Uranium nitride and silicide composite fuels used to reduce fuel oxidation

Abstract

In the 1960s, the space nuclear program for developing reactor propulsion designs led to uranium mononitride (UN) exploration as a fuel. Since then, the UN has gained traction because of its superior thermal conductivity and uranium density compared to standard UO2. Reactors using sodium and lead as liquid coolants have a. long history with UN fuel. More recently, a combination of uranium UN and uranium silicide (U3Si2) has emerged as a promising fuel option for power units. This composite fuel offers enhanced tolerance and resilience. However, several silicide compounds exist, such as USi, USi2, USi3, U3Si, U3Si2, and U3Si5. Instead, they use nitride-silicide composites, such as UN-U3Si5. The UN-U3Si5 fuel, which features a secondary fissile phase with an elevated uranium density, has garnered significant interest. In this study, we compare the performance of UN-U3Si2 and UN-U3Si5 using Kanthal APMT as cladding.