Americium-241 integral radiative capture cross section in over-moderated neutron spectrum from pile oscillator measurements in the Minerve reactor

Abstract : An experimental program, called AMSTRAMGRAM, was recently conducted in the Minerve low power reactor operated by CEA Cadarache. Its aim was to measure the integral capture cross section of $^{241}$Am in the thermal domain. Motivation of this work is driven by large differences in this actinide thermal point reported by major nuclear data libraries. The AMSTRAMGRAM experiment, that made use of well characterized JRC-IMM americium samples, was based on the oscillation technique commonly implemented in the Minerve reactor. First results are presented and discussed in this article. A preliminary calculation scheme was used to compare measurements to calculated values. It is shown that this work confirms a bias previously observed with JEFF3.1.1 (C/E-1 = -10.5 $\pm$ 4 %). On the opposite, the experiment is in close agreement with $^{241}$Am thermal point reported by JEFF3.2 (C/E-1 = -0.5 $\pm$ 4 %).