A Proactive Materials Degradation Management (PMDM) project has been carried out at the Frontier Research Initiative (FRI), New Industry Creation Hatchery Center, Tohoku University for 5 years, as a part of a Nuclear Industries Safety Agency (NISA, now the Secretariat of the Nuclear Regulation Authority) project that was originally formed in 2007 to define an Aging Management Program that addresses unexpected structural material failures in Light Water Reactors (LWRs). Such a program required, therefor...
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Proactive Evaluation of Potential and Latent Materials Degradation Phenomena by PIRT

A Proactive Materials Degradation Management (PMDM) project has been carried out at the Fronti er Research Initiative (FRI), New Industry Creation Hatchery Center, Tohoku University for 5 ye ars, as a part of a Nuclear Industries Safety Agency (NISA) project that was originally formed in 2007 to define an Aging Management Program that addresses unexpected structural material fa ilures in Light Water Reactors (LWRs). Such a program required, therefore, the development of a life prediction capability for sp...
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Proactive Evaluation of Potential/Latent Degradation Phenomena for Light Water Reactor Structural Materials and System Safety

The predictive and preventive maintenance technologies are of increasingly importance for the long term operation (LTO) of Light Water Reactor (LWR) plants. In order f or the realization of LTO, it is essential to prevent the degradation phenomena from emergence using proper maintenance programs on foreseeing the phenomena and evalua ting their rates of development. In this paper, the proactive activities and the aging degradation phenomenon which were discussed in the Proactive Aging Management Gro up Mee...
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Proactive Materials Degradation Management and Development ofCondition Monitoring Technology

A Proactive Materials Degradation Management (PMDM) project has been carried out at the Frontier Research Initiative (FRI), New Industry Creation Hatchery Center, Tohoku University for 5 yea rs, as a part of a Nuclear Industries Safety Agency (NISA, now the Secretariat of the Nuclear Regulation Authority) project that was originally formed in 2007 to define an Aging Management P rogram that addresses unexpected structural material failures in Light Water Reactors (LWRs). Such a program required, therefore,...
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Proactive Evaluation of Potential and Latent Materials Degradation Phenomena

This study discusses the stress corrosion cracking (SCC) model which improves accuracy of depth sizing of SCCs with eddy current testing (ECT). For this purpose, the factors that influence ECT for SCCs are evaluated. In this study, the crack morpholog y and oxide fillings in SCCs are evaluated. As a first step, SCCs introduced at room temperature and fatigue cracks with oxide fillings are evaluated. To discuss the EC signals of SCCs, SCCs are artificially introduced and their ECT signals are obtain ed. The...
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Evaluation of the influence of crack branching structure and oxide fillings of stress corrosion cracking for depth sizing based on eddy current testing

The predictive and preventive maintenance technologies are of increasingly importance for the long term operation (LTO) of Light Water Reactor (LWR) plants. In order for the realization of LTO, it is essential to prevent the degradation phenomena from emergence using proper maintenance programs on foreseeing the phenomena and evaluating their rates of development. In this paper, the research subjects which should be required for the aging degradation phenomenon in LWR structural materials which were ...
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Proactive Material Degradation Research Subjects for LWR

Plastic strain as a function of the distance from a growing stress corrosion crack tip is quantitatively evaluated by three-dimensional ela stic-plastic finite element analysis. The strain distribution obtained by node-release simulation of crack growth follows the logarithmic l aw. The criteria for the transition from a stationary crack to a growing crack were investigated. Results suggested that the prediction of crack growth by the FRI model, in which oxidation kinetics and continuum mechanics has been...
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Finite Element Analysis of Plastic Strain Distribution at a Distance from Growing Stress Corrosion Crack in Light Water Reactor Environment

Surface oxide behavior on alloys in high temperature plays an important role in the stress corrosion clacking (SCC) mechanism according to plausibl e existing SCC models. In this investigation, roughness analysis of oxide/alloy interface on stainless steels after exposure in oxygenated high pur ity water under high stress conditions. A special emphasis was placed on how the oxidation penetration localized and went through the surface harde ned layer. It was pronounced that SCC initiation on hardened layer ...
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Oxidation Behavior of Austenitic Alloys under High Stress Condition in High Temperature Water-Effect of Surface Hardened Layer

In this study, nickel-chromium binary alloys are used on the oxidation test in high temperature water to reveal the effect of chromium conten t on the oxidation behavior under high stress condition. It was shown that the oxidation behavior was affected by chromium content, stress co ndition and surface hardened layer. The feature which induced the localization of oxidation behavior was found on the oxide film of low chro mium alloys. It was thought that the presence of threshold conditions about chromium c...
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The Oxidation Behavior of Austenitic Alloys under High Stress Condition in High Temperature Water-Effect of Chromium Content