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Sanada, Yukihisa; Oshikiri, Keisuke*; Kanno, Marina*; Abe, Tomohisa
Nuclear Instruments and Methods in Physics Research A, 1062, p.169208_1 - 169208_7, 2024/05
As part of the decommissioning work at the Fukushima Daiichi Nuclear Power Plant (FDNPP), the release of stored treated water began in 2023. In this study, we developed a practical tritium monitor to continuously monitor the concentration of tritiated water, as confirmed by batch sampling measurements at the FDNPP. The monitor is arranged with a flow cell detector comprising inexpensive plastic scintillator pellets and incorporating simultaneous measurements by three detectors, a veto detector, and lead shielding to reduce the influence of environmental -rays. The system reached a detection limit of 911 Bq L-1 with a measurement time of 30 min, which is lower than the discharge standard for tritiated water of 1,500 Bq L-1. The system can also qualitatively distinguish the presence of disturbances due to interfering radionuclides other than tritium or background radiation using the -ray spectrum.
Yokoyama, Keisuke; Uwaba, Tomoyuki
Journal of Nuclear Science and Technology, 60(10), p.1219 - 1227, 2023/10
Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)no abstracts in English
Project 6 Meeting Members for Tsukuba International Strategic Zone
JAEA-Review 2021-016, 102 Pages, 2021/11
In December 2011, the Prime Minister designated Tsukuba and some areas in Ibaraki Prefecture as "Comprehensive Special Zones". In the Tsukuba International Strategic Zone, nine advanced research and development (R&D) projects are underway with the goal of promoting industrialization of life innovation and green innovation utilizing the science and technology in Tsukuba. In these projects, the domestic production of medical radioisotope (Technetium-99m, Tc) was certified as a new project in October 2013, and R&D have been performed in collaboration with related organizations with Japan Atomic Energy Agency (JAEA) as the project leader. Japan is the third largest consumer of molybdenum-99 (Mo) after the United States and Europe, and all Mo are imported. Supply will be insufficient if overseas reactors are shut down due to trouble or if transportation (air and land transportations) is stopped due to volcanic eruptions and some accidents. Thus, early domestic production of Mo is strongly required. This project is a technology development aimed at domestic production of Mo, which is a raw material of Tc used as a diagnostic agent. This report summarizes the activities carried out in the first and second phase of the domestic production of medical radioisotope (Tc) (here referred to as the "Project 6") in Tsukuba International Strategic Zone (FY2014-2020).
Kato, Masato
Encyclopedia of Nuclear Energy, Vol.2, p.298 - 307, 2021/00
Uwaba, Tomoyuki; Yokoyama, Keisuke; Nemoto, Junichi*; Ishitani, Ikuo*; Ito, Masahiro*; Pelletier, M.*
Nuclear Engineering and Design, 359, p.110448_1 - 110448_7, 2020/04
Times Cited Count:1 Percentile:12.16(Nuclear Science & Technology)Coupled computer code analyses of irradiation performance of axially heterogeneous mixed oxide (MOX) fuel elements with high burnup in a fast reactor were conducted. Post-irradiation experiments revealed local concentration of Cs near the interfaces between MOX fuel and blanket columns including the internal blanket of the fuel elements as well as an increase in their cladding diameters. The analyses indicated that the local Cs concentration occurred as a result of Cs axial migration from the MOX fuels toward the blanket pellets near the interfaces. Swelling of the blanket pellets induced by the formation of low-density Cs-U-O compound was not sufficient to cause pellet-to-cladding mechanical interaction (PCMI). The PCMI analyzed in the MOX fuel column regions was insignificant, and the cladding diameter increases were caused mainly by void swelling in cladding and irradiation creep due to fission gas pressure.
Nishikata, Kaori; Ishida, Takuya; Yonekawa, Minoru; Kato, Yoshiaki; Kurosawa, Makoto; Kimura, Akihiro; Matsui, Yoshinori; Tsuchiya, Kunihiko; Sano, Tadafumi*; Fujihara, Yasuyuki*; et al.
KURRI Progress Report 2014, P. 109, 2015/07
As one of effective applications of the Japan Materials Testing Reactor (JMTR), JAEA has a plan to produce Mo by (n,) method ((n,)Mo production), a parent nuclide of Tc. In this study, preliminary irradiation test was carried out with the high-density molybdenum trioxide (MoO) pellets in the hydraulic conveyer (HYD) of the Kyoto University Research Reactor (KUR) and the Tc solution extracted from Mo was evaluated. After the irradiation test of the high-density MoO pellets in the KUR, Tc was extracted from the Mo solution and the recovery rate of Tc achieved the target values. The Tc solution also got the value that satisfied the standard value for Tc radiopharmaceutical products by the solvent extraction method.
Nishikata, Kaori; Kimura, Akihiro; Ishida, Takuya; Shiina, Takayuki*; Ota, Akio*; Tanase, Masakazu*; Tsuchiya, Kunihiko
JAEA-Technology 2014-034, 34 Pages, 2014/10
As a part of utilization expansion after the Japan Material Testing Reactor (JMTR) re-start, research and development (R&D) on the production of medical radioisotope Mo/Tc by (n, ) method using JMTR has been carried out in the Neutron Irradiation and Testing Reactor Center of the Japan Atomic Energy Agency. Mo is usually produced by fission method. On the other hand, Mo/Tc production by the (n, ) method has advantages for radioactive waste, cost reduction and non-proliferation. However, the specific radioactivity per unit volume by the (n, ) method is low compared with the fission method, and that is the weak point of the (n, ) method. This report summarizes the investigation of raw materials, the fabrication tests of high-density MoO pellets by the plasma sintering method for increasing of Mo contents and the characterization of sintered high-density MoO pellets.
Takenaga, Hidenobu; Oyama, Naoyuki; Bruskin, L. G.*; Mase, Atsushi*; Takizuka, Tomonori; Fujita, Takaaki
Plasma Physics and Controlled Fusion, 48(5A), p.A401 - A408, 2006/05
Times Cited Count:6 Percentile:21.5(Physics, Fluids & Plasmas)no abstracts in English
Polevoi, A. R.*; Shimada, Michiya; Sugihara, Masayoshi; Igitkhanov, Y. L.*; Mukhovatov, V.*; Kukushkin, A. S.*; Medvedev, S. Y.*; Zvonkov, A. V.*; Ivanov, A. A.*
Nuclear Fusion, 45(11), p.1451 - 1456, 2005/11
Times Cited Count:33 Percentile:70.37(Physics, Fluids & Plasmas)Requirements for pellet injection parameters for plasma fuelling are assessed for ITER scenarios with enhanced particle confinement. A pellet injection throughput of 100 Pam/s would be sufficient. The assessment is based on the integrated transport simulations including models of pedestal transport, reduction of helium transport and boundary conditions compatible with SOL/divertor simulations. The requirements for pellet injection for the inductive H-mode scenario (HH98(y,2) = 1) are reconsidered taking account of a possible reduction of the particle loss obtained in some experiments at low collisionalities. The assessment of fuelling requirements is carried out for the hybrid and steady state scenarios with enhanced confinement with HH98(y,2) 1. A robustness of plasma performance to the variation of particle transport is demonstrated. A new type of steady state (SS) scenario is considered with neutral beam current drive (NBCD) and electron cyclotron current drive (ECCD) instead of lower hybrid current drive (LHCD).
Kawano, Yasunori; Nakano, Tomohide; Isayama, Akihiko; Asakura, Nobuyuki; Tamai, Hiroshi; Kubo, Hirotaka; Takenaga, Hidenobu; Bakhtiari, M.; Ide, Shunsuke; Kondoh, Takashi; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 81(8), p.593 - 601, 2005/08
An experiment to investigate mitigation effects of impurity pellet injection on disruption generated runaway electrons was carried out in the JT-60U tokamak device. Deposition of impurity neon pellets into a post-disruption runaway plasma was observed with increment of bulk electron density. At the impurity pellet injection, decay time of runaway current became shorter as factor of 2. There was an approximately linear relationship between changes in decay rate of runaway current and a photo-neutron signal which indicated loss of runaway electrons from the plasma. Consequently, enhanced loss of runaway electrons from a tokamak plasma, hence mitigation effect on them, by injection of impurity neon pellets was found.
Kawano, Yasunori; Nakano, Tomohide; Isayama, Akihiko; Hatae, Takaki; Konoshima, Shigeru; Oyama, Naoyuki; Kondoh, Takashi; Tamai, Hiroshi; Kubo, Hirotaka; Asakura, Nobuyuki; et al.
Europhysics Conference Abstracts (CD-ROM), 29C, 4 Pages, 2005/00
In order to mitigate the post-disruption runaway electrons, experiments has been carried out with impurity pellet injection. As a result, we have observed the prompt exhaust of the runaway electrons and the reduction of runaway plasma. We have presented one possible explanation for basic behavior of the runaway plasma current that it follows the balance of the avalanche generation of runaway electrons and their slowing down predicted by the model, including effects by synchrotron radiation. On the other hand, standing on the fact that the current quench time is extended by runaway electrons, the experiment for avoiding the current quench by runaway electrons has been carried out. The runaway electrons reinforced the discharge to survive against the low Te of less than several tens eV and an additional impurity pellet injection, and thus the plasma current was maintained and terminated as programmed. To study the dynamics of runaway electrons precisely, a new active and direct diagnostic concept using the laser inverse Compton scattering has been proposed.
Takenaga, Hidenobu; Oyama, Naoyuki; Isayama, Akihiko; Inagaki, Shigeru*; Takizuka, Tomonori; Fujita, Takaaki; Miura, Yukitoshi
Europhysics Conference Abstracts (CD-ROM), 29C, 4 Pages, 2005/00
no abstracts in English
Shimada, Michiya; Mukhovatov, V.*; Federici, G.*; Gribov, Y.*; Kukushkin, A.*; Murakami, Yoshiki*; Polevoi, A. R.*; Pustovitov, V. D.*; Sengoku, Seio; Sugihara, Masayoshi
Nuclear Fusion, 44(2), p.350 - 356, 2004/02
Recent performance analysis has improved confidence in achieving Q 10 in inductive operation in ITER. Performance analysis based on empirical scaling shows the feasibility of achieving Q 10 in inductive operation with a sufficient margin. Theory-based core modeling indicates the need of high pedestal temperature (2-4 keV) to achieve Q 10, which is in the range of projection with pedestal scaling. The heat load of type-I ELM could be made tolerable by high density operation and further tilting the target plate (if necessary). Pellet injection from High-Field Side would be useful in enhancing Q and reducing ELM heat load. Steady state operation scenarios have been developed with modest requirement on confinement improvement and beta (HH98(y,2) 1.3 and betaN 2.6). Stabilisation of RWM, required in such regimes, is feasible with the present saddle coils and power supplies with double-wall structure taken into account.
Shimada, Michiya; Mukhovatov, V.*; Federici, G.*; Gribov, Y.*; Kukushkin, A. S.*; Murakami, Yoshiki*; Polevoi, A. R.*; Pustovitov, V. D.*; Sengoku, Seio; Sugihara, Masayoshi
Nuclear Fusion, 44(2), p.350 - 356, 2004/02
Times Cited Count:39 Percentile:75.67(Physics, Fluids & Plasmas)Performance analysis based on empirical scaling shows the feasibility of achieving Q 10 in inductive operation. Analysis has also elucidated a possibility that ITER can potentially demonstrate Q 50, enabling studies of self-heated plasmas. Theory-based core modeling indicates the need of high pedestal temperature (3.2 - 5.3 keV) to achieve Q 10, which is in the range of projection with presently available pedestal scalings. Pellet injection from high-field side would be useful in enhancing Q and reducing ELM heat load in high plasma current operation. If the ELM heat load is not acceptable, it could be made tolerable by further tilting the target plate. Steady state operation scenarios at Q = 5 have been developed with modest requirement on confinement improvement and beta (HH98(y,2) 1.3 and betaN 2.6). Stabilisation of RWM, required in such regimes, is feasible with the present saddle coils and power supplies with double-wall structure taken into account.
Ichige, Hisashi; Hiratsuka, Hajime; Honda, Masao; Miya, Naoyuki
Heisei-14-Nendo Tokyo Daigaku Sogo Gijutsu Kenkyukai Gijutsu Hokokushu, p.2_91 - 2_93, 2003/03
no abstracts in English
Takenaga, Hidenobu; Kubo, Hirotaka; Higashijima, Satoru; Asakura, Nobuyuki; Sugie, Tatsuo; Konoshima, Shigeru; Shimizu, Katsuhiro; Nakano, Tomohide; Itami, Kiyoshi; Sakasai, Akira; et al.
Fusion Science and Technology (JT-60 Special Issue), 42(2-3), p.327 - 356, 2002/09
Times Cited Count:10 Percentile:15.15(Nuclear Science & Technology)no abstracts in English
Kamada, Yutaka; Fujita, Takaaki; Ishida, Shinichi; Kikuchi, Mitsuru; Ide, Shunsuke; Takizuka, Tomonori; Shirai, Hiroshi; Koide, Yoshihiko; Fukuda, Takeshi; Hosogane, Nobuyuki; et al.
Fusion Science and Technology (JT-60 Special Issue), 42(2-3), p.185 - 254, 2002/09
Times Cited Count:34 Percentile:48.48(Nuclear Science & Technology)With the main aim of providing physics basis for ITER and the steady-state tokamak reactors, JT-60/JT-60U has been developing and optimizing the operational concepts, and extending the discharge regimes toward sustainment of high integrated performance in the reactor relevant parameter regime. In addition to achievement of the equivalent break-even condition (QDTeq up to 1.25) and a high fusion triple product = 1.5E21 m-3skeV, JT-60U has demonstrated the integrated performance of high confinement, high beta-N, full non-inductive current drive with a large fraction of bootstrap current in the reversed magnetic shear and in the high-beta-p ELMy H mode plasmas characterized by both internal and edge transport barriers. The key factors in optimizing these plasmas are profile and shape controls. As represented by discovery of various Internal Transport Barriers, JT-60/JT-60U has been emphasizing freedom and restriction of profiles in various confinement modes. JT-60U has demonstrated applicability of these high confinement modes to ITER and also clarified remaining issues.
Kamada, Yutaka; Takenaga, Hidenobu; Isayama, Akihiko; Hatae, Takaki; Urano, Hajime*; Kubo, Hirotaka; Takizuka, Tomonori; Miura, Yukitoshi
Plasma Physics and Controlled Fusion, 44(5A), p.A279 - A286, 2002/05
Times Cited Count:77 Percentile:89.73(Physics, Fluids & Plasmas)no abstracts in English
Kizu, Kaname; Sasajima, Tadayuki; Masaki, Kei; Hiratsuka, Hajime; Ichige, Hisashi; Honda, Masao; Miya, Naoyuki
Journal of Plasma and Fusion Research SERIES, Vol.5, p.446 - 449, 2002/00
no abstracts in English
Kizu, Kaname; Hosogane, Nobuyuki; Hiratsuka, Hajime; Ichige, Hisashi; Sasajima, Tadayuki; Masaki, Kei; Miya, Naoyuki; Honda, Masao; Iwahashi, Takaaki*; Sasaki, Noboru*; et al.
Fusion Engineering and Design, 58-59, p.331 - 335, 2001/11
Times Cited Count:16 Percentile:73.21(Nuclear Science & Technology)no abstracts in English