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

保全分野では点検、検査、モニタリングによる有用なBIG DATAが存在する。また、複雑な非線形シミュレーションが必要であり、ヒューマンエラー低減、働き方改革では非線形な人間系の分析が必要となる。ここでは保全分野へのAI適用性を考察する。...

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...
英字タイトル:
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

Dr. Mainte, an integrated simulator for maintenance optimization of LWRs (Light Water Reactors) has been developed based on PFM (Probabilistic Fracture Mechanics) analyses in terms of safety, availability and economic efficiency, environmental impact and social acceptance. For the further improvement of maintenance activities, the importance of reducing human errors is often pointed out. Human errors are well recognized to be affected by mental stress conditions. Due to the amendment of Industrial Safe...
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Effects of Human Error and its Reduction Analyzed by Dr. Mainte, Integrated Simulator of Maintenance Optimization of LWRs 2

Dr. Mainte, an integrated simulator for maintenance optimization of LWRs (Light Water Reactors) has been developed based on PFM (Probabilistic Fracture Mechanics) analyses. The concept of the simulator is to provide a decision-making system to optimize maintenance activities for representative components and piping systems in nuclear power plants totally and quantitatively in terms of safety, availability and economic efficiency, environmental impact and social acceptance. For the further improvement ...
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Effects of Human Error and its Reduction Analyzed by Dr. Mainte, Integrated Simulator of Maintenance Optimization of LWRs

As an attempt to apply AI in the field of maintenance, we have been developing a diagnosis method of check valves to detect the internal leakage and the signal before the leakage based on the signal analysis of their vibration measurements by a portable system with AE (Acoustic Emission) sensors. CNN (Convolutional Neural Network) was applied to the measured raw waveform and its frequency distribution corresponding to the leakage rates in order to classify the leakage rates. The leakage rate was gradually i...
英字タイトル:
Study on the Application of AI to Check Valve Diagnosis

We have developed Check Valve Inspection System using acoustic emission sensor and ultrasonic sensor, to examine degradation and detailed motion (Full open, Tapping, Oscillation, etc.) of the swing check valve. This inspection system was applied check valves in the seawater system line of domestic nuclear power plants. The examination was carried out before and after replacing the check valve. Comparing the results of the inspection system and the results of overhaul, effectiveness of this system has b...
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Development of check valve inspection technique

The purpose of this research is development of tension measurement method using hammering sound diagnosis technology using Acoustic Emission sensor. Experiments using actual size anchors and FEM analysis quantitatively evaluated the relationship between the vibration characteristics of the anchor head and the tension introduced into the anchor. As a result, it is possible to evaluate the anchor tension based on the natural vibration characteristics of the anchor head. ...
英字タイトル:
Evaluation of tension of ground anchor by hammering test using AE sensor Vol.1