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Journal Articles

Completion of solidification and stabilization for Pu nitrate solution to reduce potential risks at Tokai Reprocessing Plant

Mukai, Yasunobu; Nakamichi, Hideo; Kobayashi, Daisuke; Nishimura, Kazuaki; Fujisaku, Sakae; Tanaka, Hideki; Isomae, Hidemi; Nakamura, Hironobu; Kurita, Tsutomu; Iida, Masayoshi*; et al.

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 8 Pages, 2017/04

TRP has stored the plutonium in solution state for long-term since the last PCDF operation in 2007 was finished. After the great east Japan earthquake in 2011, JAEA had investigated the risk against potential hazard of these solutions which might lead to make hydrogen explosion and/or boiling of the solution accidents with the release of radioactive materials to the public when blackout. To reduce the risk for storing Pu solution (about 640 kg Pu), JAEA planned to perform the process operation for the solidification and stabilization of the solution by converted into MOX powder at PCDF in 2013. In order to perform PCDF operation without adaption of new safety regulation, JAEA conducted several safety measures such as emergency safety countermeasures, necessary security and safeguards (3S) measures with understanding of NRA. As a result, the PCDF operation had stared on 28th April, 2014, and successfully completed to convert MOX powder on 3rd August, 2016 for about 2 years as planned.

Journal Articles

Rapid and simple measurement of H$$_{2}$$ emission from active faults using compact sampling equipments

Shimada, Koji; Tanaka, Hidemi*; Saito, Tomohiko*

Resource Geology, 58(2), p.196 - 202, 2008/06

 Times Cited Count:2 Percentile:15.99(Geology)

To shorten the duration of higher concentration of hydrogen immediately after a fault-gas-monitoring installation (install effect), a downsized equipment using commercial sensor was arranged. The install effect, which obstacle to genuine gas emission from faults, is finished within 35 minutes after excavation of monitoring holes along the active Atotsugawa fault, central Japan. It shows that types of hydrogen emission can be captured within about 1 hour procedure. Shortening the detection time should enable a quick evaluation of temporal and spatial heterogeneity of hydrogen emission along Quaternary fault implying fault activity.

Journal Articles

Descriptions of meso- and microscopic structures of fault zone rocks obtained from tunnel penetrated across the Mozumi-Sukenobe fault, central Japan

Tanaka, Hidemi*; Ito, Tanio*; Nohara, Tsuyoshi; Ando, Masataka*

Geodynamics of Atotsugawa Fault System, p.103 - 121, 2007/00

The Mozumi-Sukenobe fault, running ENE-WSW and dipping almost vertically, is one of the Atotsugawa right-lateral active faults in central Japan. A 500 m long horizontal tunnel was excavated across the Mozumi-Sukenobe fault, utilizing the pre-existing tunnel of the Kamioka Mine for geological and geophysical integrated research of the fault zones. In order to clarify the fault zone architecture and rock distribution, we have investigated the distribution across the tunnel and obtained samples directly from the tunnel. The following results were obtained by meso-and microscopic observations and mineralogical examination of fault rocks; (1) Two fracture zones (referred to as zones A and B) are distinguished. They are 15 and 50 m in thickness, respectively, composed of foliated fault breccia in a damaged zone and foliated fault gouge in the fault cores. The core-zones contain an 8 cm slip layer for zone A and several thin (10 cm) slip layers for zone B. (2) Most of the fault rocks obtained from the fault cores of the two fracture zones show a distinct foliated texture, which is clearly a product of cataclastic flow deformation. Very thin, ultra-fine grained slip layers, generated by seismic rapid slip, are also detected from fault core of zones A and B. The cross-cutting relationship between foliated and rapid slip textures indicate a repeated process of slow and rapid slips in zones A and B. (3) The results of mineral assemblage analysis show that these fault rocks are dominated by smectite clay minerals as well as by mica minerals and chlorite, all of which could be potential candidates for the main reason of the stable slip. Combining all these data, we conclude that the Mozumi-Sukenobe fault is activated by extremely slow frictional-viscous creep which releases crustal strain energy. However, stress would also be released by earthquakes based on the existence of earthquake slip surfaces in the fault cores of the Mozumi-Sukenobe fault.

Journal Articles

${it In situ}$ hydraulic tests in the active fault survey tunnel, Kamioka mine, excavated through the active Mozumi-Sukenobe fault zone and their hydrogeological significance

Nohara, Tsuyoshi; Tanaka, Hidemi*; Watanabe, Kunio*; Furukawa, Noboru*; Takami, Akira*

Island Arc, 15(4), p.537 - 545, 2006/12

 Times Cited Count:4 Percentile:13.62(Geosciences, Multidisciplinary)

The spatial hydrogeological and structural character of the active Mozumi-Sukenobu Fault (MSF) was investigated along a survey tunnel excavated through the MSF in the Kamioka Mine, Central Japan. Major groundwater conduits on both sides of the MSF are recognized. One is considered to be a sub-vertical conduit between the tunnel and the surface, the other is estimated to be a major reservoir of old meteoric water alongside the MSF. Studies indicate that part of the MSF is a sub-vertical continuous barrier that obstructs younger meteoric water observed in the southeastern part of the Active Fault Survey Tunnel (AFST) and recharge to the rock mass intersected by the northwestern part of the AFST. It is considered that the MSF is a continuous barrier resulting in the storage of a large quantity of older groundwater to the northwest. The observations indicate that the major reservoir is not the fault breccia associated with the NE-SW oriented faults of the MSF. Rather, the reservoir is considered to be the zone in which blocks of fractured rocks occur beside high angle faults corresponding to X shears that coincide in orientation with the present-day regional stress field and antithetic Riedel shears of the MSF. It is considered that secondary porosity is developed in the major reservoir by the destruction of filling minerals and fracture development beside these shears. The results of borehole investigations in the AFST indicate that increase in hydraulic conductivity is not directly related to increased density of fractures around the MSF. Our results suggested that minor conduits are sporadically distributed in the sedimentary rocks around the MSF in the AFST.

Oral presentation

The Concentration of H$$_{2}$$ gas corresponding to attitudes of incohesive fault rock layers

Shimada, Koji; Niwa, Masakazu; Nohara, Tsuyoshi; Tanaka, Hidemi*

no journal, , 

no abstracts in English

Oral presentation

The GROund Water Data Analyzing System (GROWDAS) of wide applicability utilizing quadrapole mass spectrometer for monitoring the dissolved gas

Shimada, Koji; Tanaka, Hidemi*; Hirokawa, Tomotaka*; Saito, Tomohiko*; Tsunomori, Fumiaki*

no journal, , 

no abstracts in English

Oral presentation

Development of a novel hemostatic and coagulating device in neuroendoscopic surgery; Usefulness of laser irradiating composite type optical fiberscope

Watanabe, Shinya*; Akutsu, Hiroyoshi*; Oka, Kiyoshi; Seki, Takeshi*; Akatsu, Tomohiro*; Tanaka, Hidemine*; Yamamoto, Tetsuya*; Ihara, Satoshi*; Matsumura, Akira*

no journal, , 

no abstracts in English

Oral presentation

Crustal resistivity structure beneath the source region of 2014 northern Nagano earthquake

Asamori, Koichi; Hama, Yuki; Umeda, Koji*; Tanaka, Hidemi*

no journal, , 

no abstracts in English

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