Lattice Physics Analysis of Burnups and Isotope Inventories of U, Pu, and Nd of Irradiated BWR 9×9-9 UO_2 Fuel Assemblies

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As part of a validation study of burnup calculations of BWR cores, lattice physics analyses were performed on the measured burnups and the isotopic inventories of U, Pu, and Nd isotopes of eight samples taken from 9×9-9 BWR fuel assemblies of three and five cycles of irradiations. Burnup calculations in assembly geometry were carried out with a neutronics code system, SRAC, and a Monte Carlo burnup calculation method, MVP-BURN, based on a nuclear data library, JENDL-3.3. The measured burnups were determined based on the Nd-148 method, where the fission yield of 148Nd, energy release per fission, and correction factors for neutron captures by 147Nd and 148Nd were analytically obtained by averaging with burnups. The C/Es of the sample burnups are 0.96 to 1.07 for both analysis methods. By modifying the power histories to adjust the calculated burnups to the measurements of the samples, burnup calculations were performed again and the isotope inventories were compared with the measurements. The C/Es of the inventories are 1.00 to 1.09 for 235U, 0.91 to 1.04 for 239Pu, 0.96 to 1.07 for 240Pu, and 0.90 to 1.02 for 241Pu for the six samples excluding those of a corner fuel rod.
一般社団法人日本原子力学会の論文
2008-06-01