An innovating gamma-spectroscopy experimental technique for measuring the integral capture cross section of actinides

This paper describes innovative measurements of integral radiative capture rates of minor actinides, performed in the MINERVE facility. They aim at resolving potential discrepancies on capture cross sections, especially in the framework of nuclear safety and of waste management. For this purpose, specific samples containing pure isotopes mixed in natural UO2 pellets have been fabricated. The measurements consist of γ-ray spectrometry on irradiated fuel samples in order to determine the reaction rates with their specific activities and the corresponding spectral indices, defined as the ratio of (n, γ) capture rate to the total fission rate. This study focuses on the following isotopes: 232Th, 237Np, 242Pu and presents the comparison of experimental results with calculation results obtained with deterministic (APOLLO2) and probabilistic (MCNP4C2) codes, with the JEF2.2, ENDF/B-VI.8 and JEFF3.1 data libraries. (authors)