Many anchor bolts have been used for fixing many components in nuclear power plant (NPP), securing safety against seismic ev ents. Some methods have been developed to detect crack-like defects in bolts which may occur after seismic events. On the ot her hand, assuming long term use of NPP, a method to detect bolt thinning was thought to be needed. In this study, by using bolt specimens with an artificially grinded portion, a new method to detect thinning and to measure its depth was developed....
英字タイトル:
Development of inspection method for thinned bolts by PA-UT

Corrosion of ultra-low carbon type 304 stainless steel in boiling nitric acid solution was analyzed by statistical approach. A large scale mock-up of an evaporator was introduced to perform corrosion test of heat exchanger tubes, and change in loss of wall thickness and intergranular penetration depths of the tubes during test duration was measured and analyzed statistically applying normal distribution and Gumbel distribution. As the results, it was considered that tube wall was corroded uniformly an...
英字タイトル:
Statistical Approach on Corrosion of Stainless Steel in Boiling Nitric Acid for Prevention Maintenance of Nuclear Fuel Reprocessing Plant

Corrosion of ultra-low carbon type 304 stainless steel in boiling nitric acid solution was analyzed by statistical approach. A large scale mock-up of an evaporator was introduced to perform corrosion te st of heat exchanger tubes, and change in loss of wall thickness and intergranular penetration depths of the tubes during test duration was measured and analyzed statistically applying normal distributi on and Gumbel distribution. As the results, it was considered that tube wall was corroded uniformly and m...
英字タイトル:
Statistical Approach on Corrosion of Stainless Steel in Boiling Nitric Acidfor Prevention Maintenance of Nuclear Fuel Reprocessing Plant

Hamaoka Nuclear Power Station got a regulatory approval for a decommissioning plan of Unit 1 & 2 on November 18, 2009. Curre ntly, system decontamination and dismantlement of facilities outside radioactive control area are under process. At the same time, we still have our maintenance program for integrity of required system functions. This paper describes an outline of a revise of maintenance program associated with approval for the decommissioning plan. ywords: decommissioning, maintenance...
英字タイトル:
Maintenance program after Approval of Decommissioning Plan of Hamaoka Unit 1 & 2