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Journal Articles

R&D status of hydrogen production test using IS process test facility made of industrial structural material in JAEA

Noguchi, Hiroki; Takegami, Hiroaki; Kamiji, Yu; Tanaka, Nobuyuki; Iwatsuki, Jin; Kasahara, Seiji; Kubo, Shinji

International Journal of Hydrogen Energy, 44(25), p.12583 - 12592, 2019/05

 Times Cited Count:14 Percentile:48.89(Chemistry, Physical)

JAEA has been conducting R&D on thermochemical water-splitting hydrogen production IS process to develop one of heat applications of high-temperature gas-cooled reactor. A test facility was constructed using corrosion-resistant industrial materials to verify integrity of the IS process components and to demonstrate continuous and stable hydrogen production. The performance of components installed in each section was confirmed. Subsequently, a trial operation of integration of the processing sections was successfully carried out for 8 hours with hydrogen production rate of approximately 10 NL/h. After that, hydrogen production operation was extended to 31 hours (approximately hydrogen production rate of 20 NL/h) by introducing a corrosion-resistance pump system with a developed shaft seal technology.

Journal Articles

Fracture characterization and rock mass behavior induced by blasting and mechanical excavation of shafts in Horonobe Underground Research Laboratory

Aoyagi, Kazuhei; Tokiwa, Tetsuya*; Sato, Toshinori; Hayano, Akira

Proceedings of 2019 Rock Dynamics Summit in Okinawa (USB Flash Drive), p.682 - 687, 2019/05

In high-level radioactive disposal projects, it is important to investigate the extent of the excavation damaged zone (EDZ) for safety assessment because EDZ can provide a migration pathway for radionuclides from the facility. To investigate the quantitative differences between EDZs formed because of blasting and mechanical excavation, we studied the characteristics of fractures induced by excavation based on fracture mapping performed during shaft sinking (V- and E-Shafts). As a result, it was found that blasting excavation can lead to the formation of a large number of newly created fractures (EDZ fractures) compared with mechanical excavation. In addition, the seismic velocity (P-wave velocity) measured during blasting excavation (E-Shaft) was lower than that measured during mechanical excavation (V-Shaft). Furthermore, we found that the support pattern that reinforces forward rocks to be appropriate for limiting damage to the shaft wall.

Journal Articles

A Study on support design for deep shaft sinking in rock masses of low strength and anisotropic initial stress

Motoshima, Takayuki*; Koike, Masashi*; Hagihara, Takeshi*; Aoyagi, Kazuhei

Dai-46-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.208 - 213, 2019/01

The short step construction method is the standard construction method for deep shaft excavation. However, considering the shaft construction in the sedimentary rock widely distributed in Japan, the support concrete stress can become excessive especially when there are bad conditions such as low rock strength, anisotropic initial stress, or high ground pressure. In this research, we introduced the dual support design to the short step construction method in order to reduce the support stress, and confirmed the validity by three dimensional numerical analysis. Validation analysis was conducted using the in-situ data in the Horonobe Underground Research Project conducted by Japan Atomic Energy Agency.

Journal Articles

Fracture characterization and rock mass damage induced by different excavation methods in the Horonobe URL of Japan

Tokiwa, Tetsuya*; Tsusaka, Kimikazu*; Aoyagi, Kazuhei

International Journal of Civil Engineering, 16(4), p.371 - 381, 2018/04

 Times Cited Count:2 Percentile:11.72(Engineering, Civil)

Journal Articles

Investigation of an excavation damaged zone in the east access shaft at the Horonobe Underground Research Laboratory

Aoyagi, Kazuhei; Ishii, Eiichi; Fujita, Tomoo; Motoshima, Takayuki*

Dai-44-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.313 - 318, 2016/01

The objective of this research is to investigate the extent and failure mechanism of an Excavation Damaged Zone (EDZ) induced around the East Access Shaft in the Horonobe Underground Research Laboratory. As a result of hydraulic tests, hydraulic conductivity within 2 m from the shaft wall was increased by 1 to 3 orders of magnitude. This result is consistent with the extent of the development of fractures detected by borehole televiewer surveys. Furthermore, the dominant failure mechanism of the fractures around the shaft wall was almost tensile; also these fractures were caused by the short-term excavation-induced unloading.

Journal Articles

Permeability estimation based on crack tensor on site scale

Yamasaki, Masanao*; Tsusaka, Kimikazu*; Otani, Tatsuhiko*; Shinji, Masato*

Doboku Gakkai Rombunshu, F2 (Chika Kukan Kenkyu) (Internet), 71(1), p.1 - 10, 2015/04

Japan Atomic Energy Agency has been constructed the Underground Research Laboratory in Hokkaido. In the shaft excavation, length, direction and aperture of geological observation are measured and analyzed in order to estimate rock permeability around lining. In this report, correlation between frequency of cracks and rock permeability based on crack tensor and stereology was discussed. Prediction equation of rock permeability from the frequency of cracks on the shaft wall was also proposed.

Journal Articles

A Study of mechanical stability of support elements and surrounding rock mass during shaft sinking through a fault

Tsusaka, Kimikazu*; Inagaki, Daisuke*; Nago, Makito*; Ijiri, Yuji*

Proceedings of 8th Asian Rock Mechanics Symposium (ARMS-8) (USB Flash Drive), 9 Pages, 2014/10

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