ORAM and shutdown PRA comparison study

A comparison study between results obtained from an Outage Risk Assessment and Management (ORAM) model and a shutdown Probabilistic Risk Analysis (PRA) model was conducted. The purpose of the study was to provide useful risk information for better outage planning by focusing resources and contingency plans on risk significant configurations. The comparison study used selected configurations from the 8th refueling outage of the Hope Creek Generation Station (HCGS), a Boiling Water Reactor (BWR). A total of Eleven configurations were compared. Three configurations were selected to evaluate the impact of the Service Water System during the early stage of a refueling outage. (There are existing studies suggesting that the designed redundancy of Service Water Systems is needed during the early stage of a shutdown.) Four configurations were selected because they were deemed risk significant by the ORAM analysis. (For configurations deemed risk significant by ORAM results, compensatory actions have been taken and contingency plans have been developed to mitigate potential deviations from the configuration. The shutdown PRA was used to evaluate the necessity and effectiveness of these contingency plans and compensatory actions.) To increase the comparison population, an additional four configurations were randomly selected. Thus, a total of 15 configurations were evaluated by the shutdown PRA, and a total of 11 configurations were studied by the ORAM. (author)