Ultrasonic testing was conducted on two long (218-245 mm), Type 304 stainless steel blocks with a hexagonal cross-section (50 mm face-to-face thickness) that were removed from the reflector region of the decommissioned EBR-II reactor. Ultrasonic testing is one of the widely used non-destructive testing techniques for material characterization. Ultrasonic waves, currently used as a non-destructive technique to detect cracks, change as a result of interacting with microstructural components and can be em...
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Development of non-destructive inspection technique for microstructures under irradiation using austenitic stainless steel blocks

Abstract We developed a hammering sound inspecting system using AE sensor with objectivity and recordability and confirmed that it is possible to grasp the state of concrete (internal cavity and surface peeling) from the vibration analysis result obtained , And confirmed the usefulness of concrete health diagnosis using this system. ...
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Development of nondestructive inspection system for soundness diagnosis of concrete structure

In the future social infrastructure diagnosis for concrete structures such as bridges, tunnels and buildings, it is expected that the digital hammering inspection, which is objective, quantitative, and recordable to the conventional hammering inspection, will play a significant role. However, since there are a wide variety of defects due to poor construction and age-related deteriorations in the concrete structures, they have not been quantitatively identified enough by the digital hammering inspection in t...
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A study on internal structure diagnosis of concrete structures incorporated with digital hammering inspection, AI and simulation technologies (1) Direct problem analysis using AI

One of the most common inspection methods for concrete structures is hammering inspection. While this method makes it possible to quickly inspect a vast number of inspection targets, it has the problem of lacking objectivity of judgment results and recordability. In this study, we aimed to develop a technology to quantitatively diagnose the internal structure of concrete structures by digital hammering inspection. The approach of the research was to build an AI trained by CNN with a database that relates th...
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A study on internal structure diagnosis of concrete structures incorporated with digital hammering inspection, AI and simulation technologies (2) Inverse problem analysis using AI

Non-destructive testing technique was developed for embedded plates using phased-array ultrasonic testing (PAUT). The bending angle of their studs was quantitatively estimated by using the sector scan of PAUT, which is usually difficult by using conventional UT. In addition, this technique is capable of visualizing the weld shape of the stud by using the linear scan of PAUT. Mockup tests were carried out in order to verify the effectiveness of the technique....
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Development of Testing Technique on Embedded Plates Using Phased-Array Ultrasonic Testing

Abstract As an attempt to apply AI in the field of maintenance, we have been studying "forward analysis", "inverse analysis" and "future prediction". As for the “forward analysis”, as a theoretical verification of the digital hammering inspection results using the AE sensor, the natural frequency obtained in the hammering inspection is confirmed by “time history response analysis”. Because there is a combination of the shape, material properties to be inspected, measuring position of natural frequency, etc....
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Attempts of forward analysis, reverse analysis and future prediction using AI in the field of maintenance

Non-destructive evaluation technique was developed for embedded hardware using hammering inspection with AE (Acoustic Emission) sensor. The integrity of the studs welded on the hardware is judged from both the vibration duration of the embedded hardware and the frequency analysis of the vibration signal. The hammering inspection has been applied to the reprocessing plant of JNFL (Japan Nuclear Fuel Limited) for three years and we are now planning the improvement of the efficiency of the inspection in variou...
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Improvement of the efficiency of hammering inspection using AE sensor for embedded hardware

Special attentions have been increasingly paid for the diagnosis of social infrastructures after the collapse of ceiling of Sasago tunnel of Chuo Expressway. It is reported that the main cause was due to the age-related degradation of chemical anchors. Chemical anchors are also frequently used in nuclear power stations. Here we have been trying to apply PFM (Probabilistic Fracture Mechanics) to the diagnosis of social infrastructures using Dr. Mainte, an integrated simulator to optimize maintenance activi...
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A Study of Application of PFM (Probabilistic Fracture Mechanics) to the Diagnosis of Social Infrastructures ]

Development of methods of detecting degradation of irradiated reactor structural materials is required for successful operation of nuclear power plants. Ultrasonic waves, currently used as a non-destructive technique to detect cracks, change as a result of interacting with microstructural components and can be employed to measure radiation-induced changes in microstructure. Bulk-averaged measurements of microstructural changes can be determined usi ng ultrasonic velocity, attenuation and back-wall echo, wh...
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Development of non-destructive inspection technique for microstructuresunder irradiation using decommissioned materials(1) An experimental approach

Abstract It is desired to develop an ultrasonic inspection technique non-destructively measuring various forms of irradiation-induced degradation in structural components of nuclear reactors. In order to evaluate the depth distributions of ir radiation-induced microstructural changes, we have developed a numerical simulation model of ultrasonic wave changes caused by microstructural changes in austenitic stainless steel based on the developed theory of ultrasonic wave propagation for comparison with experi...
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Development of non-destructive inspection technique for microstructures under irradiation using decommissioned materials(2) An theoretical approach