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Ishidera, Takamitsu; Kurosawa, Seiichi*; Hayashi, Masanori*; Uchikoshi, Keiji*; Beppu, Hikari*
Clay Minerals, 51(2), p.161 - 172, 2016/05
Times Cited Count：4 Percentile：13.09(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.
Goto, Takahiro*; Mitsui, Seiichiro; Takase, Hiroyasu*; Kurosawa, Susumu*; Inagaki, Manabu*; Shibata, Masahiro; Ishiguro, Katsuhiko*
MRS Advances (Internet), 1(63-64), p.4239 - 4245, 2016/00
NUMO and JAEA have conducted a joint research since FY2011, which is designed to enhance the methodology of repository design and performance assessment in preliminary investigation stage for deep geological disposal of radioactive waste. As a part of this joint research, we have been developing glass dissolution models which consider various processes in EBS, such as precipitation of Fe-silicates associated with iron overpack corrosion, and Si transport through corrosion products in the cracked overpack. The objectives of the modeling work are to evaluate relative importance of relevant processes and to identify further R&D issues towards development of a convincing safety case. Sensitivity analyses suggested that predicted glass dissolution time ranges from 1
10
to 110
years or more due to uncertainties in the current understanding of the key processes, namely precipitation of Fe-silicates and transport characteristics of the altered glass layer.
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.
Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Hayano, Akira; Makino, Hitoshi; Wakasugi, Keiichiro; Mitsui, Seiichiro; Oda, Chie; Kitamura, Akira; Osawa, Hideaki; et al.
JAEA-Research 2013-037, 455 Pages, 2013/12
JAEA-Research-2013-037.pdf:42.0MB
Following FY2011, JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and performance assessment in preliminary investigation stage. With regard to (1) study on rock suitability in terms of hydrology, the tree diagram of methodology of groundwater travel time has been extended for crystalline rock, in addition, tree diagram for sedimentary rock newly has been organized. With regard to (2) study on scenario development, the existing approach has been improved in terms of a practical task, and applied and tested for near field focusing on the buffer. In addition, the uncertainty of some important processes and its impact on safety functions are discussed though analysis. With regard to (3) study on setting radionuclide migration parameters, the approaches for parameter setting have been developed for sorption for rocks and solubility, and applied and tested through parameter setting exercises for key radionuclides.
Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Makino, Hitoshi; Hayano, Akira; Mitsui, Seiichiro; Taniguchi, Naoki; Oda, Chie; Kitamura, Akira; Osawa, Hideaki; et al.
JAEA-Research 2012-032, 298 Pages, 2012/09
JAEA-Research-2012-032.pdf:33.68MB
JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and performance assessment in preliminary investigation phase. The topics and the conducted research are follows; (1) Study on selection of host rock: in terms of hydraulic properties, items for assessing rock property, and assessment methodology of groundwater travel time has been organized with interaction from site investigation. (2) Study on development of scenario: the existing approach has been embodied, in addition, the phenomenological understanding regarding dissolution of and nuclide release from vitrified waste, corrosion of the overpack, long-term performance of the buffer are summarized. (3) Study on setting nuclide migration parameters: the approach for parameter setting has been improved for sorption and diffusion coefficient of buffer/rock, and applied and tested for parameter setting of key radionuclides. (4) Study on ensuring quality of knowledge: framework for ensuring quality of knowledge has been studied and examined aimed at the likely disposal facility condition.
Sakuraba, Naotoshi; Numata, Masami; Komiya, Tomokazu; Ichise, Kenichi; Nishi, Masahiro; Tomita, Takeshi; Usami, Koji; Endo, Shinya; Miyata, Seiichi; Kurosawa, Tatsuya; et al.
JAEA-Technology 2009-071, 34 Pages, 2010/03
JAEA-Technology-2009-071.pdf:21.07MB
As a part of maintenance technology of a large-sized glove box for handling of TRU nuclides, we developed replacement technology for front acrylic panels using the bag-in/bag-out method and applied this technology to replace the deteriorated front acrylic panels at Waste Safety Testing Facility (WASTEF) in Nuclear Science Research Institute of Japan Atomic Energy Agency (JAEA). As a consequence, we could safely replace the front acrylic panels under the condition of continuous negative pressure only with partial decontamination of the glove box. We also demonstrated that the present technology is highly effective in points of safety, workability and cost as compared to the usual replacement technology for front acrylic panels of a glove box, where workers in an air-line suit replace directly the front acrylic panels in a green house.
Tsujimura, Seiichi; Funabashi, Hideyuki; Ishibashi, Makoto*; Takase, Toshio*; Kurosawa, Mitsuru*
JAEA-Research 2007-030, 105 Pages, 2007/03
JAEA-Research-2007-030.pdf:7.72MB
Uranium waste has characteristics that it is rarely expected to decay its radioactivity and it is not almost recessary to consider external exposure to radiation from waste package. We studied resonable sub-surface disposal concepts for uranium waste considering the characteristics. It showed feasibility of this system. In 2006, the study was done to evaluate the correlation between dose to the public and the parameter in consideration of the uncertainty of the parameter by comprehensive sensitivity analysis calculating repeatedly dose with the data sets by random sampling in parameter ranges given adequately, because last year's study was an evaluation intended for a limited site. The result was that two parameters, "flow velocity of underground water of repository neighborhood" and "distribution coefficient of uranium in natural barrier", had correlation with dose to the public.
Tsujimura, Seiichi; Funabashi, Hideyuki; Ishibashi, Makoto*; Takase, Toshio*; Kurosawa, Mitsuru*
JAEA-Research 2006-029, 96 Pages, 2006/07
JAEA-Research-2006-029.pdf:3.97MB
Uranium waste has characteristics that it is rarely expected to decay its radioactivities and it is not almost necessary to consider external exposure to radiation from waste package. We studied reasonable sub-surface disposal concepts for uranium waste in 2004 and 2005 considering the characteristics. In 2005, we studied necessity of engineered barrier for the disposal of uranium waste, considering change of chemical condition around disposal facilities over long periods of time. Safety assessment was made to analyze effect of difference in sorption parameters at reduction and oxidation conditions. The assessment showed that change from reduction to oxidation around disposal facilities did not lead to increase dose to the public. The assessment with realistic sorption parameters showed that dose to the public was not more than 10 
Sv/y. The results proved that it was not necessary to keep reduction conditions around disposal facilities. This two-year- study showed that there was possibility of sub-surface disposal system without engineered barrier for uranium waste.
Ishidera, Takamitsu; Kurosawa, Seiichi*; Otsuka, Shunji*; Hayashi, Masanori*; Uchikoshi, Keiji*; Suzuki, Yasuyuki*
no journal, ,
no abstracts in English
Ishidera, Takamitsu; Kurosawa, Seiichi*; Hayashi, Masanori*; Suzuki, Yasuyuki*
no journal, ,
In the geological disposal of high-level radioactive waste (HLW) in Japan, potential impact of bentonite colloid on the migration of radionuclides needs to be evaluated in the performance assessment of geological disposal. Japan Atomic Energy Agency (JAEA) has been investigating sorption behavior of radionuclides on bentonite colloid and developing the evaluation model for the radionuclide sorption behavior on bentonite colloid. In our previous studies, the sorption behavior of Cs and Am on bentonite colloid was well interpreted by the evaluation model based on a previously reported sorption model for non-colloidal bentonite. In the presentation, the evaluation model for distribution coefficient of radionuclides sorption on bentonite colloid will be introduced in detail and the application result of evaluation model to the sorption behavior of Np on bentonite colloid will be shown.
Nakata, Kotaro*; Ishidera, Takamitsu; Kurosawa, Seiichi*; Hayashi, Masanori*; Beppu, Hikari*; Sukegawa, Akihiro*
no journal, ,
no abstracts in English
Iijima, Kazuki; Yoshikawa, Hideki; Kurosawa, Seiichi*
no journal, ,
Diffusion behavior of humic acid in compacted bentonite was investigated with Kunigel V1 in 0.1M NaCl solution. In case of 1.2 Mg/m
of dry density, breakthrough of the fumic acid was observed after 100 days. On the other hand, in case of 1.6 and 1.8 of dry density, no breakthrough was observed even after 500 days. Based on the measurement of size distribution of humic acid by GPC, it is suggested that relatively bigger humic acid cannot diffuse but smaller one due to the filtration effect of compacted bentonite.
Ishidera, Takamitsu; Kurosawa, Seiichi*
no journal, ,
no abstracts in English
Iijima, Kazuki; Kurosawa, Seiichi*; Tobita, Minoru*; Kibe, Satoshi*
no journal, ,
Diffusion behavior of humic acid in compacted bentonite was investigated by through-diffusion experiments under the conditions with various dry density and NaCl concentration. Limitation of filtration effect of the compacted bentonite with 1.2 Mg m
of dry density in 1 mol dm of NaCl solution is around 3,000 of molecular weight, based on the molecular weight distribution of humic acid before and after the experiment measured by size exclusion chromatography.
Iijima, Kazuki; Kurosawa, Seiichi*; Kibe, Satoshi*; Tobita, Minoru*; Ouchi, Yuji*
no journal, ,
Diffusion behavior of humic acid and Nd in the presence of humic acid was investigated and modeled. Breakthrough of humic acid is observed in 0.1 and 1M NaCl with 1.2-1.6 Mg/m dry density of compacted bentonite. The presence of humic acid facilitates the migration of Nd. Diffusion Parameters were evaluated from experimental results using the one dimensional diffusion model in which migration of several Nd species with different diffusion behaviors keeping equilibrium in parallel was taken into account. Obtained diffusion parameters for humic acid and Nd will be used for prediction of diffusion behavior of radionuclides in the presence of humic acid under various conditions.
Ishidera, Takamitsu; Kurosawa, Seiichi*; Kibe, Satoshi*; Ouchi, Yuji*
no journal, ,
no abstracts in English
Mitsui, Seiichiro; Oe, Toshiaki*; Inagaki, Yaohiro*; Okubo, Takahiro*; Kurosawa, Susumu*; Goto, Takahiro*; Inagaki, Manabu*; Ishiguro, Katsuhiko*; Takase, Hiroyasu*; Takahashi, Hirokazu*
no journal, ,
In order to develop robust performance assessment models, we have been preparing an information basis regarding glass properties and glass dissolution/alteration processes under disposal conditions as a part of NUMO-JAEA joint project. Our iterative working process for the preparation of the information basis comprises five steps: (1) integration of current knowledge; (2) development of glass dissolution scenarios based on current knowledge; (3) development of conceptual model; (4) sensitivity analyses to evaluate relative importance of relevant processes and associated uncertainties; and (5) identification of future R&D issues towards further improvement of the information basis. The current status will be presented in this talk.
Nakata, Kotaro*; Ishidera, Takamitsu; Kurosawa, Seiichi*; Hayashi, Masanori*; Beppu, Hikari*; Sukegawa, Akihiro*
no journal, ,
no abstracts in English
Ishidera, Takamitsu; Tran, P.*; Kurosawa, Seiichi*; Kibe, Satoshi*
no journal, ,
no abstracts in English
fuel and nucleonics analysis, 2; Measurements of FP nuclidesIto, Mitsuo; Fukaya, Hiroyuki; Ueno, Takashi; Miyata, Seiichi; Sonoda, Takashi; Usami, Hidehiko; Sakazume, Yoshinori; Kurosawa, Tatsuya; Kawasaki, Yasushi; Inagawa, Jun; et al.
no journal, ,
no abstracts in English
