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Laboratory, SwedenSasamoto, Hiroshi; Isogai, Takeshi*; Kikuchi, Hirohito*; Sato, Hisao*; Svensson, D.*
Clay Minerals, 52(1), p.127 - 141, 2017/03
Times Cited Count：3 Percentile：10.42(Chemistry, Physical)Compacted bentonite has been considered as a candidate of engineering barrier material in many countries for the safe disposal of high-level radioactive waste. SKB set up an in situ experiment (named ABM project) to compare the stability of different bentonites under the conditions exposed to an iron source and elevated temperature (up to 130
C as maximum) at the sp Hard Rock Laboratory, Sweden. Results for the Japanese bentonite (Kunigel V1) are summarized in the present paper. Mineralogical investigation using X-ray diffraction (XRD) and X-ray spectroscopy (SEM-EDX) suggested that no indication of smectite transformation or newly formed clay phases were observed. However, a distinct change of exchangeable cations of smectite was indicated (i.e., from Na type to Fe type) in the bentonite at the vicinity of the steel heater. Physical investigation by measurements of hydraulic conductivity and swelling property suggested that no significant change occur in the bentonite even at the vicinity of the steel heater. Such results might be considered due to the limited portion affected by the iron-bentonite interactions and partially occurred ion exchange reactions. Chemical investigation based on the measurements of methylane blue (MB), cation exchange capacity (CEC) and exchangeable cations showed that the lateral distribution for these parameters were basically constant without the significant gradient.
Isogai, Takeshi*; Sasamoto, Hiroshi
JAEA-Research 2009-059, 28 Pages, 2010/02
JAEA-Research-2009-059.pdf:5.47MB
Porewater model of bentonite is important to evaluate the behavior of radionuclides and corrosion of overpack material for performance assessment of geologic disposal of high level radioactive waste. In the present study, as a matter of consideration for applicability of porewater model to the actual geological environment, experiments of bentonite-water interactions using groundwater sampled from Horonobe underground laboratory were conducted. In order to test the applicability of model, comparison between the data obtained by experiments and modeling results by porewater model based on chemical equilibrium was performed.
Yamasaki, Chisato*; Murakami, Katsuhiko*; Fujii, Yasuyuki*; Sato, Yoshiharu*; Harada, Erimi*; Takeda, Junichi*; Taniya, Takayuki*; Sakate, Ryuichi*; Kikugawa, Shingo*; Shimada, Makoto*; et al.
Nucleic Acids Research, 36(Database), p.D793 - D799, 2008/01
Times Cited Count：51 Percentile：71.25(Biochemistry & Molecular Biology)Here we report the new features and improvements in our latest release of the H-Invitational Database, a comprehensive annotation resource for human genes and transcripts. H-InvDB, originally developed as an integrated database of the human transcriptome based on extensive annotation of large sets of fulllength cDNA (FLcDNA) clones, now provides annotation for 120 558 human mRNAs extracted from the International Nucleotide Sequence Databases (INSD), in addition to 54 978 human FLcDNAs, in the latest release H-InvDB. We mapped those human transcripts onto the human genome sequences (NCBI build 36.1) and determined 34 699 human gene clusters, which could define 34 057 protein-coding and 642 non-protein-coding loci; 858 transcribed loci overlapped with predicted pseudogenes.
Isogai, Takeshi*; Sasamoto, Hiroshi; Shibata, Masahiro
JAEA-Data/Code 2006-017, 37 Pages, 2006/07
JAEA-Data-Code-2006-017.pdf:4.39MB
We have been developping the technique for measuring the chemical composition of porewater using low-decolorant pH test papers and high-absorbancy pads embedded in compacted bentonite. Previously, we reported that the pH of porewater near the infiltration surface slightly decreased with time in compacted bentonite contacted with distilled water. Preliminary thermodynamic calculations have suggested that the porewater pH decrease near the infiltration surface observed in experiments using distilled water may be due to partial oxidation of trace amounts of pyrite in Kunigel V1. Such interpretation has not been verified experimentally by using Kunipia F which does not include pyrite as the accessory minerals in bentonite, however. Additionally, it is also suspected that the material used in the experiments (i.e., ceramic filter) and the experimental condition (i.e., bentonite contacts with the static solution) can affect the variations of porewater pH near the infiltration surface. Thus the following experiments with distilled water were conducted to identify the reason of temporal pH variations near the infiltration surface. (1) Experiments using Kunipia F, (2) Experiments using the alternative filter (i.e., combination of plastic filter with membrane filter), (3) Experiments using the alternative experimental condition (i.e., bentonite contacts with the stirred solution) Results indicate that the decrease of porewater pH near the infiltration surface is observed, although the Kunipia F is used. Difference of variations is not observed by using the alternative filter and experimental condition. Therefore, it would be suggested that the pH decrease near the infiltration surface may not be due to these factors but be due to another factor which affects the porewater pH variations.
Sasamoto, Hiroshi; Kurosawa, Susumu; Isogai, Takeshi*; Yoshikawa, Hideki
Hoshasei Haikibutsu Anzen Kenkyu Nenji Keikaku (Heisei-13-Nendo
Heisei-17-Nendo) Kenkyu Seika Hokokushu, p.146 - 152, 2006/03
no abstracts in English
Saji, Shinichi*; Ito, Masakazu*; Shibata, Masahiro; Jintoku, Takashi*; Isogai, Takeshi*
JNC TN8400 2005-017, 86 Pages, 2005/09
Porewater chemistry in Buffer Material is one of the most important information for assessment of corrosion behavior on the overpack, and of solubility and sorption of nuclides in the buffer etc. In the Second Progress Report of HLW in Japan (H12 Report), porewater chemistry is estimated by batch modeling calculation based on the batch experiment. However, it is expected that, in the disposal vault, temporal-spatial evolution of porewater chemistry occurrs. After H12 report, JNC started experimental study and modeling work for further understanding of the chemical evolution. However, modeling for long term evaluation of porewater chemistry is calculated on the basis of the short term laboratory experiment. Thus, the long term reliability of the model needs to be verified by comparing natural analogue.In this study, bentonite deposit under the river bed was sampled as function of depth by boring. At the sampling point, the river improvement was carried out in 1987 and river water contact with bentonite deposit since then. Mineral composition, chemical composition, inter layer cation concentration, CEC and methylene blue adsorption etc. of the sample are measured.As a result, erosion of the smectite, decreasing of pH and leaching out of SO4 are obsereved. However, clear trend of the depth direction is not obtained for the reason of natural inhomogeneous system.
Sasamoto, Hiroshi; Yoshida, Yasushi*; Isogai, Takeshi*; Suyama, Tadahiro*; Jintoku, Takashi*; Shibata, Masahiro; Yui, Mikazu
Saikuru Kiko Giho, (28), p.27 - 33, 2005/09
JNC has developed the databases of nuclides migration for safety assessment of high-level radioactive waste (HLW), and the databases have been used in the second progress report to present the technical reliability of HLW geological disposal in Japan. The technical level and applicability of databases developed by JNC have been evaluated highly not only in Japan but also in overseas. Thus we have performed the followings in order to provide the databases broadly in the word and to promote the use of databases; 1) development of tools to convert the database format from geochemical code PHREEQE to PHREEQC, GWB and EQ3/6, 2) open the web site including the databases to the public. As a result, a down-load system of databases from web site has been applied and the database users have significantly increased. Additionally it has been performed that we consider the useful comments from database user for modification and/or update of databases.
Isogai, Takeshi*; Jintoku, Takashi; Sasamoto, Hiroshi
JNC TN8400 2003-050, 74 Pages, 2004/03
JNC-TN8400-2003-050.pdf:5.85MB
We determined the pH and chemical compositions of porewaters in compacted bentonite as a function of time. The experiments were carried out using the low-decolorant pH test papers and high-absorbancy pads embedded in compacted bentonite (Kunigel-V1R=100[%]) having dry densities of 1.6 [g/cm
]. We also measured the chemical composition and exchangeable cation concentrations of the bentonite after the experiments. The experiments were conducted in a controlled-atmosphere glove box (O
(g) content is less than 1[ppm]) using distilled water, synthesized seawater and a low-alkaline cement porewater (i.e., HFSC: High Flyash contained Silica fume Cement) as initial solutions. The pH of the distilled water and synthesized seawater was adjusted to pH=9 by adding NaOH solution. Distilled water was reacted with crushed HFSC to produce a solution representing low-alkaline cement solution (pH= about 11). - Distilled water: The pH of porewaters further away from the interface did not vary significantly (pH = 8.0 to 9.0), but the pH of porewaters near the infiltration interface slightly decreased (pH = 7.5-8.5 
pH = 7.0-8.0). - Synthesized seawater: The pH values were roughly constant at the interface between 6.5 and 7.0, but the pH of porewaters further away from the interface slightly decreased with time (pH = 6.5-7.0 pH = 6.0-6.5). - HFSC solution: Like the experiment with involving distilled water, the pH of porewaters contacted with HFSC solution further away from the interface were roughly constant between 8.5 and 10.0, but the pH of porewaters near the infiltration surface significantly decreased with time from pH = 9.5 to pH = 7.5-8.5. Although the determination of porewater chemistry in compacted bentonite was carried out, it was difficult to obtain the quantitative profile for variation during the experiment except the experiment using synthesized seawater.
Isogai, Takeshi*; Oda, Chie
JNC TN8400 2000-025, 48 Pages, 2000/09
Porewater chemistly in compacted bentonite would affect a performance of engineered barrier system in a high-level radioactive waste repository, whereas there are little information of the porewater based on experimental data. The previous study provided a new method of direct pH measurement for highly compacted bentonite system and demonstrated some tests for compacted bentonite samples (the dry densities: 1.6 [g/cm] and 1.8 [g/cm]) both with the de-ionized water and with the NaCl solution. In this study, the solution equilibrated with low alkalinity cement were used in the direct pH measurement to see the effect of the composition of the external solutions, in which the bentonite column immersed. The result showed that the pH value of porewater in the cementitious condition was around 9 during the immersed time 1 to 3 months, while after 6 months became the porewater pH 10.6, which was equal to pH of the external solution.
Oda, Chie; Isogai, Takeshi*; Sato, Mitsuyoshi*
JNC TN8400 2000-006, 104 Pages, 1999/11
no abstracts in English
Oda, Chie; Isogai, Takeshi*; Sato, Mitsuyoshi*; Shibata, Masahiro
JNC TN8400 99-015, 35 Pages, 1999/03
None
Konno, Yuta*; Maeyama, Takeshi*; Saegusa, Jun; Shinohara, Hirofumi*; Ota, Hiroshi*; Isogai, Keisuke*
no journal, ,
no abstracts in English
