Yamaguchi, Masaaki; Kato, Tomoko; Suzuki, Yuji*; Makino, Hitoshi
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 27(2), p.72 - 82, 2020/12
An efficient analytical tool to calculate temporal change of topography and repository depth due to uplift and erosion was developed for use in performance assessment of high level radioactive waste geological disposal. The tool was developed as ArcGIS model, incorporating simplified landform development simulation, to enable trial calculation of various conditions such as initial topography, uplift rate and its distributions, and repository location. This tool enables to support decision on which processes, features, and their changes should be taken into account for performance assessment, by calculating topography change and repository depth change under various conditions.
Kokubu, Yoko; Fujita, Natsuko; Miyake, Masayasu; Watanabe, Takahiro; Ishizaka, Chika; Okabe, Nobuaki; Ishimaru, Tsuneari; Matsubara, Akihiro*; Nishizawa, Akimitsu*; Nishio, Tomohiro*; et al.
Nuclear Instruments and Methods in Physics Research B, 456, p.271 - 275, 2019/10
JAEA-AMS-TONO has been in operation at the Tono Geoscience Center, Japan Atomic Energy Agency since 1998 and 20 years have passed from the beginning of its utilization. The AMS system is a versatile system based on a 5 MV tandem Pelletron type accelerator. The system has been used to measure carbon-14 (C), beryllium-10 (Be) and aluminium-26 (Al). In addition, the development of measurement of iodine-129 (I) has been started. The main use is measurement of C in geological samples for dating studies in neotectonics and hydrogeology. In order to increase the speed of sample preparation, we introduced the automated graphitization equipment and made a gas-strip line to collect dissolved inorganic carbon in groundwater samples. Measurement of Be and Al has been used for geoscience studies and the detection limit in the measurement of Be was improved by Be-counting suppression. Recently tuning of measurement condition of I has been progressed.
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 0.150.01 pMC (IAEA-C1) using the AGE3 system. Therefore, we concluded that the system can be adapted for radiocarbon dating of geological samples.
Kokubu, Yoko; Fujita, Natsuko; Matsubara, Akihiro*; Nishizawa, Akimitsu*; Nishio, Tomohiro; Miyake, Masayasu; Ishimaru, Tsuneari; Watanabe, Takahiro; Ogata, Nobuhisa; Shimada, Akiomi; et al.
JAEA-Conf 2018-002, p.5 - 8, 2019/02
no abstracts in English
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
Fujita, Natsuko; Miyake, Masayasu; Watanabe, Takahiro; Kokubu, Yoko; Matsubara, Akihiro*; Kato, Motohisa*; Okabe, Nobuaki; Isozaki, Nobuhiro*; Ishizaka, Chika*; Torazawa, Hitoshi*; et al.
Dai-31-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.92 - 95, 2018/12
no abstracts in English
Fujita, Natsuko; Miyake, Masayasu; Watanabe, Takahiro; Kokubu, Yoko; Ishimaru, Tsuneari; Matsubara, Akihiro*; Isozaki, Nobuhiro*; Nishio, Tomohiro*; Kato, Motohisa*; Torazawa, Hitoshi*; et al.
Dai-19-Kai AMS Shimpojiumu, 2016-Nendo "Jumoku Nenrin" Kenkyukai Kyodo Kaisai Shimpojiumu Hokokushu, p.68 - 71, 2017/06
no abstracts in English
Ueno, Fumiyoshi; Irisawa, Eriko; Kato, Chiaki; Igarashi, Takahiro; Yamamoto, Masahiro; Abe, Hitoshi
Proceedings of European Corrosion Congress 2016 (EUROCORR 2016) (USB Flash Drive), 7 Pages, 2016/09
In this study, we focused on the effect of the boiling of nitric acid solution on the corrosion of a stainless steel-made concentrator in reduced pressure in fuel reprocessing plant. In order to perform the simulation test in a non-radioactive condition, nitric acid solution with the addition of vanadium as an oxidizing metal ion were used. Corrosion tests were carried out under the conditions of boiling at reduced pressure, and of non-boiling at normal pressure and several temperatures. As a result, corrosion was accelerated by the solution boiling while it was not by non-boiling at the same temperature. It was found also that the temperature dependence of corrosion rate is the same in the both conditions of boiling and non-boiling. The corrosion accelerating effect will be discussed on the basis of the reaction among nitric acid, NOx and vanadium, etc.
Irisawa, Eriko; Ueno, Fumiyoshi; Kato, Chiaki; Abe, Hitoshi
Zairyo To Kankyo, 65(4), p.134 - 137, 2016/04
In order to investigate the effect of boiling under reduced pressure on corrosion of stainless steel in the nitric acid solution, the corrosion tests simulating the high-level radioactive liquid waste evaporator were performed. The results of immersion tests of stainless steels in the solution with and without boiling showed that the corrosion rates in boiling solution were larger than those in not boiling solution in case of same temperature of solution. Moreover, the cathode polarization curves showed that the corrosion potential of stainless steel in boiling solutions were shifted nobler, and the current intensity became larger than that in not boiling solutions. According to these results, it can be concluded that boiling of solution under reduced pressure accelerate the corrosion rates.
Irisawa, Eriko; Seki, Masaharu*; Ueno, Fumiyoshi; Kato, Chiaki; Motooka, Takafumi; Abe, Hitoshi
Proceedings of 21st International Conference & Exhibition; Nuclear Fuel Cycle for a Low-Carbon Future (GLOBAL 2015) (USB Flash Drive), p.1108 - 1112, 2015/09
Nemoto, Yoshiyuki; Kato, Hitoshi; Kaji, Yoshiyuki; Yoshida, Hiroyuki
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 5 Pages, 2015/05
For the evaluation of reactor pressure vessel (RPV) lower head rupture probably occurred during the severe accident in Fukushima Daiichi Nuclear Power Plants, JAEA is conducting the thermal-hydraulics / mechanical coupling analysis. In the mechanical analysis based on the finite element method (FEM), material property data previously obtained from uni-axial material tests are applied. The lower head of BWR such as Fukushima NPP, has complicated structure compared to PWR, with control rod guide tubes, stub tubes, etc., therefore the mechanical analyses need to treat multi-axial deformation of the materials. To perform such mechanical analysis, the applicability of the analytical model using uni-axial data for multi-axial deformation analysis must be validated. In this study, the internal pressure creep tests were performed because which can realize the multi-axial deformation condition. In addition, mechanical analyses were conducted and the analytical results were compared with the experimental data.
Sugiyama, Hitoshi*; Takahashi, Keita*; Kato, Naoto*; Terada, Atsuhiko; Kamiji, Yu; Hino, Ryutaro
Jidosha Gijutsukai Gakujutsu Koenkai Zensatsushu, (109-14), p.5 - 10, 2014/10
Numerical analysis has been performed for vertical buoyant flow of air-hydrogen mixture in rectangular indoor space with ventilators. The unsteady and laminar flow has been calculated by using the coupled conservation equations of hydrogen and momentum. Calculated results are compared with the experiment data of hydrogen concentration and velocity profile in order to confirm the validity of the presented numerical method and clarify the mechanism of hydrogen dispersion. Although agreement is certainly not perfect in all detail, the main features are reasonably reproduced. Adding to this, calculated results suggest that hydrogen concentration depends on Froude number.
Sugiyama, Hitoshi*; Otemori, Toshiki*; Kato, Naoto*; Terada, Atsuhiko; Kamiji, Yu; Hino, Ryutaro
Jidosha Gijutsukai Gakujutsu Koenkai Zensatsushu, (147-14), p.25 - 30, 2014/10
Numerical analysis has been performed for three-dimensional developing turbulent flow in a rectangular duct containing straight cylinder placed near a bottom wall. In this kind of turbulent flow, it has been pointed out as a characteristic features that anisotropic turbulence generates the secondary flow of the second kind and pulsation flow is measured in narrow gap region located between cylinder and bottom wall. Comparisons with the experimental results suggest that the present method is able to predict velocity profiles correctly and reproduce both the secondary flow of the second kind and the generation of pulsation flow near the narrow region between cylinder and bottom wall.
Sato, Hiroyuki; Terada, Atsuhiko; Hayashida, Hitoshi; Kamiji, Yu; Kobayashi, Jun; Yamagishi, Isao; Morita, Keisuke; Kato, Chiaki
JAEA-Research 2013-042, 25 Pages, 2014/03
Spent zeolite adsorption vessels in the Fukushima No.1 nuclear power plant are kept for long-term with washing out with fresh water for prevention of corrosion remaining salt component in vessel. However, corrosion result is concerned by residual concentration of salt component, washing out experiment is carried out using actual and unspent adsorption vessel (KURION). KURION adsorption vessel is filled with 1,650 ppm of sodium chloride (1,000 ppm of chloride ion) and washed out with pure water for estimating washing effect in this experiment. Pure water is streamed with volume flow rate 4.5 m/h, chloride concentration in vessel is measured with drainage sample water. 1,000 ppm of chloride concentration is decreased till 0.5 ppm and below by washing out with about double pure water volume of adsorbing material filling volume in vessel, washing out is more effective in KURION adsorption vessel.
Takahashi, Nobuaki*; Murata, Hirohiko*; Mitsubori, Hitoshi*; Sakuraba, Junji*; Soga, Tomohiro*; Aoki, Yasushi*; Kato, Takanori*; Saito, Yuichi; Yamada, Keisuke; Ikenaga, Noriaki*; et al.
Review of Scientific Instruments, 85(2), p.02C306_1 - 02C306_3, 2014/02
Eto, Haruhiko*; Aoki, Yasushi*; Mitsubori, Hitoshi*; Arakawa, Y.*; Mitsumoto, Toshinori*; Yajima, S.*; Sakuraba, Junji*; Kato, Takanori*; Okumura, Yoshikazu
Review of Scientific Instruments, 85(2), p.02B107_1 - 02B107_3, 2014/02
High current hydrogen negative ion source is required to increase the accelerated beam current of the cyclotrons for many medical applications such as cancer therapy and medical radioisotope production. A new negative ion source has been designed and fabricated. The ion source is a multi-cusp type. Optimization of the ion source is in progress, such as the optimization of the magnetic filter which prevents high temperature electrons from entering into the negative ion production region, improvement of the extraction electrode's shape and configuration of dipole magnets etc. A small quantity of Cs has been introduced into the ion source to enhance the negative ion beam current. The ion source produced 16mA of DC hydrogen negative ion beam with the Cs-seeded operation at a low arc discharge power of 2.8 kW.
Okagaki, Yuria*; Sugiyama, Hitoshi*; Kato, Naoto*; Hino, Ryutaro
Jidosha Gijutsukai Rombunshu, 43(4), p.949 - 955, 2012/07
Turbulent heat transfer enhancement using periodically arranged ribs processed on the graphite sleeve of a fuel rod aims to increase heat generation density of the fuel rod, which can potentially improve the economics of a block type high-temperature gas-cooled reactor. Rectangular cross section of rib is selected because of easy processing. Furthermore, it is important to find optimum rib topology such as pitch and height to maximize turbulent heat transfer performance. In order to develop a turbulent model as a design tool for rib-roughened fuel rod, numerical analysis has been conducted to verify applicability of an algebraic Reynolds stress model, which is computationally efficient, to non-isotropic turbulent flow in rib roughened channels. The results of the analysis on a square duct with periodically arranged ribs on the bottom wall are shown to reproduce very well the flow characteristics such as flow separation and reattachment behind the ribs. The model is therefore expected to be applicable to rib-enhanced fuel rod design.
Sumiya, Shuichi; Watanabe, Hitoshi; Nakano, Masanao; Takeyasu, Masanori; Nakada, Akira; Fujita, Hiroki; Isozaki, Tokuju; Morisawa, Masato; Mizutani, Tomoko; Kokubun, Yuji; et al.
JAEA-Review 2012-015, 166 Pages, 2012/05
Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2010 to March 2011. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Plant on Tokyo Electric Power Co. in 2011 March. Appendices present comprehensive information, such as monitoring program, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data exceeded the normal range of fluctuation by the accidental release was evaluated in the appendices.
Okagaki, Yuria*; Sugiyama, Hitoshi*; Kato, Naoto*; Terada, Atsuhiko; Hino, Ryutaro
Proceedings of 19th International Conference on Nuclear Engineering (ICONE-19) (CD-ROM), 8 Pages, 2011/10
Turbulent flow and heat transfer characteristics in a square duct of 100 mm height with 45 degree square ribs of 10 mm height was analyzed numerically by using algebraic Reynolds stress model including the fixed turbulent Prandtl number and algebraic turbulent heat flux models. In this research, analytical results were compared with the experimental and predicted data reported by Bonhoff et al, which were measured and analyzed turbulent flow fields at Reynolds number 50000 based on bulk velocity and duct height by means of a PIV system and a Reynolds stress model. As a result of this study, it was verified that the presented method was able to predict turbulent flow in duct with ribs through the comparison of calculated results with the experimental data.
Okagaki, Yuria*; Sugiyama, Hitoshi*; Hino, Ryutaro; Kato, Naoto*; Terada, Atsuhiko
Nihon Kikai Gakkai Kanto Shibu Burokku Godo Koenkai Koen Rombunshu, p.35 - 36, 2011/09
Turbulent flow and heat transfer characteristics in a square duct of square ribs was analyzed numerically by using algebraic Reynolds stress model. In this research, as the first step of design code development for HTGR heat exchanger equipment, analytical results were compared with the experimental and predicted data reported by Casarsa et al., which were measured by means of a PIV system.