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Title: Non-stoichiometry in U 3Si 2

Uranium silicides, in particular U 3Si 2, are being explored as an advanced nuclear fuel with increased accident tolerance as well as competitive economics compared to the baseline UO 2 fuel. Here we use density functional theory calculations and thermochemical analysis to assess the stability of U 3Si 2 with respect to non-stoichiometry reactions in both the hypo- and hyper-stoichiometric regimes. We find that the degree of non-stoichiometry in U 3Si 2 is much smaller than in UO 2 and at most reaches a few percent at high temperature. Non-stoichiometry impacts fuel performance by determining whether the loss of uranium due to fission leads to a non-stoichiometric U 3Si 2±x phase or precipitation of a second U-Si phase. Lastly, we also investigate the U 5Si 4 phase as a candidate for the equilibrium phase diagram.
Authors:
 [1] ;  [2] ; ORCiD logo [3] ; ORCiD logo [4] ; ORCiD logo [4]
  1. Westinghouse Electric Sweden AB, Vasteras (Sweden); Imperial College London, London (United Kingdom)
  2. Imperial College London, London (United Kingdom)
  3. Westinghouse Electric Co. LLC, Cranberry Woods, PA (United States)
  4. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
LA-UR-17-20854
Journal ID: ISSN 0022-3115; TRN: US1701554
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 482; Journal Issue: C; Journal ID: ISSN 0022-3115
Publisher:
Elsevier
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Nuclear Energy (NE)
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; accident tolerant fuel; density functional theory; stoichiometry; silicide
OSTI Identifier:
1343721
Alternate Identifier(s):
OSTI ID: 1396826