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Central Research Institute of Electric Power Industry (CRIEPI)


Description of the legal entity

Central Research Institute of Electric Power Industry with its registered office at 1-6-1, Otemachi, Chiyoda-ku, Tokyo 100-8126, JAPAN, hereinafter called as “CRIEPI,” is a non-profit general incorporated foundation providing research and development services in various fields including nuclear, thermal, hydraulic and renewable power generation as well as energy transmission and environmental conservation.

The Materials Science Research Laboratory (MSRL) in CRIEPI pursues solutions to material technology issues relevant to electric utilities and other energy industries. The laboratory provides materials engineering solutions that not only enable the advanced operation of energy equipment, but also play an active role in general research and development of new materials. Structural Materials Sector in MSRL is promoting researches on the technology development of structural integrity assessment and maintenance of the components used under extreme environments, such as high temperature and irradiation, of the fossil and nuclear power plants.

In recent 10 years, CRIEPI has been working on development and standardization activities to utilize 4mm – thick C(T) specimens (Mini-C(T) specimens) for Master Curve evaluation of reactor pressure vessel materials. The already accumulated knowledge and data through those activities will contribute the proposed project planning as preliminary technical background, and will enforce the technical basis, which will be established as the outcome of the proposed project.

Profile of staff members involved

  • Dr Masato Yamamoto (male): Masato Yamamoto graduated as a Master in Mechanical engineering from Kyushu University in 1994. He earned his PhD in mechanical engineering from Kyoto University in 2007 with his thesis on fatigue and creep fatigue crack propagation behavior of Nickel based superalloy used in gas turbine blades. After he joined to CRIEPI in 1994, he had been involved in high temperature fatigue and creep-fatigue investigations for thermal power materials for 15 years. In these 8 years, he has been deeply involved with the fracture toughness investigations for utilization of miniature C(T) specimens to the Master Curve evaluation of RPV materials.
  • Dr Tomoki Shinko (male): Tomoki Shinko graduated as a Master in Mechanical Engineering from Hokkaido University in 2015. He earned his PhD in mechanical engineering from ISAE-ENSMA in 2019 with his thesis on fatigue crack propagation behavior in commercially pure iron under high pressure gaseous hydrogen environment. After he joined to CRIEPI in 2019, he has been involved in fracture toughness evaluation of RPV materials using Mini-C(T) specimen.

Relevant publications, and/or products, services

  • Miura N., Soneda N., “Evaluation of Fracture Toughness by Master Curve Approach Using Miniature C(T) Specimens” (2010), Trans. ASME, Journal of Pressure Vessel Technology, Vol. 134, 021402.
  • Yamamoto M., et al, "International Round Robin Test on Master Curve Reference Temperature Evaluation Utilizing Miniature C(T) Specimen" (2014), ASTM STP 1576, STP157620140020
  • Yamamoto M., "The Master Curve Fracture Toughness Evaluation of Irradiated Plate Material JRQ using Miniature-C(T) Specimens" (2017), Procs. the ASME 2017 Pressure Vessels & Piping Conference, PVP2017-55085
  • Yamamoto M., et al., “A Round Robin Program of Master Curve Evaluation using Miniature C(T) Specimens (Comparison of T0 for a Weld Metal),” (2017), Transactions of SMiRT-24, BEXCO, Busan, Korea
  • Server W., Yamamoto M., Carter R. G., “Inter-laboratory Results and Analyses of Mini-C(T) Specimen Testing of an Irradiated Linde 80 Weld Metal,” (2018), Procs. the ASME 2018 Pressure Vessels & Piping Conference, PVP2018-84950
  • Yamamoto M., Nagai M., “PTS Evaluation Case Study Considering Actual Through-wall Fracture Toughness Distribution,” (2019), Proceedings of the ASME 2019 Pressure Vessels & Piping Conference, PVP2019-93964, July 14-19, 2019, San Antonio, TX, USA

Relevant previous projects or activities

  • Mini-C(T) Master Curve Round-Robin Tests on un-irradiated base metal
  • Mini-C(T) Master Curve Round-Robin Tests on un-irradiated weld metal
  • Mini-C(T) Master Curve Round-Robin Tests on irradiated low upper shelf weld metal

Significant infrastructure and/or any major items of technical equipment

  • Cold area: Mini-C(T) fracture toughness testing frame, which generate many of data points in the current base data of Mini-C(T) Mater Curve evaluation.
  • Controlled area: Atom probe tomography and other microstructural observation facilities to characterize the irradiated RPV steels and core internal materials.

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