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Watanabe, Yusuke; Hayashida, Kazuki; Kato, Toshihiro; Kubota, Mitsuru; Aosai, Daisuke*; Kumamoto, Yoshiharu*; Iwatsuki, Teruki
JAEA-Data/Code 2018-002, 108 Pages, 2018/03
JAEA-Data-Code-2018-002.pdf:6.53MB
Japan Atomic Energy Agency has been investigating groundwater chemistry to understand the effect of excavation and maintenance of underground facilities as part of the Mizunami Underground Research Laboratory (MIU) Project in Mizunami, Gifu, Japan. In this report, we compiled data of groundwater chemistry and microbiology obtained at the MIU in the fiscal year 2016 and 2014 to 2016, respectively. In terms of ensuring traceability of data, basic information (e.g. sampling location, sampling time, sampling method and analytical method) and methodology for quality control are described.
Hayashida, Kazuki; Kato, Toshihiro*; Kubota, Mitsuru*; Murakami, Hiroaki; Amano, Yuki; Iwatsuki, Teruki
Chikyu Kagaku, 52(1), p.55 - 71, 2018/03
In this study, the simulated experimental drift was constructed in the granite of 500 m depth at Mizunami Underground Research Laboratory, and the hydrochemical process after the drift closure was observed. The groundwater chemistry around the drift changed with the change of the groundwater flow in the fractures when the gallery was constructed. The redox potential increased due to the infiltration of oxygen from the drift into the rock. After closing the drift, the redox potential of the groundwater plunged due to microbial activity, while the groundwater became alkalized conditon due to the influence of cement material such as shotcrete. The amount of cement material consumed for this alkalization was small, and it was considered that its influence would last long in accordance with the amount of cement used.
Kato, Toshihiro; Iwatsuki, Teruki; Nishio, Tomohiro*
JAEA-Technology 2017-009, 30 Pages, 2017/06
JAEA-Technology-2017-009.pdf:2.6MB
Groundwater age is an important information to infer the groundwater flow. The radiocarbon (
C) dating of the groundwater is primary method for the evaluation of groundwater flow. The carbon in the groundwater generally exist as a dissolved inorganic carbon (DIC). Though DIC in groundwater samples is usually collected by chemical precipitation method, the method requires lots of preparation to sample the carbon. Furthermore there are problems with the reproducibility on precipitation and measurement value. This study newly examined the application of gas-strip method to collect DIC in groundwater sample by using JAEA-made gas-strip system. The performance of the CO
gas-stripping from groundwater and the influence of sulfide are investigated. Based on these results, the operation procedures of gas-strip system and preparation method for the groundwater samples were summarized in this report.
Iwatsuki, Teruki; Munemoto, Takashi*; Kubota, Mitsuru*; Hayashida, Kazuki; Kato, Toshihiro*
Applied Geochemistry, 82, p.134 - 145, 2017/05
Times Cited Count：9 Percentile：34.27(Geochemistry & Geophysics)This study investigated the behavior of rare earth elements (REEs) associated with suspended particles in deep granitic groundwater and in a sealed drift at a depth of 500 m in the Mizunami Underground Research Laboratory (URL) in Japan. Approximately 10%
60% of REEs in groundwater are associated with suspended particles. Carbonate particles in groundwater are most likely derived from in situ precipitation of supersaturated carbonate minerals such as calcite. Thermodynamic calculations show that the dissolved REE carbonate complexes in the closed drift decreased in the drift closure period. These complexes may have been absorbed or co-precipitated within the shotcrete on the drift wall. The usage of cement based materials would generate environmental conditions in which REEs are fundamentally immobile in and around the underground facilities.
Hayashida, Kazuki; Kato, Toshihiro; Munemoto, Takashi; Aosai, Daisuke*; Inui, Michiharu*; Kubota, Mitsuru; Iwatsuki, Teruki
JAEA-Data/Code 2017-008, 52 Pages, 2017/03
JAEA-Data-Code-2017-008.pdf:3.84MB
Japan Atomic Energy Agency has been investigating groundwater chemistry to understand the effect on excavating and maintenance of underground facilities as part of the Mizunami Underground Research Laboratory (MIU) Project in Mizunami, Gifu, Japan. In this report, we compiled data of groundwater chemistry obtained at the MIU in the fiscal year 2015. In terms of ensuring traceability of data, basic information (e.g. sampling location, sampling time, sampling method, analytical method) and methodology for quality control are described.
C collected by precipitation and gas-strip methods for dating groundwaterNakata, Kotaro*; Hasegawa, Takuma*; Iwatsuki, Teruki; Kato, Toshihiro
Radiocarbon, 58(3), p.491 - 503, 2016/09
Times Cited Count：5 Percentile：21.51(Geochemistry & Geophysics)Dissolved inorganic carbon (DIC) for C analysis of groundwater is usually extracted by a gas-strip or precipitation method. In this study, the certainty of the two methods for C dating were confirmed. DIC and C concentrations obtained by the gas-strip method were close to the theoretically predicted C value. Conversely, the C value obtained by the precipitation method always showed higher values than the predicted values. The difference in C value between gas-strip and precipitation methods was assumed to arise owing to contamination of modern carbon used in the precipitation method. The applicability of the precipitation method for groundwater should be considered carefully according to the DIC, C concentration of groundwater and purpose of the study being conducted.
Hama, Katsuhiro; Mikake, Shinichiro; Ishibashi, Masayuki; Sasao, Eiji; Kuwabara, Kazumichi; Ueno, Tetsuro; Onuki, Kenji*; Beppu, Shinji; Onoe, Hironori; Takeuchi, Ryuji; et al.
JAEA-Review 2015-024, 122 Pages, 2015/11
JAEA-Review-2015-024.pdf:80.64MB
Japan Atomic Energy Agency (JAEA) at Tono Geoscience Center (TGC) is pursuing a geoscientific research and development project namely the Mizunami Underground Research Laboratory (MIU) Project in crystalline rock environment in order to construct scientific and technical basis for geological disposal of High-level Radioactive Waste (HLW). The MIU Project has three overlapping phases: Surface-based Investigation phase (Phase I), Construction phase (Phase II), and Operation phase (Phase III). The MIU Project has been ongoing the Phase III, as the Phase II was concluded for a moment with the completion of the excavation of horizontal tunnels at GL-500m level in February 2014. This report presents the results of the investigations, construction and collaboration studies in fiscal year 2014.
Takeuchi, Masayuki; Hanada, Keiji; Aose, Shinichi; Koizumi, Tsutomu; Kato, Toshihiro*
Journal of Physics and Chemistry of Solids, 66(2-4), p.521 - 525, 2005/00
Times Cited Count：34 Percentile：75.68(Chemistry, Multidisciplinary)None
Takeuchi, Masayuki; Kato, Toshihiro*; Washiya, Tadahiro; Takashi, Suganuma,; Aose, Shinichi
Saikuru Kiko Giho, (23), p.31 - 40, 2004/00
The corrosion resistance of ceramic materials was discussed through thermodynamic calculation and corrosion test. The corrosion test was basically carried out in alkari molten salt under chlorine gas. In addition, the effects of oxygen, carbon and simulated fission products on ceramics corrosion were evaluated in molten salt under chlorine gas. As results, silicon nitrides, mullite and cordierite had a good corrosion resistance in above conditions.
Takeuchi, Masayuki; Koizumi, Tsutomu; Kato, Toshihiro*
Zairyo To Kankyo, 52(6), p.299 - 307, 2003/00
None
; Kato, Toshihiro*; Hanada, Keiji; ; Aose, Shinichi
JNC TN8430 2002-004, 32 Pages, 2002/12
JNC-TN8430-2002-004.pdf:18.95MB
Pyrochemical reprocessing using molten salts (RIAR process) has been recently developed for spent nuclear oxide fuel and discussed in feasibility study. It is required to improve the corrosion resistance of equipments such as electrolyzer because the process is operated in severe corrosion environment. In this study, the corrosion resistance of ceramic materials was discussed through the thermodynamic calculation and corrosion test. The corrosion test was basically carried out in alkali molten salt under chlorine gas condition. And further consideration about the effects of oxygen, carbon and main fission product's chlorides were evaluated in molten salt. The result of thermodynamic calculation shows most of ceramic oxides have good chemical stability on chlorine, oxygen and uranyl chloride, however the standard Gibb's free energies with carbon have negative value. On the other hand, eleven kinds of ceramic materials were examined by corrosion test, then silicon nitride, mullite and cordierite have a good corrosion resistance less than 0.1mm/y. Cracks were not observed on the materials and flexural strength did not reduce remarkably after 480 hours test in molten salt with Cl-O bubbling. In conclusion, these three ceramic materials are most applicable materials for the pyrochemical reprocessing process with chlorine gas condition.
Takeda, Seiichiro; ; ; ; Kato, Toshihiro*; *; Fujisaku, Kazuhiko*
JNC TN8400 2002-007, 135 Pages, 2001/12
JNC-TN8400-2002-007.pdf:9.39MB
Corrosion performance of materials used for nuclear fuel reprocessing plant was studied for the extension of their lifetime during in-service period. Research was performed focusing on characteristics of reprocessing solution which is very important corrosion factor on environmental side. In the first stage, fundamental corrosion behavior of several kinds of candidate materials such as 304ULC, 310Nb, Ti, Ti-5Ta and Zr was investigated in pure nitric acid solution. Then corrosion performance of such materials in reprocessing environment was made cleared by means of so-called hot test which is used actual reprocessing solution under radioactive conditions. The results are summarized as follows. (1) With regards to the effects of uranium and plutonium on corrosion, high valence plutonium (Pu(Ⅵ)) accelerated the corrosion of stainless steels in nitric acid, but uranium did not affect on them. It is caused by trans-passive dissolution based on the shift of corrosion potential to the noble position. It is thought that the potential shift is caused by increase of the cathodic current on the stainless steel surface due to the reduction of Pu(Ⅵ) to Pu(IV). (2) In fission product (FP) elements, ruthenium accelerated the corrosion of stainless steel in nitric acid when its concentration was comparatively high. Other FP's did not affect on them. The corrosion potential of stainless steel shifts toward noble region by adding ruthenium in nitric acid where high corrosion rates are exhibited. It is thought that the potential shift is caused by the enhancement of cathodic reactions on metal surface due to co-existence of ruthenium in nitric acid. (3) Ti, Ti-5Ta and Zr showed excellent corrosion resistance in nitric acid with and without Plutonium and ruthenium. Especially, Ti and Ti-5Ta showed the improvement of corrosion resistance by co-existing Plutonium or ruthenium. It was explained by chemical stability of surface oxide film due to plutonium or ruthenium oxidant.
Kato, Toshihiro*; ; ; ; Ishibashi, Yuzo; Takeda, Seiichiro
PNC TN8410 98-070, 31 Pages, 1998/02
None
; Takeda, Seiichiro; Kawata, Tomio; Kato, Toshihiro*; *
PNC TN8410 91-279, 49 Pages, 1991/11
no abstracts in English
Arai, Yoichi; Takeuchi, Masayuki; Kato, Toshihiro*
no journal, ,
no abstracts in English
Arai, Yoichi; Takeuchi, Masayuki; Koizumi, Tsutomu; Kase, Takeshi; Kato, Toshihiro*
no journal, ,
no abstracts in English
Arai, Yoichi; Takeuchi, Masayuki; Kase, Takeshi; Koizumi, Tsutomu; Kato, Toshihiro*
no journal, ,
no abstracts in English
Arai, Yoichi; Takeuchi, Masayuki; Okochi, Haruo; Kato, Toshihiro*; Kase, Takeshi; Nakajima, Yasuo
no journal, ,
no abstracts in English
Ambai, Hiromu; Sano, Yuichi; Kato, Toshihiro
no journal, ,
Corrosion behaviors in fluid flow condition can be different from those in static condition. Also it is noted that corrosion rates make a big change by nitric acid flow in nuclear fuel reprocessing plants. Until now, long term immersion tests in fluid flow condition which need coupons removing were conducted and thus a method which can test in a shorter time is required. In this study, we used scanning electrochemical measurement system which can measure corrosion potentials of material surfaces etc. and tried in-situ observations of effects on electrochemical properties from solution composition and flow rate in high concentration nitric acid flow condition. Furthermore, we considered a testing method to predict corrosion behaviors from same data and corrosion wastage data.
Munemoto, Takashi; Omori, Kazuaki; Hasegawa, Takashi; Kato, Toshihiro; Yuguchi, Takashi; Iwatsuki, Teruki; Hama, Katsuhiro
no journal, ,
no abstracts in English
