Sensitivity and Uncertainty Analysis on UAM Benchmark Exercise I-2 with MCS

Sensitivity and uncertainty (S/U) analysis is important for design and safety analysis of nuclear reactor. It can be used to introduce appropriate safety margins and define the top contributors to the uncertainties. The OECD/NEA Uncertainty Analysis in Modelling (UAM) benchmark for design, operation, and safety analysis of light water reactors (LWRs) has been developed to quantify the uncertainties in LWR systems. In this paper, S/U analyses have been performed with MCS on 2-D TMI-1 PWR fuel assembly and mini-core problems. There are two different states, which are Hot full power (HFP) unrodded and HFP rodded cases, for the fuel assembly problems. HFP state is considered for the mini-core problem. S/U analyses have been performed with MCS on the 2-D TMI-1 PWR fuel assembly with HFP-unrodded and HFP-rodded states, and 2-D mini-core at HFP state. ENDF/B-VII.1 nuclear data library is used as a continuous-energy neutron cross section. Two different covariance data, which are 44-group ENDF/B-VII.1 and 44-group SCALE6.1, are used for the uncertainty quantification. There are large discrepancies between the cases using ENDF/B-VII.1 covariance data and SCALE 6.1 covariance data. The eigenvalue uncertainty with ENDF/B-VII.1 covariance data is 0.7%, and it is 0.45% when SCALE6.1 covariance data is used.