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Journal Articles

Thermodynamic study of the complexation of humic acid by calorimetry

Kimuro, Shingo; Kirishima, Akira*; Kitatsuji, Yoshihiro; Miyakawa, Kazuya; Akiyama, Daisuke*; Sato, Nobuaki*

Journal of Chemical Thermodynamics, 132, p.352 - 362, 2019/05

A combination of potentiometry and calorimetry was used for the determination of the thermodynamic quantities of complexation of generic and groundwater humic acid (HA), which was isolated from deep groundwater at Horonobe, Hokkaido, Japan, with copper (II) ions and uranyl (VI) ions. The apparent complexation constant of Horonobe HA was independent of the pH, whereas that of generic HA was dependent on the pH. This observation indicates that the polyelectrolyte effect of Horonobe HA is negligible because of its small molecular size. In addition, the effect of the heterogeneity of Horonobe HA was not significant. Moreover, the complexation enthalpy of Horonobe HA was consistent with that of homogeneous poly(acrylic acid), which means the complexation of Horonobe HA was not affected by the functional group heterogeneity . Consequently, the characteristic complexation mechanism of Horonobe HA was revealed based on the determined thermodynamic quantities.

JAEA Reports

Synchrotron radiation based XAFS analysis of the simulated nuclear waste glass samples prepared by bottom drain test in the full-scale mock-up melter (KMOC) (Contract research)

Okamoto, Yoshihiro; Nagai, Takayuki; Shiwaku, Hideaki; Kano, Shigeru; Himeno, Haruyuki*; Kobayashi, Hiroshi*; Nakatani, Mikio*

JAEA-Research 2018-013, 18 Pages, 2019/03

JAEA-Research-2018-013.pdf:1.98MB

The chemical state and local structure of some elements in the simulated nuclear waste glass samples (20 batches) prepared by bottom drain test in the full scale mock-up tests using KMOC melter were investigated by synchrotron radiation based X-ray absorption fine structure (XAFS) analysis. As a result of the analysis of cerium element, it was confirmed that the oxidation proceeds gently as the batch advanced. For manganese, iron, and zinc, there was almost no difference between batches, which seemed to be stabilized by getting into the frame structure of the borosilicate glass. There were no elements that seemed to be clearly crystalline except for platinum group elements. Remarkable precipitation was hardly observed in zirconium and molybdenum with the imaging analysis.

JAEA Reports

Data of long term hydro-pressure monitoring on Tono Regional Hydrogeological Study Project for fiscal year 2015-2016

Keya, Hiromichi; Takeuchi, Ryuji; Iwatsuki, Teruki

JAEA-Data/Code 2018-020, 58 Pages, 2019/03

A wide range of geoscientific research aims to establish comprehensive techniques for the investigation, analysis and assessment of the deep geological environment in fractured crystalline rock. The Regional Hydrogeological Study (RHS) project is a one of the geoscientific research program at Tono Geoscience Center. This project started since April 1992 and main investigations were finished to March 2004. Since 2005, hydrogeological and hydrochemical monitoring have been continued using the existing monitoring system. This report describes the results of the long term hydro-pressure monitoring from April 2015 to March 2017.

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.

Journal Articles

Development of clearance verification equipment for uranium-bearing waste

Yokoyama, Kaoru; Ohashi, Yusuke

Applied Radiation and Isotopes, 145, p.19 - 23, 2019/03

Dismantled materials generated from nuclear facilities are reused or directed to repository sites. If scrap metals with complicated shapes can be cleared, the amounts of radioactive waste can be reduced. A clearance verification system is constructed to determine the amount of uranium in decontaminated metals in a drum using the 1.001 MeV gamma rays of $$^{234m}$$Pa, produced in the decay of $$^{238}$$U. The experimental study with simulated waste drums demonstrated that the quantification errors of uranium fall within 25 % for 0.5 g of uranium.

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.

JAEA Reports

Excavation of shafts and research galleries at the Mizunami Underground Research Laboratory (construction work of MIU part VII); Construction progress report, fiscal year 2016-2017

Geoscience Facility Construction Section, Tono Geoscience Center

JAEA-Review 2018-026, 92 Pages, 2019/02

JAEA-Review-2018-026.pdf:11.89MB

This progress report presents an outline compilation of construction activities, primary tasks performed, construction progress and safety patrol report, in Fiscal Year 2016-2017. The outline of construction activities is a summary based on the scope of work planned in Fiscal Year 2016-2017: the main activities are based on the Tono Geoscience Center weekly reports; and the construction progress is based on the planned and actual schedules. Regarding the actual performance of the construction work of MIU part VII (March 16, 2016 -March 15, 2018) performance carried out from April 1, 2016 until March 15, 2018 is described in this report and the performance started from March 16, 2018 is supposed to be described in progress report of construction work of MIU part VIII.

JAEA Reports

Hydraulic tests for the excavation damaged zone around the 350m niches in the Horonobe Underground Research Project

Yoshino, Hiromitsu*; Samata, Yoichi; Niunoya, Sumio*; Ishii, Eiichi

JAEA-Data/Code 2018-015, 169 Pages, 2019/02

JAEA-Data-Code-2018-015.pdf:16.45MB
JAEA-Data-Code-2018-015-appendix1(DVD-ROM).zip:115.02MB
JAEA-Data-Code-2018-015-appendix2(DVD-ROM).zip:64.3MB
JAEA-Data-Code-2018-015-appendix3(DVD-ROM).zip:27.77MB
JAEA-Data-Code-2018-015-appendix4(DVD-ROM).zip:96.39MB
JAEA-Data-Code-2018-015-appendix5(DVD-ROM).zip:104.89MB

In Horonobe Underground Research Laboratory Project, hydraulic tests for the excavation damaged zone have been performed in order to characterize the hydrological properties of the zone. This report summarized the results of the hydraulic tests and pore-pressure monitoring which have been done by March 2016.

JAEA Reports

Proceedings of the 30th Meeting for Tandem Accelerators and their Associated Technologies

Ishimaru, Tsuneari; Shimada, Akiomi; Kokubu, Yoko; Fujita, Natsuko

JAEA-Conf 2018-003, 147 Pages, 2019/02

JAEA-Conf-2018-003.pdf:58.99MB

The 30th Meeting of Tandem Accelerators and their Associated Technologies was held on July 6 and 7, 2017 at Tono Geoscience Center of the Japan Atomic Energy Agency. This meeting involved the participation of 97 persons from universities, research institutes and companies which have tandem accelerators and/or electrostatic accelerators. The purpose of the meeting is to contribute to research and development of accelerator technology through exchange of information among the engineers and the researchers who are interested in a tandem accelerator or an electrostatic accelerator. The meeting consisted of oral and poster sessions, and there were 33 presentations which contained about the current status of tandem accelerator facilities, technical developments and research using accelerators, etc. This proceedings summarizes the contents of the presentations at the meeting.

JAEA Reports

Proceedings of the 20th Japanese Symposium on Accelerator Mass Spectrometry

Ishimaru, Tsuneari; Shimada, Akiomi; Kokubu, Yoko; Fujita, Natsuko; Watanabe, Takahiro

JAEA-Conf 2018-002, 134 Pages, 2019/02

JAEA-Conf-2018-002.pdf:15.31MB

This proceedings issue includes the presentation contents of the 20th Japanese Symposium on Accelerator Mass Spectrometry (JAMS-20). The JAMS-20 was held by Tono Geoscience Center, Japan Atomic Energy Agency, on December 14-15th, 2017. The number of participants was seventy five during two days. On the Symposium, thirty two presentations were made for facility status reports, analytical developments and application techniques.

Journal Articles

Assessment of the potential for criticality in the far field of a used nuclear fuel repository

Atz, M.*; Salazar, A.*; Hirano, Fumio; Fratoni, M.*; Ahn, J.*

Annals of Nuclear Energy, 124, p.28 - 38, 2019/02

The likelihood for criticality in the far field of a repository was evaluated for direct disposal of commercial light water reactor used nuclear fuel. Two models were used in combination for this evaluation: (1) a neutronics model to estimate the minimum critical masses of spherical, water-saturated depositions of fuel material; (2) a transport model to simulate the dissolution of fuel material from multiple canisters and the subsequent transport of the solutes through host rock to a single accumulation location. The results suggest that accumulation of a critical mass is possible under conservative conditions but that these conditions are unlikely to occur, especially in the vicinity of a carefully-arranged repository.

Journal Articles

3D-microstructure analysis of compacted Na- and Cs-montmorillonites with nanofocus X-ray computed tomography and correlation with macroscopic transport properties

Takahashi, Hiroaki*; Tachi, Yukio

Applied Clay Science, 168, p.211 - 222, 2019/02

Microstructural and mass transport properties of compacted Na- and Cs-montmorillonites with different swelling properties were investigated by combining 3D microstructure analysis using nanofocus X-ray CT and diffusion measurement of HDO. The X-ray CT observations indicated that macropores in the dry state of compacted Na-montmorillonite are filled with gel phases, and the grain sizes of clay particles shifted toward smaller values through the saturation and swelling processes. By contrast, no gel phase and no decrease in the grain and pore volumes were observed for saturated Cs-montmorillonite. The geometrical factors of the macropores including tortuosity and geometric constrictivity of saturated Cs-montmorillonite determined by the X-ray CT was consistent with the corresponding values derived in the HDO diffusion test. In the case of Na-montmorillonite, the larger differences between the geometric factors evaluated by the X-ray CT and the diffusion tests can be explained by the electrostatic constrictivity factor and the additional geometrical factors in gel phase and interlayer that are smaller than the detection limit of the X-ray CT.

Journal Articles

The present status of the AGE3 automated graphitization equipment for radiocarbon dating at the JAEA-AMS-TONO

Watanabe, Takahiro; Kokubu, Yoko; Fujita, Natsuko; Ishizaka, Chika*; Nishio, Tomohiro; Matsubara, Akihiro*; Miyake, Masayasu; Kato, Motohisa*; Isozaki, Nobuhiro*; Torazawa, Hitoshi*; et al.

JAEA-Conf 2018-002, p.116 - 119, 2019/02

AMS is widely used for radiocarbon dating of geological samples. However, improvement in efficiency of sample preparation techniques are needed for high-time resolution dataset. In 2016, automated graphitization equipment (AGE3, IonPlus AG) has been installed in Toki Research Institute of Isotope Geology and Geochronology, Tono Geoscience Center, JAEA. Background values and carbon recovery rates during preparation process of AGE3 should be estimated before application in radiocarbon dating. In this study, the AGE3 system was evaluated using the international standard materials (IAEA-C1, C4, C5, C6, C7, C9 and NIST-SRM4990C) at JAEA-AMS-TONO. Graphite samples was prepared by the AGE3 system and radiocarbon concentration of these standards was measured by AMS. The results were agreement with the consensus values. Background values were 0.15$$pm$$0.01 pMC (IAEA-C1) using the AGE3 system. Therefore, we concluded that the system can be adapted for radiocarbon dating of geological samples.

Journal Articles

Improvement of methods for measurement of $$^{129}$$I/$$^{127}$$I ratio at JAEA-AMS-TONO

Okabe, Nobuaki; Fujita, Natsuko; Matsubara, Akihiro*; Miyake, Masayasu; Nishio, Tomohiro*; Nishizawa, Akimitsu*; Isozaki, Nobuhiro*; Watanabe, Takahiro; Kokubu, Yoko

JAEA-Conf 2018-002, p.51 - 54, 2019/02

no abstracts in English

Journal Articles

Development of isobar separation method based on ion channeling

Matsubara, Akihiro*; Fujita, Natsuko; Miyake, Masayasu; Isozaki, Nobuhiro*

JAEA-Conf 2018-002, p.68 - 71, 2019/02

no abstracts in English

Journal Articles

Preliminary results of $$^{10}$$Be of the rock samples from the lake terrace of the Lake Pumayum Co in Tibetan Plateau

Nara, Fumiko*; Watanabe, Takahiro; Kokubu, Yoko; Horiuchi, Kazuho*

JAEA-Conf 2018-002, p.124 - 127, 2019/02

In-situ cosmogenic radionuclides have been used to understand earth surface processes, such as the erosion rate and exposure age dating of rocks. This is a preliminary report on in-situ $$^{10}$$Be values measurements by Accelerator Mass Spectrometry (AMS) for rock samples from the shore of the Lake Pumoyum Co in Tibetan plateau. The $$^{10}$$Be concentrations ranged from 5.5-7.5$$times$$10$$^{6}$$ atom/g similar to those of the surface sediments of Lake Pumoyum Co. The calculated erosion rates were 5.2-7.6 mm/kyr, values close to those previously reported by Lal et al. (2003).

Journal Articles

The 20th anniversary of JAEA-AMS-TONO

Ishimaru, Tsuneari

JAEA-Conf 2018-013, p.13 - 16, 2019/02

In the Tono Geoscience Center, JAEA-AMS-TONO was introduced in March 1997 and it will be the 20th year in this year. After introduction, we maintained the carbon-14 measurement first and we were able to steadily accumulate results.

Journal Articles

Present status of the accelerator facility at the JAEA-AMS-TONO; 2016

Fujita, Natsuko; Miyake, Masayasu; Watanabe, Takahiro; Kokubu, Yoko; Ishimaru, Tsuneari; Matsubara, Akihiro*; Nishio, Tomohiro*; Kato, Motohisa*; Isozaki, Nobuhiro*; Torazawa, Hitoshi*; et al.

JAEA-Conf 2018-013, p.96 - 99, 2019/02

no abstracts in English

Journal Articles

Derivation of a charge state distribution around axial channeling condition

Matsubara, Akihiro*; Fujita, Natsuko; Miyake, Masayasu; Isozaki, Nobuhiro*; Nishizawa, Akimitsu*

JAEA-Conf 2018-013, p.135 - 139, 2019/02

no abstracts in English

Journal Articles

A Method for estimating the highest potential hydraulic conductivity in the excavation damaged zone in mudstone

Aoyagi, Kazuhei; Ishii, Eiichi

Rock Mechanics and Rock Engineering, 52(2), p.385 - 401, 2019/02

Excavation of deep underground openings induces permeable fractures around the opening due to stress redistribution. Such a zone is called excavation damaged zone (EDZ). In a high-level radioactive waste disposal project, the EDZ might provide pathways for the migration of radionuclides around the facility. Thus, this study focused on the development of a method for estimating the highest potential hydraulic conductivity in the EDZ around a gallery in the Horonobe Underground Research Laboratory, Japan. Borehole televiewer surveys, rock core observations, and hydraulic tests were undertaken to investigate the extent and magnitude of hydraulic conductivity in the EDZ around the gallery. The observed extent of the EDZ shows good agreement with the EDZ estimated from hydro-mechanical coupling analysis. The measured hydraulic conductivities of the EDZ are within the range of those based on the Mean Stress Index (MSI), which is defined as the ratio of the effective mean stress derived from numerical analyses to the tensile strength of intact rock. Given that the rock mass is relatively homogeneous and artificial damage (e.g., blasting-induced damage) can be neglected, as in the Horonobe Underground Research Laboratory, the MSI model is likely to be applicable in estimating the highest potential hydraulic conductivity in the EDZ.

10082 (Records 1-20 displayed on this page)