Research on no-contact remote monitoring technology for nuclear power structural members

As the main cause of radioactivation in nuclear power plants which is considered to be the factor of occupational radiation exposure, there are the phenomena of the falling-off of fine metal particles from the surfaces of structural members by cavitation erosion, radioactivation, and adhesion to member surfaces. If the surfaces of members are rough, these phenomena are remarkably promoted. The smoothing and the evaluation of soundness of the inner surfaces of tubular members have become important subjects. In this research, for the purpose of accurately measuring and evaluating the factors affecting the reliability and safety of small diameter tubes such as flaws and cracks when their inner surfaces are smoothed, the researches on optical no-contact monitoring technology and the technology of evaluating material surface have been carried out. In this fiscal year, the defect detection sensor using oblique incidence optical system and the multi-nozzle type pneumatic holding mechanism for in-tube measuring system were made for trial. The electrolytic polishing experiment using SUS 316 stainless steel samples was carried out. Reports are made on these studies. (K.I.)