Modelling FeCrAl cladding thermo-mechanical performance. Part II: Comparative analysis with Zircaloy under LOCA conditions

Abstract

The demonstration of the enhanced thermo-mechanical response of iron-chromium-aluminum (FeCrAl) cladding under any circumstances, particularly under postulated accident scenarios, requires the development of analytical capabilities. By extending FRAPTRAN-2.0 to model the instantaneous plasticity and high-temperature creep of FeCrAl, among other properties, its performance under LOCA conditions has been assessed in comparison with that of Zircaloy-4. Based on the conditions set in the IFA-650.10 test of the HALDEN project, FeCrAl has shown an enhanced thermo-mechanical response due mainly to its superior mechanical strength, which led to a significant extension of the time to failure, even with a reduced cladding thickness. This time gain is expected to be even longer given that irradiation-induced hardening (not considered in the present model) might further delay the onset of plastic deformation. This effect is planned to be implemented in the future in-house extension of FRAPTRAN-2.0.