Realistic analysis of uncontrolled boron dilution accident

Realistic Response of Ulchin 1,2 reactor system during uncontrolled boron dilution accident has been analyzed using the MARS code. As an initiating event from full power operating conditions, a coincident breach of a reactor coolant pump seal and a seal water heat exchanger is selected. And, as an initiating event from mid-loop operating conditions, a breach of a residual heat removal system heat exchanger is chosen. From the analyses of limiting scenarios where no operator action is credited, the sustainable margins for the system safety and the operator action time have been quantified. And, through the realistic scenario analysis, the effectiveness of operator actions provided in the emergency operating procedure has been validated