Toward UO₂ micro/macro machining: a laser processing approach

¹ CEA, DES, IRESNE, DEC, Cadarache F-13108 Saint-Paul-lez-Durance, France
² Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, Marseille, France

thomas.doualle@cea.fr

Published online: 19 November 2021

Abstract

Linked to experimental data acquisition and to development of improved models, a better detailed description of the behaviour of the nuclear ceramics as regard to the fission gases release during thermal transient representative of nuclear accidents such as RIA (Reactivity Initiated Accident) and or LOCA (LOss of Coolant Accident) requires access to local information within the fuel pellet, and no longer averaged over the whole of the pellet. One of the major challenge in this context is the sample size, which depends on the main objective of the study, typically from the order of a few hundred microns to millimeters. Few techniques allow this dynamic while being compatible with irradiated fuel constraints. Laser micromachining is a high precision non-contact material removal process that would be adapted to this dynamic. We present experimental and numerical studies, carried out in order to evaluate the possibility to apply this process for the preparation of irradiated UO₂ samples of various dimensions. First, preliminary experimental and numerical works conduced on graphite, as model material, which have comparable properties (in particular their behaviours under laser irradiation and their melting point) in order to validate the feasibility, will be detailed. Afterwards, based on these results, we present our first results on UO₂. The objective is to transfer the technique to non-irradiated UO₂ and then to the irradiated material.