RABBIT CAPSULE IRRADIATION OF UO$sub 2$. Terminal Report

Technical Report · Fri Jun 01 04:00:00 EDT 1962

OSTI ID:4785259

Duncan, R N

Factors, which affect the thermal performance capability of UO/sub 2/ fuel rods, were evaluated by a series of short time rabbit capsule irradiation experiments. Six capsules containing three fuel rod sandples in each were irradiated for 40 hours at fuel rod power levels of from 11 to 24 (KW/ft) (360 to 785 (W/cm)). The capsules were designed to minimize variation in both radial and axial thermal neutron flux. The fuel rod configuration was a 5 inch column of UO/ sub 2/ pellets, 0.430 inches in diameter, 94 plus or minus 1.5% of theoretical density, clad with Zircaloy-2. The temperature distribution within the UO/sub 2/ fuel was estimated by post-irradiation measurements of the radius at which various microstructural changes such as grain growth, columnar grain formation, and melting of the UO/sub 2/ occurred. Comparison of the UO/sub 2/ microstructures from fuel rods with initial cold diametral gaps of 0.006, 0.012, and 0.025 inches indicated that the UO2 surface and center temperature increased with increasing gap. The UO/sub 2/ in fuel rods initially backfilled with helium operated at lower temperatures than those containing argon. Results indicate that the thermal conductivity of UO/sub 2/ at high temperatures is higher than that obtained by extrapolating existing low temperature data. The thermal conductivity of UO/sub 2/ between 450 and 2760 deg C (UO/sub 2/ melting point) is estimated to be 0.030 (W/cm deg C) or 1.75 (BTU/hr ft deg F). Center melting will occur only at fuel rod power levels of 28 (KW/ft) (860 (W/cm)) or greater for fuel rods with a UO/sub 2/ pellet surface temperature of 450 deg C. (auth)

• Research Organization: Westinghouse Electric Corp. Atomic Power Div., Pittsburgh
• NSA Number: NSA-16-032142
• OSTI ID: 4785259
• Report Number(s): CVNA-142
• Country of Publication: United States
• Language: English

Related Subjects

CAPSULES
CONFIGURATION
DENSITY
DISTRIBUTION
EXPANSION
FUEL CANS
FUEL ELEMENTS
GRAIN SIZE
HIGH TEMPERATURE
INERT GASES
IRRADIATION
LATTICES
MATERIALS TESTING
MEASURED VALUES
MELTING
METALS, CERAMICS, AND OTHER MATERIALS
NEUTRON FLUX
PELLETS
PLANNING
POWER
QUANTITATIVE ANALYSIS
RODS
SERVOMECHANISMS
SURFACES
TEMPERATURE
THERMAL CONDUCTIVITY
THERMAL NEUTRONS
URANIUM DIOXIDE
VARIATIONS
ZIRCALOY