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Journal Articles

Degassing behavior of noble gases from groundwater during groundwater sampling

Nakata, Kotaro*; Hasegawa, Takuma*; Solomon, D. K.*; Miyakawa, Kazuya; Tomioka, Yuichi*; Ota, Tomoko*; Matsumoto, Takuya*; Hama, Katsuhiro; Iwatsuki, Teruki; Ono, Masahiko*; et al.

Applied Geochemistry, 104, p.60 - 70, 2019/05

 Times Cited Count:0 Percentile:100(Geochemistry & Geophysics)

no abstracts in English

Journal Articles

Cross-checking groundwater age by $$^{4}$$He and $$^{14}$$C dating in a granite, Tono area, central Japan

Hasegawa, Takuma*; Nakata, Kotaro*; Tomioka, Yuichi*; Goto, Kazuyuki*; Kashiwaya, Koki*; Hama, Katsuhiro; Iwatsuki, Teruki; Kunimaru, Takanori*; Takeda, Masaki

Geochimica et Cosmochimica Acta, 192, p.166 - 185, 2016/11

 Times Cited Count:4 Percentile:68.61(Geochemistry & Geophysics)

Groundwater dating was performed simultaneously by the $$^{4}$$He and $$^{14}$$C methods in granite of the Tono area in central Japan. Groundwater was sampled at 30 packed-off sections of six 1000-m boreholes. $$^{4}$$He concentrations increased and $$^{14}$$C concentrations decreased along a groundwater flow path on a topographic gradient. $$^{4}$$He ages were calculated by using the in situ $$^{4}$$He production rate derived from the porosity, density, and U and Th content of the rock, neglecting external flux. The linear relation between the $$^{4}$$He ages and the noncorrected $$^{14}$$C ages, except in the discharge area. Simultaneous measurements make it feasible to estimate the accumulation rate of $$^{4}$$He and initial dilution of $$^{14}$$C, which cannot be done with a single method. Cross-checking groundwater dating has the potential to provide more reliable groundwater ages.

Journal Articles

Shallow groundwater intrusion to deeper depths caused by construction and drainage of a large underground facility; Estimation using $$^{3}$$H, CFCs and SF$$_{6}$$ as trace materials

Hagiwara, Hiroki; Iwatsuki, Teruki; Hasegawa, Takuma*; Nakata, Kotaro*; Tomioka, Yuichi*

Nippon Suimon Kagakkai-Shi, 45(2), p.21 - 38, 2015/07

This study evaluates a method to estimate shallow groundwater intrusion in and around a large underground research facility (Mizunami Underground Research Laboratory - MIU). Water chemistry, stable isotopes ($$delta$$D and $$delta$$$$^{18}$$O), tritium ($$^{3}$$H), chlorofluorocarbons (CFCs) and sulfur hexafluoride (SF$$_{6}$$) in groundwater were monitored around the facility (from 20 m down to a depth of 500 m), for a period of 5 years. The results show that shallow groundwater inflows into deeper groundwater at depths of between 200-400 m. In addition, the content of shallow groundwater estimated using $$^{3}$$H and CFC-12 concentrations is up to a maximum of about 50%. This is interpreted as the impact on the groundwater environment caused by construction and operation of a large facility over several years. The concomitant use of $$^{3}$$H and CFCs is an effective method to determine the extent of shallow groundwater inflow caused by construction of an underground facility.

Journal Articles

Application of supercritical fluid extraction to metal separation in the field of nuclear technology

Meguro, Yoshihiro; Tomioka, Osamu; Takahashi, Kuniaki; Wada, Ryutaro*; Yamamoto, Seiichi*; Fukuzato, Ryuichi*

Proceedings of 8th International Symposium on Supercritical Fluids (ISSF 2006) (CD-ROM), 6 Pages, 2006/11

A large-scale apparatus having a reaction vessel of ca. 4000 cm$$^3$$ was developed for supercritical CO$$_2$$ leaching. An ultrasonic wave oscillator, stirring device, and piston compressor were equipped to the apparatus to enhance mass transfer rate of substances in supercritical CO$$_2$$. A sea sand sample, an incinerated ash sample, and a porous alumina brick sample, in which uranium oxide was adsorbed, were prepared as simulated samples of radioactive wastes and uranium was tried to remove from these samples to supercritical CO$$_2$$ including nitric acid - tri-n-butyl phosphate complex as a reactant using the apparatus. By several times of the uranium separation, more than 99% of uranium was removed from the sea sand sample and the ash sample. When the mass transfer enhanced system was operated, it was confirmed that separation efficiency of uranium was improved and then 99% of uranium could be removed form the ash sample.

Journal Articles

Recovery of alkali salt by supercritical fluid leaching method using carbon dioxide

Watanabe, Takeshi*; Tsushima, Satoru*; Yamamoto, Ichiro*; Tomioka, Osamu; Meguro, Yoshihiro; Nakashima, Mikio; Wada, Ryutaro*; Nagase, Yoshiyuki*; Fukuzato, Ryuichi*

Proceedings of 2nd International Symposium on Supercritical Fluid Technology for Energy and Environment Applications (Super Green 2003), p.363 - 366, 2004/00

Recovery of salts by supercritical fluid leaching (SFL) method using carbon dioxide was experimentally studied. It was confirmed that LiCl was recovered with a mixed fluid of carbon dioxide and methanol, and KCl and SrCl$$_2$$ were recovered with a mixed fluid of carbon dioxide, methanol and crown ether. The influence of crown ether for KCl and SrCl$$_2$$ extraction were found to increase in the order of 15-crown-5 (15C5) $$<$$ 18-crown-6 (18C6) $$<$$ dicychlohexyl-18-crown-6 (DC18C6). It is expected that other salts can be recovered selectively with a mixed fluid of carbon dioxide, methanol and suitable crown ether.

Journal Articles

Development of radioactive waste treatment by Supercritical Fluid Leaching (SFL) method

Nagase, Yoshiyuki*; Masuda, Kaoru*; Wada, Ryutaro*; Yamamoto, Ichiro*; Tomioka, Osamu; Meguro, Yoshihiro; Fukuzato, Ryuichi*

Proceedings of 2nd International Symposium on Supercritical Fluid Technology for Energy and Environment Applications (Super Green 2003), p.254 - 257, 2004/00

no abstracts in English

Journal Articles

Measurements of the depth profile of the refractive indices in oxide films on SiC by spectroscopic ellipsometry

Iida, Takeshi*; Tomioka, Yuichi*; Yoshimoto, Kimihiro*; Midorikawa, Masahiko*; Tsukada, Hiroyuki*; Orihara, Misao*; Hijikata, Yasuto*; Yaguchi, Hiroyuki*; Yoshikawa, Masahito; Ito, Hisayoshi; et al.

Japanese Journal of Applied Physics, Part 1, 41(2A), p.800 - 804, 2002/02

 Times Cited Count:15 Percentile:45.51(Physics, Applied)

no abstracts in English

Oral presentation

JAEA-CRIEPI collaboration study on mass transport by groundwater in and around the Mizunami Underground Research Laboratory

Hama, Katsuhiro; Iwatsuki, Teruki; Hasegawa, Takuma*; Nakata, Kotaro*; Tomioka, Yuichi*; Goto, Kazuyuki*

no journal, , 

The dating of groundwater has been carried out by the measurement of radionuclides in groundwater in and around the Mizunami underground research laboratory.

Oral presentation

Central Research Institute of Electric Power Industry - Japan Atomic Energy Agency Joint Research; A Study of the hydraulic properties and transport characteristics around the Mizunami Underground Laboratory Project

Hasegawa, Takuma*; Nakata, Kotaro*; Tomioka, Yuichi*; Goto, Kazuyuki*; Kashiwaya, Koki*; Hama, Katsuhiro

no journal, , 

The groundwater flow velocity is one of the important items in the safety assessment for the HLW disposal. Generally, it is too difficult to measure the groundwater flow velocity directly. Therefore, to determine the groundwater age by radio active isotopes are effective. However, there are some problems to apply the metrology to the natural samples. For example, because the ratio of Carbon isotope changes by dissolving of the carbonate mineral and resolving the organic materials, the development of the technique for correcting this is needed. In this study, the groundwater ages are measured by $$^{4}$$He and $$^{14}$$C, etc. and compared these results as a joint research with Central Research Institute of Electric Power Industry.

Oral presentation

CRIEPI-JAEA collaborative study "Study on hydrogeological and mass transport property of rock mass in and around the Mizunami Underground Research Laboratory; Development of groundwater dating technology"

Nakata, Kotaro*; Hasegawa, Takuma*; Tomioka, Yuichi*; Tanaka, Yasuharu*; Hama, Katsuhiro; Iwatsuki, Teruki

no journal, , 

The technology development of groundwater dating has been carried out as a part of CRIEPI-JAEA collaboration. The carbon-14 in the organic matter dissolved in groundwater is used to estimate groundwater age. The estimated age is almost same as the age that estimated by the He-4 in groundwater. This suggested that the age estimation by carbon-14 in organic matter can be useful tool to enhance the reliability of the data on groundwater age.

Oral presentation

Shallow groundwater intrusion to deeper depths caused by construction and drainage of a large underground facility; Estimation using $$^{3}$$H, CFCs and SF$$_{6}$$ as trace materials

Hagiwara, Hiroki; Iwatsuki, Teruki; Hasegawa, Takuma*; Nakata, Kotaro*; Tomioka, Yuichi*

no journal, , 

This study evaluates a method to estimate shallow groundwater intrusion in and around a large underground research facility (Mizunami Underground Research Laboratory - MIU). Water chemistry, stable isotopes ($$delta$$D and $$delta$$$$^{18}$$O), tritium ($$^{3}$$H), chlorofluorocarbons (CFCs) and sulfur hexafluoride (SF$$_{6}$$) in groundwater were monitored around the facility (from 20 m down to a depth of 500 m), for a period of 5 years. The results show that shallow groundwater inflows into deeper groundwater at depths of between 200-400 m. In addition, the content of shallow groundwater estimated using $$^{3}$$H and CFC-12 concentrations is up to a maximum of about 50%. This is interpreted as the impact on the groundwater environment caused by construction and operation of a large facility over several years. The concomitant use of $$^{3}$$H and CFCs is an effective method to determine the extent of shallow groundwater inflow caused by construction of an underground facility.

Oral presentation

Study of groundwater residence time in Mizunami Underground Research Laboratory

Hasegawa, Takuma*; Nakata, Kotaro*; Tomioka, Yuichi*; Ota, Tomoko*; Hama, Katsuhiro; Iwatsuki, Teruki; Kato, Toshihiro*; Hayashida, Kazuki

no journal, , 

Groundwater dating using $$^{14}$$C, $$^{4}$$He, noble gas method was conducted in Mizunami Underground Research laboratory. The availability of degassing method for $$^{14}$$, flux estimation method for He were examined. It was identified that the groundwater have been derived in glacial age. The integration of distinct dating method is available to estimate precise age of groundwater.

Oral presentation

CRIEPI-JAEA collaboration study on mass transport by groundwater in and around the Mizunami Underground Research Laboratory

Hasegawa, Takuma*; Nakata, Kotaro*; Tomioka, Yuichi*; Ota, Tomoko*; Hama, Katsuhiro; Iwatsuki, Teruki; Kato, Toshihiro*; Hayashida, Kazuki

no journal, , 

no abstracts in English

Oral presentation

Groundwater dating conducted in Mizunami Underground Research Laboratory

Hasegawa, Takuma*; Nakata, Kotaro*; Tomioka, Yuichi*; Ota, Tomoko*; Hama, Katsuhiro; Iwatsuki, Teruki; Kato, Toshihiro*; Hayashida, Kazuki

no journal, , 

Groundwater dating was conducted to Mizunami Underground Research Laboratory (MIU). $$^{14}$$C age and $$^{4}$$He age were estimated about 20,000 years around MIU. The estimation of noble gas temperature is also conducted. The estimated recharge temperature is around 6$$^{circ}$$C. This temperature is about 9$$^{circ}$$C cooler than present annual average temperature, which agree with estimation of modern analog method conducted near MIU.

Oral presentation

Multiple groundwater dating conducted at Mizunami URL

Hasegawa, Takuma*; Nakata, Kotaro*; Tomioka, Yuichi*; Ota, Tomoko*; Okamoto, Shunichi*; Hama, Katsuhiro; Watanabe, Yusuke; Iwatsuki, Teruki

no journal, , 

no abstracts in English

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