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Title: Modelling the thermal conductivity of (UxTh1-x)O2 and (UxPu1-x)O2

The degradation of thermal conductivity due to the non-uniform cation lattice of (UxTh1-x)O2 and (UxPu1-x)O2 solid solutions has been investigated by molecular dynamics, using the non-equilibrium method, from 300 to 2000 K. Degradation of thermal conductivity is predicted in (UxTh1-x)O2 and (UxPu1-x)O2 as compositions deviate from the pure end members: UO2, PuO2 and ThO2. The reduction in thermal conductivity is most apparent at low temperatures where phonon-defect scattering dominates over phonon-phonon interactions. The effect is greater for (UxTh1-x)O2 than UxPu1-x)O2 due to the greater mismatch in cation size. Parameters for an analytical expressions have been developed that describe the predicted thermal conductivities over the full temperature and compositional ranges. Finally, these expressions may be used in higher level fuel performance codes.
Authors:
 [1] ;  [2] ;  [3]
  1. Imperial College, London (United Kingdom); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Westinghouse Electric Sweden AB, Vasteras (Sweden)
  3. Imperial College, London (United Kingdom)
Publication Date:
OSTI Identifier:
1255065
Report Number(s):
LA-UR--15-24388
Journal ID: ISSN 0022-3115; PII: S0022311515301082
Grant/Contract Number:
EP/I036400/1; AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 466; Journal Issue: C; Journal ID: ISSN 0022-3115
Publisher:
Elsevier
Research Org:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; 36 MATERIALS SCIENCE; 11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS MOX; mixed oxide; nuclear fuel; thermal conductivity; thermal diffusivity; UO2, PuO2, ThO2