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...
英字タイトル:
Development of non-destructive inspection technique for microstructures under irradiation using austenitic stainless steel blocks

Chemical anchor is a glue-type anchor and it has been used to fix components to concrete structures in nuclear power plant. Decrease in adhesive power of glue is supposed to occur due to a construction failure or a long term use under various environments in actual plant. We have begun some internal researches and selected Acoustic Emission method (AE) as a non- destructive inspection tool among some methods. The AE method was selected by a comparison of some methods, and then the methodology was brushed...
英字タイトル:
Development of inspection method for chemical anchor

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. ...
英字タイトル:
Development of nondestructive inspection system for soundness diagnosis of concrete structure

We have developed a simple diagnosis method using an AE (Acoustic Emission) sensor applicable to chemical anchors in nuclear power plants. With purpose of its application to the field, waveform database to identify improper installation or ageing was constructed. We also confirmed applicability of the diagnosis method to other types of anchor (e.g. anchor bolts, mechanical anchors). Details of development chronology are described in this paper. . ...
英字タイトル:
Developing a simplified diagnosis method for anchor bolts

The recent situation of nuclear power generation gradually requires not only the economic viewpoint but also even greater efforts in accurate evaluations on safety and availability issues. Accordingly, assessments on the integrity of structural components are critical both now and in the future. Structural materials which suffer from age-related degradations especially should have methods to evaluate degradations due to changes in material properties. It is clear that conventionally used extrapolations of...
英字タイトル:
Integration of modeling, database and inspection technique for the prediction of the material behavior under irradiation

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...
英字タイトル:
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...
英字タイトル:
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...
英字タイトル:
Effects of Human Error and its Reduction Analyzed by Dr. Mainte, Integrated Simulator of Maintenance Optimization of LWRs 2