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Title: A semi-empirical model for the formation and depletion of the high burnup structure in UO 2

In the rim zone of UO 2 nuclear fuel pellets, the combination of high burnup and low temperature drives a microstructural change, leading to the formation of the high burnup structure (HBS). In this work, we propose a semi-empirical model to describe the formation of the HBS, which embraces the polygonisation/recrystallization process and the depletion of intra-granular fission gas, describing them as inherently related. To this end, we per-formed grain-size measurements on samples at radial positions in which the restructuring was incomplete. Moreover, based on these new experimental data, we assume an exponential reduction of the average grain size with local effective burnup, paired with a simultaneous depletion of intra-granular fission gas driven by diffusion. The comparison with currently used models indicates the applicability of the herein developed model within integral fuel performance codes.
Authors:
ORCiD logo [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [5]
  1. European Commission, Karlsruhe (Germany). Joint Research Centre; Department of Energy, Milan (Italy)
  2. European Commission, Karlsruhe (Germany). Joint Research Centre; Technical Univ. of Munich (Germany)
  3. Department of Energy, Milan (Italy)
  4. Idaho National Lab. (INL), Idaho Falls, ID (United States)
  5. European Commission, Karlsruhe (Germany). Joint Research Centre
Publication Date:
Report Number(s):
INL/JOU-16-39368
Journal ID: ISSN 0022-3115; PII: S0022311516307279
Grant/Contract Number:
AC07-05ID14517
Type:
Accepted Manuscript
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 487; Journal Issue: C; Journal ID: ISSN 0022-3115
Publisher:
Elsevier
Research Org:
Idaho National Lab. (INL), Idaho Falls, ID (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; fuel performance; grain size measurement; high burnup structure
OSTI Identifier:
1393171