Density functional theory calculations of defect and fission gas properties in U-Si fuels

Technical Report · Wed Feb 03 00:00:00 EST 2016

DOI:https://doi.org/10.2172/1237246· OSTI ID:1237246

Andersson, Anders David ^[1]

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1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Accident tolerant fuels (ATF) are being developed in response to the Fukushima Daiichi accident in Japan. One of the options being pursued is U-Si fuels, such as the U₃Si₂ and U₃Si₅ compounds, which benefit from high thermal conductivity (metallic) compared to the UO₂ fuel (insulator or semi-conductor) used in current Light Water Reactors (LWRs). The U-Si fuels also have higher fissile density. In order to perform meaningful engineering scale nuclear fuel performance simulations, the material properties of the fuel, including the response to irradiation environments, must be known. Unfortunately, the data available for U-Si fuels are rather limited, in particular for the temperature range where LWRs would operate. The ATF HIP is using multi-scale modeling and simulations to address this knowledge gap. The present study investigates point defect and fission gas properties in U₃Si₂, which is one of the main fuel candidates, using density functional theory (DFT) calculations. Based on a few assumption regarding entropy contributions, defect and fission diffusivities are predicted. Even though uranium silicides have been shown to amorphize easily at low temperature, we assume that U₃Si₂ remains crystalline under the conditions expected in Light Water Reactors (LWRs). The temperature and dose where amorphization occurs has not yet been well established.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC52-06NA25396
• OSTI ID: 1237246
• Report Number(s): LA-UR-15-27996; TRN: US1600299
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
ACCIDENT-TOLERANT NUCLEAR FUELS
URANIUM SILICIDES
DENSITY FUNCTIONAL METHOD
FISSION PRODUCTS
WATER MODERATED REACTORS
WATER COOLED REACTORS
URANIUM DIOXIDE
POINT DEFECTS
THERMAL CONDUCTIVITY
ENTROPY
COMPARATIVE EVALUATIONS
DENSITY
DIFFUSION
COMPUTERIZED SIMULATION
AMORPHOUS STATE
IRRADIATION
PERFORMANCE
PHYSICAL RADIATION EFFECTS