In order to optimize plant maintenance, it is important to diagnose an integrity of equipment and use it for maintenance planning. We developed the integrity diagnostic method combining statistical model and physical model. The statistical model detects abnormality from process data and estimates abnormal parameters. The physical model estimates failure equipment from abnormal parameters. As a result of test data evaluation, it was confirmed that the proposed method can detect anomalies and estimate faulure...
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Development of integrity diagnosis technique for plant equipment

Eddy current testing (ECT) with multi coil probe has been developing for enhancing surface inspection. Defect extraction method based on phase angle of lissajous waveform was effective to identify between defects and noises. This paper describes applicability of crack extraction method for magnetic material. The criteria based on feature of phase angle on magnetic material could extract defects to separate from noises like liftoff using experiment and simulation....
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Crack Extraction technique for Magnetic Materials by Eddy Current Testing with Multi Coil Probe

Rapid growth in renewable energy (RE) is essential for achieving carbon neutrality. However, the resilience of bulk power system is decreased due to the installation of large amount of RE, and there is a possibility that the transmission accident causes disasters such as a large-scale blackout. As a result, the amount of RE is limited in order not to cause such disasters. In such a situation, nuclear power plants will be useful items to reinforce the resilience of bulk power system. In this research, we eva...
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Study of utilization of nuclear power plants for increasement of renewable energy installation

A steam tube-leak is a very critical issue in industrial plants because the steam jet from the damaged point immediately causes damage to the surrounding tubes. Therefore, an early detection of the tube leak is important to reduce the maintenance cost and the outage time. In this study, we conducted a detection test of the steam tube leak using acceleration sensors; they are expected to catch a radial tube-vibration induced by acoustic propagation. Through the test, we found that the sensor detected a radia...
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Development of detection method for a steam tube-leak in a boiler using acceleration sensors

We have developed a method using mobile devices to identify plant equipments, especially for repair. After the accident of March 2011 at Fukushima, many nuclear plant operations have still been downed and it leads to the insufficiency of mature experience. The work assistance with IT is getting required under this situation. The IT device can provide appropriate information, e.g. operating instructions, to workers depending on the situation. In order to recognize the current location the arrangement informa...
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Development of Identification Method of Equipments for Repair in Nuclear Plant

High reliability is essential to wireless communication system in nuclear power plants. Since there are many obstacles made of metals in nuclear power plants, most of transceivers are located in the non-line-of-sight environment. The non-line-of-sight environment makes highly-reliable communication difficult. To solve this issue, we have proposed the rotating polarization wave (RPW) communication for instrument control. In this report, the effectiveness of the RPW is evaluated in the actual factory and the ...
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Application of wireless technology to nuclear power plants

Visual testing with underwater camera is performed for the inspection of structures in RPV. It has the case to be difficult to identify whether the indication is the crack or the imitated shape like scratch. In this case, the judgment needs much time. In this issue, the distinction method by surface ultrasonic wave emitted on the structure have been developed. This method could perform the in-situ judgment between the crack and the imitated shape by ultrasonic imaging technique with array probe....
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Inspection technique for surface cracking by ultrasonic wave to optimize in-vessel inspection

We have developed a method using mobile devices to recognize the current location in a plant where radio/marker such as GPS is not available. Depending on the site situation the device can provide appropriate information, e.g. operating instructions, to workers. In order to recognize the current location, we identify surrounding plant equipment and register its location as the current one. The mobile device with 3-D depth acquisition can extract a plurality of pipes, collate its feature amount with the DB, ...
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Development of Location Detection Method in Plant Independent of Wireless Signal and Position Marker Identification

A pipe-wall thinning measurement is required to ensure integrity of a piping system in a power plant. Aiming to reduce the inspection time of the pipe-wall thinning measurement, we have been developing an innovative measurement technology which enables the pipe-wall thinning inspection without removing the insulation, based on the non-contact ultrasonic sensor proposed by University of Bristol. To apply this technology to the actual plant inspection, the sensor durability needs to be confirmed. In this stud...
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Investigation into applicability of a non-contact ultrasonic sensor to pipe-wall thinning inspection of power plants

A pipe-wall thinning measurement is required to ensure integrity of a piping system in a power plant. Aiming to reduce the inspection time of the pipe-wall thinning measurement, we have been developing an innovative measurement technology which enables the pipe-wall thinning inspection without removing the insulation, based on the non-contact ultrasonic sensor. To confirm applicability of this sensor to the pipe-wall thinning inspection in actual plants, we performed the thickness measurement tests by using...
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Applicability confirmation of the non-contact ultrasonic sensor by the pipe simulating actual plant conditions