Measurement of partial (n, n’γ) reaction cross-sections on highly radioactive nuclei of interest for energy production

¹ Université de Strasbourg, CNRS, IPHC/DRS UMR 7178, 23 rue du Loess 67037 Strasbourg, France
² CEA, DES, IRESNE, DER, SPRC, LEPh, Cadarache, F-13108 Saint-Paul-lez-Durance, France
³ CEA, DAM, DIF, F-91297 Arpajon, France
⁴ Université Paris-Saclay, CEA, Laboratoire Matière sous Conditions Extrêmes, 91680 Bruyères-Le-Châtel, France
⁵ Horia Hulubei National Institute for Physics and Nuclear Engineering, 077125 Bucharest, Romania
⁶ Nuclear Data Section, International Atomic Energy Agency, Wagramer Strasse, A-1400 Vienna, Austria
⁷ Department of Chemistry, P.O. 55, 00014 University of Helsinki, Finland
⁸ European Commission, Joint Research Centre, Retieseweg 111, B-2440 Geel, Belgium

^* e-mail: francois.claeys@iphc.cnrs.fr

Published online: 26 May 2023

Abstract

In the context of the development of Gen. IV nuclear reactors, the GIF (Generation IV. International Forum) has selected six innovative technologies. Among them, one can highlight the concept of breeding for ²³²Th/²³³U and ²³⁸U/²³⁹Pu fuel cycles. But those nuclei, crucial for such cycles, suffer from a lack of precise knowledge (nuclear structure, reaction cross sections). In particular, it has been demonstrated that neutron inelastic scattering reaction cross sections are not known with sufficient precision for the isotopes ²³⁸U and ²³⁹Pu, and not known at all experimentally for ²³³U. In order to perform simulations of innovative reactor cores for the development of those technologies, the knowledge of the reaction cross section has to be improved which implies that new measurements have to be done. The GRAPhEME (GeRmanium array for Actinides PrEcise MEasurements) experimental setup, developed by the IPHC laboratory from CNRS and installed at the EC-JRC-Geel GELINA facility is a powerful tool to answer this need [1, 2]. Combining the prompt γ-ray spectroscopy and the time-of-flight methods, it measures partial (n, xnγ) reaction cross sections. This paper reports on the improvements made on the GRAPhEME setup and data analysis methodology to tackle the challenge of (n, xnγ) cross section measurements on high activity actinides. Results obtained so far on ²³³U are presented compared to TALYS calculations.