EDF Fragment Relocation Model Based on the Displacement of Rigid Bodies

Abstract

In order to release the restricting conditions imposed to the reactor operations with regards to PCMI (Pellet-Cladding Mechanical Interaction), the simulation of a fuel rod thermomechanical behavior has to be improved. The computer programming has to cope with the more and more sophisticated mathematical modellings induced by the complexity and the interdependance of the phenomena. Therefore EDF is developing a new code - CYRAN03 - since 1990 putting emphasis on its evolution capacities. Concerning more precisely the PCMI simulation, the pellet fragmentation and the fragments relocation is one of the major aspect one must account for. Thanks to recent analytical experiments, EDF developed a new modelling based on the displacement of rigid bodies and on the calculation of the interaction efforts between the fragments. This paper presents the basis of the model, its introduction within the CYRAN03 code and its calibration on a specific analytical experiment. The modelling is then tested against PWR fuel rods deformations km the EDF data base. The results are presented and discussed.