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.

Keywords:

• ²³⁷Np
• ²⁴¹Am
• fission
• capture
• JENDL3.2
• ENDF/B-VI
• JEF2.2
• KUCA
• Integral test