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

Abstract

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.