| Abstract Scope |
Neutron irradiation changes the mechanical properties of low alloy steel reactor pressure vessels within nuclear power plants. To ensure safe operation over the lifetime of the plant, surveillance programs are implemented which are used to monitor the integrity of the reactor pressure vessel. As part of this surveillance, capsules, which contain Charpy V-notch impact specimens of reactor pressure vessel material, are periodically withdrawn from within the reactor and tested. For plants operating beyond the initial license period, additional Charpy data are needed at high neutron fluence levels to inform operation beyond 60 years. Due to limited irradiated steel material property data, Charpy specimen reconstitution, which entails welding new end tabs onto a portion of a broken Charpy specimen, provides an avenue to obtain additional data. Currently, the standard which governs Charpy reconstitution, ASTM E1253, has limited material guidance on end tab selection. As a result, various end tab materials which meet the current standard requirements can yield dramatically different weld quality. Variations in weld quality can be attributed to differences in microstructural formation during the welding process, which are influenced by the material composition. |