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

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 yetmore » been well established.« less
Authors:
 [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
OSTI Identifier:
1237246
Report Number(s):
LA-UR--15-27996
TRN: US1600299
DOE Contract Number:
AC52-06NA25396
Resource Type:
Technical Report
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
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