Sensitivity Analysis and Uncertainty Quantification of FFTF Cycle 8C Using the NEAMS Workbench

摘要

The FFTF Cycle 8C core was modeled using the NEAMS Workbench PyARC interface to compute the reactivity coefficients, the neutron and the gamma power distributions. These will be used for benchmark simulations using SAS4A/SASSYS-1. The present work discusses the impact of cross-section processing approximation and of nuclear data uncertainty on the eigenvalue and reactivity feedback coefficients. For FFTF, both the heterogeneous cross-section treatment and the TWODANT step were found to provide relatively marginal impact on the reactivity coefficients, but do impact the k-effective by 650pcm. In addition, the nuclear data uncertainty was propagated to the neutronic feedback coefficients and was found to be responsible for 1% to 18% uncertainty on some reactivity feedback coefficients. These uncertainties will be propagated through the LOFWOS transient in FFTF to see if the uncertainties coming from the nuclear data help explain some of the discrepancy observed between the best estimate results and the experiment.