Integral Test for Np237 and Am241 Cross Sections in JENDL, ENDF and JEF Libraries

Abstract

Experiments using Kyoto university critical Assembly (KUCA) were performed for measuring the capture and fission reaction rates of 237Np and 241Am. A back-to-back fission chamber was employed for the measurement of the fission rate of 237Np and 241Am relative to 235U. The capture rate of 237Np relative to 197Au was measured by using activation method. Eleven cores, of which the spectra were changed systematically, were mocked up for the present measurements. Five cores among the eleven were utilized for the fission reaction rate measurement. The experiment was analyzed using the Monte Carlo code MVP, the transport code TWOTRAN and the diffusion code CITATION using the libraries based on JENDL3.2, ENDF/B-VI and JEF2.2. As the results, for 237Np, JENDL3.2 showed good agreement for both capture and fission. However, for the fission rate of 241Am, JENDL3.2 underestimates 15-20%. On the other hand, ENDF/B-VI and JEF2.2 shows different C/Es for 237Np and 241Am.