Monte Carlo calculation analysis of PWR-type fuel assembly mockup cores loaded with Gd2O3-UO2 fuel rods in B&W 1810 series critical experiments

Abstract

ABSTRACT To extend the information on the validation of the JENDL-4.0 nuclear data library, continuous-energy Monte Carlo calculation was applied to the analysis of the twenty-two PWR-type fuel assembly mockup cores in the Babcock and Wilcox (B&W) 1810 series critical experiments which provided the benchmark data for the validation of the nuclear tools about using Gd2O3-UO2 fuel rods. The critical analysis results showed that the effective neutron multiplication factors (keff ) ranged from 0.99933 to 1.00040 and the average value was 0.99969. The keff values were scrutinized against the numbers of the Gd2O3-UO2 fuel rods, the insertion of the Ag-In-Cd absorber rods and the B4C absorber rods, and partially loading the 4.020 wt% UO2 fuel rods. The analysis results of the core radial fission rate distributions of the six cores indicated that the calculations generally well reproduced the measurements of the fuel rods in the central fuel assemblies. It was observed that the relative differences between the calculated and measured fission rates of the Gd2O3-UO2 fuel rods were larger than those of the neighboring UO2 fuel rods. This trend was examined by comparing with the results of the precedent studies of the Monte Carlo and deterministic transport calculations.