Lattice physics analysis of measured isotopic compositions of irradiated BWR 9 × 9 UO2 fuel

Abstract

As part of a validation study of burnup calculations of BWR cores, lattice physics analyses were performed on burnups and isotopic compositions of U, Pu and fission product nuclides measured on five samples taken from 9 × 9 BWR fuel assemblies. Burnup calculations in infinite assembly geometry were carried out using MVP-BURN and SRAC codes coupled with major nuclear data libraries. The burnups determined based on the Nd-148 method were from 27.9 to 64.2 GWd/t. The typical relative differences in isotopic compositions (atom/Total-U) between the burnup calculations and measurements were −2 ∼ 19% for 234U, −20 ∼ 3% for 235U, −1.5 ∼ 0.1% for 236U, −0.04 ∼ 0.02% for 238U, −4 ∼ 11% for 238Pu, −11 ∼ −2% for 239Pu, −3 ∼ 0% for 240Pu, −12 ∼ −2% for 241Pu and −2 ∼ 3% for 242Pu. They were −2 ∼ 2% for Nd isotopes, −15 ∼ 7% for Eu isotopes, −13 ∼ 1% for Cs isotopes, −13 ∼ 8% for Sm isotopes, 0 ∼ 7% for 147Pm, −7 ∼ −2% for 95Mo, −2 ∼ −1% for101Ru and 0 ∼ 4% for 103Rh.