PRA IMPORTANCE MEASURES FOR MAINTENANCE PRIORITIZATION APPLICATIONS

Various importance measures are standardly calculated in a standard pr obabilistic risk assessment (PRA). Approaches are developed in this pa per for using two of these measures-the minimal cutset contribution an d the risk reduction importance-for prioritizing the risk importances of maintenances. One approach which is developed prioritizes maintenan ces based on the risk importance of the associated contributor. The se cond approach prioritizes maintenances based on the risk impact if the maintenance is ineffective. The core damage frequency is used as the risk measure for prioritization. The demonstration studies, which are carried out using the Surry Plant PRA, indicate that the two approache s give similar results if appropriate cutoff criteria are used. As an additional evaluation, risk unimportant maintenances are identified us ing the risk increase importance, or risk achievement worth, calculate d in the PRA.