A study on the constitutive model of irradiated austenitic stainless steel for the functionality analysis of nuclear internals

The internal components of nuclear reactor are exposed to the neutron irradiation environment. The constituent materials of the components are susceptible to remarkable changes in the mechanical properties such as elastic modulus, strength, ductility and toughness. The mechanical and thermal deformations are accompanied with the void swelling and the irradiation creep in the environment. The functionality analysis which evaluates the structural integrity of the aged internals needs to take the degradation characteristics of the material into account. In this paper, a constitutive model of austenitic stainless steel developed by EPRI is studied and implemented into numerical analysis vehicles. The mechanical properties of irradiated 304 stainless steel are presented and the deformation behaviors are simulated. The criteria and methodology for the functionality analysis are also discussed and illustrated.