the reactor cavity. And the share of CsI is 85.8% in the containment, 2.73% in primary circuit and 9.13% in reactor cavity. In addition, spray can reduce the concentration of Cs and CsI in the containment by about 52.48% and 73.44%, which has a significant effect on the mitigation of source terms.