Abstract
U3Si2–FeCrAl system has been a promising Accident Tolerant Fuels (ATFs) candidate for its higher thermal conductivity, higher uranium density and lower oxidation rate. As a part of wide efforts to analyze the thermo-mechanical behaviors of the proposed ATFs, a finite element-based fuel performance code called BEEs, developed based on MOOSE (Multiphysics Object-Oriented Simulation Environment) framework, has been extended to analyze the behaviors of U3Si2–FeCrAl under reactivity insertion accidents (RIA). In this work, CABRI-REP tests were simulated to validate the modeling capacity of BEEs for RIA firstly. Then, with the fuel behavior models applicable to U3Si2 and FeCrAl implemented in BEEs, the thermo-mechanical response of U3Si2–FeCrAl to postulated RIA conditions were evaluated and compared with UO2-Zircaloy, UO2–FeCrAl and U3Si2-Zircaloy systems. The results show that U3Si2–FeCrAl system can reduce the fuel temperature (about 400–600 K) and delay gap closure during normal operation. The performance of cladding in U3Si2–FeCrAl system is comparable with UO2-Zircaloy and UO2–FeCrAl systems. However, the fuel central temperature of U3Si2–FeCrAl system is found to increase (about 110–180 K when RIA occurs at zero burnup, and about 170–190 K when RIA occurs after normal operation) compared to systems with UO2 fuel due to the lower volumetric heat capacity of U3Si2, which can lead to a threat to fuel security in RIA conditions, especially taking the lower melting point of U3Si2 (U3Si2 is ∼1938 K and UO2 is ∼3138 K) into account.
Published Version
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