Austenitic stainless steels are widely used as structural materials in many industries. However, stainless steels are susceptible to crevice corrosion in the solution including chloride ions. In this paper, at first, the most inhibitive anion against corrosion was investigated by anodic polarization measurement of type 316L stainless steel in the solution containing Cl- with candidate inhibitive anions (WO42-, MoO42-, VO3-). MoO42- was adopted as the most inhibitive anion in this study. Next, the effec...
英字タイトル:
Effect on critical potentials for crevice corrosion initiation and repassivation of stainless steel by addition of inhibitive anion

Stress corrosion cracking (SCC) behavior of low-carbon stainless steel welds in high temperature water has been discussed with special attention on relation to the characteristics of microstructure. To investigate the effect of .-ferrite on SCC behavior, simulated heat-affected zone (partially melted zone) microstructure, where .-ferrite islands were widely distributed on grain boundary, was made by induction heating up to just below melting point. From the results of constant strain SCC test in high ...
英字タイトル:
Effect of .-ferrite on stress corrosion cracking behavior of low-carbon stainless steel weld in high temperature water

Abstract In operation of nuclear power plants (NPPs), it is required not only to preserve and improve the reliability and safety, but also to introduce more efficient and lower cost maintenance strategy simultaneously, due to the power trading deregulation in recent years. For this purpose, Condition Based maintenance (CBM), which has been extensively applied i n the nuclear power plant of U.S., is introduced as a maintenance method for rotating machines in Japanese nuclear power plant. TOSHIBA develops t...
英字タイトル:
Development and application of Monitoring and Diagnosis Techniques for Condition Based Maintenance in Nuclear Power Plant

As an advanced surveillance systems in nuclear power plants, a development of a radiation-resistant camera for visual surveillance even under severe accidents. From the result of a gamma irradiation test for a ready-made hi-vision camera, it was revealed that the increase of dark current in the image sensor was the main cause of degradation of image quality by irradiation. To suppress the dark current, three different types of CMOS image sensors with field plate structure and three transistors, photoga...
英字タイトル:
Gamma Irradiation Effects of Image Sensor for Radiation-resistant Camera

Domestic light water reactors are expected to restart sequentially after given permission in condition to meet the new regulatory requirements. Since several safety related systems were added to the plants through the process of the new regulatory requirements, the numbers of components to be inspected, which is already a large amount, will increase even more after the restart. Effective measure will be required to command maintenance activities by reasonably assigning limited resource. The authors hav...
英字タイトル:
Study on Fluid Leakage Behavior with Pipe Failure

As use of condition-based maintenance is allowed in the new regulatory inspection system employed in Japan's nuclear pow er plants in 2009, development of advanced diagnostic technologies for motor-operated valves (MOVs) is now required. This report discusses advanced technologies in valve-setup verification, valve performance evaluation, monitoring of valve/ac tuator conditions by performance diagnostic system and moreover detection of stem crack by ultrasonic diagnostic system....
英字タイトル:
Development of Advanced Diagnostic Technologies for Motor-operated Valves