CSNF Loading Curve Sensitivity Analysis

The purpose of this scientific analysis report, CSNF Loading Curve Sensitivity Analysis, is to establish the required minimum burnup as a function of initial enrichment for both pressurized water reactor (PWR) and boiling water reactor (BWR) commercial spent nuclear fuel (CSNF) that would allow permanent disposal of these waste forms in the geologic repository at Yucca Mountain. The relationship between the required minimum burnup and fuel assembly initial enrichment forms a loading curve. Loading curves, which are functions of burnup and enrichment, are the loci of values delineating the region of acceptable burnup/enrichment combinations for postclosure criticality control. In order to accommodate multiple canister criticality control design configurations, focus is placed on the transportation, aging, and disposal (TAD) canister specification requirements (DOE 2007 [DIRS 181403]) for developing a robust loading curve that is expected to bound all of the potential design variants over the 10,000-year regulatory period. In applying this methodology, the loading curve is generated once and the assigned burnup values of all assemblies considered for loading into the TAD canister are compared directly against this loading curve. Assemblies having burnup values in the unacceptable range must be loaded into waste packages or canisters with additional reactivity control mechanisms (e.g., disposal control rod assemblies). The loading curves generated in this report are intended to enable repository postclosure objectives to be met in accordance with 10 CFR Part 63 [DIRS 180319] and do not necessarily apply to transportation of CSNF.