Effects of Irradiation Growth on the Thermo-Mechanical Behaviors Evolution in Inert Matrix Fuel Elements

Abstract

Inert matrix fuel elements consisting of metal cladding and fuel meat with the fuel particles embedded into the inert matrix have higher lifetime compared to the traditional fuel elements used in the present nuclear plants. They have promising prospects to be used in the advanced nuclear reactors and disposal of nuclear wastes, and nowadays are widely used in the research and test reactors. In order to precisely predict their in-pile thermo-mechanical coupling behaviors, the relative simulation methods and several ABAQUS subroutines are built with the following irradiation damage effects involved as irradiation hardening in the metal matrix and cladding, irradiation swelling in the fuel particles and the irradiation growth effect for the cladding. Specially, the irradiation growth of the cladding is modeled in the way of anisotropic thermal expansion, and then its effects on the micro-thermo-mechanical behaviors in the inert matrix fuel elements can be investigated. The comparison of the results for the two cases with and without the irradiation growth shows: (1) irradiation growth will remarkably enhance the mechanical interactions in the cladding, such as the Mises stresses; (2) it will weaken the interaction between the fuel meat and the cladding; (3) the increment of the plate thickness will become a little smaller at low burnup, and then become larger at high burnup.