Examination of experimental data for irradiation-induced creep in nuclear graphite

Thesis/Dissertation · Mon Jan 01 04:00:00 EST 1990

OSTI ID:6066874

Mobasheran, A S

Pre- and postirradiation measurement data were studied considering linear and nonlinear creep models. The nonlinear creep model considers the creep coefficient to vary with neutron fluence due to the densificatin of graphite with neutron irradiation. Within the range of neutron fluence involved (up to 0.53 {times} 10{sup 26} neutrons/m{sup 2}, E > 50 KeV), both models were capable of explaining about 96% and 80% of the variation of the irradiation-induced creep strain with neutron fluence at temperatures of 600C and 900C, respectively. Temperature and reactor power data were analyzed to determine the best estimates for the actual irradiation temperatures. The dependence of the secondary creep coefficients (for both linear and nonlinear models) on irradiation temperature was determined assuming that the variation of creep coefficient with temperature, in the temperature range studied, is reasonalby linear. It was concluded that the variability in estimate of the creep coefficients is definitely not the results of temperature fluctuations in the experiment. The coefficients for the constitutuve equation describing the overall growth of grade H-451 graphite were also studied. It was revealed that the modulus of elasticity and the shear modulus are not affected by creep and that the electrical resistivity is slightly (less than 5%) changed by creep. However, the coefficient of thermal expansion does change with creep. The consistency of calculated Poisson's ratios for primary and secondary creep with volume change, caused by irradiation-induced creep, was also investigated. It was determined that these ratios were consistent with the volume change.

• Research Organization: Tennessee Univ., Knoxville, TN (United States)
• OSTI ID: 6066874
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603 -- Materials-- Properties
360605* -- Materials-- Radiation Effects
CARBON
CREEP
ELASTICITY
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTAL MINERALS
ELEMENTS
EXPANSION
GRAPHITE
HIGH TEMPERATURE
IRRADIATION
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
MINERALS
NEUTRON FLUENCE
NONMETALS
PHYSICAL PROPERTIES
PHYSICAL RADIATION EFFECTS
POISSON RATIO
POWER DISTRIBUTION
RADIATION EFFECTS
SHEAR PROPERTIES
TENSILE PROPERTIES
THERMAL EXPANSION
VERY HIGH TEMPERATURE