Advanced modelling of complex material properties. A significant step towards predictive computation of cladding rupture

The study of the behaviour of nuclear fuel in accidental situations is a major concern in the safety analysis of pressurized water reactors (PWR). In order to be able to provide both effective and relevant support in this analysis IRSN has, over several years, built up a vast R and D programme on fuel, based on two key cornerstones: 1. an advanced R and D, in order to understand more fully physical phenomena at small scales, 2. an applied R and D, in order to be able to establish physical basis for the elaboration of new safety criteria. This approach was extensively illustrated at the previous EUROSAFE-2009 forum in the paper by Francois Barre entitles ''Fuel behaviour under LOCA and RIA and its implication on current safety criteria''. The topic of this paper is to present the first cornerstone of this approach and to illustrate several of its main aspects. The general approach taken in this advanced R and D is based on two main themes: 1. the development of advanced modelling to predict the behaviour of materials in all situations, relying mainly on MIST (IRSN-CNRS-Universite de Montpellier joint research laboratory), on French (universities, CNRS) or international academic partners (Los Alamos, FNRS, MIT) and on industrial or semi-industrial partners (IFP, INRIA, etc); 2. the synthesis and enhancement of the knowledge acquired in nuclear safety support software (such as SCANAIR or DRACCAR). (orig.)