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JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2017

Nakano, Masanao; Fujita, Hiroki; Mizutani, Tomoko; Nemoto, Masashi; Tobita, Keiji; Kono, Takahiko; Hosomi, Kenji; Hokama, Tomonori; Nishimura, Tomohiro; Matsubara, Natsumi; et al.

JAEA-Review 2018-025, 171 Pages, 2019/02

JAEA-Review-2018-025.pdf:3.81MB

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 2016 to March 2017. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Electric Power Company Holdings, Inc. in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and were exceeded the normal range of fluctuation in the monitoring, were evaluated.

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2016

Nakano, Masanao; Fujita, Hiroki; Mizutani, Tomoko; Nemoto, Masashi; Tobita, Keiji; Hosomi, Kenji; Nagaoka, Mika; Hokama, Tomonori; Nishimura, Tomohiro; Koike, Yuko; et al.

JAEA-Review 2017-028, 177 Pages, 2018/01

JAEA-Review-2017-028.pdf:3.61MB

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 2016 to March 2017. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Electric Power Company Holdings, Inc. in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and were exceeded the normal range of fluctuation in the monitoring, were evaluated.

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2015

Nakano, Masanao; Fujita, Hiroki; Mizutani, Tomoko; Hosomi, Kenji; Nagaoka, Mika; Hokama, Tomonori; Yokoyama, Hiroya; Nishimura, Tomohiro; Matsubara, Natsumi; Maehara, Yushi; et al.

JAEA-Review 2016-035, 179 Pages, 2017/03

JAEA-Review-2016-035.pdf:4.2MB

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 2015 to March 2016. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Electric Power Company Holdings, Inc. in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and were exceeded the normal range of fluctuation in the monitoring, were evaluated.

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2014

Watanabe, Hitoshi; Nakano, Masanao; Fujita, Hiroki; Takeyasu, Masanori; Mizutani, Tomoko; Isozaki, Tokuju*; Nagaoka, Mika; Hokama, Tomonori; Yokoyama, Hiroya; Nishimura, Tomohiro; et al.

JAEA-Review 2015-034, 175 Pages, 2016/03

JAEA-Review-2015-034.pdf:8.13MB

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 2014 to March 2015. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co. in March 2011.

Journal Articles

Titanium alloy as a potential low radioactivation vacuum material

Kamiya, Junichiro; Hikichi, Yusuke; Kinsho, Michikazu; Ogiwara, Norio; Fukuda, Mitsuhiro*; Hamatani, Noriaki*; Hatanaka, Kichiji*; Kamakura, Keita*; Takahisa, Keiji*

Journal of Vacuum Science and Technology A, 33(3), p.031605_1 - 031605_8, 2015/05

 Times Cited Count:2 Percentile:11.36(Materials Science, Coatings & Films)

For the vacuum systems of high-intensity beam accelerators, low radioactivation materials with good vacuum characteristics and high mechanical strength are required. The titanium alloy Ti-6Al-4V was investigated as a potential low activation vacuum material with high mechanical strength for the fabrication of vacuum components, particularly the flanges of beam pipes, in the J-PARC 3 GeV synchrotron. The dose rate of Ti-6Al-4V when irradiated by a 400 MeV proton was observed to decrease more rapidly than that of stainless steel. Furthermore, the generated radioactive isotopes were nuclides with relatively short half-lives. The outgassing rate of Ti-6Al-4V was the same as the typical value for stainless steel. Additionally, the hydrogen concentration in bulk Ti-6Al-4V was reduced to approximately 1 ppm by vacuum firing. These results indicate that Ti-6Al-4V is a good candidate for use as a low activation vacuum material with high mechanical strength.

Journal Articles

Effects of the radial electric field on the confinement of fast ions in ITER

Tani, Keiji*; Honda, Mitsuru; Oikawa, Toshihiro*; Shinohara, Koji; Kusama, Yoshinori; Sugie, Tatsuo

Nuclear Fusion, 55(5), p.053010_1 - 053010_15, 2015/05

AA2014-0355.pdf:2.0MB

 Times Cited Count:2 Percentile:11.3(Physics, Fluids & Plasmas)

The effects of a radial electric field (EF) on the losses of alpha particles and NBI fast ions in typical ITER operation scenarios for both error fields due to test blanket modules (TBMs) and toroidal field (TF) ripple were evaluated using an iterative method to execute an orbit-following Monte-Carlo code and a one-dimensional transport code. The EF effect on the loss of fast ions strongly depends on the operation scenario as well as on the error field. The electric field is very significant in the loss of fast ions in a 9MA ITER operation scenario with a higher safety factor and in the error field associated with TBMs. The EF effect in the error field of TF-ripple is very small in any operation scenario. The radial electric field changes the toroidal precession of fast ions and consequently alter their condition of resonance with the error field, which may account for the EF effect on the loss of fast ions in ITER with TBMs.

Journal Articles

Development of radiation-resistant optical fiber for application to observation and laser spectroscopy under high radiation dose

Ito, Chikara; Naito, Hiroyuki; Nishimura, Akihiko; Oba, Hironori; Wakaida, Ikuo; Sugiyama, Akira; Chiyatani, Keiji

Journal of Nuclear Science and Technology, 51(7-8), p.944 - 950, 2014/07

 Times Cited Count:12 Percentile:75.09(Nuclear Science & Technology)

In the Fukushima Daiichi Nuclear Power Station, it is necessary to survey the locations and conditions of fuel debris inside reactor pressure vessels or primary containment vessels under water and radiation environment in preparation for removing fuel debris. An optical fiber is well known for features such as signal transmission, light weight, superior insulation performance, water resistance and electromagnetic noise resistance. These features allow the optical fiber to simplify the instrumentation systems for in-vessel inspection, as long as provide that the optical fiber can be used under high radiation dose environment. The radiation resistance of an optical fiber was improved by increasing the amount of hydroxyl up to 1000 ppm in pure silica fiber. The improved optical fibers were irradiated with $$gamma$$-ray up to 1 $$times$$ 10$$^{6}$$ Gy using a $$^{60}$$Co source. They indicated a large peak around 600 nm and a peak tail from ultraviolet region, but no large absorption in infrared region except a hydroxyl absorption peak of 945 nm. We have confirmed that the optical fiber containing 1000 ppm hydroxyl has enough radiation resistance for radiation induced transmission losses and the infrared imaging is effective for observation under high radiation doses.

Journal Articles

Titanium alloy as low activation vacuum material

Kamiya, Junichiro; Ogiwara, Norio; Kinsho, Michikazu; Kamakura, Keita*; Hamatani, Noriaki*; Hatanaka, Kichiji*; Fukuda, Mitsuhiro*; Takahisa, Keiji*

Journal of the Vacuum Society of Japan, 56(5), p.167 - 171, 2013/05

no abstracts in English

Journal Articles

Effects of rippled fields due to ferritic inserts and ELM mitigation coils on energetic ion losses in a 15 MA inductive scenario in ITER

Shinohara, Koji; Tani, Keiji*; Oikawa, Toshihiro*; Putvinski, S.*; Schaffer, M.*; Loarte, A.*

Nuclear Fusion, 52(9), p.094008_1 - 094008_12, 2012/09

 Times Cited Count:14 Percentile:57.67(Physics, Fluids & Plasmas)

Journal Articles

Effects of ELM mitigation coils on energetic particle confinement in ITER steady-state operation

Tani, Keiji*; Shinohara, Koji; Oikawa, Toshihiro*; Tsutsui, Hiroaki*; Miyamoto, Seiji; Kusama, Yoshinori; Sugie, Tatsuo

Nuclear Fusion, 52(1), p.013012_1 - 013012_21, 2012/01

 Times Cited Count:30 Percentile:82.76(Physics, Fluids & Plasmas)

Journal Articles

Effects of complex symmetry-breakings on alpha particle power loads on first wall structures and equilibrium in ITER

Shinohara, Koji; Kurki-Suonio, T.*; Spong, D. A.*; Asunta, O.*; Tani, Keiji*; Strumberger, E.*; Briguglio, S.*; Koskela, T.*; Vlad, G.*; G$"u$nter, S.*; et al.

Nuclear Fusion, 51(6), p.063028_1 - 063028_12, 2011/06

 Times Cited Count:41 Percentile:87.57(Physics, Fluids & Plasmas)

Journal Articles

3D effect of ferromagnetic materials on alpha particle power loads on first wall structures and equilibrium on ITER

Shinohara, Koji; Kurki-Suonio, T.*; Spong, D.*; Asunta, O.*; Tani, Keiji*; Strumberger, E.*; Briguglio, S.*; G$"u$nter, S.*; Koskela, T.*; Kramer, G.*; et al.

Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03

Journal Articles

Thirty years experience at the experimental fast reactor Joyo; High quality core management and irradiation field characterization technique

Maeda, Shigetaka; Ito, Chikara; Aoyama, Takafumi; Maeda, Yukimoto; Chatani, Keiji

Transactions of the American Nuclear Society, 103(1), p.581 - 582, 2010/11

The experimental fast reactor Joyo of the Japan Atomic Energy Agency is the first liquid sodium fast reactor in Japan. Thirty years of successful operation of Joyo has shown excellent safety and reliability, and has contributed much to the LMFBR development program. Many kinds of irradiation experience have been accumulated to develop the fuels and materials for the prototype reactor Monju and future fast reactors. Accumulated data have been registered with OECD/NEA database with expectation that these data will be widely used. Joyo is presently temporary shutdown because of periodical inspection including in-vessel inspection and repair. After restart, Joyo will play a key role for a wide variety of science and technology fields as fast neutron irradiation bed.

Journal Articles

Ripple loss of alpha particles in a low-aspect ratio tokamak reactor

Tani, Keiji*; Nishio, Satoshi; Tobita, Kenji; Tsutsui, Hiroaki*; Mimata, Hideyuki*; Iio, Shunji*; Aoki, Takayuki*

Denki Gakkai Rombunshi, A, 129(9), p.569 - 574, 2009/09

Studies on the loss of fusion produced alpha particles enhanced by toroidal field (TF) ripple in a low-aspect-ratio tokamak reactor (VECTOR) have been made by using an orbit-following Monte-Carlo code. In actual TF coil systems, the ripple loss of alpha particles is strongly reduced as the aspect ratio becomes low (the power loss is proportional to A$$^{8.8}$$ for A more than 2.5) and the reduction of the number of TF coils results in a large amount of ripple losses even in a low-aspect-ratio tokamak.

Journal Articles

Numerical study of the ripple resonance diffusion of alpha particles in tokamaks

Mimata, Hideyuki*; Tani, Keiji*; Tsutsui, Hiroaki*; Tobita, Kenji; Iio, Shunji*; Shimada, Ryuichi*

Plasma and Fusion Research (Internet), 4, p.008_1 - 008_8, 2009/04

The energy dependence of the diffusion coefficients of alpha particles in rippled magnetic fields of tokamaks are numerically investigated with an orbit following Monte Carlo code. The diffusion coefficients are enhanced around the ripple resonance energy while they are reduced and has a minimum near the resonance energy, and hence they have an M-shaped dependence on the energy. The ripple resonance is caused by a radial change of the toroidal precession of banana particles, and creates islands in the phase space related with the toroidal and poloidal angles. Since the particles outside the separatrix mainly contribute to the diffusion, the M-shaped energy dependence is explained by both island structure and initial distribution of particles in the phase space. Such a ripple resonant diffusion is dominant for fusion-produced alpha particles in the slowing down process.

Journal Articles

Simulation studies on alpha-particle-driven current in tokamak reactors

Tani, Keiji; Azumi, Masafumi*

Nuclear Fusion, 48(8), p.085001_1 - 085001_9, 2008/08

 Times Cited Count:13 Percentile:49.86(Physics, Fluids & Plasmas)

Simulation studies are made for alpha-driven currents in tokamak reactors by using an orbit-following Monte-Carlo code. The finite banana width of alpha particles causes an asymmetry particle trapping and consequently an alpha current is driven by the imbalance of transit particles. The current driven by alpha transit particles (simply referred to as transit current) is greatly enhanced by a collaborative effect of the finite banana-width trajectories and a non-uniformity of alpha particle source. The pitch-angle scattering is also very important for the transit current. Fusion produced alpha particles can drive substantial current to assist the bulk bootstrap current in steady state tokamak reactors.

Journal Articles

Hexafluoro complex of rutherfordium in mixed HF/HNO$$_{3}$$ solutions

Toyoshima, Atsushi; Haba, Hiromitsu*; Tsukada, Kazuaki; Asai, Masato; Akiyama, Kazuhiko*; Goto, Shinichi*; Ishii, Yasuo; Nishinaka, Ichiro; Sato, Tetsuya; Nagame, Yuichiro; et al.

Radiochimica Acta, 96(3), p.125 - 134, 2008/03

 Times Cited Count:27 Percentile:86.74(Chemistry, Inorganic & Nuclear)

Formation of an anionic fluoride-complex of element 104, rutherfordium (Rf) produced in the $$^{248}$$Cm($$^{18}$$O,5n)$$^{261}$$Rf reaction was studied by an anion-exchange method based on an atom-at-a-time scale. It was found that the hexafluoro complex of Rf, [RfF$$_{6}$$]$$^{2-}$$, was formed in the studied fluoride ion concentrations of 0.0005 - 0.013 M. Formation of [RfF$$_{6}$$]$$^{2-}$$ was significantly different from that of the homologues Zr and Hf, [ZrF$$_{6}$$]$$^{2-}$$ and [HfF$$_{6}$$]$$^{2-}$$; the evaluated formation constant of [RfF$$_{6}$$]$$^{2-}$$ is at least one-order of magnitude smaller than those of [ZrF$$_{6}$$]$$^{2-}$$ and [HfF$$_{6}$$]$$^{2-}$$.

Journal Articles

Burn control simulation experiments in JT-60U

Shimomura, Koji*; Takenaga, Hidenobu; Tsutsui, Hiroaki*; Mimata, Hideyuki*; Iio, Shunji*; Miura, Yukitoshi; Tani, Keiji; Kubo, Hirotaka; Sakamoto, Yoshiteru; Hiratsuka, Hajime; et al.

Fusion Engineering and Design, 82(5-14), p.953 - 960, 2007/10

 Times Cited Count:3 Percentile:26.87(Nuclear Science & Technology)

no abstracts in English

Journal Articles

FBR cycle development

Negishi, Hitoshi; Chatani, Keiji; Tanigawa, Shingo

Genshiryoku Nenkan 2008, p.53 - 61, 2007/09

The Japanese government assessed the result of "Feasibility Study on Commercialized FR Cycle System 2nd Phase" and a major concept that is the combination of a sodium cooled FBR (oxide fuel), an advanced aqueous reprocessing and a simplified pelletizing was selected. From now on, the JAEA invests the development resource to a major concept intensively, and aims to put it to practical use by new project, "FaCT". In "Monju", the plant improvement construction have been working on schedule, and the various tests for restart are advanced. The R&D results in "Monju" will be applied to FBR development near future. "Joyo" has been operated over 70,000 hours, and has provided the fields to develop FBR fuel & material. In addition, the external utilization of "Joyo" is enhancing now. FBR development is activating worldwide. The international cooperation under GIF, GNEP and INPRO and the research collaboration with America/France are carrying.

Journal Articles

Confinement of alpha particles in a low-aspect-ratio tokamak reactor

Tani, Keiji; Tobita, Kenji; Iio, Shunji*; Tsutsui, Hiroaki*; Nishio, Satoshi; Aoki, Takayuki*

Denki Gakkai Rombunshi, A, 125(11), p.938 - 942, 2005/11

Studies on the loss of fusion produced alpha particles enhanced by toroidal field (TF) ripple in a low-aspect-ratio tokamak reactor (VECTOR) have been made by using an orbit-following Monte-Carlo code. The ripple loss is strongly reduced as the aspect ratio becomes low. Consequently, alpha particles are well confined in VECTOR. Thanks to the good confinement of alphas in a low-aspect-ratio system, the number of TF coils can be reduced to about 6, one half of the original VECTOR, by installing cooling systems near the outer edge of plasma and making allowances for about 30% increase in the bore diameter of TF coils.

115 (Records 1-20 displayed on this page)