Multiphysics modeling of accident tolerant fuel-cladding U₃Si₂-FeCrAl performance in a light water reactor

The performance of the proposed advanced fuel-cladding system U₃Si₂-FeCrAl was studied based on the suggestion that U₃Si₂-FeCrAl system is a potential accident tolerant fuel candidate from a neutronics assessment. The U₃Si₂ fuel was reported with a number of advanced thermophysical properties and FeCrAl alloy was reported with a better oxidation resistance and a larger thermal neutron absorption cross section. This study presents the development of a model for U₃Si₂-FeCrAl combination system by the modification of our CAMPUS code. Then the fuel performance was compared with UO₂-Zircaloy, UO₂-FeCrAl and U₃Si₂-Zircaloy systems. And finally sensitivity analysis has been performed on the fuel input parameters of UO₂ fuel and cladding thickness of FeCrAl cladding. The U₃Si₂-Zircaloy system was found to decrease the fuel centerline temperature dramatically but with a very early gap closure time due to the large thermal expansion coefficient of U₃Si₂ fuel, while the U₃Si₂-FeCrAl system was found to not only decrease the fuel centerline temperature a lot, but also further delay the gap closure time, which would delay the pellet-cladding mechanical interaction time. Sequentially, the fission gas release and plenum pressure were also found to be decreased a lot. Then the nuclear reactor safety is expected to be improved by applying the U₃Si₂-FeCrAl system.