It becomes to be recognized that material hardening can enhances the SCC growth rate considerably. In SCC growth evaluation in PLR weld joints of BWR, it is confirmed that the material hardening due to thermal shrinkage during welding affects SCC growth rate. In order to ev aluate the degree of hardening of PLR weld joints, Vickers hardness distributions have been measured on some actual pipe joints. In latest researches, however, another parameters such as yield strength and plastic strain are considered ...

It becomes to be recognized that material hardening can enhances the SCC growth rate considerably. In SCC growth evaluation in PLR weld joints of BWR, it is confirmed that the material hardening due to thermal shrinkage during welding affects SCC growth rate. In order to ev aluate the degree of hardening of PLR weld joints, Vickers hardness distributions have been measured on some actual pipe joints. In latest researches, however, another parameters such as yield strength and plastic strain are considered ...

Pipe wall thickness measurements by ultrasonic (UT) sensors can be difficult as the roughness of the inner surface develops by certain corrosion mechanisms. In this study, the applicability of flexible UT sensors with single and dual element transducer were evaluated using carbon steel plates with localized sand erosion that simulates pipe walls with rough inner surface. While the thickness measurement by single transducer sensors with B-B method failed after certain amount of erosion, the newly develop...
英字タイトル:
Evaluation of online thickness monitoring system for wall thinning by erosion.

背景および概要近年、国内の沸騰水型原子力発電プラント（BWR）炉心シュラウドや再循環系（PLR）配管等の低炭素ステンレス鋼製機器の溶接部で、多数の応力腐食割れ（Stress Corrosion Cracking: 以下、SCC） が確認された［1］。2003年10月には健全性評価制度が法制化され、SCC 等の欠陥が発生した機器についても、機械学会維持規格［2］に基づく技術的評価により健全性が確認されれば継続運転が可能となった。ただし、PLR配管のSCCに ついては、従来の超音波探傷検査（UT）では十分な精......

Access methods to the investigation point are limited in the investigation via small diameter opening or in severe environment. In this study, a carbon fiber reinforced plastic (CFRP)-rod access mechanism is developed. The deflection of the rod is controlled utilizing the lightweight, high strength and rigidity-designable properties of CFRP so that the tip of the rod inserted from a small-diameter opening reaches to the investigation site without any active mechanism. ...
英字タイトル:
Development of deflection-controlled CFRP inspection rod inserted from small openings

1. 緒 言電気事業法の改正により、2003年10月より原子力発電設備の維持基準が導入された。これに伴い発電事業者は法定の「定期事業者検査」を実施すること、また、き裂等の欠陥を発見した場合、当該機器の運転を継続するためには、欠陥の進展を予測し、機器の構造健全性を確認することが義務付けられた［1］。本稿では、近年、国内の沸騰水型原子力発電プラント（以下、BWR）の低炭素ステンレス鋼製炉心シュラウドで多くの事例が確認された応力腐食割れ（以下、SCC）を例に、機械学会維持基準［2］に基づく構造健全性評価の考え方......

Experimental evaluations were conducted to verify whether the significant SCC growth is possible or not in Ni base weld metals during cold shutdown period of light-water reactors. As a result, it has been confirmed that the SCC growth rate decreases with decreasing temperature and the growth rate below 100 °C is low enough to be neglected in plant evaluations. ...
英字タイトル:
Evaluation of SCC growth susceptibility of Ni base alloy weld metal during the shutdown period of Light-water reactors

L-grade stainless steels such as 316NG, SUS316L and SUS304L are used for the BWR reactor internals and re-circulation pipes. The L-grade stainless steels are known as typical SCC resistant materials because they are hardly thermally sensitized in usual welding process due to its lower carbon contents. However SCC of the L-grade material components were recently reported. This paper summarizes the recent knowledge and reports about the SCC behavior of L-grade stainless steels and its mitigation and ...
英字タイトル:
Stress corrosion cracking of L-grade stainless steel in high temperture water