Continued safe availability of nuclear power is dependent on the materials performance of structures and components of the nuclear facility. The integrity evaluation of nuclear reactor pressure vessels (RPVs), through material property measurements, is a critical safety assessment. One method for structural integrity evaluation of RPVs is to monitor mechanical property changes of the materials susceptible to neutron radiation embrittlement by periodic destructive testing of surveillance specimens (Charpy impact, tensile specimens, and fracture toughness, if available). Lifetime extension programs and mitigation processes such as thermal annealing increase the need for additional surveillance specimens as well as require reconstitution of available test materials.

The in-situ SSM technology provides nondestructive determinations of key mechanical and fracture toughness properties (tensile, ductility, and static and dynamic fracture toughness) of RPV materials to monitor the structural integrity of RPVs subjected to neutron embrittlement. It can be used to verify and quantify the recovery of ductility and fracture toughness following thermal annealing.

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