EFFECT OF TEMPERATURE ON RADIATION-INDUCED CONTRACTION OF REACTOR GRAPHITE

Radiation-induced contraction as a function of temperature was studied in needle-like and conventional coke graphites from 450 to 1200 deg C. Fast neutron exposures ranged up to 3.2 x 10/sup 21/ nvt, E) 0.18 Mev, corresponding to approximately 20,000 Mwd/at. in a Hanford graphitemoderated reactor. The results significantly extend information on the effect of high temperature irradiation on needle-like coke graphites manufactured with particle size, impregnation, and graphitization temperature as variables. In general, the transverse contraction rate goes through a broad minimum between the temperatures of 850 and 950 deg C with the least contraction occurring at approximately 800 deg C. Needle coke and CSF graphites show the same effect but the contraction of needle coke graphites is approximately 0.8 that of CSF at all temperatures. In the parallel direction, the rates of contraction are the same for both CSF and needle-coke graphites. (auth