Study of transient events during the full-system chemical decontamination operation of the Kori-1 nuclear power plant

The Kori-1 nuclear power plant (NPP), a Westinghouse 2-loop pressurized water reactor in Korea, permanently ceased operations on June 18, 2017. Before the main decommissioning activities, full chemical decontamination of primary systems will be performed to secure the safety of workers and minimize the quantity of radioactive waste. In this study, the steady and transient flow characteristics for the chemical decontamination operations were analyzed via a simulation using the Multidimensional Analysis of Reactor Safety, KINS Standard version. Then, based on the accumulated flow mass released from the reactant cooling systems during transient events, the radioactivity levels were estimated using the oxide layer removal ratio obtained from the chemical decontamination experiment. The loss of residual heat removal, steam generator tube rupture (SGTR), power-operated relief valve open (PORV Open), and combination of SGTR and PORV Open simulations were investigated in terms of the transient events. Finally, a strategy for managing transient events during the full-system chemical decontamination operation of the Kori-1 NPP is proposed.