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Journal Articles

Decrease of radionuclide sorption in hydrated cement systems by organic ligands; Comparative evaluation using experimental data and thermodynamic calculations for ISA/EDTA-actinide-cement systems

Ochs, M.*; Dolder, F.*; Tachi, Yukio

Applied Geochemistry, 136, p.105161_1 - 105161_11, 2022/01

Various types of radioactive wastes and environments contain organic substances that can stabilize the aqueous complexes with radionuclides and therefore lead to a decrease of sorption. The present study focuses on testing a methodology to quantify sorption reduction factors (SRFs) in the presence of organic ligands for cement systems. Three approaches for the estimation of SRFs; (1) analogy with solubility enhancement factors, (2) radionuclide speciation based on the thermodynamic calculations, and (3) experimental sorption data in ternary systems, were coupled and tested for the representative organic ligands (ISA and EDTA) and selected key radionuclides (actinides). Our approach allows to critically evaluate the dependence of SRFs for various systems on the chosen method of quantification, in accordance with the data availability for a given systems. The reliable SRFs can only be derived from the sorption measurements in ternary systems. SRF often need to be derived in the absence of such direct evidence, and estimations need to be made based on analogies and speciation information. However, such estimates may be subject to substantial uncertainties.

Journal Articles

Growing need for humanities and social science studies in uranium waste disposal

Yasuda, Hiroshi*; Fumoto, Hiromichi*; Saito, Tatsuo

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 63(8), p.610 - 614, 2021/08

Regarding the handling of uranium bearing waste, which is contaminated with uranium, which is a naturally occurring radionuclide, and its descendant nuclides, in recent years, the Japan Nuclear Regulatory Commission, etc. have been carefully and actively deliberated based on the knowledge of natural science and safety engineering. It was carried out, and as of March 2021, a certain policy has been shown. On the other hand, when disposing of uranium waste, which may cause dose exposure to future generations, the authors consider not only the science and engineering perspectives that have been conducted so far, but also the humanities and social science perspectives. We have been discussing with experts in related fields, thinking that it is necessary. In this report, we will introduce the background that brought about such an idea and the direction of future discussions.

JAEA Reports

Horonobe Underground Research Laboratory Project; Investigation program for the 2021 fiscal year

Nakayama, Masashi

JAEA-Review 2021-009, 54 Pages, 2021/07

JAEA-Review-2021-009.pdf:5.02MB

The Horonobe URL Project is being pursued by the JAEA to enhance the reliability of relevant disposal technologies for geological disposal of High-level Radioactive Waste through investigations of the deep geological environment within the host sedimentary rock at Horonobe Town in Hokkaido, north Japan. In 2021 fiscal year (2021/2022), JAEA continue to conduct research on "Demonstration of EBS in geological environment", "Demonstration of disposal concept", and "Validation of buffer capacity of the sedimentary rock to tectonism", which are the important issues shown in the Horonobe underground research plan after 2020 fiscal year. The main studies to be conducted in 2021 fiscal year are as follows. As "Demonstration of EBS in geological environment", we will shift to the test under the condition that the influence of heating is eliminated in the full scale EBS experiment. As "Demonstration of disposal concept", as a demonstration of the closure techniques, it details the conditions under which long-term transitions in the tunnel and surrounding bedrock have a significant impact on safety assessments. And we will continue engineering scale experiment to confirm the workability and performance of plugs and laboratory tests to examine the interaction between backfilling materials and buffer materials. As "Validation of buffer capacity of the sedimentary rock to tectonism", we will analyze the results of the hydraulic disturbance test and continue to study the hydraulic disconnection of faults/fissures in the Wakkanai Formation. As an advancement of technology for investigating and evaluating areas where the flow of groundwater is extremely slow, a boring exploration will be conducted to confirm the three-dimensional distribution of the fossil seawater area.

Journal Articles

The Impact of cement on argillaceous rocks in radioactive waste disposal systems; A Review focusing on key processes and remaining issues

Wilson, J.*; Bateman, K.; Tachi, Yukio

Applied Geochemistry, 130, p.104979_1 - 104979_19, 2021/07

 Times Cited Count:1 Percentile:0.56(Geochemistry & Geophysics)

The concept of deep geological disposal will include the multiple use of cement-based materials. In the case of argillaceous host rocks, the presence of hyperalkaline cement porefluid results in the destabilization of primary minerals in the argillite, resulting in the development of a zone of alteration at cement-rock interfaces. The process understanding gained from experimental, analogue, and modelling studies has been reviewed, and remaining areas of uncertainty identified. Although there is a reasonably good understanding of the mineral assemblages that are likely to occur due to cement-rock interactions, there are still some areas where a degree of uncertainty remains, in particular: the evolution of cement-argillite interfaces at T $$>$$ 25$$^{circ}$$C; the rates at which secondary minerals form; the extent of pore clogging due to secondary mineral precipitation; the implications of alteration for radionuclide transport.

JAEA Reports

JAEA-TDB-RN in 2020; Update of JAEA's thermodynamic database for solubility and speciation of radionuclides for performance assessment of geological disposal of high-level and TRU wastes

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 ($$Delta_{rm f}$$$$G^{circ}_{rm m}$$), change in standard enthalpy change of formation ($$Delta$$$$H$$$$^{circ}$$$$_{rm m}$$), standard molar entropy ($$S^{circ}$$$$_{rm m}$$) and, heat capacity ($$C^{circ}_{rm p}$$), change in standard Gibbs free energy of reaction ($$Delta_{rm r}G^{circ}$$$$_{rm m}$$), change in standard enthalpy change of reaction ($$Delta$$$$_{rm r}$$$$H$$$$^{circ}$$$$_{rm m}$$) and standard entropy change of reaction ($$Delta_{rm r}S^{circ}_{rm m}$$) as well as logarithm of equilibrium constant (log$$_{10}$$$$K^{circ}$$) 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$$_{10}$$$$K^{circ}$$ 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.

Journal Articles

Prediction of thermodynamic data for radium suitable for thermodynamic database for radioactive waste management using an electrostatic model and correlation with ionic radii among alkaline earth metals

Kitamura, Akira; Yoshida, Yasushi*

Journal of Radioanalytical and Nuclear Chemistry, 327(2), p.839 - 845, 2021/02

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

Thermodynamic data for radium for radioactive waste management have been predicted using an electrostatic model and correlation with the ionic radii of the alkaline earth metals. Estimation of the standard Gibbs free energy of formation and standard molar entropy of aqueous radium species and compounds has been based on such approaches as extrapolation of the thermodynamic properties of strontium and barium, and use of a model of ion pair formation. The predicted thermodynamic data for radium have been compared with previously reported values.

JAEA Reports

Horonobe Underground Research Laboratory Project; Investigation report for the 2019 fiscal year

Nakayama, Masashi; Saiga, Atsushi

JAEA-Review 2020-042, 116 Pages, 2021/01

JAEA-Review-2020-042.pdf:10.33MB

The Horonobe Underground Research Laboratory Project will be conducted in three phases, namely "Phase 1: Surface-based investigations", "Phase 2: Construction Phase" (investigations during construction of the underground facilities) and "Phase 3: Operation phase" (research in the underground facilities). This report summarizes the results of the investigations for the 2019 fiscal year (2019/2020). The investigations, which are composed of "Geoscientific research" and "R and D on geological disposal technology", were carried out according to "Horonobe Underground Research Laboratory Project Investigation Program for the 2019 fiscal year". The results of these investigations, along with the results which were obtained in other departments of Japan Atomic Energy Agency (JAEA), are properly offered to the implementations and the safety regulations. For the sake of this, JAEA has proceeded with the project in collaboration with experts from domestic and overseas research organizations.

Journal Articles

Methodology development and determination of solubility-limiting solid phases for a performance assessment of geological disposal of high-level radioactive and TRU wastes

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.

JAEA Reports

Horonobe Underground Research Laboratory Project; Investigation program for the 2020 fiscal year

Nakayama, Masashi; Saiga, Atsushi

JAEA-Review 2020-022, 34 Pages, 2020/11

JAEA-Review-2020-022.pdf:3.99MB

The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies for geological disposal of High-level Radioactive Waste through investigations of the deep geological environment within the host sedimentary rock at Horonobe Town in Hokkaido, north Japan. The investigations will be conducted in three phases, namely "Phase 1: Surface-based investigations", "Phase 2: Construction phase" (investigations during construction of the underground facilities) and "Phase 3: Operation phase" (research in the underground facilities). According to the research plan described in the 3rd Mid- and Long- term Plan of JAEA, "Demonstration of EBS in geological environment", "Demonstration of disposal concept", and "Validation of buffer capacity of the sedimentary rock to tectonism" are important issues of the Horonobe URL Project, and schedule of future research and backfill plans of the URL will be decided by the end of 2019 Fiscal Year. JAEA summarizes the research and development activities of the important issues carried out during the 3rd Mid- and Long-term Plan, and set out three important issues after 2020 fiscal year. After consultation with Hokkaido and Horonobe town, JAEA formulated the Horonobe underground research plan after 2020 fiscal year within the 3rd and 4th Mid- and Long-term Plan. This report summarizes the investigation program for the 2020 fiscal year (2020/2021).

Journal Articles

Frontline of R&D for decommissioning and waste disposal, 1; R&D for processing and disposal of low-level radioactive waste and closure of uranium mine

Tsuji, Tomoyuki; Sugitsue, Noritake; Sato, Fuminori; Matsushima, Ryotatsu; Kataoka, Shoji; Okada, Shota; Sasaki, Toshiki; Inoue, Junya

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 62(11), p.658 - 663, 2020/11

no abstracts in English

Journal Articles

Pressure resistance thickness of disposal containers for spent fuel direct disposal

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.

Journal Articles

Activity report of the task group of radiation protection about wastes containing natural radioactive nuclides

Saito, Tatsuo; Kobayashi, Shinichi*; Zaitsu, Tomohisa*; Shimo, Michikuni*; Fumoto, Hiromichi*

Hoken Butsuri (Internet), 55(2), p.86 - 91, 2020/06

Safety cases for disposal of uranium bearing waste and NORM with uranium has not yet been fully developed in Japan, because of safety assessment of extraordinary long timespan and uncertainty in unexpected incidents with uncompleted radon impact evaluation measures arising from uranium waste disposal facility in far future. Our task group of radiation protection for wastes with natural radioactive nuclides studied some safety cases with disposal of uranium bearing waste and NORM in terms of nuclides, U-235, U-238 and their progenies, and comprehensively discussed the current state of their disposal in comparison to the ideas of international organizations such as ICRP and IAEA. We developed our ideas for long term uncertainty and radon with the knowledge of experts in each related area of direction, repeating discussions, focusing out the orientation of each directions, and outlined the recommendations with our suggestions of solving important issues in the future to be addressed.

JAEA Reports

Synthesis report on the R&D for the Horonobe Underground Research Laboratory; Project carried out during fiscal years 2015-2019

Nakayama, Masashi; Saiga, Atsushi; Kimura, Shun; Mochizuki, Akihito; Aoyagi, Kazuhei; Ono, Hirokazu; Miyakawa, Kazuya; Takeda, Masaki; Hayano, Akira; Matsuoka, Toshiyuki; et al.

JAEA-Research 2019-013, 276 Pages, 2020/03

JAEA-Research-2019-013.pdf:18.72MB

The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies for geological disposal of High-level Radioactive Waste through investigations of the deep geological environment within the host sedimentary rock at Horonobe Town in Hokkaido, north Japan. The investigations will be conducted in three phases, namely "Phase 1: Surface based investigations", "Phase 2: Construction phase" (investigations during construction of the underground facilities) and "Phase 3: Operation phase" (research in the underground facilities). According to the research plan described in the 3rd Mid- and Long- term Plan of JAEA, "Near-field performance study", "Demonstration of repository design option", and "Verification of crustal-movement buffering capacity of sedimentary rocks" are important issues of the Horonobe URL Project, and schedule of future research and backfill plans of the project will be decided by the end of 2019 Fiscal Year. The present report summarizes the research and development activities of these 3 important issues carried out during 3rd Medium to Long-term Research Phase.

Journal Articles

Development of thermodynamic database for performance assessment of geological disposal of high-level radioactive waste and TRU waste

Kitamura, Akira

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 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.

JAEA Reports

Horonobe Underground Research Laboratory Project; Investigation program for the 2019 fiscal year

Aoyagi, Kazuhei

JAEA-Review 2019-008, 20 Pages, 2019/07

JAEA-Review-2019-008.pdf:3.33MB

As part of the research and development program on the geological disposal of high-level radioactive waste (HLW), the Horonobe Underground Research Center, a division of the Japan Atomic Energy Agency (JAEA), is implementing the Horonobe Underground Research Laboratory Project (Horonobe URL Project) with the aim at investigating sedimentary rock formations. According to the research plan described in the 3rd Mid- and Long- term Plan of JAEA, "Near-field performance study", "Demonstration of repository design option", and "Verification of crustal-movement buffering capacity of sedimentary rocks" are the top priority issues of the Horonobe URL Project, and schedule of future research and backfill plans of the project will be decided by the end of 2019 Fiscal Year. The Horonobe URL Project is planned to extend over a period of about 20 years. The investigations will be conducted in three phases, namely "Phase 1: Surface-based investigations", "Phase 2: Construction phase" (investigations during construction of the underground facilities) and "Phase 3: Operation phase" (research in the underground facilities). This report summarizes the investigation program for the 2019 fiscal year (2019/2020). In the 2019 fiscal year, investigations in "geoscientific research", including "development of techniques for investigating the geological environment", "development of engineering techniques for use in the deep underground environment" and "studies on the long-term stability of the geological environment", are continuously carried out. Investigations in "research and development on geological disposal technology", including "improving the reliability of disposal technologies" and "enhancement of safety assessment methodologies", are also continuously carried out.

JAEA Reports

Update of JAEA-TDB; Update of thermodynamic data for zirconium and those for isosaccahrinate, tentative selection of thermodynamic data for ternary M$$^{2+}$$-UO$$_{2}$$$$^{2+}$$-CO$$_{3}$$$$^{2-}$$ system and integration with JAEA's thermodynamic database for geochemical calculations

Kitamura, Akira

JAEA-Data/Code 2018-018, 103 Pages, 2019/03

JAEA-Data-Code-2018-018.pdf:5.66MB
JAEA-Data-Code-2018-018-appendix1(DVD-ROM).zip:0.14MB
JAEA-Data-Code-2018-018-appendix2(DVD-ROM).zip:0.15MB
JAEA-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.

JAEA Reports

Horonobe Underground Research Laboratory Project; Investigation report for the 2017 fiscal year

Hanamuro, Takahiro; Saiga, Atsushi

JAEA-Review 2018-027, 125 Pages, 2019/02

JAEA-Review-2018-027.pdf:21.79MB

The Horonobe Underground Research Laboratory Project is planned to extend over a period 20 years. The investigations will be conducted in three phases, namely "Phase 1: Surface-based investigations", "Phase 2: Construction Phase" (investigations during construction of the underground facilities) and "Phase 3: Operation phase" (research in the underground facilities). This report summarizes the results of the investigations for the 2017 fiscal year (2017/2018). The investigations, which are composed of "Geoscientific research" and "R&D on geological disposal technology", were carried out according to "Horonobe Underground Research Laboratory Project Investigation Program for the 2017 fiscal year". The results of these investigations, along with the results which were obtained in other departments of Japan Atomic Energy Agency (JAEA), are properly offered to the implementations and the safety regulations. For the sake of this, JAEA has proceeded with the project in collaboration with experts from domestic and overseas research organizations.

Journal Articles

Thermodynamic model for Zr solubility in the presence of gluconic acid and isosaccharinic acid

Kobayashi, Taishi*; Teshima, Takeshi*; Sasaki, Takayuki*; Kitamura, Akira

Journal of Nuclear Science and Technology, 54(2), p.233 - 241, 2017/02

 Times Cited Count:3 Percentile:40.62(Nuclear Science & Technology)

Zr solubility in the presence of gluconic acid (GLU) and isosaccharinic acid (ISA) was investigated as a function of hydrogen ion concentration (pH$$_{rm c}$$) and the total concentration of GLU or ISA. The dependence of the increase in Zr solubility on the pH$$_{rm c}$$ and GLU concentration suggested the existence of Zr(OH)$$_{4}$$(GLU)$$_{2}$$$$^{2-}$$ in the neutral pH region and Zr(OH)$$_{4}$$(GLU)(GLU$$_{rm -H}$$)$$^{3-}$$ in the alkaline pH region above pH$$_{rm c}$$ 10 as the dominant species in the presence of 10$$^{-3}$$ - 10$$^{-1}$$ mol/dm$$^{3}$$ (M) GLU. In the presence of ISA, the dominant species Zr(OH)$$_{4}$$(ISA)$$_{2}$$$$^{2-}$$ and Zr(OH)$$_{4}$$(ISA)(ISA$$_{rm -H}$$)$$^{3-}$$ were proposed to occur in the neutral and alkaline pH regions, similar to those found in the presence of GLU. From X-ray diffraction analysis, the solubility-limiting solid phase in the presence of GLU and ISA was considered to be Zr(OH)$$_{4}$$(am). The formation constants of the Zr gluconate and isosaccharinate complexes were determined by least squares fitting analysis of the solubility data, and the obtained values were discussed in comparison with those of tetravalent actinides.

Journal Articles

Progress in the geological disposal program in Japan

Deguchi, Akira*; Umeki, Hiroyuki*; Ueda, Hiroyoshi*; Miyamoto, Yoichi; Shibata, Masahiro; Naito, Morimasa; Tanaka, Toshihiko*

LBNL-1006984 (Internet), p.12_1 - 12_22, 2016/12

The H12 report demonstrated the feasibility of safe and technically reliable geological disposal in 1999. The Government of Japan re-evaluated the geological disposal program in terms of technical feasibility based on state-of-the-art geosciences and implementation process, because more than 10 years have passed from H12 and the Great Earthquake and nuclear accident have increased public concern regarding nuclear issues and natural hazards to cause accidents at nuclear facilities. Following the re-evaluation, the Government concluded further to promote geological disposal program, and thus the Basic Policy for Final Disposal was revised in 2015 including a new approach to siting process with identification of "Scientifically Preferable Areas". NUMO and relevant research organizations such as JAEA have been carrying out R and D activities to increase technical reliability for geological disposal. NUMO has started to develop a generic safety case.

JAEA Reports

Development of waste management system

Mitsuda, Motoyuki; Sasaki, Toshiki

JAEA-Technology 2015-013, 29 Pages, 2015/06

JAEA-Technology-2015-013.pdf:0.96MB

For implementation of disposal of the radioactive waste generated from Japan Atomic Energy Agency, Waste Management System which manages all of the waste data has been developed. We surveyed the kinds of data needed for the waste management at each site, and we set the standard waste management data items. We developed conceptual design for the waste management system and established the system for major sites, Nuclear Science Research Institute, Ningyo-toge Environmental Engineering Center, Fugen Decommissioning Engineering Center, Oarai Research and Development Center, Nuclear Fuel Cycle Engineering Laboratories. For other small sites, we accumulate waste data to the common waste storage database. Therefore, we have developed the system which manages the quality assurance waste data depending on waste treatment situation in JAEA.

59 (Records 1-20 displayed on this page)