Post-installed adhesive anchor bolts are commonly used on all types projects, from standard buildings to bridges and nuclear power plants. They are exposed to varying and diverse environmental conditions which are significant successfully to make connections to concrete structures for many years. In order to maintain the safety and reliability of concrete structures such as buildings or bridges on higher level over a long period time, we developed a new non-destructive inspection system of adhesive an...
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Development of non-destructive inspection technique for adhesive anchor bolts using AE sensor (1) An experimental approach

We have developed a non-destructive inspection technique using the AE (acoustic em sion) sensor. It is intended to be non-destructive evaluation in soundness of the adhesion anchor is installed in a nuclear power plant. We analyzed the Eigen frequ cy of the adhesive anchor measured by the AE sensor using a finite element method . Results of the analysis of the Eigen frequency, the change in Eigen frequency cou ld be confirmed between the adhesive anchor which simulates the Peeling of the resi n by aging de...
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Development of non-destructive inspection technique for adhesive anchor bolts using AE sensor (2) Theoretical examination

Test method has not been maintained for late-expansive aggregates (which cause cracks in concrete after 10 years or more), in addition to the early-expansive aggregates which have been considered as the major cause of ASR in Japan. In order to confirm the effectiveness of the aggregate test method of JNES flow (the method mainly composed of international methods RILEM AAR - 3 and AAR - 4) and to prepare applicable aggregate test method, we conducted comparative tests using domestic and foreign aggregate...
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Evaluation on Aggregate Testing Method for ASR Potential Evaluation

Time-of-flight ultrasonic measurements were conducted on a thick hexagonal block of 304 type austenitic stainless steel, which was used as a reflector in EBR-II and was irradiated to 23 ~ 33 dpa at 37 0 ~ 410 ?C. The results of ultrasonic-implied void swelling and carbide-induced densification were compared with those obtained by immersion density measurements and transmission electron microscope o bservations. The three types of measurements were found to agree rather well with each other, and the variati...
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Development of a non-destructive inspection technique for detecting irradiation-induced microstructural changes of austenitic stainless steels by use of an EBR-II reflector

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

Recently, many concrete structures such as bridge piers of the highway, damaged by Alkali Silica Reaction (ASR) have been observed in Japan. From this background, based on the latest knowledge of domestic and international, the ASR diagnostic method that emphasizes the petrological examination after the core sampling was proposed on Japan Nuclear Energy Safety Organization (JNES) report. In this research, in order to confirm the effectiveness of ASR diagnostic method for concrete structures proposed in JNES...
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Evaluation on ASR diagnostic method for concrete structures

In Japan, the decommissioning of a number of nuclear power plant is planned or underway. In order to implement the decommissioning safely and rationally, not only the nuclear industry but also a wide range of stakeholders, such as the local governments where the plants are located, must cooperate to solve the issues that are barriers to the safe and rational implementation of the decommissioning. For this background, Mitsubishi Research Institute carried out to identify the cross-industry issues of decommis...
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Issues and Solution for Safe and Rational Decommissioning of Nuclear Power Plants

Regarding the nuclear regulatory inspection system that came into effect in April 2020, the authors conducted a questionnaire and interview surveys with NRA staff involved in inspection work for the purpose of improving inspection capability and efficient operation of inspections. As a result of the investigation, it became clear that the inspector's conceptual understanding of nuclear regulatory inspection has permeated. In particular, it was confirmed that the understanding of the four concepts of nuclear...
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Research on the efficient operation of nuclear regulatory inspections and the improvement of inspectors' abilities Part1

Regarding the nuclear regulatory inspection system that came into effect in April 2020, we conducted a questionnaire survey and interview survey with NRA staff involved in inspection activities for the purpose of improving inspection competence and efficient operation of inspection system. As a result of the survey, it became clear that the inspectors' understanding of the concept of nuclear regulatory inspection system was pervasive, while improvements related to the improvement of the inspector's competen...
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Research on the efficient operation of nuclear regulatory inspection system and inspectors' capabilities Part 2

Preparations related to details of forming the inspection system and trials Phase1 and Phase 2 will be implemented for the full startup in 2020. As the problems obtained in the trial operation, the lack of understanding for the risk-informed / performance-based inspection and the screening of the findings became apparent. Therefore, in this paper, with the aim of contributing to the development of the market price for evaluation, we conducted a trial of Significance Determination Process (SDP) using the US ...
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Application of guide (trial operation version) about Significance Determination Process (SDP)for inspection findings about fire protection in United States