Keff Sensitivity/Uncertainty Analysis of the Phase VII Burnup Credit Benchmark - 279

The aim of this paper is to present the keff sensitivity/uncertainty analysis for the Phase-VII Burnup Credit Benchmark using the sensitivity profiles obtained with the perturbation option of MCNP and the variance/covariance cross section and decay data from different uncertainty data libraries. Firstly, results obtained for Phase-VII Benchmark using the nuclear data library JEFF- 3.1.1, and the computer programs ACAB (for the inventory prediction) and MCNP (for criticality calculation) are presented. Additional calculations have been performed to assess the importance of nuclear data and computational tools. Secondly, a sensitivity/uncertainty analysis permits to conclude that the uncertainties in decay data libraries are negligible in keff calculation; and cross-section data uncertainties and their impact in keff for long-term disposal have been assessed. (authors)