K-Infinite Trends with Burnup, Enrichment, and Cooling Time for BWR Fuel Assemblies

This report documents the work performed by ORNL for the Yucca Mountain Project (YMP)
M&O contractor, Framatome Cogema Fuels. The goal of this work was to obtain k values for inf
infinite arrays of flooded boiling-water-reactor (BWR) fuel assemblies as a function of various
burnup/enrichment and cooling-time combinations. These scenarios simulate expected limiting
criticality loading conditions (for a given assembly type) for drift emplacements in a repository. Upon
consultation with the YMP staff, a Quad Cities BWR fuel assembly was selected as a baseline
assembly. This design consists of seven axial enrichment zones, three of which contain natural
uranium oxide. No attempt was made to find a 􀀀bounding
or even 􀀀typical
assembly design due to
the wide variety in fuel assembly designs necessary for consideration. The current work concentrates
on establishing a baseline analysis, along with a small number of sensitivity studies which can be
expanded later if desired.