In order to evaluate the primary water stress corrosion cracking growth rate (PWSCCGR) for the actual components made of TT Alloy 690 and associated welds up to the end of PWR plant lifetime, the effects of heat treatment, cold working and long-term ageing on the PWSCCGRs for the commercial TT Alloy 690 and weld metal were studied. In this study, various level of cold worked or re-solution heat treated commercial TT Alloy 690, intentionally inhomogeneous laboratory melted TT Alloy 690 and weld metal Alloy 52 were used before and after long-term ageing in air at 360 to 475 oC during up to about 20,000 hours. And also, the possibility about the long range ordering or short range ordering (LRO/SRO) affected by the heat history up to the end of PWR plant lifetime was evaluated by the micro-Vickers hardness
measurements and selected area electron diffraction analyses by TEM, using the Ni-33at%Cr model alloy as the reference material. From these test results, it is considered that the possibility about the LRO/SRO formation and increase of PWSCCGRs after long-term ageing for commercial TT Alloy 690 and weld metal Alloy 52 is very low and shall not become an important issue, up to the end of the PWR plant lifetime.