Transmutation of actinides in inert-matrix fuels: fabrication studies and modelling of fuel behaviour

A review of the ongoing research of inert-matrix fuels for the transmutatio n of actinides is given. Three fabrication routes are described, co-precipi tation (CPP), low-impact mixing of powders (LMP) and mixing of particles an d powders (MPP). These methods have been tested for various combinations of actinide host materials and inert matrices. Most attention is given to a f uel concept consisting of an actinide-containing host phase and spinel as t he inert matrix. To understand the phase relations and melting behaviour of this hybrid Fuel type the binary phase diagrams in the system (Zr,Y,Pu)O-2 + MgAl2O4 are being modelled and some results are presented. In addition, the thermal behaviour of MgAl2O4-based inert-matrix fuels is investigated. The thermal conductivity of polycrystalline spinel is measured and in-pile temperature measurements of an UO2 + MgAl2O4 target are analysed. (C) 1999 Elsevier Science B.V. All rights reserved.