A thermal conductivity model for U-Si compounds
- Idaho National Lab. (INL), Idaho Falls, ID (United States)
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
U3Si2 is a candidate for accident tolerant nuclear fuel being developed as an alternative to UO2 in commercial light water reactors (LWRs). One of its main benefits compared to UO2 is higher thermal conductivity that increases with temperature. This increase is contrary to UO2, for which the thermal conductivity decreases with temperature. The reason for the difference is the electronic origin of thermal conductivity in U3Si2, as compared to the phonon mechanism responsible for thermal transport in UO2. The phonon thermal conductivity in UO2 is unusually low for a fluorite oxide due to the strong interaction with the spins in the paramagnetic phase. The thermal conductivity of U3Si2 as well as other U-Si compounds has been measured experimentally [1-4]. However, for fuel performance simulations it is also critical to model the degradation of the thermal conductivity due to damage and microstructure evolution caused by the reactor environment (irradiation and high temperature). For UO2 this reduction is substantial and it has been the topic of extensive NEAMS research resulting in several publications [5, 6]. There are no data or models for the evolution of the U3Si2 thermal conductivity under irradiation. We know that the intrinsic thermal conductivities of UO2 (semi-conductor) and U3Si2 (metal) are very different, and we do not necessarily expect the dependence on damage to be the same either, which could present another advantage for the silicide fuel. In this report we summarize the first step in developing a model for the thermal conductivity of U-Si compounds with the goal of capturing the effect of damage in U3Si2. Next year, we will focus on lattice damage. We will also attempt to assess the impact of fission gas bubbles.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE Office of Nuclear Energy (NE)
- DOE Contract Number:
- AC52-06NA25396
- OSTI ID:
- 1342838
- Report Number(s):
- LA-UR-16-27736; TRN: US1701909
- Country of Publication:
- United States
- Language:
- English
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