Disposal Criticality Analysis Methodology Topical Report1 describes a methodology for performing postclosure criticality analyses within the repository at Yucca Mountain, Nevada. An important component of the postclosure criticality analysis is the calculation of conservative isotopic concentrations for spent nuclear fuel. This report documents the isotopic calculation methodology. The isotopic calculation methodology is shown to be conservative based upon current data for pressurized water reactor and boiling water reactor spent nuclear fuel.

In July 1999, the U.S. Nuclear Regulatory Commission (NRC) Spent Fuel Project Office
(SFPO) issued Interim Staff Guidance 8 Revision 1 (ISG8R1) to provide recommendations for the use
of burnup credit in storage and transport of pressurized-water reactor (PWR) spent fuel. Subsequent to
the issuance of ISG8R1, the NRC Office of Regulatory Research (RES) has directed an effort to
investigate the technical basis for extending the criteria and recommendations of ISG8R1 to allow

This paper presents an assessment of the benefits for extended burnup credit in transporting
pressurized-water-reactor (PWR) spent nuclear fuel (SNF) in the United States. A prototypic 32-
assembly cask and the current regulatory guidance were used as bases for this assessment. By
comparing recently released PWR discharge data with actinide-only-based loading curves, this
evaluation shows that additional negative reactivity (through either increased credit for fuel burnup or

The Materials Characterization Center (MCC) at Battelle Pacific Northwest Laboratory (PNL) has the responsibility to select appropriate spent fuel Approved Testing Materials (ATMs) and to characterize, via hot-cell studies, certain detailed properties of the discharged fuel. The purpose of this report isto develop a collective description of the entire spent fuel inventory in terms of various fuel properties relevant to ATMs using information available from the Characteristics Data Base (CDB), which is sponsored by the U.S.

This report is part of a report series designed to document benchmark-quality radiochemical assay data
against which computer code predictions of isotopic composition for spent nuclear fuel can be validated
to establish the uncertainty and bias associated with the code predictions. The experimental data analyzed
in the present report were acquired from two international programs: (1) ARIANE and (2) REBUS, both
coordinated by Belgonucleaire. All measurements include extensive actinide and fission product data of

The Interim Staff Guidance on burnup credit (ISG-8) issued by the United States Nuclear Regulatory
Commission’s (U.S. NRC) Spent Fuel Project Office recommends restricting the use of burnup credit to
assemblies that have not used burnable absorbers. This recommended restriction eliminates a large portion
of the currently discharged spent fuel assemblies from cask loading, and thus severely limits the practical
usefulness of burnup credit. In the absence of readily available information on burnable poison rod (BPR)

The objectie of this calculation is to document the Grand Gulf, Unit 1, (GG1) fuel depletion calculations. The GG1 reactor is a boiling water reactor (BWR) owned and operated by Entergy Operations Inc. The Commercial Reactor Criticality (CRC) evaluations support the development and validation of the neutronic models used for criticality analyses involving commercial spent nuclear fuel in a geologic repository. This calculation is performed as part of the evaluation CRC program. This report is an engineering calculation supporting the burnup credit methodology of YMP 2000 (Ref.

The purpose of this calculation is to estimate the probability of misloading a commercial spent
nuclear fuel waste package with a fuel assembly(s) that has a reactivity (i.e., enrichment and/or
burnup) outside the waste package design. The waste package designs are based on the expected
commercial spent nuclear fuel assemblies and previous analyses (Macheret, P. 2001, Section 4.1
and Table 1). For this calculation, a misloaded waste package is defined as a waste package that