CRACK-TIP CONSTRAINT AND FRACTURE TOUGHNESS OF AN INNER-SURFACE CRACK UNDER THERMAL SHOCK

This paper considered the crack-tip constraint and fracture toughness of a semi-elliptical surface crack inside a hollow cylinder that experiences loss of coolant accident (LOCA). The magnitude of the crack-tip constraint was measured by evaluating the in and out of plane T-stress; i.e., T-11. Results showed that T-11 was negative at the deepest point, and that conservatism can be expected in using the fracture toughness obtained from standard fracture toughness test specimens. Finally, this conservatism was estimated quantitatively by applying a framework to correlate test specimen crack depth effect on fracture toughness with T-stresses.