The nuclear reactor regulation law was amended three years ago (2012). In this amendment, the operation period of the commercial nuclear power plants in Japan was limited to 40 years. This limit may produce various problems in plant life management. So this paper proposes several recommendations for improvement. ...
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Recommendations related to the Problem of Limiting the Life of Japanese Nuclear Plants to 40 Years

1. はじめに 我国の原子力発電所の運転期間 40 年制限に関する規制上の課題と提言 東北大学流体科学研究所 高木 敏行 Toshiyuki TAKAGI 東北大学大学院工学研究科 青木 孝行 Takayuki AOKI 2. プラント運転期間と寿命に関する考え方 福島第一原子力発電所事故を踏まえて平成 24 年に改正 された原子炉等規制法において、 我国で原子力発電所が 運転できる期間は 40 年間と規定された。 また、 原子力規 制委員会の認可を受ければ、 その期間を 1 回に限り 20 年 を超えな......

Abstract This article outlines the development of structure adaptive nondestructive evaluation technology using eddy currents. A couple of eddy current testin g (ECT) systems are utilized. One performs high spatial resolution with multi-coil array probes, enabling us to identify crack positions by means of image pr ocessing. The other employs double excitation coil probes to detect relatively deep cracks from the scanning surface, showing detectability more than 5mm in d epth. Profiling/sizing cracks estim...
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Development of Structure Adaptive Nondestructive Evaluation Technology using Eddy Currents

A method of eddy current testing (ECT) data mapping for surface breaking evaluation is studied. The multicoil ECT probe utilized in this paper consists of Trans mit-Receive (TR) type sensors as array elements to obtain the information on crack directions. Switching two directional scans, U- and T- modes, gives two-dimen sional vector mapping as ECT images. The ECT signals of the TR type sensor also give the information on crack directions from their variation displayed on the c omplex number plane. Extract...
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Surface Flaw Evaluation by Vectorized Eddy Current Testing Image

This paper proposes a methodology of lift-off measurement using optical system embedded in Eddy Current Testing (ECT) system. Firstly, the influence of lift-off on ECT signal was evaluated. Secondly, both ECT signal with lift-off shifting and the lift-off signal were acquired by means of an ECT probe with an optical displacement sensor. Then two cases of the crack shapes reconstructions were carried out using inverse analysis code. One was computed with taking the measured lift-off into account and t...
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Methodology of Lift-off Measurement Using Optical System in Eddy Current Testing

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

It is well-known that Cr depletion in Inconel 600 changes its magnetic properties, and there is a possibility that electromagnetic nondestructive evaluation has capability of evaluating sensitization of Inconel 600 quantitatively. In this study, we discuss application of eddy current method to the evaluation. For the purpose, magnetic proper ties of Inconel 600 with different aging times were evaluated by B-H loop analyzer. Results show that some magnetic parameters correlate well with Cr depletion. Focus...
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Evaluation of Sensitization of Inconel 600 Using Eddy Current Method

This study aims at proposing a novel magnetic testing method, eddy current magnetic signature method for evaluation of residual strain in carbon steels. This method characterize the eddy current magnetic signatures that is eddy current signals in an impedance plain during magnetization process. In order to discuss the feasibility of this method, eddy current magnetic signatures of a set of tensile test specimens are investigated. The relationship between eddy current signature and plastic deformation is di...
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Nondestructive Evaluation of Residual Strain in Carbon Steels by Eddy Current Magnetic Signature Method

This paper discusses the possibility of in-situ quantitative evaluation of crack propagation using Eddy Current Monitoring (ECM) system in a Boiling Water Reactor (BWR) environment. For the purpose, ECM experiment was conducted at a System Safety Benchmark Facility (SSBF). The target for the monitoring was a large-scale pipe specimen made of austenitic stainless steels 304L, 316L, and carbon steel STS410, connected by weld joints of nickel based alloy 182 within the SSBF. Slits were prepared at the H...
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Quantitative Monitoring of Crack Propagation in High Temperature Environment Using Eddy Current Testing

本特集記事は講演を文章にしていただき、原子力保全のDX化の解説記事として保全学誌2023年7月号および10月号に掲載するものである。第22回保全セミナーに参加することができなかった会員の皆様や、当日参加したが内容を再確認されたい会員の方々に興味を持っていただけるものと考えている。...