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Journal Articles

Diffusion of acetic acid, butyric acid, and butanol in compacted montmorillonite

Ishidera, Takamitsu

Journal of Radioanalytical and Nuclear Chemistry, 330(1), p.149 - 158, 2021/10

 Times Cited Count:0 Percentile:0.01(Chemistry, Analytical)

Journal Articles

Development of evaluation method for diffusion and filtration behavior of colloid in compacted bentonites using dendrimers

Endo, Takashi*; Tachi, Yukio; Ishidera, Takamitsu; Terashima, Motoki

Nihon Genshiryoku Gakkai Wabun Rombunshi, 20(1), p.9 - 22, 2021/03

Evaluation method of colloid diffusion and filtration in compacted bentonites was developed using dendrimers. Diffusion and filtration behavior of PAMAM dendrimers with the size of 5.7$$sim$$7.2nm was investigated by the through-diffusion experiment in bentonite compacted to 0.8 Mg/m$$^{3}$$ and saturated with 0.005$$sim$$0.5mol/L NaCl. Effective diffusivities (De) and filtration ratios (Rf) of dendrimers were determined from the breakthrough curves and the depth profiles in compacted bentonite, respectively. The De values of negatively charged dendrimer increased when porewater salinity increased and dendrimer size decreased as influenced by anion exclusion effect in negatively charged clay surfaces. The Rf values increased when porewater salinity decreased and dendrimer size increased, demonstrating significant fractions of dendrimer were filtered by narrow pores in complex pore networks. These trends consistent with the previous studies emphasize the validity of the evaluation method using dendrimer.

Journal Articles

Surface complexation of Ca and competitive sorption of divalent cations on montmorillonite under alkaline conditions

Sugiura, Yuki; Ishidera, Takamitsu; Tachi, Yukio

Applied Clay Science, 200, p.105910_1 - 105910_10, 2021/01

 Times Cited Count:2 Percentile:0.03(Chemistry, Physical)

Journal Articles

Key factors controlling radiocesium sorption and fixation in river sediments around the Fukushima Daiichi Nuclear Power Plant, 2; Sorption and fixation behaviors and their relationship to sediment properties

Tachi, Yukio; Sato, Tomofumi*; Takeda, Chizuko*; Ishidera, Takamitsu; Fujiwara, Kenso; Iijima, Kazuki

Science of the Total Environment, 724, p.138097_1 - 138097_10, 2020/07

 Times Cited Count:2 Percentile:39.03(Environmental Sciences)

To understand and predict radiocesium transport behaviors in the environment, sorption and fixation behaviors of radiocesium on river sediments from Ukedo and Odaka rivers around the Fukushima Daiichi Nuclear Power Plant were investigated systematically focusing on Cs sorption and fixation mechanisms and their relationship with Cs concentrations and sediment properties including clay mineralogy and organic matter.

Journal Articles

Sorption behavior of selenide on montmorillonite

Sugiura, Yuki; Tomura, Tsutomu*; Ishidera, Takamitsu; Doi, Reisuke; Francisco, P. C. M.; Shiwaku, Hideaki; Kobayashi, Toru; Matsumura, Daiju; Takahashi, Yoshio*; Tachi, Yukio

Journal of Radioanalytical and Nuclear Chemistry, 324(2), p.615 - 622, 2020/05

 Times Cited Count:1 Percentile:0.01(Chemistry, Analytical)

Journal Articles

Interaction of Fe$$^{II}$$ and Si under anoxic and reducing conditions; Structural characteristics of ferrous silicate co-precipitates

Francisco, P. C. M.; Mitsui, Seiichiro; Ishidera, Takamitsu; Tachi, Yukio; Doi, Reisuke; Shiwaku, Hideaki

Geochimica et Cosmochimica Acta, 270, p.1 - 20, 2020/02

 Times Cited Count:4 Percentile:74.86(Geochemistry & Geophysics)

Journal Articles

Sorption behavior of U and Np on zeolite

Ishidera, Takamitsu; Tachi, Yukio; Akagi, Yosuke*; Ashida, Takashi

Progress in Nuclear Science and Technology (Internet), 5, p.221 - 224, 2018/11

In Fukushima Daiichi Nuclear Power Station, radionuclides are removed from contaminated water by the decontamination system using zeolite. In this study, sorption properties of U and Np on zeolite were investigated by batch sorption experiments to obtain fundamental information for predicting the radionuclides inventory. High distribution coefficients were observed for U in the simulated sea water diluted 10 times by deionized water. In contrast, low distribution coefficient of U was observed in simulated sea water. Low distribution coefficients were observed for Np independent of simulated sea water concentration. Batch sorption experiments of U carried out as functions of sodium ion and total inorganic carbon concentration suggested that the distribution coefficient of U was strongly affected by the total inorganic carbon concentration. This result suggests that aqueous species of radionuclides and their sorption behavior need to be considered to estimate the inventory of radionuclides in zeolite.

Journal Articles

Brief introduction of repository design and engineering technology, and safety assessment on the geological disposal of radioactive waste

Ishidera, Takamitsu

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 23(1), p.99 - 101, 2016/06

In this presentation, the author introduced an overview of the research and development on repository design and engineering technology and safety assessment on the geological disposal of radioactive waste as well as the examples of evaluation methods used in these R&Ds and recent studies.

Journal Articles

Diffusion and retention behaviour of Cs in illite-added compacted montmorillonite

Ishidera, Takamitsu; Kurosawa, Seiichi*; Hayashi, Masanori*; Uchikoshi, Keiji*; Beppu, Hikari*

Clay Minerals, 51(2), p.161 - 172, 2016/05

 Times Cited Count:4 Percentile:20.47(Chemistry, Physical)

The sorption and diffusion behavior of Cs in illite-added compacted montmorillonite was investigated by through-diffusion experiment. The obtained distribution coefficient of Cs for the illite-added compacted montmorillonite was several times larger than that for the montmorillonite without illite, while no increase of effective diffusion coefficient was observed for the illite-added compacted montmorillonite. The dominant sorption site of Cs on illite is considered to be the frayed edge site (FES) considering the Cs concentration in this experiment. Therefore, the surface diffusion of Cs sorbing on the FES on illite surface was considered to be negligible in compacted montmorillonite.

JAEA Reports

Enhancement of the methodology of repository design and post-closure performance assessment for preliminary investigation stage, 3; Progress report on NUMO-JAEA collaborative research in FY2013 (Joint research)

Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Makino, Hitoshi; Wakasugi, Keiichiro; Mitsui, Seiichiro; Kitamura, Akira; Yoshikawa, Hideki; Oda, Chie; Ishidera, Takamitsu; et al.

JAEA-Research 2014-030, 457 Pages, 2015/03

JAEA-Research-2014-030.pdf:199.23MB

JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and post-closure performance assessment in preliminary investigation stage. With regard to (1) study on rock suitability in terms of hydrology, based on some examples of developing method of hydro-geological structure model, acquired knowledge are arranged using the tree diagram, and model uncertainty and its influence on the evaluation items were discussed. With regard to (2) study on scenario development, the developed approach for "defining conditions" has been reevaluated and improved from practical viewpoints. In addition, the uncertainty evaluation for the effect of use of cementitious material, as well as glass dissolution model, was conducted with analytical evaluation. With regard to (3) study on setting radionuclide migration parameters, based on survey of precedent procedures, multiple-approach for distribution coefficient of rocks was established, and the adequacy of the approach was confirmed though its application to sedimentary rock and granitic rock. Besides, an approach for solubility setting was developed including the procedure of selection of solubility limiting solid phase. The adequacy of the approach was confirmed though its application to key radionuclides.

Journal Articles

Corrosion products from carbon steel formed in compacted bentonite under reducing conditions

Ishidera, Takamitsu; Xia, X.*; Idemitsu, Kazuya*; Kikuchi, Yoshio*

Journal of Nuclear Science and Technology, 45(8), p.763 - 772, 2008/08

 Times Cited Count:5 Percentile:37.69(Nuclear Science & Technology)

For safety assessment of high-level radioactive waste disposal, it is important to identify the forms of corrosion products migrating from overpack material into compacted bentonite. In this study, the carbon steel, which was previously corroded electrochemically under aerobic condition, was in contact with compacted Kunigel V1 and Kunipia F under reducing condition for 3-4 years at room temperature. The corrosion products migrating from carbon steel into compacted bentonites were investigated by the selective dissolution analysis, which can estimate the crystallinity of Fe-bearing compounds. The valence of iron in corrosion products was investigated spectrophotometrically. Furthermore, the alteration of smectite contained in compacted bentonite to Fe-smectite was analyzed by X-ray diffractometry (XRD). The results of selective dissolution and valence analysis suggested that the corrosion products in compacted bentonite were amorphous, non-crystalline or poorly ordered Fe(OH)$$_{2}$$ and Fe(OH)$$_{3}$$. In the XRD profiles, no diffraction peak suggesting the existence of Fe-smectite in the compacted bentonite was found. Therefore, the corrosion products in compacted bentonite were considered to have no effect on the alteration of smectite contained in Kunigel V1 and Kunipia F to Fe-smectite.

Journal Articles

Effect of sodium nitrate on the diffusion of Cl$$^{-}$$ and I$$^{-}$$ in compacted bentonite

Ishidera, Takamitsu; Miyamoto, Shinya*; Sato, Haruo

Journal of Nuclear Science and Technology, 45(7), p.610 - 616, 2008/07

 Times Cited Count:11 Percentile:59.39(Nuclear Science & Technology)

For safety assessment of TRU waste disposal, the effective diffusion coefficients ($$D$$$$_{e}$$) for CO$$_{3}$$$$^{2-}$$, Cl$$^{-}$$ and I$$^{-}$$ ions in compacted bentonite (Kunigel V1) were determined as a function of NaNO$$_{3}$$ concentrations from 0.01 to 5 mol/dm$$^{3}$$. The $$D$$$$_{e}$$ values increased from 10$$^{-12}$$ to 10$$^{-11}$$ m$$^{2}$$/s with increasing NaNO$$_{3}$$ concentration. The rock capacity factor $$alpha$$, indicative of the effective porosity, were also increased with increasing NaNO$$_{3}$$ concentration. The maximum $$alpha$$ values of 0.21 for Cl$$^{-}$$ ion and of 0.25 for I$$^{-}$$ ion at 5 mol/dm$$^{3}$$ NaNO$$_{3}$$ concentration were lower than the net porosity of compacted bentonite (0.40). Therefore, the increases in the $$D$$$$_{e}$$ values were interpreted by the decrease of anion exclusion effect. The $$D$$$$_{e}$$ values for Cl$$^{-}$$ and I$$^{-}$$ ions normalized by the diffusivities for diffusants in the bulk water were found to increase in proportion to the $$alpha$$ values on the log-log diagram. The maximum $$alpha$$ value for CO$$_{3}$$$$^{2-}$$ ion was higher than the net porosity. The high concentration of CO$$_{3}$$$$^{2-}$$ ion was also found in the concentration profile in compacted bentonite. This retention of CO$$_{3}$$$$^{2-}$$ ion was possibly accounted for by isotopic exchange of $$^{14}$$C with inactive carbon of calcite in Kunigel V1.

Journal Articles

Acquisition of the data and their conversion to the data bases for the radionuclides migration under deep underground environment

Yoshikawa, Hideki; Shibata, Masahiro; Sasamoto, Hiroshi; Iijima, Kazuki; Sato, Haruo; Kitamura, Akira; Ishidera, Takamitsu; Fujiwara, Kenso; Kurosawa, Susumu; Xia, X.; et al.

Hoshasei Haikibutsu Anzen Kenkyu Nenji Keikaku (Heisei-13-Nendo$$sim$$Heisei-17-Nendo) Kenkyu Seika Hokokushu, p.153 - 170, 2006/03

no abstracts in English

JAEA Reports

The Effect of NaNO$$_{3}$$on Diffusion of CO$$_{3}$$$$^{2-}$$, Cl$$^{-}$$and I$$^{-}$$ Ions in Tuff

Ishidera, Takamitsu; Sato, Haruo

JNC TN8400 2005-018, 49 Pages, 2005/09

JNC-TN8400-2005-018.pdf:1.6MB

The migration data of$$^{14}$$C,$$^{36}$$Cl and$$^{129}$$I nuclides are required for safety assessment of TRU waste disposal. The specific phenomena for TRU waste disposal such as the influence of NaNO$$_{3}$$concentration and the hyper alkaline groundwater due to degradation of cementitious materials should be considered for reliable safety assessment. In this study, the effective diffusion coefficient (De) for CO$$_{3}$$$$^{2-}$$, Cl$$^{-}$$and I$$^{-}$$ions in tuff were determined with various NaNO$$_{3}$$ concentrations under hyper alkaline condition. The obtained De values for CO$$_{3}$$$$^{2-}$$, Cl$$^{-}$$and I$$^{-}$$ions were on the order of 10$$^{-12}$$-10$$^{-11}$$m$$^{2}$$/s and decreased with increasing NaNO3 concentration. The De values for HDO and HTO were also decreased with increasing NaNO$$_{3}$$ concentration. Because the degradation of tuff samples was not observed by X-Ray diffractometry, SEM and EPMA, the decreases in the De values were considered to be due to the decreases in the diffusivities in free water. The apparent diffusion coefficient (Da) values for Cl$$^{-}$$ion with 5mol/dm$$^{3}$$ NaNO$$_{3}$$concentration and for CO$$_{3}$$$$^{2-}$$ion were lower than those of the other conditions. These low Da values suggested retardation in tuff samples.

Journal Articles

The Effect of Silica Sand Content on Diffusion of CO$$_{3}$$$$^{2-}$$, Cl$$^{-}$$ and I$$^{-}$$ ions in Compacted Bentonite

Ishidera, Takamitsu; Miyamoto, Shinya*; Sato, Haruo

JAERI-Conf 2005-007, p.264 - 269, 2005/05

For safety assessment of TRU waste disposal, the effective diffusion coefficients (De) for CO$$_{3}$$$$^{2-}$$, Cl$$^{-}$$ and I$$^{-}$$ ions in compacted bentonite (Kunigel V1) were determined as a function of silica sand contents under hyper alkaline condition. The obtained De values for three diffusants were on the order of 10$$^{-13}$$ - 10$$^{-11}$$ m$$^{2}$$/s and increased with increasing silica sand content. The effective porosity for diffusion of Cl$$^{-}$$ and I$$^{-}$$ ions, estimated from the rock capacity factor values, were also increased with increasing silica sand content. This close relationship indicated that the increases in the De values were due to the increase in effective porosity with increasing silica sand content. In the case of CO$$_{3}$$$$^{2-}$$ ion, the rock capacity factor values were higher than those for Cl$$^{-}$$ and I$$^{-}$$ ions. The Da values for CO$$_{3}$$$$^{2-}$$ ion were approximately one order of magnitude lower than those for Cl$$^{-}$$ and I$$^{-}$$ ions. The differences in these behaviors suggested a possibility of isotopic exchange of $$^{14}$$C with the carbon of calcite contained in Kunigel V1.

JAEA Reports

Diffusion of Iron and Neptunium in Buffer Material

Arima, Tatsumi*; Idemitsu, Kazuya*; Xia, X.; Ishidera, Takamitsu; Iijima, Kazuki

JNC TY8400 2004-005, 59 Pages, 2004/05

JNC-TY8400-2004-005.pdf:1.3MB

For the safety assessment of high level waste disposal, it is necessary to investigate the radionuclide migration in the presence of corrosion products of carbon steel under reducing condition. In this study, the reliable apparent diffusion coefficients of neptunium (Np) in bentonite were obtained by in-diffusion method and migration of the corrosion products was investigated. Furthermore, effects of the corrosion of carbon steel on Np diffusion were discussed. The corrosion of carbon steel under reducing condition provided Fe$$^{2+}$$ions, which were considered to migrate in the interlayer spaces of montmorillonite sheets of bentonite exchanging with two Na$$^{+}$$ions. The corrosion rate of carbon steel was controlled by the diffusivity of Fe$$^{2+}$$ions into bentonite when they were accumulated at the surface of carbon steel. The corrosion rate increased with increasing dry density of bentonite because of the increase of the diffusivity of Fe$$^{2+}$$ions. The corrosion rate was estimated to be ~0.1 micro m/y, which was remarkable lower than the setting value, 20 micro m/y, in the second progress report. The Np profiles in the bentonite consisted of two overlapping slopes, a fast and a slow fractions, for both the experiments with and without carbon steel. The apparent diffusion coefficients of the fast and the slow fraction of Np were 10$$^{-13}$$~10$$^{-12}$$m$$^{2}$$/s and 10$$^{-15}$$~10$$^{-14}$$m$$^{2}$$/s, which were considered to be the diffusion of Np(V) and Np(IV), respectively. The corrosion of carbon steel provided strong reducing condition to keep most Np in the low oxidation state, Np(IV), which has lower solubility and mobility than Np(V). Therefore, it could be expected that the corrosion of carbon steel will restrain effectively migration of Np into the bentonite.

JAEA Reports

The Effect of Silica Sand Content and NaNO$$_{3}$$Concentration on Diffusions of C, Cl and I in Compacted Bentonite

Ishidera, Takamitsu; Miyamoto, Shinya*; Sato, Haruo

JNC TN8400 2004-001, 21 Pages, 2004/05

JNC-TN8400-2004-001.pdf:0.43MB

For safety assessment of geological disposal of TRU waste, it is necessary to obtain the diffusivities of C-14, Cl-36 and I-129 and to estimate the effects of the dissolution of NaNO$$_{3}$$and high pH groundwater condition caused by dissolution of cementitious materials. Therefore, the effective diffusion coefficients (De) and the apparent diffusion coefficients (Da) of CO$$_{3}$$$$^{2-}$$, Cl$$^{-}$$and I$$^{-}$$in compacted bentonite were obtained as a function of silica sand content and NaNO$$_{3}$$concentration under high pH condition by Through-diffusion method. Furthermore, the diffusion mechanisms of CO$$_{3}$$$$^{2-}$$, Cl$$^{-}$$and I$$^{-}$$were discussed.The obtained De values of CO$$_{3}$$$$^{2-}$$, Cl$$^{-}$$and I$$^{-}$$were in a range of 10$$^{-13}$$to 10$$^{-10}$$m$$^{2}$$/s order and Da values in a range of 10$$^{-12}$$to 10$$^{-11}$$m$$^{2}$$/s order (CO$$_{3}$$$$^{2-}$$) and 10$$^{-10}$$m$$^{2}$$/s order (Cl$$^{-}$$and I$$^{-).}$$The De and Da values of CO$$_{3}$$$$^{2-}$$, Cl$$^{-}$$and I$$^{-}$$increased with increasing silica sand content. The changes of De and Da values appeared to be estimated by smectite partial density. The De values of CO$$_{3}$$$$^{2-}$$, Cl$$^{-}$$and I$$^{-}$$increased with increasing NaNO$$_{3}$$concentration. The increases were interpreted by the decrease of anion exclusion effect. Furthermore, it seems that the pathways of Cl$$^{-}$$and I$$^{-}$$were limited to the interstitial pore space. The CO$$_{3}$$$$^{2-}$$ions were probably retained in the Kunigel V1 as the precipitation of calcite.

Journal Articles

The Effect of Silica Sand Content and NaNO$$_{3}$$on Diffusion of CO$$_{3}$$$$^{2-}$$, Cl$$^{-}$$ and I$$^{-}$$ in Compacted Bentonite

Ishidera, Takamitsu; Shinya, Miyamoto,; Sato, Haruo

Saikuru Kiko Giho, (25), p.85 - 93, 2004/00

The concept of air transport of A Type package containing nuclear fuel materials according to the nuclear disaster countermeasures law, and the experience of a transportation of plutonium solution from France are shown.

Journal Articles

The Effects of Silica Sand Content and NaNO$$_{3}$$ Concentration on Diffusion of C, Cl and I in Compacted Bentonite

Ishidera, Takamitsu; Sato, Haruo; Miyamoto

Migration 2003, PB-4, 145 Pages, 2003/00

None

Journal Articles

Corrosion of Carbon Steel in Compacted Bentonite and its Effect on Neptunium Diffusion under Reducing Condition

Xia, X.; Ishidera, Takamitsu; Arima, Tatsumi*; Inagaki, Yaohiro*

P.290-291(2003), p.290 - 291, 2003/00

None

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