In-pile studies of inert matrices with emphasis on magnesia and magnesium aluminate spinel

Abstract

Various inert matrices – oxide, nitride and metallic – were irradiated in the French Phénix reactor in order to study their behaviour under a fast neutron fluence ( E > 0.1 MeV). This paper summarises the material selection criteria and the irradiation conditions of the MATrices for INcineration of Actinides (MATINA) 1 experiment. Emphasis is given on non-destructive examinations of the pins and on more complete examinations performed on (MgO + UO 2) and (MgAl 2O 4 + UO 2) pellets which were irradiated up to a fast neutron fluence of 2 × 10 26 m −2. For these pellets, dimensional examinations, scanning electronic microscopy pictures and electron-probe microanalyses, were performed before and after irradiation. Fission gas release was also studied. These preliminary results show a good behaviour of both magnesia and spinel under irradiation.