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JAEA Reports

Effects of overpack corrosion on redox potential of bentonite pore water under geological disposal environment; Important parameter acquisition and a preliminary ${it E}$h analysis (Contract research)

Otsuka, Ichiro; Taki, Hiroshi*; Yamaguchi, Tetsuji; Iida, Yoshihisa; Yamada, Fumika; Inada, Daisuke*; Tanaka, Tadao

JAEA-Research 2008-043, 101 Pages, 2008/03

JAEA-Research-2008-043.pdf:6.24MB

The influence of carbon steel overpack corrosion on redox potential (${it E}$h) of bentonite pore water under geological disposal environment was investigated. The thermodynamics data of corrosion products, the corrosion rate of carbon steel, and the information on cathode reactions were acquired by experiments and literature survey. We conducted preliminary analysis of ${it E}$h, ascertained the validity of Phreeq C and identified important points on the analysis. Results were summarized as follows. (1) Thermodynamic data of Fe$$^{2+}$$, FeOH$$^{+}$$, Fe(OH)$$_{2}$$(aq), Fe(OH)$$_{3}$$$$^{-}$$, Fe(OH)$$_{4}$$$$^{2-}$$, Fe$$^{3+}$$, FeS$$_{2}$$(pyrite), FeCO$$_{3}$$(siderite),Fe(OH)$$_{2}$$(s), Fe$$_{3}$$O$$_{4}$$(magnetite), Fe(cr) were determined by literature survey. The solubility product of Fe$$_{2}$$CO$$_{3}$$(OH)$$_{2}$$ was determined experimentally, and thermodynamic data were estimated. (2) The corrosion rate of carbon steel was obtained as a function of pH and sulfide ion concentration. (3) After corrosion tests of carbon steel, no CH$$_{4}$$, HS$$^{-}$$ and H$$_{2}$$S, the reduction product of CO$$_{3}$$$$^{2-}$$ and SO$$_{4}$$$$^{2-}$$,were not detected in liquid and gas phases. (4) Preliminary analysis showed that the redox couple changed as HS$$^{-}$$(aq)/SO$$_{4}$$$$^{2-}$$, CH$$_{4}$$(aq)/CO$$_{3}$$$$^{2-}$$, H$$_{2}$$(aq)/H$$_{2}$$O during the evaluation period. After 1000 years, ${it E}$h attained about -500 to -600 mV (vs. NHE) or -750 mV controlled by CH$$_{4}$$(aq)/CO$$_{3}$$$$^{2-}$$,or H$$_{2}$$(aq)/H$$_{2}$$O, respectively.

Journal Articles

Development and verification of a reactive transport model for long-term alteration of bentonite-cement-seawater systems

Yamaguchi, Tetsuji; Yamada, Fumika; Negishi, Kumi*; Hoshino, Seiichi; Mukai, Masayuki; Tanaka, Tadao; Nakayama, Shinichi

Physics and Chemistry of the Earth, 33(Suppl.1), p.S285 - S294, 2008/00

It is important to assess long-term alteration of engineered barrier composed of bentonite and cement for the safety assessment of radioactive waste disposal. In order to promote our development of the assessment methodologies, we developed a secondary mineral formation model for cement based materials and a hydraulic conductivity model for bentonite buffer materials. These models were verified by comparing with experimental observations. We also calculated changes in mineralogy of bentonite buffer materials and accompanying changes in the hydraulic conductivity over 10,000 y. We identified the temperature as an important factor dominating the alteration of the buffer. We also identified that the alteration is limited by slow kinetics of the dissolution of montmorillonite and by the diffusive mass transfer. Our calculation showed that the mineralogical change proceeds rather fast during the initial 1,000 y and slows down afterwards, and that salinity of the groundwater has both positive and negative effects on the hydraulic conductivity.

Journal Articles

Experimental results of 40-kA Nb$$_{3}$$Al cable-in-conduit conductor for fusion machines

Takahashi, Yoshikazu; Sugimoto, Makoto; Isono, Takaaki; Nakajima, Hideo; Ando, Toshinari; Oshikiri, Masayuki*; Hosono, Fumikazu*; *; *; Hanawa, Hiromi*; et al.

IEEE Transactions on Magnetics, 30(4, Part2), p.2531 - 2534, 1994/07

no abstracts in English

Oral presentation

Development of a coupled mass-transport/chemical reaction code for simulating variation in hydraulic conductivity of bentonite buffer in radioactive waste disposal

Yamada, Fumika; Yamaguchi, Tetsuji; Maeda, Toshikatsu; Mizuno, Tsuyoshi; Sakamoto, Yoshifumi*; Negishi, Kumi*; Tanaka, Tadao; Iida, Yoshihisa

no journal, , 

no abstracts in English

Oral presentation

Modeling of pore-water chemistry as a common base for understanding dissolution of montmorillonite and mass transport in compacted bentonite

Iida, Yoshihisa; Yamaguchi, Tetsuji; Yamada, Fumika; Maeda, Toshikatsu; Sakamoto, Yoshifumi*; Mizuno, Tsuyoshi; Tanaka, Tadao; Nakayama, Shinichi

no journal, , 

no abstracts in English

Oral presentation

Experimental research for long term evaluation on radioactive waste disposal; Progress in 2006

Tanaka, Tadao; Yamaguchi, Tetsuji; Iida, Yoshihisa; Kimura, Yuichiro; Taki, Hiroshi; Fujiwara, Takeshi; Ueda, Masato*; Mukai, Masayuki; Yamada, Fumika; Mizuno, Tsuyoshi; et al.

no journal, , 

no abstracts in English

Oral presentation

Diffusivity in hardened cement paste altered by contacting aqueous carbonate solutions

Hoshino, Seiichi; Yamaguchi, Tetsuji; Mukai, Masayuki; Yamada, Fumika; Negishi, Kumi*; Tanaka, Tadao; Nakayama, Shinichi

no journal, , 

no abstracts in English

Oral presentation

Effect of overpack corrosion on redox potential of bentonite pore water, 2; Determination of corrosion rate and cathode reaction by ampoule test

Otsuka, Ichiro; Taki, Hiroshi*; Yamaguchi, Tetsuji; Iida, Yoshihisa; Yamada, Fumika; Tanaka, Tadao; Nakayama, Shinichi; Kato, Osamu*; Tateishi, Tsuyoshi*

no journal, , 

no abstracts in English

Oral presentation

Effect of overpack corrosion on redox potential of bentonite pore water, 1; Estimation of redox potential by geochemical simulation

Yamada, Fumika; Otsuka, Ichiro; Yamaguchi, Tetsuji; Iida, Yoshihisa; Tanaka, Tadao; Nakayama, Shinichi

no journal, , 

no abstracts in English

Oral presentation

Experimental research for long term evaluation on radioactive waste disposal; Progress in 2007, Approach to modeling of alteration of cement based materials

Hoshino, Seiichi; Yamada, Fumika; Negishi, Kumi*; Mukai, Masayuki; Iida, Yoshihisa; Yamaguchi, Tetsuji; Tanaka, Tadao; Nakayama, Shinichi

no journal, , 

no abstracts in English

Oral presentation

Experimental research for long term evaluation on radioactive waste disposal; Progress in 2007

Kimura, Yuichiro; Yamaguchi, Tetsuji; Iida, Yoshihisa; Otsuka, Ichiro; Taki, Hiroshi*; Mukai, Masayuki; Yamada, Fumika; Hoshino, Seiichi; Kadowaki, Mitsushi; Tanaka, Tadao; et al.

no journal, , 

no abstracts in English

Oral presentation

Experimental study on mineralogical changes with interaction between cement and bentonite

Hoshino, Seiichi; Yamada, Fumika*; Mukai, Masayuki; Yamaguchi, Tetsuji; Tanaka, Tadao

no journal, , 

no abstracts in English

Oral presentation

Experimental research for long-term assessment of radioactive waste disposal, Status at 2008; Studies on alteration of cement and bentonite

Hoshino, Seiichi; Kadowaki, Mitsushi; Yamada, Fumika*; Mukai, Masayuki; Iida, Yoshihisa; Yamaguchi, Tetsuji; Tanaka, Tadao; Nakayama, Shinichi

no journal, , 

no abstracts in English

Oral presentation

Carbon-14 measurements of PM$$_{2.5}$$ from Noto peninsular in Kanazawa, Japan

Yamada, Rena*; Ikemori, Fumikazu*; Nakamura, Toshio*; Minami, Masayo*; Watanabe, Takahiro; Kinouchi, Kento*; Matsuki, Atsushi*

no journal, , 

PM$$_{2.5}$$ is becoming the focus of international attention, particularly in eastern Asia, because of air pollution and the health risks. Carbon is one of the major components in aerosol. Therefore, sources of the carbon compound should be known for the understanding material cycles and mechanism of the rise. Radiocarbon analysis is unique and useful techniques for estimation of carbon sources in environmental samples including aerosol. Hence half-life of radiocarbon is 5730 years, percent modern carbon (pMC) value based on radiocarbon concentration of fossil fuels are negligible. Therefore, pMC value can reveal the components of carbon in aerosol (biomass carbon versus fossil fuel). In this study, aerosol samples were taken at Noto Peninsula in Ishikawa pref., Japan, in order to estimate contribution rate of biomass carbon and/or fossil fuel in PM$$_{2.5}$$. The pMC values of PM$$_{2.5}$$ at Noto were more than 70 in the summer of 2014. These results show that biomass contribution is relative high in the area.

Oral presentation

Source apportionment of carbonaceous matter in PM$$_{2.5}$$ at NOTO peninsula using $$^{14}$$C analysis

Yamada, Rena*; Ikemori, Fumikazu*; Nakamura, Toshio*; Minami, Masayo*; Watanabe, Takahiro; Kinouchi, Kento*; Matsuki, Atsushi*

no journal, , 

Aerosols and clouds seeded by them both affect the heat budget of the Earth, but their RF (radiative forcing) still involves large uncertainty (IPCC 2013). One of the least understood properties of aerosols is the source and contribution of the organics. Our recent observation revealed that submicron aerosol particles in Noto peninsula also have a relatively high concentration (approximately more than 50%) of carbonaceous matter throughout the year. It is difficult to presume its sources specifying its chemical species in many scenes because of its great variety. However, we can presume its source by using carbon isotope ratio. We conducted sampling in NOTOGRO (NOTO ground-based research observatory), lying at the edge of Noto peninsula, from 26th Jun to 23rd July, 2014. We corrected PM$$_{2.5}$$ using high volume air sampler for every week. Flow rate was 700L/min, and quartz fiber filter was used for sampling. $$^{14}$$C was analyzed using AMS $$^{14}$$C system (High Voltage Engineering Europe, Model 4130-AMS) and $$^{13}$$C using IRMS (isotope ratio mass spectrometer) in Nagoya University. As a result, it was found that 4 samples collected from 26th Jun to 23rd July had approximately 70 percent modern carbon (pMC). This result shows that modern plant (and/or biomass burning) activities mainly contribute to the submicron organic particle concentration in Noto peninsula.

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