Abstract
Flow-accelerated corrosion (FAC) is a pipe wall thinning phenomenon caused by a combination of thermal-hydraulic, water chemistry, and material factors. The current management of the pipe wall thinning of Japanese nuclear power plants is based on the thinning rate and residual lifetime evaluated using the measured pipe wall thickness. While current management has the advantage of directly identifying the residual wall thickness of pipes and the timing of replacement and repair, there are issues with management for piping sections and systems where the actual residual lifetime cannot be accurately identified because it has not been measured or because it is difficult to measure. To rationalize the current management, we have been developing FALSET, a pipe wall thinning prediction software, to improve its prediction accuracy and to study its specific applications in wall thinning management. The reactor water cleanup system (CUW system) in a BWR plant, which is a self-managed system in terms of wall thinning management, is located in a high-dose area, and thus needs to be managed rationally while minimizing radiation exposure. In this study, we compared the residual lifetime of the CUW system of a BWR plant calculated using the initial thickness measurement and the predicted residual lifetime by FALSET, and examines the issues to be solved when the prediction method is applied to the wall thinning management of the self-managed system.
