The authors have proposed a novel eddy current testing(ECT) probe for thick-walled plates. A basic concept of the probe is that a couple of differential pick-up coils is arranged between two exciting coils carrying currents opposite to each other. This arrangement allows strong eddy currents opposite to scan surfaces and the weak decay of eddy currents in the thickness direction. In this study, the present probe was applied to ECT of welding area. For the purpose, experiments were carried out u...
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Weld Inspection Using Eddy Current Testing Probe for Thick-walled Plates

In this study, a new simulation method is developed for optimization of maintenance strategy in NPP as a multiple-objective optimization problem (MOP). The result of operation is evaluated as the average of the following three measures in 3 000trials: Cost of Electricity (COE) as economic risk, Frequency of unplanned shutdown as plant reliability, and Unavailability of Regular Service System (RSS) and Engineering Safety Features (ESF) as safety measures. The following maintena nce parameters are considered...
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Development of an evaluation method for optimization of maintenance strategy in commercial plant

Ultrasonic Integrity of anchor bolts of nuclear power plants is evaluated using test bolts with 1.6mm and 3.2 mm EDM notches. All notches are detected by the following three ultrasonic testing methods: longitudinal normal beam method, hased array (sectorial scanning) method and 3-dimensional phased array method. It is effective in detection of notches to use visual images obtained by ultrasonic phased array m ethods. Additionally, 3D phased array technique can provide fast und wide evaluation of integrity ...
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Ultrasonic integrity evaluation of Anchor Bolts of Nuclear Power Plants

The improvement of defect detection and sizing capabilities for nondestructive inspection technique has been required in order to ensure the reliable operation an d life extension of nuclear power plant. Phased array UT technique has superior capabilities for beam steering and focusing to objective regions, and real time B- scan imaging without mechanical scanning. Water gap phased array UT is capable to apply to inspection of welds of BWR internals such as shroud, shroud support, an d so on. Outline of TO...
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Application of Phased Array UT in BWR Internals

This study demonstrates the possibility of applying magnetic methods to pressure vessel surveillanc e at nuclear power plants. Magnetic hesteresis-minor-loop measurement and TEM observation were pref ormed on thermally aged Fe-1.0wt%Cu model alloys. Minor loop parameters decreased with increasing a ging time. The mechanism is discussed in terms of Cu precipitation behaviors of cold-rolled alloys....
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Relation between Precipitation Behaviors and Magnetic Properties in Cold-rolled FeCu Model Alloys

This study demonstrates the possibility of applying magnetic methods to pressure vessel surveillance at nuclea r power plants. Charpy impact test and magnetic hysteresis-loop measurement were preformed on Fe-1.0wt%Cu model alloys. The ductile-brittle transition temperature and the coercivity increased by cold-rolling and thermal agi ng. This correlation originates from an increase in the dislocation density and a formation of Cu precipitates....
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Magnetic Properties of FeCu Model Alloys Embrittled by Cold-rolling and Thermal Aging

Method of simultaneous chemical decontamination of stainless and carbon steel was developed to reduce dose exposure and to reduce radioactive waste during nuclear power plant decontamination. New chemical decontamination is conducted by using reducing agent containing oxalic acid and oxidizing agent containing permanganate ion repeatedly, then, conducted by using 2000 mg/L of malonic acid. It was confirmed that Co-60 deposited on test pieces, which had been prepared in high temperature high pressure lo...
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Development of Chemical Decontamination Technique for Decommissioning

The research and education program “Advanced Research and Education Program for Nuclear Decommissioning (ARED)” is proceeded in Tokyo Tech with views to sustainable development of human resources having advanced knowledge and experiences concerning decommissioning engineering, and development of advanced technologies to resolve a number of complicated challenges. This paper reports about the present status of the development of human resources. ...
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Human resource development for the research and education program in Tokyo Tech

This study developed an apparatus for the measurement of magnetic properties of tensile test specimen. Experimental results show that the difference shape of BH curves of the steels cold-rolled with different rolling reduction. The coercive force has good correlation with Ductile-brittle transition temperature and Vickers hardness of the specimen. This result indicate s the possibility of nondestructive evaluation for the mechanical properties of tensile test pieces using magnetic methods....
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NDE for Mechanical Properties of Ferromagnetic Steels using Magnetic Measurement Apparatus

To confirm soundness of the piping, the measurement using ultrasonic thickness meters is performed generally. Ho wever, this method cannot apply to pipes which are inaccessible by component such as supports or reinforcement p lates, because the method uses normal beam technique.This paper describes the medium range transmission techniqu es using angle beam probes which provide potential for measurement of wall thickness of inaccessible components....
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A Study of the Technique for Measurement of Wall Thickness underReinforcement Plates