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Journal Articles

Evaluation of hydrogeochemical processes provoked by tunnel excavation and closure based on simulated experiment in a mock-up test drift

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.

JAEA Reports

Physico-chemical studies on the disposal of miscellaneous radioactive waste through A single-step process (III)

Iwase, Masanori*

JNC-TJ8400 2000-063, 78 Pages, 2000/03

JNC-TJ8400-2000-063.pdf:1.93MB

This study is aimed at controlling oxidation reaction of molten metal by ash in incineration systems, and at positively utilizing the oxidation reaction for decontamination of slag. In this year, in order to investigate physico-chemical properties of mixed fused salt containing alkali sulfates, with special focus on the behaviour of oxygen anion in the melts, Cu$$^{2+}$$ / Cu$$^{+}$$ redox equilibrium experiments were carried out. Among the effect of various parameters on Cu$$^{2+}$$ / Cu$$^{+}$$ ratio in binary and ternary alkali sulfate melts, the effect of partial pressures of oxygen and SO$$_{2}$$ was mainly investigated in the study. Variation in Cu$$^{2+}$$ / Cu$$^{+}$$ ratio were presented as the function of partial pressures of oxygen and SO$$_{2}$$, respectively. Possible thermodynamic interpretation were made on the experimental results. In addition, the dissolution of Cr$$_{2}$$O$$_{3}$$ in mixed alkali sulfates were also investigated as a first step to elucidate the mechanism of hot corrosion. With this investigation, an important finding was obtained that the solubility of Cr$$_{2}$$O$$_{3}$$ for melts with same average ionic radius, in other words, oxygen ion activity, were essentially identical under constant temperature and atmosphere.

JAEA Reports

Literature survey of redox reactions in the new field

*; Sasamoto, Hiroshi; *; Inagaki, Manabu*; Yui, Mikazu

JNC-TN8400 2000-007, 32 Pages, 2000/01

JNC-TN8400-2000-007.pdf:0.69MB

This report presents a summary of literature survey about geochemical reactions which are important to evaluate the redox conditions in the near field rock mass and buffer. The results of literature survey are summarized as follows; (1)Minerals including ferrous iron and organic materials in the rock mass are important reductants. Initial stage after closure of repository, oxygen will be consumed by pyrite, because the reaction rate between pyrite and oxygen is relatively fast. (2)It is possible to estimate the redox capacity for reductants by rock (mineral)-water iteraction experiment in a laboratory. And it is expected that the ferrous iron-rich rock and higher porosity rock may have bigger redox capacity. (3)It is possible to estimate the oxygen consumption rate by reductants such as minerals including ferrous iron. The rate law and rate constant for the oxidation reaction of ferrous iron in the solution are also determined. As a conclusion, it seems that we can evaluate kinetically the evolution of geochemical conditions in the near field rock mass and buffer by excavation of drifts, based on data derived from these existing literatures.

Journal Articles

JAEA Reports

Development of Thermodynamic Databases for Geochemial Calculations

Arthur, R. C.*; Sasamoto, Hiroshi; Shibata, Masahiro; Yui, Mikazu; Neyama, Atsushi*

JNC-TN8400 99-079, 287 Pages, 1999/09

JNC-TN8400-99-079.pdf:9.78MB

Two thermodynamic databases for geochemical calculations supporting research and development on geological disposal concepts for high level radioactive waste are described in this report. One, SPRONS.JNC, is compatible with thermodynamic relations comprising the SUPCRT model and software, which permits calculation of the standard molal and partial molal thermodynamic properties of minerals, gases, aqueous species and reactions from 1 to 5000 bars and 0 to 1000$$^{circ}$$C. This database includes standard molal Gibbs free energies and enthalpies of formation, standard molal entropies and volumes, and Maier-Kelly heat capacity coefficients at the reference pressure (1 bar) and temperature (25$$^{circ}$$C) for 195 minerals and 16 gases. It also includes standard partial molal Gibbs free energies and enthalpies of formation, standard partial molal entropies, and Helgeson, Kirkham and Flowers (HKF) equation-of-state coefficients at the reference pressure and temperature for 1147 inorganic and organic aqueous ions and complexes. SPRONS.JNC extends similar databases described elsewhere by incorporating new and revised data published in the peer-reviewed literature since 1991. The other database, PHREEQE.JNC, is compatible with the PHREEQE series of geochemical modeling codes. It includes equilibrium constants at 25$$^{circ}$$C and 1 bar for mineral-dissolution, gas-solubility, aqueous-association and oxidation-reduction reactions. Reaction enthalpies, or coefficients in an empirical log K(T) function, are also included in this database, which permits calculation of equilibrium constants between 0 and 100$$^{circ}$$C at 1 bar. All equilibrium constants, reaction enthalpies, and logK(T) coefficients in PHREEQE.JNC are calculated usig SUPCRT and SPRONS.JNC, which ensures that these two databases are mutually consistent. They are also internally consistent insofar as all the data are compatible with basic thermodynamic definitions and functional relations in the SUPCRT ...

Journal Articles

A Critical evaluation of the redox properties of uranium, neptunium and plutonium ions in acidic aqueous solutions

Kihara, Sorin*; Yoshida, Zenko; Aoyagi, Hisao; Maeda, Koji*; Shirai, Osamu; Kitatsuji, Yoshihiro; Yoshida, Yumi*

Pure and Applied Chemistry, 71(9), p.1771 - 1807, 1999/09

no abstracts in English

JAEA Reports

Thermodynamic Date for Predicting Concentrations of AnO$$_{2}$$$$^{+}$$ and AnO$$_{2}$$$$^{2+}$$ Species in Geologic Environments

Choppin, G. R.*; Bronikowski, M.*; Chen, J.*; Byegard, J.*; Rai, D.*; Yui, Mikazu

JNC-TN8400 99-012, 155 Pages, 1999/01

JNC-TN8400-99-012.pdf:5.53MB

This report provides thermodynamic data for predicting concentrations of pentavalent and hexavalent actinide species (AnO$$_{2}^{+}$$ and AnO$$_{2}^{2+}$$) in geologic environments, and contributes to an integration of the JNC chemical thermodynamic database, JNC-TDB (previously PNC-TDB), for the performance analysis of geological isolation system for high-level radioactive wastes. Thermodynamic data for the formation of complexes or compounds with hydroxide, chloride, fluoride, carbonate, nitrate, sulfate and phosphate are discussed in this report. The estimation of the stability constants by use of the Born equation is included. The Pitzer parameters for AnO$$_{2}^{+}$$ and AnO$$_{2}$$$$^{2+}$$, redox potentials and equilibrium constants of redox reactions for actinides are also included.

JAEA Reports

None

PNC-TJ1150 98-004, 64 Pages, 1998/03

PNC-TJ1150-98-004.pdf:2.1MB

None

JAEA Reports

None

PNC-TJ1150 98-003, 99 Pages, 1998/03

PNC-TJ1150-98-003.pdf:4.39MB

None

JAEA Reports

None

Yokoi, Koichi*; *; *; *

PNC-TJ1380 96-002, 68 Pages, 1996/03

PNC-TJ1380-96-002.pdf:3.16MB

None

Journal Articles

Sequential separation of neptunium, plutonium, americium and curium using coprecipitation with bismuth phosphate

Kimura, Takaumi

Journal of Radioanalytical and Nuclear Chemistry, 139(2), p.307 - 314, 1990/00

 Times Cited Count:2 Percentile:67.56(Chemistry, Analytical)

no abstracts in English

Journal Articles

Extraction chromatography in the TBP-HNO$$_{3}$$ system, II; Characteristics of the TBP/XAD-4 resin on separation of actinide elements

Kimura, Takaumi

Journal of Radioanalytical and Nuclear Chemistry, 141(2), p.307 - 316, 1990/00

 Times Cited Count:11 Percentile:26.42(Chemistry, Analytical)

no abstracts in English

JAEA Reports

None

Gonda, Kozo; *

PNC-TN841 79-26, 240 Pages, 1979/02

PNC-TN841-79-26.pdf:5.11MB

no abstracts in English

JAEA Reports

None

Segawa, Takeshi*; Hoshino, Tadaya*; *; *; ; *; *

PNC-TN841 74-14, 48 Pages, 1974/06

PNC-TN841-74-14.pdf:1.39MB

no abstracts in English

Oral presentation

Redox behavior of RuO$$_{2}$$ particles in borosilicate glass melts

Nagai, Takayuki; Inose, Takehiko*; Sato, Seiichi*; Hatakeyama, Kiyoshi*; Seki, Katsumi*

no journal, , 

no abstracts in English

Oral presentation

Relation between redox reaction of vanadium and nitrogen oxide in nitric acid solution

Irisawa, Eriko; Suzuki, Kazunori*; Kumagai, Mikio*; Kato, Chiaki; Ueno, Fumiyoshi; Abe, Hitoshi

no journal, , 

For the corrosion of stainless steels in the nitric acid solution containing oxidizing metallic ions, it is important factor that the relation between re-oxidation of metallic ions which is reduced with the corrosion reaction and the redox reaction of nitric acid. To make clear the effect of nitrogen oxides formed from nitric acid on oxidation behavior of tetravalent vanadium, changing of concentrations of nitrogen oxide discharged to gas phase from solution and nitrous acid in solution during oxidation reaction of vanadium were measured. The results showed that the nitrogen dioxide acted as oxidant on the oxidation reaction of vanadium.

18 (Records 1-18 displayed on this page)
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