In the development of a methodology to account for exposure effects on the reactivity of spent Boiling Water Reactor (BWR) fuel in the proposed Monitored Geologic Repository (MGR) at Yucca Mountain, the accuracy of the methods used to predict the inventories of fissile and fissionable nuclides as well as neutron poisons present in the spent fuel must be established. One aspect ofthis confirmatory effort is accomplished by performing benchmark problems for known in-reactor critical configurations - Commercial Reactor Criticals (CRCs).