Effect of Prestress and Stress on the Strength and Oxidation Rate of Nuclear Graphite

摘要

Effects of prestress or stress during oxidation on the reactivities and strengths of PGX and H451 graphites were examined at oxidation temperatures of 450-600C in air and 550-750C in 2% H2O/He. Little or no effect of compressive strengths was found. A small effect on the reactivity of H451 graphite was observed in the case of 2% H2O/He, i.e. the rate was enhanced by no more than 30% for compressive prestress levels of up to 90% of the fracture strength. Tensile and compressive stresses during oxidation did not affect the reactivities of these graphites at stress levels of up to 28% of the mean compressive strength and 35% of the mean tensile strength for H451 graphite, and 44% and 56% for PGX graphite, respectively.