REVIEW OF HALDEN REACTOR PROJECT HIGH BURNUP FUEL DATA THAT CAN BE USED IN SAFETY ANALYSES

The fuels and materials testing programmes carried out at the OECD Hal den Reactor Project are aimed at providing data in support of a mechan istic understanding of phenomena, especially as related to high burnup fuel. The investigations are focused on identifying long term propert y changes, and irradiation techniques and instrumentation have been de veloped over the years which enable to assess fuel behaviour and prope rties in-pile. The examples presented include data on thermal and mech anical behaviour, axial gas flow and pressure equilibration, fission g as release, and fuel swelling and cladding creep. The in-pile measurem ents can be used for understanding and modelling of phenomena such as pellet-cladding mechanical interaction, fuel thermal conductivity degr adation, a possible enhancement of fission gas release and cladding li ft-off at high burnup. They do not only relate to fuel performance dur ing normal operation, but can also be applied in safety analyses to de fine the starting conditions of transients and to assess the further d evelopments. (C) 1997 Elsevier Science S.A.