Fast Neutron Irradiation Impact on Thermophysical Properties of Inert Materials Intended As Support Matrix for Transmutation Targets Bearing Minor Actinides

Abstract

This paper contains the results of density, lattice parameter, microstructure, thermal diffusivity and specific heat measurements performed on three neutron irradiated inert matrices: MgO, AI2O3 and MgaiO* The irradiation was carried out in Phénix as part of the MATINA experiment The measurements were performed for both fresh and irradiated materials. The impact of the irradiation on geometrical and crystallographic swelling of the three materials is depicted. The apparent specific heat measurements on irradiated samples showed an exothermic effect linked to the recovery of irradiation damages. The thermal diffusivity degradation was measured and its recovery was investigated as a function of the annealing temperature by performing thermal annealing cycles. The impact of irradiation damage on the thermal conductivity of these malerials and the annealing behavior are discussed and compared to the literature. Besides, the effect of thermal annealing treatments in a fiimace at 1270 and 1670 K on the density and the lattice parameter of irradiated samples for AisOs, MgAl^ and MgO is described.