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

Benoit Geslot,Patrick Blaise,Adrien Gruel,Vicente Becares,Pierre Leconte,Paul Ros,Gilles Noguere,Ludovic Mathieu,Stefan Kopecky,David Villamarin,Arjan Plompen,Peter Schillebeeckx

doi:10.1051/epjconf/201714606016

Abstract

An experimental program, called AMSTRAMGRAM, was recently conducted in the Minerve low power reactor operated by CEA Cadarache within the frame of the CHANDA initiative (Solving CHAllenges in Nuclear Data). 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 EC-JRC 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 measured and calculated results. It is shown that this work confirms a bias previously observed with JEFF-3.1.1 (C/E-1 = −10.5 ± 2%). On the opposite, the experiment is in close agreement with 241 Am thermal point reported in JEFF-3.2 (C/E-1 = 0.5 ± 2%).

Highlights

For nearly 10 years, several experiments have been conducted to improve 241Am radiative capture cross section
The AMSTRAMGRAM experiment, that made use of well characterized EC-JRC americium samples, was based on the oscillation technique commonly implemented in the Minerve reactor
This paper presents preliminary experimental results from the AMSTRAMGRAM program conducted by CEA in the Minerve reactor, in collaboration with EC-JRC

Summary

Introduction

For nearly 10 years, several experiments have been conducted to improve 241Am radiative capture cross section. Evaluated cross sections from major libraries differ from 10% to 15%, especially in the thermal domain [1,2,3]. A difference of 9% on the thermal point can be observed between JEFF-3.2 and ENDF/B-VII. nuclear data libraries. An international collaborative working group organized by NEA-OECD started in 2015 with the aim of explaining such discrepancies [4]. In this framework, an experimental program was recently conducted by CEA Cadarache in the Minerve reactor. Its main objective was to measure 241Am integral capture cross section in a very thermal neutron spectrum, providing valuable information on the 241Am thermal point, with a target accuracy of 3% (1σ )

Methods

Results

Conclusion