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 ...
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Effect of .-ferrite on stress corrosion cracking behavior of low-carbon stainless steel weld in high temperature water

When crevice corrosion occurs in Cl- containing solutions, Cl- concentration in the crevice increases by a few orders of magnitude due t o potential gradient. This is one of the reasons why localized corrosion takes place in a crevice. If there are non-aggressive anions ( such as MoO42-) coexist in the bulk with Cl-,it is expected that the non-aggressive anions migrate into the crevice competitively with C l- and it helps to improve the crevice environment. The purpose of this study is to investigate the e...
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Effects of non-aggressive anions as a mitigation measure to crevice corrosion in a chloride containing environment

Abstract: Crevice corrosion was occurred at the adsorption tower with silver impregnated carbon of Advanced Liquid Processing System (ALPS). The influence of silver impregnated activated carbon on crevice corrosion of 316L stainless steel was investigated by corrosion test and electrochemical measurement. Crevice corrosion was observed on the specimen tested with the activated carbon. On the other hand, no corrosion was observed on that without the activated carbon in both pH7.4 and pH12 solution (art...
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Influence of activated carbon on crevice corrosion in adsorption tower of Advanced Liquid Processing System (ALPS)

To ensure integrity of structures and components in nuclear power plants, the demand has been increased for establishing nondestructive method for detection of pre-existing plastic strain. In this study, potentiostatic etching method is applied to detect and quantitatively measure plastic strain imposed to austenitic stainless steels by tensile straining. After potentiostatic etching (1N HNO3, -600mVSCE, 20min), twin lines and slip lines appear as etched lines on the surface of specimen because of the...
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Inspection of Plastic Deformation Mechanism in Austenitic Stainless Steel by potentiostatic etching Detection Method

To ensure integrity of structures and components in nuclear power plants, the demand has been increased for establishing nondestructive method for detection of pre-existing plastic strain. In this study, potentiostatic etch ing method is applied to detect and quantitatively measure plastic strain imposed to austenitic stainless steels by tensile straining. After potentiostatic etching (1N HNO3, -600mVsce, 20min), twin lines and slip lines appe ar as etched lines on the surface of specimen because of the pr...
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Inspection of Temperature / Steel Composition Dependency of Plastic Deformation Mechanismin Austenitic Stainless Steel by potentiostatic etching Detection Method.

To ensure integrity of structures and components in nuclear power plants, the demand has been increased for establishing nondestructive method for detection of pre-existing plastic strain. In this study, we examined applicability of potentiostatic etching method, which developed in our past paper, for actual austenitic steel components. On etching condition, solution temperature is one of the critical parameter. Thus this method should be conducted at a constant temperature between 30°C -40°C. Using r...
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Applicability of potentiostatic etching method for evaluation of plastic strain in austenitic stainless steel structure

To ensure integrity of the structure such as nuclear power plant, the demand has been increased for establishing nondestructive method for detection of pre-existing plastic st rain. In this study, potentiostatic etching method is applied to detect and measure plastic strain imposed to austenitic stainless steel by tensile straining. After potensiost atic etching (1N HNO3, -600mVsce, 20min), the twin band appears as etched line on the surface of specimens. The etched twin band is observed by optical microsc...
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Potentiostatic Etching Method for Detection of Pre-existing Plastic Strainin Austenitic Stainless Steel

SCC behavior near the fusion line of 316L SS welds in high SCC behavior near the fusion line of 316L SS welds in high temperature water has been investigated with special attention on relation to the characteristics of microstructure. Island-type S-ferrite has been distributed on grain boundary, namely along the potential crack path, in partially melted zone of 316L SS weld samples. Most of crack tips have been located on d-ferrite in partially melted zone of both weld samples. Cr2O3 which makes low oxida...
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SCC Retardation Mechanism near Fusion Boundary in 316L SS Welds from Microstructure Point of View

Since the Great Eastern Japan Earthquake, the most important issue that we have to face in reconstruction and local renewal is the safe decommissioning of Tokyo Electric Power Company's Fukushima Daiichi nuclear power plant reactors. Tohoku University is one of the first institutions to formulate diverse recovery projects in order to support the resolution of various difficulties that materialized after the disaster. One of these pillar projects that the university has undertaken is the Reactor Decommi...
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Current status in Tohoku University fundamental research on nuclear decommissioning and human resources development project

1.はじめに 平成 23 年に発生した東京電力株式会社福島第一原子 力発電所の事故から約 6 年が経過した現在、今後 30 年 以上の長期に亘ることが予想されている同発電所 1 ~ 4 号機の廃止措置は、国家の威信を賭けた大事業として政 府を筆頭とするオールジャパン体制で中長期ロードマッ プ [1] に基づき、懸命な努力がなされている。この世界 にも前例の無い大きな課題(技術的挑戦)を解決し、廃 止措置を安全かつ着実に進めていくには、我が国の関連 組織の総力を挙げた取組みが必要となっている。 このような中......