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OKondo, Yosuke*; Achouri, N. L.*; Al Falou, H.*; Atar, L.*; Aumann, T.*; Baba, Hidetada*; Boretzky, K.*; Caesar, C.*; Calvet, D.*; Chae, H.*; et al.
Nature, 620(7976), p.965 - 970, 2023/08
Times Cited Count：6 Percentile：93.26(Multidisciplinary Sciences)no abstracts in English
Ne at the transition into the island of inversion; Detailed structure study of NeWang, H.*; Yasuda, Masahiro*; Kondo, Yosuke*; Nakamura, Takashi*; Tostevin, J. A.*; Ogata, Kazuyuki*; Otsuka, Takaharu*; Poves, A.*; Shimizu, Noritaka*; Yoshida, Kazuki; et al.
Physics Letters B, 843, p.138038_1 - 138038_9, 2023/08
Times Cited Count：2 Percentile：83.53(Astronomy & Astrophysics)Detailed 
-ray spectroscopy of the exotic neon isotope Ne has been performed using the one-neutron removal reaction from Ne. Based on an analysis of parallel momentum distributions, a level scheme with spin-parity assignments has been constructed for Ne and the negative-parity states are identified for the first time. The measured partial cross sections and momentum distributions reveal a significant intruder p-wave strength providing evidence of the breakdown of the N = 20 and N = 28 shell gaps. Only a weak, possible f-wave strength was observed to bound final states. Large-scale shell-model calculations with different effective interactions do not reproduce the large p-wave and small f-wave strength observed experimentally, indicating an ongoing challenge for a complete theoretical description of the transition into the island of inversion along the Ne isotopic chain.
Saegusa, Jun; Yoda, Tomoyuki; Murakami, Mitsuhiro; Takeishi, Minoru
Kankyo Hoshano Josen Gakkai-Shi, 5(2), p.79 - 93, 2017/06
After the Fukushima Daiichi Nuclear Power Plant (NPP) accident in March 2011, environmental radiation monitoring works have been continuously conducted throughout the Fukushima prefecture of Japan. Five-year transitions of ambient dose rates at 15 locations 20-60 km away from the NPPs were precisely analyzed to investigate their chronological change. Measured dose rates were successfully fitted into a function consisting of a factor reflecting the physical decay of radiocesium and the other component such as the weathering effect. The ecological half-lives derived from the function ranged from 3 to 27 years (average 10 years). The radiation shielding effect by snow covering was also studied with the obtained functions. Due to the effect, dose rates were lowered by 15-50% by 20-cm-deep snow covering, and the ambient doses integrated over the five years were found to decrease by up to 7% compared to those without the snow covering that can be predicted from the fit function.
Ooka, Makoto; Maekawa, Yasunari; Tomizuka, Chiaki; Murakami, Tomoyuki*; Katagiri, Genichi*; Ozaki, Hiroshi*; Kawamura, Hiroshi
JAEA-Technology 2015-003, 31 Pages, 2015/03
JAEA-Technology-2015-003.pdf:3.95MB
An action for the decommissioning of the Fukushima Daiichi Nuclear Power Station (Tokyo Electric Power Company) is pushed forward now. For fuel debris Remove, it is necessary to fill the Primary Containment Vessel (PCV) with water. Because a coolant leaks out from the PCV, it becomes the most important problem to seal leak the coolant. Nuclear Plant Decommissioning Safety Research Establishment has examined the method of seal leak using the photocoagulation resin. However, originally the photocoagulation resin is used as coating or the painting, and the applicability to seal leak water is unknown. This report describes the result that examined the applicability to seal leak using photocoagulation resin.
Gowa, Tomoko*; Shiotsu, Tomoyuki*; Urakawa, Tatsuya*; Oka, Toshitaka; Murakami, Takeshi*; Oshima, Akihiro*; Hama, Yoshimasa*; Washio, Masakazu*
Radiation Physics and Chemistry, 80(2), p.264 - 267, 2011/02
Times Cited Count：8 Percentile：53.23(Chemistry, Physical)High linear energy transfer (LET) heavy ion beams were irradiated to poly(tetrafluoroethylene-co-ethylene) (ETFE) under vacuum and in air. The irradiation effects in ETFE as a function of the depth was precisely evaluated by analyzing each one of the films of the irradiation samples which were made of stacked ETFE films. It was indicated that conjugated double bonds would be generated by heavy ion beam irradiation, and their amounts should show the Bragg-curve-like distributions. Also, it was suggested that higher LET beams would induce radical formation in high density and longer conjugated C=C double bonds could be generated by the second-order reactions. Moreover, for irradiation samples in air, C=O was produced correlating to the yield of oxygen molecules diffusing from the sample surface.
Sumi, Mika; Abe, Katsuo; Kageyama, Tomio; Nakazawa, Hiroaki; Katchi, Tomokazu*; Murakami, Yoshiki*; Hishi, Tomoyuki*; Ai, Hironobu*
Proceedings of INMM 50th Annual Meeting (CD-ROM), 9 Pages, 2009/07
Currently, many laboratories who measure Pu and U concentration by isotope dilution mass spectrometry (IDMS) use Large Size Dried (LSD) spikes, which contain both Pu and U in individual vials. Plutonium Fuel Development Center (PFDC) prepared LSD spikes for MOX samples and has been used while LSD spikes prepared at inspection laboratories and commercially supplied are mainly aimed to measure input solution for reprocessing. Difficulties of importing reference materials are increasing though the needs of Pu reference materials are increasing. Stable securing Pu reference material is essential for facility operation and it is considered to be important to acquire technique to prepare domestic Pu reference material. Pu were prepared from MOX powder at PFDC and used for LSD spike preparation. Practical tests were performed with JNFL. Experience of preparation and utilization of LSD spike for MOX, consideration of certification method for MOX-Pu will be explained also in this paper.
Murakami, Tomoyuki; Nishihara, Tetsuo; Kunitomi, Kazuhiko
Nihon Genshiryoku Gakkai Wabun Rombunshi, 7(3), p.231 - 241, 2008/09
Japan Atomic Energy Agency has been developing a nuclear hydrogen production system by using heat from the Very High Temperature Reactor (VHTR). This system will handle a large amount of combustible gas and toxic gas. The risk from a fire, an explosion and an acute toxic exposure caused by an accident of chemical material leakage at the hydrogen production system is assessed. It is an important subject in design to ensure the safety of the nuclear plant and the risk for the public health to be sufficiently small. This report provides the basic policy about the safety evaluation on the accident of the fire, the explosion and the toxic material release from the hydrogen production system near the nuclear plant. Based on this policy, we performed a safety analysis of the GTHTR-300C. This analysis provides us with useful information about a separation distance from the nuclear plant to the hydrogen production system and a prospect that the accident of the hydrogen production system does not significantly increase a risk for the public.
Sakaba, Nariaki; Tachibana, Yukio; Shimakawa, Satoshi; Ohashi, Hirofumi; Sato, Hiroyuki; Yan, X.; Murakami, Tomoyuki; Ohashi, Kazutaka; Nakagawa, Shigeaki; Goto, Minoru; et al.
JAEA-Technology 2008-019, 57 Pages, 2008/03
JAEA-Technology-2008-019.pdf:8.59MB
The small-sized and safe cogeneration High Temperature Gas-cooled Reactor (HTGR) that can be used not only for electric power generation but also for hydrogen production and district heating is considered one of the most promising nuclear reactors for developing countries where sufficient infrastructure such as power grids is not provided. Thus, the small-sized cogeneration HTGR, named High Temperature Reactor 50-Cogeneration (HTR50C), was studied assuming that it should be constructed in developing countries. Specification, equipment configuration, etc. of the HTR50C were determined, and economical evaluation was made. As a result, it was shown that the HTR50C is economically competitive with small-sized light water reactors.
Murakami, Tomoyuki; Terada, Atsuhiko; Nishihara, Tetsuo; Inagaki, Yoshiyuki; Kunitomi, Kazuhiko
Nihon Genshiryoku Gakkai Wabun Rombunshi, 5(4), p.316 - 324, 2006/12
The Very High Temperature Reactor (VHTR) is expected to be the best energy source for the hydrogen production. This system will handle a large amount of hydrogen which is combustible gas. It is one of the most important subjects in design with this system to assure the safety of the reactor system against the damage due to fire and the explosion accident. This analysis provides with quantitative information about correlation between the combustible gas movement distance and various parameters which influences the gas dispersion. Based on these analytical results, we propose the best method which is able to evaluate damage of the nuclear plant by blast overpressure. This method will be used efficiently for the safety evaluation for the future VHTR hydrogen production System.
Nishihara, Tetsuo; Ohashi, Kazutaka; Murakami, Tomoyuki; Kunitomi, Kazuhiko
Nihon Genshiryoku Gakkai Wabun Rombunshi, 5(4), p.325 - 333, 2006/12
A design study of the hydrogen cogeneration high temperature gas cooled reactor (GTHTR300C) based on the achievement of gas turbine high temperature reactor design has been carried out in Japan Atomic Energy Agency. The safety design philosophy of the GTHTR300C to keep hydrogen economy and to attract a lot of interest from non nuclear industries is discussed. The hydrogen production system which is coupled to the secondary helium loop of the intermediate heat exchanger installed upstream of the gas turbine system shall be designed as a non nuclear graded system. General nuclear safety shall be ensured by the items installed in the reactor system. Functions of secondary helium loop which are primary helium cooling and pressure control and purification of secondary helium are required to continue normal operation. Means to maintain these functions are proposed by using equipment of the reactor system and the gas turbine system without the hydrogen production system so that the power generation can continue independently of operational state of the hydrogen production system. Means of protection against external event of flammable and/or toxic gas release are also considered.
Nishihara, Tetsuo; Kunitomi, Kazuhiko; Murakami, Tomoyuki
Proceedings of 3rd International Topical Meeting on High Temperature Reactor Technology (HTR 2006) (CD-ROM), 8 Pages, 2006/10
An accidental release of hydrogen is the most important safety issues in the HTGR hydrogen production system because the hydrogen production plant is close to the reactor building. Evaluation of the hydrogen dispersion around the reactor building is necessary to perform the safety assessment against hydrogen explosion. Numerical analyses for diffusion using the STAR-CD are carried out to survey the effect of inventory, pipe diameter, existence of wall and so on. Maximum horizontal distance from the release point to the explosive hydrogen cloud is compared each other. Blast overpressure is evaluated by Multi-Energy Method. The available energy of explosion is calculated using the results of diffusion analysis. Coupling the numerical analyses of the hydrogen diffusion and the blast overpressure derives a precision separation distance between the hydrogen production plant and the HTGR. The plant layout of the HTGR hydrogen production system can be optimized by using this proposed method.
Maruyama, So; Fujimoto, Nozomu; Sudo, Yukio; Murakami, Tomoyuki*; Fujii, Sadao*
Nucl. Eng. Des., 152, p.183 - 196, 1994/00
Times Cited Count：15 Percentile：75.28(Nuclear Science & Technology)no abstracts in English
Maruyama, So; Yamashita, Kiyonobu; Fujimoto, Nozomu; Murata, Isao; Sudo, Yukio; Murakami, Tomoyuki*; Fujii, Sadao*
Journal of Nuclear Science and Technology, 30(11), p.1186 - 1194, 1993/11
Times Cited Count：7 Percentile：68.63(Nuclear Science & Technology)no abstracts in English
Maruyama, So; Murakami, Tomoyuki*; Fujii, Sadao*; Fujimoto, Nozomu; Tanaka, Toshiyuki; Sudo, Yukio; Saito, Shinzo
Proc. of the 1st JSME/ASME Joint Int. Conf. on Nuclear Engineering,Vol. 1, p.425 - 430, 1991/00
no abstracts in English
Fumizawa, Motoo; Suzuki, Kunihiro; Murakami, Tomoyuki*; *
Nihon Genshiryoku Gakkai-Shi, 31(7), p.828 - 836, 1989/07
Times Cited Count：3 Percentile：41.84(Nuclear Science & Technology)no abstracts in English
Maruyama, So; Fujimoto, Nozomu; Kiso, Yoshihiro*; Murakami, Tomoyuki*; Sudo, Yukio
JAERI-M 88-173, 76 Pages, 1988/09
no abstracts in English
Fumizawa, Motoo; Suzuki, Kunihiro; Murakami, Tomoyuki*; *
JAERI-M 88-165, 26 Pages, 1988/09
no abstracts in English
Maruyama, So; Fujimoto, Nozomu; Kiso, Yoshihiro*; Murakami, Tomoyuki*; Takikawa, Noboru*; *; Sudo, Yukio
JAERI-M 88-154, 147 Pages, 1988/08
no abstracts in English
Maruyama, So; Murakami, Tomoyuki*; Kiso, Yoshihiro*; Sudo, Yukio
JAERI-M 88-138, 39 Pages, 1988/07
no abstracts in English
Fumizawa, Motoo; Suzuki, Kunihiro; Murakami, Tomoyuki*
JAERI-M 88-031, 52 Pages, 1988/02
no abstracts in English
