Progress in core and cermet fuel modelling to calculate severe accidents

The use of cermet type composite fuels leads to an optimised use of plutoni um; a good thermomechanical behaviour due to a low operating temperature th anks to a high thermo-conductivity, that favours high burn-up due to the lo w fission gas release. However, the increase in the metallic mass, an alloy of zircaloy, in the core, as well as the composite nature of the fuel with two very different melting temperatures (similar to 1873 K for the metal, and 2573 K for the ceramic) lead to a behaviour very different from that of the traditional ceramic fuel in the event of an accident. (C) 2001 Elsevie r Science Ltd. All rights reserved.