Evaluation of the thermal shock fracture toughness of reactor graphites by arc discharge heating

This paper presents a new technique to determine the thermal shock fracture toughness by a basic analysis of stress intensity factors of the disk with an edge crack. The thermal shock fracture toughness is defined as Ksub(IC)k/Eα (Ksub(IC) standing for fracture toughness of the mode I; k for thermal conductivity; E for Young's modulus; α for thermal expansion coefficient) and is determined en bloc by measuring the threshold electric power of the arc discharge produced when an edge crack propagates in the disk. This is intimately correlated to the thermal shock resistance presented previously. Experimental data for four kinds of reactor graphite are shown. (author)