Specimen selection for reactor vessel surveillance program

The reactor pressure vessel survaillance program quantitatively defines the amount of irradiation embrittlement sustained by the pressure vessel materials during operation. In the past, only Charpy V-notch and Tensile specimens were encapsulated and irradiated during operation to determine the shift in the nil-ductility transition temperature and the changes of the tensile properties. Since the addition of fracture mechanics procedures in 1972 to the ASME Boiler and Pressure Vessel Code there has been a need to obtain a direct measurement of the fracture toughness properties of some special materials. One way of accomplishing this is by including Compact Fracture specimens in addition to Charpy and Tensile specimens. The considerations taken in selecting the type, geometry, thickness, and number of fracture mechanics specimens are described. The finite element analysis and experimental program performed for the qualification of the round Compact Fracture specimens are described