In Japanese NPPs, FAC is being managed by rules based on actual pipe wall thickness measurement values with large margins, which often leads to large number of inspection points for each plant. Therefore, there are requirements for construction of quantitative evaluation method which can be adapted to domestic NPPs, officially, and reduce cost and time for each outage. For this need, fundamental studies with experiments and calculations were conducted by focusing on hydraulic factors. In the experiments, FAC on carbon steel test specimen was observed in contracted rectangular duct. FAC thinning rate were measured optically by laser displacement sensor and time variance data of thinning surface geometry were obtained, which showed merge and growth of pits created by FAC. The flow features around the specimen were calculated with numerical analysis in detail. Local thinning rate almost ! showed a proportional trend to both local velocity and fluctuation velocity on the surface, which will be transformed to local mass transfer rate affecting FAC as future works.

Joined CRIEPI in 1996. Thermal-hydraulic as main field. Engaged with studies of gas-liquid two-phase flow in NPPs, scale adhesion in PWRs. Started FAC studies since Mihama accident in 2004.