OECD/NEA Burnup Credit Calculational Criticality Benchmark Phase I-B Results

Burnup credit is an ongoing technical concern for many countries that operate commercial
nuclear power reactors. In a multinational cooperative effort to resolve burnup credit issues, a
Burnup Credit Working Group has been formed under the auspices of the Nuclear Energy Agency
of the Organization for Economic Cooperation and Development. This working group has
established a set of well-defined calculational benchmarks designed to study significant aspects of
burnup credit computational methods. These benchmarks are intended to provide a means for the
intercomparison of computer codes, methods, and data applied in spent fuel analysis. The
benchmarks have been divided into multiple phases, each phase focusing on a particular feature of
burnup credit analysis. This report summarizes the results and findings of the Phase I-B benchmark,
which was proposed to provide a comparison of the ability of different code systems and data
libraries to perform depletion analysis for the prediction of spent fuel isotopic concentrations.
Results included here represent 21 different sets of calculations submitted by 16 different
organizations worldwide, and are based on a limited set of nuclides determined to have the most
important effect on the neutron multiplication factor of light-water-reactor spent fuel.
A comparison of all sets of results demonstrates that most methods are in agreement to within
10% in the ability to estimate the spent fuel concentrations of most actinides. All methods are
within 11% agreement about the average for all fission products studied. Furthermore, most
deviations are less than 10%, and many are less than 5%. The exceptions are 149Sm, 151Sm, and 155Gd.