Assessing the relative safety impact of fire protection modifications

Nuclear plant fire protection modifications based upon Appendix R to 10 CFR 50 generally compete for the same pool of resources as other proposed modifications not related to fires. In general, the relevance of the fire protection modifications to safety is not considered in a manner that is consistent with that used with non-fire modifications. Thus, there is no consistent basis for allocating resources among the entire set of potential plant improvement projects. Strict fire protection requirements often satisfy deterministic rules at the expense of other modifications which may have a larger impact on safety. To alleviate this problem a method is developed to rank fire modifications consistent with that used to assess other plant improvement projects, providing a utility with a basis for resource allocation. A case study at Davis-Besse demonstrates that regulatory acceptance of this methodology provides substantial relief to utility resource allocation problems. The analysis described is an application of risk assessment technology to the process of ranking proposed plant fire modifications. This approach allows the decision-maker to bridge the gap between deterministic regulatory rules and probabilistic measures of public safety. The result is a cost effective decision-making tool that can be used to prioritize the scheduling of proposed fire modifications in a manner consistent with methods used for non-fire modifications