Research and Evaluation of Low Temperature Crack Propagation of Ni Base Alloys in Actual Plants

Many published results have shown that fracture resistance of Ni base alloys is remarkably reduced by intergranular cracking in low temperature (<150°C) hydrogenated water. This phenomenon is called low temperature crack propagation (LTCP). In order to study maintenance assessment of actual components, J-R tests for Ni base alloys (Alloy 690, 600, Alloy 52, 82 and 152 weld metal) were carried out in simulated PWR primary water to investigate susceptibility to LTCP.