GRASS-SST. Fission-Gas Release & Fuel Swelling

Technical Report · Tue Oct 25 00:00:00 EDT 1988

OSTI ID:139433

Zawadzki, S ^[1]

---

1. Argonne National Lab., IL (United States)

GRASS-SST is a comprehensive, mechanistic model for the prediction of fission-gas behavior in UO2-base fuels during steady-state and transient conditions. GRASS-SST treats fission-gas release and fuel swelling on an equal basis and simultaneously treats all major mechanisms that influence fission-gas behavior. Models are included for intra and inter-granular fission-gas bubble behavior as well as a mechanistic description of the role of grain-edge interlinked porosity on fission-gas release and swelling. GRASS-SST calculations include the effects of gas production from fissioning uranium atoms, bubble nucleation, a realistic equation of state for xenon, lattice bubble diffusivities based on experimental observations, bubble migration, bubble coalescence, re-solution, temperature and temperature gradients, interlinked porosity, and fission-gas interaction with structural defects (dislocations and grain boundaries) on both the distribution of fission-gas within the fuel and on the amount of fission-gas within the fuel and on the amount of fission-gas released from the fuel. GRASS-SST includes the effects of the degree of nonequilibrium in the UO2 lattice on fission-gas bubble mobility and bubble coalescence and also accounts for the observed formation of grain-surface channels. GRASS-SST also includes mechanistic models for grain-growth/grain boundary sweeping and for the behavior of fission gas during liquefaction/dissolution and fuel melting conditions.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States)
• Sponsoring Organization: Nuclear Regulatory Commission, Washington, DC (United States). Office of Nuclear Regulatory Research
• OSTI ID: 139433
• Report Number(s): ESTSC/NRC-000075C017000; NESC-1094
• Resource Relation: Other Information: PBD: 25 Oct 1988
• Country of Publication: United States
• Language: English

Related Subjects

99 MATHEMATICS
COMPUTERS
INFORMATION SCIENCE
MANAGEMENT
LAW
MISCELLANEOUS
22 NUCLEAR REACTOR TECHNOLOGY
05 NUCLEAR FUELS
G CODES
FISSION PRODUCT RELEASE
MATHEMATICAL MODELS
COMPUTER PROGRAM DOCUMENTATION
SENSITIVITY ANALYSIS
REACTOR SAFETY
NUCLEAR FUELS
URANIUM OXIDES
SWELLING
WATER COOLED REACTORS
GRAIN GROWTH
GRAIN BOUNDARIES
STEADY-STATE CONDITIONS
TRANSIENTS
BUBBLES
REACTOR LATTICES