Transition and upper shelf fracture toughness properties of an A508 Class 3 PWR nozzle cut-out

In this work the resistance to ductile and brittle fracture modes in an A508 Class 3 PWR nozzle cut-out has been examined using conventional fracture mechanics tests. Within the transition temperature regime considerable variability in toughness was found with some evidence that the near inside wall position was less tough then close to the outside wall. Cleavage fracture occurred at temperatures up to 60 C and a few data were below the ASME and lower bound reference toughness/ temperature lines defined in the 1982 Light Water Reactor Study Group report on pressure vessel integrity. At 290 to 300 C specimen orientation significantly influenced tearing resistance but had little effect on initiation toughness. The observed orientation effects were consistent with an inclusion dominated fracture process. The levels of upper shelf toughness were less than those previously found in a Japanese A508 forging, and similar to those of French A533B Class 1 plate produced about the same time. A comparison is made between the chemical analysis, tensile, Charpy impact, drop weight and fracture toughness properties of this forging and the appropriate ASME and Sizewell B specification. (author)