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Journal Articles

Comprehensive analysis and evaluation of Fukushima Daiichi Nuclear Power Station Unit 2

Yamashita, Takuya; Sato, Ikken; Honda, Takeshi*; Nozaki, Kenichiro*; Suzuki, Hiroyuki*; Pellegrini, M.*; Sakai, Takeshi*; Mizokami, Shinya*

Nuclear Technology, 206(10), p.1517 - 1537, 2020/10

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

Journal Articles

Guidance for developing fuel design limit of high temperature gas-cooled reactor

Sato, Hiroyuki; Aoki, Takeshi; Ohashi, Hirofumi

Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 10 Pages, 2020/08

The present study aims to propose a guidance that facilitates to determine fuel design limits of commercial HTGR on the basis of licensing experience through the HTTR construction. The guidance consists of a set of FOMs and a process to determine their evaluation criteria. The FOMs are firstly identified to satisfy safety requirements and a basic concept of safety guides established in a special committee under the AESJ with the support of the Research Association of High Temperature Gas Cooled Reactor Plant. The development process for the evaluation criteria takes into account not only the top-level regulatory criteria but also design dependent constraints including the performance of fission product containment in physical barriers other than fuel, fuel qualification criteria, design specifications of an instrumentation and control system. As a result, a comprehensive and transparent procedure for designers of prismatic-type commercial HTGR has been developed.

Journal Articles

Methodology development for transient flow distribution analysis in high temperature gas-cooled reactor

Aoki, Takeshi; Sato, Hiroyuki; Ohashi, Hirofumi

Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 6 Pages, 2020/08

The flow distribution analysis, which is a part of thermal hydraulic design of the prismatic-type of the high temperature gas cooled reactor (HTGR) considering unintended flows between graphite blocks, has been performed for steady and conservative conditions. On the other hand, the transient analysis for satisfactorily realistic conditions will be helpful for the design improvement of prismatic-type HTGR. The present study aims to develop the transient flow distribution analysis code and confirm its applicability for the transient flow distribution analysis for prismatic-type HTGRs during anticipated operational occurrences and accidents utilizing experiences on high temperature engineering test reactor (HTTR) design. The calculation model and code were developed and validated for analysis of the unintended flows in the core and the molecular diffusion dominant in beginning air ingress behavior in an air ingress accident.

Journal Articles

Development of a flow network calculation code (FNCC) for high temperature gas-cooled reactors (HTGRs)

Aoki, Takeshi; Isaka, Kazuyoshi; Sato, Hiroyuki; Ohashi, Hirofumi

Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 7 Pages, 2020/08

The flow distribution analysis performed in the HTGR design has to take into account the interaction thermal and radiation deformations of the graphite structure, and the gaps between the graphite structures forming unintended flow. In the present study, a user-friendly flow network calculation code (FNCC) has been developed on the basis of experiences of High Temperature engineering Test Reactor (HTTR) design for HTGR design with enhanced compatibility with other HTGR design codes and with considering graphite block deformation in iteration process without manual control. The validation of FNCC was performed for the one-column flow distribution test. The analytical results using FNCC showed good agreement with the experimental results. It is concluded that FNCC was validate for the analysis of distributions of flowrate and pressure for the flow network model including the unintended flow paths in prismatic-type HTGRs.

Journal Articles

Research and development for safety and licensing of HTGR cogeneration system

Sato, Hiroyuki; Aoki, Takeshi; Ohashi, Hirofumi; Yan, X. L.

Nuclear Engineering and Design, 360, p.110493_1 - 110493_8, 2020/04

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

JAEA has been conducting research and development with a central focus on the utilization of HTTR, the first HTGR in Japan, towards the realization of industrial use of nuclear heat. On the basis of licensing experience through the HTTR construction, JAEA initiated an activity to establish an international safety standard for licensing of commercial HTGR cogeneration systems fully taking into account safety features of HTGRs. We have developed a roadmap towards licensing of commercial HTGR cogeneration systems. A test plan using the HTTR to support the establishment of safety standards and safety analysis methods are also presented. In addition, we confirmed that a vessel cooling system, a passive air-cooled decay heat removal system, satisfies the safety requirement.

Journal Articles

The Energy-resolved neutron imaging system, RADEN

Shinohara, Takenao; Kai, Tetsuya; Oikawa, Kenichi; Nakatani, Takeshi; Segawa, Mariko; Hiroi, Kosuke; Su, Y.; Oi, Motoki; Harada, Masahide; Iikura, Hiroshi; et al.

Review of Scientific Instruments, 91(4), p.043302_1 - 043302_20, 2020/04

 Times Cited Count:1 Percentile:28.29(Instruments & Instrumentation)

Journal Articles

A Simplified Cluster Analysis of Electron Track Structure for Estimating Complex DNA Damage Yields

Matsuya, Yusuke; Nakano, Toshiaki*; Kai, Takeshi; Shikazono, Naoya*; Akamatsu, Ken*; Yoshii, Yuji*; Sato, Tatsuhiko

International Journal of Molecular Sciences (Internet), 21(5), p.1701_1 - 1701_13, 2020/03

 Times Cited Count:0 Percentile:100(Biochemistry & Molecular Biology)

Among various DNA damage induced after irradiation, clustered damage composed of at least two vicinal lesions within from 10 to 20 base pairs is recognized as fatal damage to human tissue. Such clustered damage yields have been evaluated by means of computational approaches; however, the simulation validity has not been sufficiently made yet. Meanwhile, the experimental technique to detect clustered DNA damage has been evolved in the recent decades, so both approaches with simulation and experiment get used to be available for investigating clustered damage recently. In this study, we have developed a simple model for estimating clustered damage yield based on the spatial density of ionization and electronic excitation events obtained by the PHITS code, and compared the computational results to the experimental clustered damage coupled with base damage (BD) measured by gel electrophoresis and atomic force microscopy. The computational results agreed well with experimental fractions of clustered damage of strand breaks (SB) and BD, when the yield ratio of BD/SSB is assumed to be 1.3. From the comparison of complex DNA double-strand break coupled with BDs between simulation and experimental data, it was suggested that aggregation degree of the events along electron track reflects the complexity of DNA damage. The resent simulation enables to quantify the type of clustered damage which cannot be measured in in vitro experiment, which succeeded in interpreting the experimental detection efficiency for clustered BD.

Journal Articles

A $$Sigma p$$ scattering experiment at J-PARC and the analysis status

Nakada, Yoshiyuki*; Hasegawa, Shoichi; Hayakawa, Shuhei*; Hosomi, Kenji; Ichikawa, Yudai; Imai, Kenichi; Nanamura, Takuya*; Naruki, Megumi*; Sako, Hiroyuki; Sato, Susumu; et al.

JPS Conference Proceedings (Internet), 26, p.023024_1 - 023024_5, 2019/11

Journal Articles

First $$gamma$$-ray spectroscopy of an $$sd$$-shell hypernucleus, $$^{19}_{Lambda}$$F

Yang, S. B.*; Hasegawa, Shoichi; Hayakawa, Shuhei*; Hosomi, Kenji; Ichikawa, Yudai; Imai, Kenichi; Sako, Hiroyuki; Sato, Susumu; Tamura, Hirokazu*; Tanida, Kiyoshi; et al.

JPS Conference Proceedings (Internet), 26, p.023015_1 - 023015_5, 2019/11

Journal Articles

Study of $$Y^*$$ in nuclei through C$$(K^-, pi^+)X$$ spectrum at 1.8 GeV/$$c$$ in the J-PARC E05 experiment

Honda, Ryotaro*; Hasegawa, Shoichi; Hayakawa, Shuhei; Hosomi, Kenji; Imai, Kenichi; Ichikawa, Yudai; Nanamura, Takuya; Naruki, Megumi; Sako, Hiroyuki; Sato, Susumu; et al.

JPS Conference Proceedings (Internet), 26, p.023014_1 - 023014_4, 2019/11

Journal Articles

Search for excited state of $$_{Sigma }^{4}{rm He}$$ hypernucleus in the J-PARC E13 experiment

Nakagawa, Manami*; Hasegawa, Shoichi; Hayakawa, Shuhei; Hosomi, Kenji; Ichikawa, Yudai; Imai, Kenichi; Sako, Hiroyuki; Sato, Susumu; Tamura, Hirokazu; Tanida, Kiyoshi; et al.

JPS Conference Proceedings (Internet), 26, p.023005_1 - 023005_3, 2019/11

Journal Articles

Modeling of yield estimation for DNA strand breaks based on Monte Carlo simulations of electron track structure in liquid water

Matsuya, Yusuke; Kai, Takeshi; Yoshii, Yuji*; Yachi, Yoshie*; Naijo, Shingo*; Date, Hiroyuki*; Sato, Tatsuhiko

Journal of Applied Physics, 126(12), p.124701_1 - 124701_8, 2019/09

 Times Cited Count:5 Percentile:30.92(Physics, Applied)

Biological effects after ionizing radiation exposure arise from initial DNA strand breaks. DNA damage can be estimated from the simulation with both track structure analysis and diffusion of free radicals; however, the simulation is a time-consuming process. In this study, we present a simple model for estimating yields of strand breaks based only on spatial patterns of inelastic interactions (i.e., ionization and electronic excitation) generated by electrons, which are evaluated by PHITS code without considering the production and diffusion of free radicals. In this model, the number of events per track and that of the two events pair within 3.4 nm (corresponding to 10 base pair) were stochastically sampled for calculating SSB and DSB yields, respectively. The calculated results agreed well with other simulations and experimental data on DSB yield and yield ratio of DSB/SSB for the exposure to mono-energetic electrons. The present model also can demonstrate the relative biological effectiveness at the DSB endpoint for various photon exposures. This study indicated that the spatial pattern of inelastic events composed of ionization and electronic excitation is sufficient to obtain the impact of electrons on initial induction to DNA strand break.

Journal Articles

Gamma-ray spectroscopy of single $$Lambda$$-hypernuclei at J-PARC; Results and perspective

Koike, Takeshi*; Hasegawa, Shoichi; Hayakawa, Shuhei*; Hosomi, Kenji; Ichikawa, Yudai; Imai, Kenichi; Sako, Hiroyuki; Sato, Susumu; Sugimura, Hitoshi; Tamura, Hirokazu; et al.

AIP Conference Proceedings 2130, p.020011_1 - 020011_9, 2019/07

 Times Cited Count:0 Percentile:100

Journal Articles

Observation of a $$Xi$$ bound state in the $$^{12}$$C$$(K^-, K^+)$$ reaction at 1.8 GeV/$$c$$

Nagae, Tomofumi*; Ekawa, Hiroyuki; Hasegawa, Shoichi; Hayakawa, Shuhei; Hosomi, Kenji; Ichikawa, Yudai; Imai, Kenichi; Kimbara, Shinji; Nanamura, Takuya*; Naruki, Megumi; et al.

AIP Conference Proceedings 2130, p.020015_1 - 020015_9, 2019/07

Journal Articles

Enhancement of element production by incomplete fusion reaction with weakly bound deuteron

Wang, H.*; Otsu, Hideaki*; Chiga, Nobuyuki*; Kawase, Shoichiro*; Takeuchi, Satoshi*; Sumikama, Toshiyuki*; Koyama, Shumpei*; Sakurai, Hiroyoshi*; Watanabe, Yukinobu*; Nakayama, Shinsuke; et al.

Communications Physics (Internet), 2(1), p.78_1 - 78_6, 2019/07

 Times Cited Count:4 Percentile:23.32(Physics, Multidisciplinary)

Searching for effective pathways for the production of proton- and neutron-rich isotopes through an optimal combination of reaction mechanism and energy is one of the main driving forces behind experimental and theoretical nuclear reaction studies as well as for practical applications in nuclear transmutation of radioactive waste. We report on a study on incomplete fusion induced by deuteron, which contains one proton and one neutron with a weak binding energy and is easily broken up. This reaction study was achieved by measuring directly the cross sections for both proton and deuteron for $$^{107}$$Pd at 50 MeV/u via inverse kinematics technique. The results provide direct experimental evidence for the onset of a cross-section enhancement at high energy, indicating the potential of incomplete fusion induced by loosely-bound nuclei for creating proton-rich isotopes and nuclear transmutation of radioactive waste.

Journal Articles

Gamma-ray glow preceding downward terrestrial gamma-ray flash

Wada, Yuki*; Enoto, Teruaki*; Nakamura, Yoshitaka*; Furuta, Yoshihiro; Yuasa, Takayuki*; Nakazawa, Kazuhiro*; Morimoto, Takeshi*; Sato, Mitsuteru*; Matsumoto, Takahiro*; Yonetoku, Daisuke*; et al.

Communications Physics (Internet), 2(1), p.67_1 - 67_9, 2019/06

 Times Cited Count:4 Percentile:23.32(Physics, Multidisciplinary)

Journal Articles

Micro-PIXE analysis study of ferrite products synthesized from simulated radioactive liquid waste containing chemical hazardous elements

Abe, Tomohisa; Shimazaki, Takejiro; Osugi, Takeshi; Nakazawa, Osamu; Yamada, Naoto*; Yuri, Yosuke*; Sato, Takahiro*

QST-M-16; QST Takasaki Annual Report 2017, P. 140, 2019/03

no abstracts in English

Journal Articles

Observation of a Be double-Lambda hypernucleus in the J-PARC E07 experiment

Ekawa, Hiroyuki; Ashikaga, Sakiko; Hasegawa, Shoichi; Hashimoto, Tadashi; Hayakawa, Shuhei; Hosomi, Kenji; Ichikawa, Yudai; Imai, Kenichi; Kimbara, Shinji*; Nanamura, Takuya; et al.

Progress of Theoretical and Experimental Physics (Internet), 2019(2), p.021D02_1 - 021D02_11, 2019/02

 Times Cited Count:0 Percentile:100(Physics, Multidisciplinary)

Journal Articles

Transient ionization of the mesosphere during auroral breakup; Arase satellite and ground-based conjugate observations at Syowa Station

Kataoka, Ryuho*; Nishiyama, Takanori*; Tanaka, Yoshimasa*; Kadokura, Akira*; Uchida, Herbert Akihito*; Ebihara, Yusuke*; Ejiri, Mitsumu*; Tomikawa, Yoshihiro*; Tsutsumi, Masaki*; Sato, Kaoru*; et al.

Earth, Planets and Space (Internet), 71, p.9_1 - 9_10, 2019/01

 Times Cited Count:4 Percentile:23.17(Geosciences, Multidisciplinary)

Transient ionization of the mesosphere was detected at around 65 km altitude during the isolated auroral expansion occurred at 2221-2226 UT on June 30, 2017. A general-purpose Monte Carlo particle transport code PHITS suggested that significant ionization is possible in the middle atmosphere due to auroral X-rays from the auroral electrons of $$<$$10 keV.

Journal Articles

Conceptual plant system design study of an experimental HTGR upgraded from HTTR

Ohashi, Hirofumi; Goto, Minoru; Ueta, Shohei; Sato, Hiroyuki; Fukaya, Yuji; Kasahara, Seiji; Sasaki, Koei; Mizuta, Naoki; Yan, X.; Aoki, Takeshi*

Proceedings of 9th International Topical Meeting on High Temperature Reactor Technology (HTR 2018) (USB Flash Drive), 6 Pages, 2018/10

Conceptual design study of an experimental HTGR is performed to upgrade the plant system from Japanese High Temperature engineering Test Reactor (HTTR) to a commercial HTGR. Safety systems of HTTR are upgraded to demonstrate the commercial HTGR concept, such as a passive reactor cavity cooling system, a confinement, etc. An intermediate heat exchanger (IHX) is replaced by a steam generator (SG) for a process heat supply to demonstrate the technology for a commercial use. This paper describes the conceptual design study results of the plant system of the experimental HTGR.

438 (Records 1-20 displayed on this page)