Understanding and Effectively Managing Conservatisms in Safety Analysis of Nonreactor Nuclear Facilities

This paper outlines research on understanding, characterizing, and managing conservatisms in safety analyses. This research includes a review of national and international approaches for developing and using conservative and best-estimate analyses. A probabilistic approach is discussed to support reducing conservatism while maintaining safety margins. An example of the proposed approach is applied to two case studies for nonreactor nuclear facilities. The objective of this work is to provide a means for better understanding and managing risks associated with nuclear facilities. The results from these examples show that conservative estimates could lead to excessive safety margins when compared to the best-estimate values; the amount of excess margin may be as high as one or more orders of magnitude.