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Sawaguchi, Takuma; Takai, Shizuka; Sasagawa, Tsuyoshi; Uchikoshi, Emiko*; Shima, Yosuke*; Takeda, Seiji
MRS Advances (Internet), 8(6), p.243 - 249, 2023/06
In the intermediate depth disposal of relatively high-level radioactive waste, a method to confirm whether the borehole for monitoring is properly sealed should be developed in advance. In this study, groundwater flow analyses were performed for the hydrogeological structures with backfilled boreholes, assuming sedimentary rock area, to understand what backfill design conditions could prevent significant water pathways in the borehole, and to identify the confirmation points of borehole sealing. The results indicated the conditions to prevent water pathways in the borehole and BDZ (Borehole Disturbed Zone), such as designing the permeability of bentonite material less than or equal to that of the host rock, and grouting BDZ.
Kitamura, Akira
JAEA-Data/Code 2020-020, 164 Pages, 2021/03
JAEA-Data-Code-2020-020.pdf:3.11MB
JAEA-Data-Code-2020-020-appendix(DVD-ROM).zip:0.56MB
Part of JAEA's Thermodynamic Database (JAEA-TDB) for solubility and speciation of radionuclides (JAEA-TDB-RN) for performance assessment of geological disposal of high-level radioactive and TRU wastes has been updated with subsuming the database for geochemical calculations (JAEA-TDB-GC). This report has focused to update JAEA-TDB-RN after selecting change in standard Gibbs free energy of formation (
), change in standard enthalpy change of formation (
), standard molar entropy (
) and, heat capacity (
), change in standard Gibbs free energy of reaction (
), change in standard enthalpy change of reaction (
) and standard entropy change of reaction (
) as well as logarithm of equilibrium constant (log
) at standard state. The extent of selection of these thermodynamic data enables to evaluate solubility and speciation of radionuclides at temperatures other than 298.15 K. Furthermore, the latest thermodynamic data for iron which have been critically reviewed, selected and compiled by the Nuclear Energy Agency within Organisation for Economic Co-operation and Development (OECD/NEA) have been accepted. Most of previously selected log have been refined to confirm internal consistency with JAEA-TDB-GC. Text files of the updated JAEA-TDB have been provided for geochemical calculation programs of PHREEQC and Geochemist's Workbench.
Kitamura, Akira; Yoshida, Yasushi*; Goto, Takahiro*; Shibutani, Sanae*
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 27(2), p.58 - 71, 2020/12
Evaluation and estimation of solubility values are required for a performance assessment of geological disposal of high-level radioactive and TRU wastes. Selection of solubility-limiting solid phases (SSPs) that control the solubility of radionuclides is necessary for the evaluation and estimation of solubility values. The authors have developed a methodology for selection of the SSP through a calculation of saturation indices (SIs) using thermodynamic database to show a transparent procedure for the selection. Literature survey should be performed to confirm decision of the SSP from candidate SSPs which generally have larger SIs from realistic point of view for precipitation and solubility control. The authors have selected the SSPs for the elements of interest for the latest Japanese performance assessment in bentonite and cement porewaters after grouping various water compositions.
Sugita, Yutaka; Taniguchi, Naoki; Makino, Hitoshi; Kanamaru, Shinichiro*; Okumura, Taisei*
Nihon Genshiryoku Gakkai Wabun Rombunshi, 19(3), p.121 - 135, 2020/09
A series of structural analysis of disposal containers for direct disposal of spent fuel was carried out to provide preliminary estimates of the required pressure resistance thickness of the disposal container. Disposal containers were designed to contain either 2, 3 or 4 spent fuel assemblies in linear, triangular or square arrangements, respectively. The required pressure resistance thickness was evaluated using separation distance of the housing space for each spent fuel assembly as a key model parameter to obtain the required thickness of the body and then the lid of the disposal container. This work also provides additional analytical technical knowledge, such as the validity of the setting of the stress evaluation line and the effect of the model length on the analysis. These can then be referred to and used again in the future as a basis for conducting similar evaluations under different conditions or proceeding with more detailed evaluations.
Tachi, Yukio; Suyama, Tadahiro*; Mihara, Morihiro
JAEA-Data/Code 2019-021, 101 Pages, 2020/03
JAEA-Data-Code-2019-021.pdf:4.05MB
Sorption of radionuclides in cement and bentonite as engineered barrier materials, and rocks as natural barrier is the one of key processes in the performance assessment of geological disposal of TRU and high-level waste. The magnitude of sorption, expressed normally by a distribution coefficient (K
), needs to be measured and determined taking into account the properties of barrier materials and geochemical conditions and associated uncertainty in the performance assessment. The basic concept for TRU waste disposal contains cementitious materials as an engineered barrier materials, in addition to bentonite and rock. It is therefore needed to consider the effects of the cement degradation and co-existing substances such as nitrates on radionuclide sorption. This report focused on data acquisition of distribution coefficient (K) by batch sorption experiments for the systems coupling barrier material-chemical condition-radionuclides that are needed to consider for the performance assessment of geological disposal of TRU waste. The barrier materials considered are ordinary Portland cement (OPC), degraded OPC and tuff rock. The chemical conditions are distilled water and synthetic seawater equilibrated with OPC and those containing nitrates and ammonium salts, etc. The radionuclides considered are organic carbon, inorganic carbon, Cl, I, Cs, Ni, Se, Sr, Sn, Nb, Am and Th. Although K values have been partly reported previously as RAMDA (Radionuclide Migration Datasets) for the performance assessment in the TRU-2 report, these results and addition K data are reported with the details of experimental methods and conditions.
Kitamura, Akira
Nihon Genshiryoku Gakkai-Shi ATOMO
, 62(1), p.23 - 28, 2020/01
Thermodynamic databases (TDBs) for performance assessment of geological disposal of high-level waste and TRU waste have been developed to predict solubility and speciation of radionuclides in groundwater in some countries including Japan. The present manuscript briefly describes current status of development of the TDB organized by the Nuclear Energy Agency within the Organisation of Economic Co-operation and Development (OECD/NEA) and the TDBs in some countries including Japan.
-UO
-CO
system and integration with JAEA's thermodynamic database for geochemical calculationsKitamura, Akira
JAEA-Data/Code 2018-018, 103 Pages, 2019/03
JAEA-Data-Code-2018-018.pdf:5.66MBJAEA-Data-Code-2018-018-appendix1(DVD-ROM).zip:0.14MBJAEA-Data-Code-2018-018-appendix2(DVD-ROM).zip:0.15MBJAEA-Data-Code-2018-018-appendix3(DVD-ROM).zip:0.19MB
The latest available thermodynamic data were critically reviewed and the selected values were included into the JAEA-TDB for performance assessment of geological disposal of high-level radioactive and TRU wastes. This critical review specifically addressed thermodynamic data for (1) a zirconium-hydroxide system through comparison of thermodynamic data selected by the Nuclear Energy Agency within the Organisation for Economic Co-operation and Development (OECD/NEA), (2) complexation of metal ions with isosaccharinic acid based on the latest review papers. Furthermore, the author performed (3) tentative selection of thermodynamic data on ternary complexes among alkaline-earth metal, uranyl and carbonate ions, and (4) integration with the latest version of JAEA's thermodynamic database for geochemical calculations. The internal consistency of the selected data was checked by the author. Text files of the updated and integrated thermodynamic database have been prepared for geochemical calculation programs of PHREEQC and Geochemist's Workbench.
Mizukoshi, Seiji; Oshima, Soichiro; Shimada, Taro
JAERI-Tech 2005-011, 122 Pages, 2005/03
JAERI-Tech-2005-011.pdf:13.25MB
The radiological and physical characteristic on decommissioning, such as component and structure weights and radioactivity of the 1.1 MWe class reference nuclear power plants summarized in the NUREG reports of the US NRC were classified,arranged and compared with the domestic commercial nuclear power plants and JPDR from a view point of dismantling plan and waste management for decommissioning. As the results, it was found that the radioactive component and structure weights was about 28,000ton、and non-radioactive structure weights was about 124,000ton less than the domestic commercial BWR. And it was found that this differences has mainly influenced dismantling costs for decommissioning. Farther, it was found that the concrete element composition rates of B, Ni, Nb and so were differerence of one or more figures btween the reference nuclear power plants and the domestic commercial PWR or JPDR.Also,it was found that the this difference became about two or three times by radioactivity concentration and has mainly influenced transport and disposal costs for decommissioning.
NUCEF 2001 Symposium Working Group
JAERI-Conf 2002-004, 714 Pages, 2002/03
JAERI-Conf-2002-004.pdf:69.13MB
This volume contains 94 papers presented at the 3rd NUCEF International Symposium NUCEF 2001 held on October 31 - November 2, 2001, in Tokai, Japan, following the 1st symposium NUCEF'95 (Proceedings: JAERI-Conf 96-003) and the 2nd symposium NUCEF'98 (Proceedings: JAERI-Conf 99-004). The theme of this symposium was " Scientific Basis for Criticality Safety, Separation Process and Waste Disposal". The papers were presented in oral and poster sessions on following research fields: (1) Separation Process, (2) TRU Chemistry, (3) Radioactive Waste Disposal, (4) Criticality Safety.
Nagano, Tetsushi; Nakayama, Shinichi
Genshiryoku Bakkuendo Kenkyu, 8(1), p.81 - 88, 2001/09
Japan Atomic Energy Research Institute has studied to predict the long-term migration of radionuclides in geosphere in terms of radioactive waste disposal. The research activity was introduced to junior high and high school students at a seminar of the Mineralogical Society of Japan. The content of the lecture was summarized.
Takahashi, Tomoyuki; ; Kimura, Hideo; Matsuzuru, Hideo
JAERI-M 91-216, 31 Pages, 1992/01
no abstracts in English
Kobayashi, Taishi*; Sasaki, Takayuki*; Kitamura, Akira
no journal, ,
The solubility of U(OH)
(am) was investigated in the presence of isosaccharinic acid (ISA) as a function of hydrogen ion concentration (pHc) and ISA concentration. The solubility in neutral pH region was independent of pHc, while those in alkaline pH region slightly increased with increasing pHc. The solubility was investigated as a function of ISA concentration and found to increase with a slope of approximately 2 with increasing ISA concentration. It was therefore suggested that U(OH)(ISA) and U(OH)
(ISA)
were the dominant U(IV)-ISA complexes, which were similar to those observed in Zr(IV)-ISA system. Complex formation constants were determined by the least square fitting analysis of the solubility data and the calculated solubility curve well reproduced the experimental data.
-isosaccharinic acidMiyabe, Shunsuke*; Maeno, Mamiko*; Matsubara, Kazuhito*; Tomiyasu, Kaoru*; Ogami, Chiari*; Kitamura, Akira; Kimuro, Shingo
no journal, ,
The effect of -isosaccharinic acid (ISA) on solubility of palladium (Pd) was investigated under alkaline pH conditions. Increase in palladium solubility was observed with increasing ISA concentration at pH values around 8.5 and 10.0.
