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Title: Effect of Grain Boundaries on Krypton Segregation Behavior in Irradiated Uranium Dioxide

Fission products, such as krypton (Kr), are known to be insoluble within UO2, segregating towards grain boundaries, eventually leading to a lowering of the thermal conductivity and fuel swelling. Recent computational studies have identified that differences in grain boundary structure have a significant effect on the segregation behavior of fission products. However, experimental work supporting these simulations is lacking. Atom probe tomography was used to measure the Kr distribution across grain boundaries in UO2. Polycrystalline depleted-UO2 samples was irradiated with 0.7 and 1.8 MeV Kr-ions and annealed to 1000ºC, 1300ºC, and 1600°C for 1 hour to produce a Kr-bubble dominated microstructure. The results of this work indicate a strong dependence of Kr concentration as a function of grain boundary structure. Temperature also influences grain boundary chemistry with greater Kr concentration evident at higher temperatures, resulting in a reduced Kr concentration in the bulk. While Kr migration is active at elevated temperatures, no changes in grain size or texture were observed in the irradiated UO2 samples.
Authors:
 [1] ;  [2] ;  [1] ;  [2] ;  [3] ;  [4] ;  [3] ;  [5] ;  [1]
  1. Univ. of Florida, Gainesville, FL (United States). Dept. of Materials Science and Engineering
  2. Univ. of Wisconsin, Madison, WI (United States). Dept. of Engineering Physics
  3. Boise State Univ., Boise, Idaho (United States). Dept. of Materials Science and Engineering
  4. Idaho National Lab. (INL), Idaho Falls, ID (United States)
  5. Univ. of Wisconsin, Madison, WI (United States). Dept. of Engineering Physics; Idaho National Lab. (INL), Idaho Falls, ID (United States)
Publication Date:
OSTI Identifier:
1177644
Report Number(s):
INL/JOU--14-32737
Journal ID: ISSN 1047-4838; TRN: US1500183
DOE Contract Number:
AC07-05ID14517
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of The Minerals, Metals & Materials Society; Journal Volume: 66; Journal Issue: 12
Publisher:
Springer
Research Org:
Idaho National Laboratory (INL), Idaho Falls, ID (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; GRAIN BOUNDARIES; URANIUM DIOXIDE; KRYPTON; GRAIN SIZE; IRRADIATION; KRYPTON IONS; THERMAL CONDUCTIVITY; TEMPERATURE RANGE 1000-4000 K; ABUNDANCE; SEGREGATION; MEV RANGE 01-10; KEV RANGE 100-1000; ANNEALING; POLYCRYSTALS; SWELLING; TOMOGRAPHY; ATOMS; BUBBLES; SPATIAL DISTRIBUTION; NUCLEAR FUELS; TEMPERATURE DEPENDENCE; PROBES; TEXTURE ATOM PROBE TOMOGRAPH; BUBBLE; GRAIN BOUNDARY; KRYPTON DISTRIBUTION; SEGREGATION; URANIUM DIOXIDE