The general characteristics of the loss of coolant accident (LOCA) for pressurized water reactor systems(PWR) is reviewed and the emergency core cooling system(ECCS) of the '$\mbox{\underline{Ko Ri}}$ nuclear power plant unit 1' and its time response characteristics against LOCA are investigated.
For the simulation analysis, a modified version of 'RELAP-4', a computer program for the transient analysis of PWR following LOCA is run using the parameters of ECCS of the '$\mbox{\underline{Ko Ri}}$ nuclear power plant unit 1'. In this computation, a cold- leg double-ended severance rupture is postulated. The result of the simulation computation is compared with those of similar studies for other PWR systems.