Isotopic Analysis of Actinides and Fission Products in LWR High-Burnup UO2 Spent Fuels and its Comparison with Nuclide Composition Calculated Using JENDL, ENDF/B, JEF and JEFF

Abstract

A chemical isotopic analysis of the actinides and fission products of a high-burnup PWR-UO2 fuel with an average burnup of 60.2 MWd/kgHM was carried out to accumulate extensive nuclide composition data. Furthermore, computational analysis was performed using the integrated burnup calculation code SWAT. The differences between the amounts obtained by the chemical isotopic analysis and SWAT calculation using JENDL-3.2, JENDL-3.3, ENDF/B-VI.5, ENDF/B-VI.8, JEF-2.2 and JEFF-3.0 were evaluated as the ratios of the calculated values to the experimental values (C/E ratios). For actinides, the calculated 244Cm amount, which is an important nuclide as a major neutron source in spent fuels, was underestimated. The main sensitive path for 244Cm was therefore investigated by a simple depletion calculation for actinides and the cause of the underestimation of the calculated 244Cm amount is discussed. The fission products 88Sr, 90Sr, 89Y, 106Ru, 133Cs, 135Cs and 144Nd, for which the C/E ratios were larger than 1.05 or smaller than 0.95, were investigated to improve their C/E ratios by a simple depletion calculation with simplified burnup chains and sensitivity coefficients, and the correction values for the fission yields or capture cross sections were estimated. The effect of power history on nuclide composition was also investigated. Additionally, the fission products for which the C/E ratios strongly depend on the type of library are discussed using sensitivity coefficients.