Critical Limit Development For 21 PWR Waste Package

This calculation uses regression (CLReg V1.0 computer code) and non-parametric statistical methods, as specified in References 1 and 12, to develop the critical limit for the 21 Pressurized Water Reactor (PWR) spent nuclear fuel (SNF) waste package (WP) in the proposed geologic repository at Yucca Mountain, Nevada. The critical limit is a limiting value of the effective neutron multiplication factor at which a WP configuration is considered potentially critical. The critical limit is derived from the bias and uncertainties associated with the employed criticality code (MCNP) and the modeling process. The results of this calculation support the validation of the MCNP code to accurately predict k-eff for a range of conditions that are representative of potential configurations of commercial SNF in a degraded waste package in a geologic repository.