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Hanamuro, Takahiro; Yasue, Kenichi; Kokubu, Yoko; Asamori, Koichi; Ishimaru, Tsuneari; Umeda, Koji
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.25 - 30, 2011/01
Japanese islands are located in a tectonically active zone, where earthquakes and volcanic eruptions frequently occur. Therefore the understanding of the long-term stability of geological environment is important when assessing the long-term behaviour of the geological disposal system of high level radioactive waste (HLW) in Japan. The Japan Atomic Energy Agency (JAEA) is promoting the establishment of investigation and assessment methods of the long-term stability of geological environment necessary for site selection and safety assessment of HLW geological disposal.
with DTAB and F-pentanol for decontamination of radioactive wastesKurahashi, Kensuke; Tomioka, Osamu; Meguro, Yoshihiro
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.217 - 220, 2011/01
To develop a metal separation method using supercritical CO (scCO) solvent for the decontamination process of radioactive wastes, the reverse micelle formation in scCO was investigated. Dodecyltrimethylammonium bromide (DTAB) as a surfactant to form the reverse micelles and 2,2,3,3,4,4,5,5-octafluoro-1-pentanol (F-pentanol) as a modifier to increase the solubility of DTAB into scCO were used. The reverse micelles could be formed by using 0.02 mol/dm
DTAB and 0.45 mol/dm F-pentanol. A water concentration dissolved in scCO was increased with an increase of pressure, and 0.42 mol/dm water, which was 3 times larger than that in the neat CO, could be dissolved in scCO at 38 MPa. Moreover, 0.1 mol/dm HNO
could dissolve at the same pressure as water. On the other hand, it was found that the solubility of water at outside of reverse micelles increased with F-pentanol. The ratio of water and F-pentanol affected the phase behavior of water in scCO.
Nakayama, Masashi; Sato, Haruo; Sugita, Yutaka; Ito, Seiji*; Minamide, Masashi*; Kitagawa, Yoshito*
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.51 - 56, 2011/01
In Japan, any high level radioactive waste repository is to be constructed at over 300 m depth below surface. Tunnel support is used for safety during the construction and operation, and shotcrete and concrete lining are used as the tunnel support. Concrete is a composite material comprised of aggregate, cement and various additives. Low alkaline cement has been developed for the long term stability of the barrier systems whose performance could be negatively affected by highly alkaline conditions arising due to cement used in a repository. Japan Atomic Energy Agency (JAEA) has developed a low alkaline cement, named as HFSC (Highly fly-ash contained silicafume cement), containing over 60wt% of silica-fume (SF) and fly-ash (FA). HFSC was used experimentally as the shotcrete material in construction of part of the 140 m deep gallery in Horonobe URL. The objective of this experiment was to assess the performance of HFSC shotcrete in terms of mechanics, workability, durability, and so on. HFSC used in this experiment is composed of 40wt% OPC (Ordinary Portland Cement), 20wt% SF, and 40wt% FA. This composition was determined based on mechanical testing of various mixes of the above components. Because of the low OPC content, the strength of HFSC tends to be lower than that of OPC in normal concrete. The total length of tunnel using HFSC shotcrete is about 73 m and about 500 m of HFSC was used. The workability of HFSC shotcrete was confirmed in this experimental construction.
Takeda, Seiji; Kimura, Hideo
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.131 - 140, 2011/01
Clearance levels for the solid materials contaminated with uranium were estimated based on deterministic dose calculation approach for metal reuse scenario. The activity concentrations for major radionuclides, U-234, U-235 and U-238, were calculated to be 1.5 Bq/g, 1.4 Bq/g and 1.8 Bq/g, respectively. In order to confirm the validity of the calculated concentrations, the authors estimated the uncertainties on scenario description after metal recycling and on parameter values used in the deterministic calculation. The validity of the calculated activity concentrations by the deterministic approach was confirmed from the results of both the analysis for an additional scenario on the landfill disposal of residue of slag after metal recycling and the Monte Carlo-based analysis for parameter uncertainties.
Kitamura, Akira; Doi, Reisuke; Yoshida, Yasushi*
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010), Vol.2, p.365 - 373, 2011/00
We evaluated and estimated solubility of the 25 elements in the simulated pore waters established in the second progress report (H12) for safety assessment of geological disposal of HLW in Japan using the updated thermodynamic database (JAEA-TDB) and compared with the solubility values using the previous thermodynamic database (JNC-TDB). Furthermore, we tried to establish a technique to determine the solubility limiting solid for all target elements. It was found that most of the evaluated and estimated solubility values were not changed drastically, but the solubility values and dominant aqueous species for some elements were changed using the JAEA-TDB, e.g., due to introducing the formation constant of polynuclear hydrolysis species of zirconium and replacing the formation constant of mixed carbonatohydoxo complexes of thorium. Detail of the comparison and discussion about the evaluated and estimated solubility values between the JAEA- and the JNC- TDBs will be presented.
Takeuchi, Shinji; Kunimaru, Takanori; Ota, Kunio; Frieg, B.*
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010), p.251 - 260, 2010/10
Zaima, Naoki; Morimoto, Yasuyuki; Sugitsue, Noritake; Kado, Kazumi
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.311 - 320, 2010/10
Kamei, Gento; Alexander, W. R.*; Clark, I. D.*; Degnan, P.*; Elie, M.*; Khoury, H.*; Milodowski, A. E.*; Pitty, A. F.*; Salameh, E.*; Smellie, J. A. T.*
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.141 - 147, 2010/10
Iyatomi, Yosuke; Hoshina, Hiroyuki; Seko, Noriaki; Kasai, Noboru; Ueki, Yuji; Tamada, Masao
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.485 - 490, 2010/10
Yamamoto, Yuhei; Aosai, Daisuke; Mizuno, Takashi
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.203 - 212, 2010/10
Aosai, Daisuke; Yamamoto, Yuhei; Mizuno, Takashi
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.213 - 220, 2010/10
Size distribution of elements in groundwater is one of the most important information for understanding behavior of elements in deep underground environment. Size distribution is controlled mainly by groundwater physico-chemical parameters. Because the alteration of their physico-chemical states in groundwater cause changes of size distribution, systematic methodologies of ultrafiltration maintaining in-situ pressurized and anaerobic conditions is required. In this study, instrument for ultrafiltration maintaining in-situ pressurized/anaerobic conditions was developed and size distribution analysis was also conducted. The instrument developed in this study for consisted of passivated SUS materials is designed as to keep inner groundwater sample under a pressurized/anaerobic condition. Ultrafiltration was conducted at a borehole drilled from sub-stage at a depth of 200 m at the Mizunami Underground Research Laboratory site. The results obtained here indicate that ultrafiltration method is available for collection of filtered groundwater and passivation is an essential treatment before ultrafiltration.
Daimaru, Shuji; Takeuchi, Ryuji; Takeda, Masaki; Ishibashi, Masayuki
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.149 - 158, 2010/10
no abstracts in English
Saito, Hiroshi; Taki, Tomihiro
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.533 - 537, 2010/10
Ningyo-toge Environmental Engineering Center, Japan Atomic Energy Agency (JAEA) has maintained and preserved the Ningyo-toge and Togo Mines under the related laws, including the Mine Safety Law. JAEA has been planning to close these mines to prevent mine-pollution and reduce radiological impact to as low as achievably possible, for lasting protection of individuals and the environment. Among the mine-related facilities that are subject to environmental remediation, the Mill Tilings Pond is given the top priority. So far, basic concept has been discussed in parallel with data acquisition and designing for some of remediation activities.
Kawamura, Makoto*; Tanikawa, Shinichi; Niizato, Tadafumi; Yasue, Kenichi
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.331 - 338, 2010/10
In order to assess the long-term safety of a geological disposal system for high-level radioactive waste (HLW), it is important to consider the impact of uplift and erosion, which cannot be precluded on a timescale in the order of several hundred thousand years for many locations in Japan. Geomorphic evolution, caused by uplift and erosion and coupled to climatic and sea-level changes, will impact the geological disposal system due to resulting spatial and temporal changes in the disposal environment. Degradation of HLW barrier performance will be particularly significant when the remnant repository structures near, and are eventually exposed at, the ground surface. In previous studies, fluvial erosion was identified as the key concern in most settings in Japan. Here, therefore, we present a methodology for development of a generic conceptual model for performance assessment based on best current understanding of fluvial erosion in Japan. Critical considerations that have to be taken into account when interpreting the geological record of past river-valley evolutions, as preserved in ancient fluvial deposits. Interpretation of the impact of such phenomena at relevant locations in Japan has led to development of a generic conceptual model which contains the features typical at middle reach of rivers. This paper presents the methodology to develop the conceptual model, which identifies the simplifications and uncertainties involved and assesses their consequences in the context of repository performance.
Sanada, Hiroyuki; Nakamura, Takahiro; Sugita, Yutaka
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.31 - 39, 2010/10
As part of the research and development program on the HLW geological disposal, JAEA has been implementing the Horonobe Underground Research Laboratory (URL) project investigating sedimentary rock formations distributed in Horonobe area, Hokkaido, Japan. The authors have been implementing the research and development program at Horonobe to clarify the in situ stress conditions in siliceous mudstones at the URL. The objective of this work is to establish a strategy for an in situ stress measurement program for geological disposal and to develop an understanding of the in situ stress conditions in the deep underground formed by the sedimentary rocks. The application of several stress measurement methods to the Horonobe siliceous mudstones carried out during the surface-based investigations and the investigations during construction of the underground facilities, as well as information on the initial stress state around the Horonobe URL are described in this paper.
Saegusa, Hiromitsu; Takeuchi, Shinji; Maekawa, Keisuke; Osawa, Hideaki; Semba, Takeshi
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.133 - 140, 2010/10
Mizuno, Takashi; Milodowski, A. E.*; Iwatsuki, Teruki
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.193 - 201, 2010/10
Matsuoka, Toshiyuki; Amano, Kenji; Osawa, Hideaki; Semba, Takeshi
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.169 - 173, 2010/10
It is important for site characterization project to manage decision-making process during site characterization project with transparency and traceability, and to accumulate and hand technical know-how on to the next generation. Evaluation of the impact of uncertainties in the geological environment model is important to identify and prioritize key issues for further investigations. The aim of the study is to support for the planning of initial surface-based site characterization based on the technical know-how accumulating from Mizunami Underground Research Laboratory Project and Horonobe Underground Research Laboratory project. In this study, the task-flow of the geological modeling, which is one of the geological environment models, and the related technical know-how using literature data have been summarized.
Ishimori, Kenichiro; Kameo, Yutaka; Nakashima, Mikio*; Takahashi, Kuniaki
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.117 - 123, 2010/10
Sato, Haruo
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.175 - 184, 2010/10
The self-sealing function of the clearances between buffer material and overpack and tunnel wall or disposal pit wall and between backfill material and tunnel wall is expected for bentonite which will be used as buffer material and part of the backfill material. The sealing properties of Na-bentonite have been studied for distilled water and saline water conditions, for example, it is reported that Na-bentonite seals clearance even under saline water conditions in a range of effective bentonite densities, higher than 1.3 kg/dm, for a bentonite dry density of 1.8 kg/dm and a clearance ratio of 10 % in experiments for Kunigel-V1. Although such information is useful for judging whether clearance is sealed, the filling properties of bentonite strongly depend on groundwater condition, silica sand content, montmorillonite content in the bentonite and the bentonite dry density, even though at the same effective bentonite density. In the present study, the author constructed an analytical model on the clearance filling performance for the design of buffer material and backfill material, based on the swelling properties of Na-montmorillonite which is the clay mineral constitute of Na-bentonite.
