Kinetics of recrystallization and fission-gas induced swelling in high burnup UO sub 2 and U sub 3 Si sub 2 nuclear fuels

Conference · Sat Sep 01 00:00:00 EDT 1990

OSTI ID:6651397

Rest, J; Hofman, G L

Recent experimental observations on low-temperature swelling of irradiated uranium silicide dispersion fuels have indicated that the growth of fission gas bubbles appears to be affected by fission rate. The swelling curve of the material exhibits a distinct knee'' that shifts to higher fission density with increased fission rate due to higher enrichments. Current state-of-the-art models for fission gas behavior do not predict such a dependence. Grain subdivision'' has been observed in high burnup uranium oxide. This observation, and other indirect evidence from various experiments leads to authors to speculate that a dense network of grain boundaries forms in uranium silicide at a dose corresponding to the knee'' in the swelling curve; fission gas bubbles nucleate at the boundaries and then grow at an accelerated rate relative to those in the bulk material. A theoretical formulation is presented wherein the stored energy in the material is concentrated on a network of recrystallization sites that diminish with dose due to interaction with radiation-produced defects (vacancy-solute pairs). Recrystallization is induced by statistical fluctuations when the energy per site is high enough such that the creation of grain boundary surfaces is offset by the creation of strain-free volumes with a resultant net decrease in the free energy of the material. This formulation, applied within the context of a mechanistic treatment of gas bubble behavior, is shown to provide a plausible interpretation of the observed phenomena.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOD; DOE/AD
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6651397
• Report Number(s): CONF-9009256-1; ON: DE90017813
• Resource Relation: Conference: NATO advanced research workshop on fundamental aspects of inert gases in solids, Bonas (France), 16-22 Sep 1990
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
36 MATERIALS SCIENCE
NUCLEAR FUELS
RECRYSTALLIZATION
SWELLING
URANIUM DIOXIDE
URANIUM SILICIDES
ALUMINIUM
BUBBLES
BURNUP
FISSION PRODUCTS
GASES
GRAIN BOUNDARIES
MATHEMATICAL MODELS
ACTINIDE COMPOUNDS
CHALCOGENIDES
CRYSTAL STRUCTURE
ELEMENTS
ENERGY SOURCES
FLUIDS
FUELS
ISOTOPES
MATERIALS
METALS
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
RADIOACTIVE MATERIALS
REACTOR MATERIALS
SILICIDES
SILICON COMPOUNDS
URANIUM COMPOUNDS
URANIUM OXIDES
050700* - Nuclear Fuels- Fuels Production & Properties
360102 - Metals & Alloys- Structure & Phase Studies