Review of the methodology for statistical evaluation of reactor safety analyses

Nuclear Regulatory Commission regulations require that the performance of the Emergency Core Cooling Systems (ECCS) for nuclear power plants be calculated using evaluation models. These models provide a conservative prediction of the maximum cladding temperature in the event of a design basis accident. The objective of EPRI's program in the statistical assessment of ECCS performance is to evaluate the conservatism in the evaluation models. The anticipated result will include both an estimate of the most probable or nominal maximum cladding temperature under accident conditions, and an estimate of the probability that the cladding temperature will exceed a given maximum allowable value. This report concerns one aspect of the overall effort--uncertainties through the best-estimate code. (GRA)