Effect of thermal aging under BWR condition on material properties of casting s tainless steel were evaluated by such as Charpy impact test, using replaced BWR omponent material. Solution heat treatment was performed to the same material d the material properties were obtained. Comparing each material test results , impact value of thermal aging material was lower than solution heat treatment material. By the results, thermal aging effect on material properties under BW condition was confirmed. The materi...
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Thermal Aging Evaluation of Casting Stainless Steel under BWR Environment

In order to enhance maintenance effectiveness by using risk information, Burden to Importance Ratio (BIR) is used in this study. The BIR is a measure representing the extent of maintenance burden (resources or activities) imposed on a System, Structure, or Component (SSC) in comparison with the importance value of the SSC. Therefore maintenance burden imposed on the SSC having high BIR can be reduced to the extent of its importance. The evaluation of BIR were applied to 22 valves selected among 516 Motor O...
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Maintenance Strategy: Burden to Importance Approaches

It is necessary to confirm the validity of crack detection by ultrasonic testing through a stainless steel weld in order to reduce a range impossible of detection by ultrasonic testing. Therefore, we performed ultrasonic testing used to specimen with various weld joint types for providing the basic data (probability and measurement accuracy) of ultrasonic testing methods to reflect on JEAC4207.As the result, ultrasonic testing used to longitudinal wave angle beam technique(including phased array techni...
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Ultrasonic testing through stainless steel welds

In 1999, NEL developed the transmit-receive type ECT array probe for steam generator (SG) tubing, called “X-probe”, in cooperation with foreign firms. Recently NEL has developed the advanced ECT array probe, “Smart Array Probe”, characterized with a significantly improved resolution for circumferential cracks. The doubled channels in the circumferential mode have greatly improved the circumferential resolution of Smart Array Probe. With all the circumferential mode channels on the same circle, there i...
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Development and Field Practical Performance of Smart Array Probe

0.本原稿に関して 1 利用が進められてきた。しかしながら、原子力発電に関 しては、その重要性はながらく 3 認識されているものの、 この度、タイ国原子力関係者の御厚意により、タイ国 における原子力事情に関する記事を日本保全学会に御寄 稿頂いた。英文で御作成いただいた原文は既に日本保全 学会英文誌である E-Journal of Advanced Maintenance Vol. 8-1 の GA20 として発表されているが、本稿は保全学会 会員の利便性向上のために原文を和文に翻訳したもので ある。翻訳は......

When a heat transfer tube wall in a steam generator of a sodium-cooled fast reactor fails, high-pressure steam leaks into low-pressure liquid sodium side. Then the high-temperature and highly corrosive reaction jet causes secondary failures of neighboring heat transfer tubes. The objective of the present study is to develop an experimental method to obtain data that is necessary to validate and improve a safety evaluation code on the sodium?water reaction. In the present paper, the methods of sodium?...
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Development of Erosion Test Methods on Underexpanded Inert-Gas Impinging Jets Injected in Liquid Sodium

An in-vessel repairing machine for Fast Breeder Reactor (FBR) needs to work under liquid sodium environment. W e have been worked the development of a repairing machine based on Friction Stir Welding (FSW) method. The expe riment of repairing artificial crack in liquid sodium was successful by prototype FSW-repairing machine. In th is report, we also introduce our studies on the particular problems of FSW-repairing such as burr and end hole....
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Development of a repairing machine based on Friction Stir Welding (FSW) for the sodium coolant Fast Breeder Reactor

This paper aims at a detecting corrosion on the back surface of a ick steel plate. Our proposed technique is characterized by using pulsed eddy current testing with DC magnetization. The thick steel plate is magnetized by DC Magnetizer. Therefore the magnetization g erates the magnetic flux in the plate. The permeability of the plat e changes with the corrosion. Changes in the permeability of the pl ate are detected by pulsed eddy current testing. The corrosion on e back surface of the plate was detecte...
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Corrosion Detection on Steel by using Pulsed Eddy Current Testing

In the nuclear power plant, ultrasonic testing is performed as an in-service inspection of the reactor vessel (RV-ISI) according to JSME code. MHI is using the advanced UT machine (A-UT machine) system to RV-ISI under the high radiatio n condition. RV-ISI is one of the critical path in ISI schedule, so it is strongly required to reduce the inspection t ime of RV-ISI. In this report, the counter measure to reduce RV-ISI period by using the phased array UT is described....
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Application of Phased Array UT to RV Safe End Welds Inspection

Phased array ultrasonic testing (PAUT) has performed an important role for plant maintenances. However, many parts of cast austenitic stainless steels are difficult to be inspected by UT owing to their noises from large grains. We have been noticing that depending on the PAUT conditions, (e.g. incident angles and focal depths), the tendency of echoes from defects are different from that of grain noises. Thus we have developed new PAUT system which can analyze the tendency of echoes from comprehensive PA...
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Sizing Accuracy Improvement of Defects in Cast Austenitic Stainless Steel Using Post Processing Phased Array UT