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	A New Mechanical Condition-based Maintenance Technology Using Instrumented Indentation Technique
	Survey robots for Fukushima Daiichi Nuclear Power Plant

Vol.12 No.1AA SP23 (AA172-173)-AA174 NT97

Academic Articles

Vol. 12 No. 1 (2020) p.1 - p.13

Special Issue 23

The 4th International Conference on Maintenance Science and Technology (ICMST-Tohoku 2018)

Preface

ICMST-Tohoku 2018, the 4th International Conference on Maintenance Science and Technology was held at "Sakura Hall" on Tohoku University Katahira campus in Sendai, Miyagi, Japan between the 23rd and the 26th of October 2018. ICMST-Tohoku 2018 was the latest of a highly successful series which started in Tokyo (Japan, 2012) and continued in Kobe (Japan, 2014) and Shenzhen (China, 2016).

Maintenance is still an uncharted area for humankind, and we have to study energetically. After the Fukushima accident, the credibility of nuclear safety has been an important issue worldwide. The conference continues to be the key forum for scientists and engineers interested in maintenance science and technology for nuclear power plants.

ICMST-Tohoku 2018 featured 101 presentations given to 209 attendees from nine countries. Publication in these special issues was voluntary and after peer review. This could not have been achieved without the very significant efforts of both reviewers and authors. Without this work, these special issues could not exist, and I would like to thanks them on behalf of the Publication Committee. I hope that all those who attended would share my opinion that ICMST-Tohoku 2018 was a vibrant, exciting and productive conference and that these special issues give some sense of the success of ICMST-Tohoku 2018 to the reader.

Finally, I would like to thank the members of the ICMST International Steering Committee, the Organizing Committee, the Local Organizing Committee and the Secretariat without whose tireless work ICMST-Tohoku 2018 would not have succeeded.

Guest Editor, Kenji Suzuki

1. Development of a Pipe-Wall Thinning Inspection Method Based on a Wireless UT Sensor

Akinori TAMURA, Masao ENDO, Naoyuki KONO, Shinobu OKIDO, Chenghuan ZHONG, Erik FABRE, Maria KOGIA, Anthony J. CROXFORD and Paul D. WILCOX

Aiming to reduce inspection time of pipe-wall thickness measurements in nuclear power plants, we have been developing a new inspection method based on a wireless UT sensing technology which was originally proposed by University of Bristol. Utilizing the characteristics of the wireless UT sensor, the new inspection method enables the pipe-wall measurement without removal of pipe insulation which is a time-consuming process in general. One of the issues which needs to be addressed is existence of a metal jacket covering the pipe insulator. Since the wireless UT sensor is based on electromagnetic induction between coils, a magnetic field between the coils is interruped by the metal jacket and the wireless UT sensor is not applicable in this case. In this study, we developed the intermediate coil system (PCT/JP2018/020043) as one of the options to overcome this issue. In this system, two coils and cables are added into the original wireless UT sensor. Firstly, we developed an electrical circuit model to optimize the system design, and confirmed that the developed electrical circuit model has sufficient accuracy by the comparison with the experiment result. Then we performed the feasibility test of the intermediate coil system in the pipe-wall thinning measurement by using the test apparatus which simulates the pipe in the actual nuclear power plant. From these results, we have confirmed the feasibility of the intermediate coil system in the pipe-wall thinning measurement. Further development and evaluation will be conducted to apply this system into the actual plant inspection in the future study.

2. Application of Charpy Specimens Reconstituted by Electron Beam Welding for the Evaluation of Irradiation Embrittlement of Reactor Pressure Vessels

Seiji SAKURAYA, Yasuo MORISHIMA, Tetsuya TOYOTA and Takayuki KAMINAGA

According to the recent Japanese regulations regarding plant life extension of light water reactors for operation exceeding 40 years, additional surveillance tests are required for the evaluation of irradiation embrittlement of reactor pressure vessel materials. The number of loaded specimens in boiling water reactors is limited; accordingly, securing surveillance specimens is an important issue. Reconstitution of tested Charpy specimens is one way to secure the required number of specimens. Electron beam welding has the advantages of low heat input and realization of a highly reliable weldment property; therefore, it is a candidate for the specimen reconstitution method. In this study, applicability of reconstituted Charpy specimens was studied. Electron beam welding of irradiated surveillance specimens was carried out in the hot laboratory by remote manipulation. After the welding, specimens were processed into the shape of Charpy impact specimens, and Charpy impact tests were performed. The soundness of the welded joints was evaluated and the obtained results satisfied the requirements of the Japan Electric Association Code.


	ICMST-Tohoku 2018 Oct. 23 - 26, 2018 Sendai, Japan
	ICMST-Shenzhen 2016 Nov 1 - 4, 2016 Shenzhen, China (EXIT THIS PAGE)
	ICMST-Kobe 2014 Nov 2(Sun) - 5(Wed), 2014 Kobe, Japan
Nuclear Regulation Authority	Outline of the New Safety Standards for Light Water Reactors for Electric Power Generation
	For Public Comment Outline of New Safety Standard (Design Basis)
	For Public Comment New Safety Standards (SA) Outline (Draft)
	For Public Comment Outline of New Safety Standard(Earthquake and Tsunami)(DRAFT)