Development of dynamic analysis method for Post-Accident event sequence

Hioki, Kazumasa 

The process variables, the status of the components and the Human Error Probabilities (HEPs) affect each other. Therefore, it is necessary to dynamically calculate the process variables such as the temperature, the flow rate and the liquid level considering the HEPs and the components' status in order to evaluate the efficiency of the Accident Management (AM) including the Emergency Operating Procedures (EOPs). As the traditional methods with the event trees and the fault trees cannot deal with the event sequences dynamically, several dynamic methods have been proposed. These methods, however, cannot evaluate the efficiency of EOPs of real plants because of the large memory size and long calculation time which they need. A new dynamic analysis method for post accident event sequences is developed that utilizes the initiating events and the minimal cutsets which have already been obtained through the Level-1 PSA. By concentrating the objective to the evaluation of the efficiency of EOPs, this new method can deal with large systems including the support systems and real size plant within the limited computer memory in tolerable time.