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Journal Articles

Dynamic PRA of flooding-initiated accident scenarios using THALES2-RAPID

Kubo, Kotaro; Zheng, X.; Tanaka, Yoichi; Tamaki, Hitoshi; Sugiyama, Tomoyuki; Jang, S.*; Takata, Takashi*; Yamaguchi, Akira*

Proceedings of 30th European Safety and Reliability Conference and 15th Probabilistic Safety Assessment and Management Conference (ESREL 2020 and PSAM-15) (Internet), p.2279 - 2286, 2020/11

Probabilistic risk assessment (PRA) is one of the methods used to assess the risks associated with large and complex systems. When the risk of an external event is evaluated using conventional PRA, a particular limitation is the difficulty in considering the timing at which nuclear power plant structures, systems, and components fail. To overcome this limitation, we coupled thermal-hydraulic and external-event simulations using Risk Assessment with Plant Interactive Dynamics (RAPID). Internal flooding was chosen as the representative external event, and a pressurized water reactor plant model was used. Equations based on Bernoulli's theorem were applied to flooding propagation in the turbine building. In the analysis, uncertainties were taken into account, including the flow rate of the flood water source and the failure criteria for the mitigation systems. In terms of recovery action, isolation of the flood water source by the operator and drainage using a pump were modeled based on several assumptions. The results indicate that the isolation action became more effective when combined with drainage.

Journal Articles

Enhancement of the treatment of system interactions in a dynamic PRA tool

Tanaka, Yoichi; Tamaki, Hitoshi; Zheng, X.; Sugiyama, Tomoyuki

Proceedings of 30th European Safety and Reliability Conference and 15th Probabilistic Safety Assessment and Management Conference (ESREL 2020 and PSAM-15) (Internet), p.2195 - 2201, 2020/11

Journal Articles

A Comparative study of sampling techniques for dynamic probabilistic risk assessment of nuclear power plants

Kubo, Kotaro; Zheng, X.; Tanaka, Yoichi; Tamaki, Hitoshi; Sugiyama, Tomoyuki; Jang, S.*; Takata, Takashi*; Yamaguchi, Akira*

Proceedings of Joint International Conference on Supercomputing in Nuclear Applications + Monte Carlo 2020 (SNA + MC 2020), p.308 - 315, 2020/10

Dynamic probabilistic risk assessment (PRA) is a method for improving the realism and completeness of conventional PRA. However, enormous calculation costs are incurred by these improvements. One solution is to select an appropriate sampling method. In this paper, we applied the Monte Carlo, Latin hypercube, grid-point, and quasi-Monte Carlo sampling methods to the dynamic PRA of a simplified accident sequence and compared the results for each method. Quasi-Monte Carlo sampling was found to be the most effective method in this case.

Journal Articles

Retreat from stress; Rattling in a planar coordination

Suekuni, Koichiro*; Lee, C. H.*; Tanaka, Hiromi*; Nishibori, Eiji*; Nakamura, Atsushi*; Kasai, Hidetaka*; Mori, Hitoshi*; Usui, Hidetomo*; Ochi, Masayuki*; Hasegawa, Takumi*; et al.

Advanced Materials, 30(13), p.1706230_1 - 1706230_6, 2018/03

 Times Cited Count:35 Percentile:90.91(Chemistry, Multidisciplinary)

Thermoelectric materials for highly efficient devices must satisfy conflicting requirements of high electrical conductivity and low thermal conductivity. In this paper, we studied the crystal structure and phonon dynamics of tetrahedrites (Cu,Zn)$$_{12}$$(Sb,As)$$_{4}$$S$$_{13}$$. The results revealed that the Cu atoms in a planar coordination are rattling, which effectively scatter phonons. These findings provide a new strategy for the development of highly efficient thermoelectric materials with planar coordination.

Journal Articles

Electronic structure and magnetic properties of the half-metallic ferrimagnet Mn$$_{2}$$VAl probed by soft X-ray spectroscopies

Nagai, Kodai*; Fujiwara, Hidenori*; Aratani, Hidekazu*; Fujioka, Shuhei*; Yomosa, Hiroshi*; Nakatani, Yasuhiro*; Kiss, Takayuki*; Sekiyama, Akira*; Kuroda, Fumiaki*; Fujii, Hitoshi*; et al.

Physical Review B, 97(3), p.035143_1 - 035143_8, 2018/01

AA2017-0644.pdf:1.01MB

 Times Cited Count:13 Percentile:63.24(Materials Science, Multidisciplinary)

We have studied the electronic structure of ferrimagnetic Mn$$_{2}$$VAl single crystals by means of soft X-ray absorption spectroscopy (XAS), X-ray absorption magnetic circular dichroism (XMCD), and resonant soft X-ray inelastic scattering (RIXS). We have successfully observed the XMCD signals for all the constituent elements. The Mn L$$_{2,3}$$ XAS and XMCD spectra are reproduced by spectral simulations based on density-functional theory, indicating the itinerant character of the Mn 3$$d$$ states. On the other hand, the V 3$$d$$ electrons are rather localized since the ionic model can qualitatively explain the V L$$_{2,3}$$ XAS and XMCD spectra. This picture is consistent with local $$dd$$ excitations revealed by the V L$$_{3}$$ RIXS.

Journal Articles

Effects of $$gamma$$ irradiation on the adsorption characteristics of xerogel microcapsules

Onishi, Takashi; Tanaka, Kosuke; Koyama, Shinichi; Ou, L. Y.*; Mimura, Hitoshi*

NEA/NSC/R(2017)3, p.463 - 469, 2017/11

no abstracts in English

Journal Articles

Beam commissioning of the linac for iBNCT

Naito, Fujio*; Anami, Shozo*; Ikegami, Kiyoshi*; Uota, Masahiko*; Ouchi, Toshikatsu*; Onishi, Takahiro*; Oba, Toshiyuki*; Obina, Takashi*; Kawamura, Masato*; Kumada, Hiroaki*; et al.

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1244 - 1246, 2016/11

The proton linac installed in the Ibaraki Neutron Medical Research Center is used for production of the intense neutron flux for the Boron Neutron Capture Therapy (BNCT). The linac consists of the 3-MeV RFQ and the 8-MeV DTL. Design average beam current is 10mA. Target is made of Beryllium. First neutron production from the Beryllium target was observed at the end of 2015 with the low intensity beam as a demonstration. After the observation of neutron production, a lot of improvement s was carried out in order to increase the proton beam intensity for the real beam commissioning. The beam commissioning has been started on May 2016. The status of the commissioning is summarized in this report.

Journal Articles

Stabilization of a high-order harmonic generation seeded extreme ultraviolet free electron laser by time-synchronization control with electro-optic sampling

Tomizawa, Hiromitsu*; Sato, Takahiro*; Ogawa, Kanade*; Togawa, Kazuaki*; Tanaka, Takatsugu*; Hara, Toru*; Yabashi, Makina*; Tanaka, Hitoshi*; Ishikawa, Tetsuya*; Togashi, Tadashi*; et al.

High Power Laser Science and Engineering, 3, p.e14_1 - e14_10, 2015/04

 Times Cited Count:4 Percentile:29.28(Optics)

no abstracts in English

JAEA Reports

Enhancement of the methodology of repository design and post-closure performance assessment for preliminary investigation stage, 3; Progress report on NUMO-JAEA collaborative research in FY2013 (Joint research)

Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Makino, Hitoshi; Wakasugi, Keiichiro; Mitsui, Seiichiro; Kitamura, Akira; Yoshikawa, Hideki; Oda, Chie; Ishidera, Takamitsu; et al.

JAEA-Research 2014-030, 457 Pages, 2015/03

JAEA-Research-2014-030.pdf:199.23MB

JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and post-closure performance assessment in preliminary investigation stage. With regard to (1) study on rock suitability in terms of hydrology, based on some examples of developing method of hydro-geological structure model, acquired knowledge are arranged using the tree diagram, and model uncertainty and its influence on the evaluation items were discussed. With regard to (2) study on scenario development, the developed approach for "defining conditions" has been reevaluated and improved from practical viewpoints. In addition, the uncertainty evaluation for the effect of use of cementitious material, as well as glass dissolution model, was conducted with analytical evaluation. With regard to (3) study on setting radionuclide migration parameters, based on survey of precedent procedures, multiple-approach for distribution coefficient of rocks was established, and the adequacy of the approach was confirmed though its application to sedimentary rock and granitic rock. Besides, an approach for solubility setting was developed including the procedure of selection of solubility limiting solid phase. The adequacy of the approach was confirmed though its application to key radionuclides.

Journal Articles

Compact XFEL and AMO sciences; SACLA and SCSS

Yabashi, Makina*; Tanaka, Hitoshi*; Tanaka, Takashi*; Tomizawa, Hiromitsu*; Togashi, Tadashi*; Nagasono, Mitsuru*; Ishikawa, Tetsuya*; Harries, J.; Hikosaka, Yasumasa*; Hishikawa, Akiyoshi*; et al.

Journal of Physics B; Atomic, Molecular and Optical Physics, 46(16), p.164001_1 - 164001_19, 2013/08

 Times Cited Count:68 Percentile:96.33(Optics)

Journal Articles

Full-coherent free electron laser seeded by 13th- and 15th-order harmonics of near-infrared femtosecond laser pulses

Sato, Takahiro*; Iwasaki, Atsushi*; Owada, Shigeki*; Yamanouchi, Kaoru*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; Togashi, Tadashi*; Fukami, Kenji*; et al.

Journal of Physics B; Atomic, Molecular and Optical Physics, 46(16), p.164006_1 - 164006_6, 2013/08

 Times Cited Count:3 Percentile:21.46(Optics)

By introducing 13th- (61.7 nm) and 15th-order harmonics (53.4 nm) of femtosecond laser pulses at 800 nm into an undulator of SCSS (SPring-8 Compact SASE Source) test accelerator at RIKEN, these harmonic pulses were amplified by a factor of more than 10$$^{2}$$ with a high contrast ratio through the interaction between accelerated electron bunches and the harmonic pulses. From numerical simulations of the amplification processes of high-order harmonic pulses in the undulator, optimum conditions of the electron bunch duration interacting with the high-order harmonic pulses were investigated for generating full-coherent and intense pulses in the extreme ultraviolet wavelength region.

Journal Articles

Full-coherent HHG-seeded EUV-FEL locked by EOS timing feedback

Ogawa, Kanade*; Sato, Takahiro*; Matsubara, Shinichi*; Okayasu, Yuichi*; Togashi, Tadashi*; Watanabe, Takahiro*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; et al.

Proceedings of 10th Conference on Lasers and Electro-Optics Pacific Rim and 18th OptoElectronics and Communications Conference and Photonics in Switching 2013 (CLEO-PR & OECC/PS 2013) (USB Flash Drive), 2 Pages, 2013/06

no abstracts in English

Journal Articles

High intense full-coherent radiation of free electron laser seeded by high-order harmonics in extreme-ultraviolet region

Togashi, Tadashi*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; Sato, Takahiro*; Iwasaki, Atsushi*; Owada, Shigeki*; Yamanouchi, Kaoru*; Hara, Toru*; et al.

Proceedings of Ultrafast Optics IX (CD-ROM), 2 Pages, 2013/03

We have demonstrated free-electron laser radiation seeded by high-order harmonics in the extreme-ultraviolet region. Strong enhancement of the radiation intensity by a factor of 104 was observed with timing control of an electro-optical sampling technique.

Journal Articles

Single crystal growth and transport properties of RRu$$_{2}$$Al$$_{10}$$ (R = La and Pr)

Sakoda, Masahito*; Kubota, Kazuhiro*; Tanaka, Shuhei*; Matsuoka, Eiichi*; Sugawara, Hitoshi*; Matsuda, Tatsuma; Haga, Yoshinori

Journal of the Physical Society of Japan, 81(Suppl.B), p.SB011_1 - SB011_4, 2012/12

 Times Cited Count:1 Percentile:11.71(Physics, Multidisciplinary)

Journal Articles

Morphology-controlled synthesis of Mo compounds from a nitric acid solution by the microwave heating and/or Zr-addition

Osaka, Masahiko; Tanaka, Kosuke; Sekine, Shinichi; Akutsu, Yoko; Suzuki, Tatsuya*; Mimura, Hitoshi*

Journal of Nuclear Materials, 427(1-3), p.384 - 388, 2012/08

 Times Cited Count:4 Percentile:36.4(Materials Science, Multidisciplinary)

Morphology-controlled synthesis of Mo compounds from a nitric acid solution by microwave heating was investigated for effective utilizations of Mo fission product from a high level nuclear waste. The microwave heating method was revealed to greatly accelerate crystallization and crystal growth of the synthesized powder. Addition of a small amount of Zr stabilized synthesis of a hexagonal-MoO$$_{3}$$ powder. Furthermore, the microwave heating with Zr-addition has synthesized a specific urchin-like shaped hexagonal-MoO$$_{3}$$ crystal having a good crystallinity. The present methods would be useful for effective utilization of Mo from high level nuclear waste in terms of their practicability and ability to the morphology control.

Journal Articles

Extreme ultraviolet free electron laser seeded by high-order harmonic

Togashi, Tadashi*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; Sato, Takahiro*; Iwasaki, Atsushi*; Owada, Shigeki*; Yamanouchi, Kaoru*; Hara, Toru*; et al.

Proceedings of 11th International School and Symposium on Synchrotron Radiation in Natural Science (ISSRNS 2012), p.1 - 21, 2012/05

The 13th harmonic of a Ti:sapphire laser has been significantly amplified with the SCSS test accelerator. The temporal and spatial overlap of the electron beam and the high harmonic radiation were precisely tuned for achieving the seeded free electron laser operation. With numerical simulation the present HH-seeded FEL scheme could readily be applied to the wavelength region down to 10 nm.

Journal Articles

Reformation of hazardous wastes into useful supporting materials for fast reactor fuels

Osaka, Masahiko; Miwa, Shuhei; Tanaka, Kosuke; Akutsu, Yoko; Ikeda, Kaoru*; Mimura, Hitoshi*; Suzuki, Tatsuya*; Usuki, Toshiyuki; Yano, Toyohiko*

Annals of Nuclear Energy, 38(12), p.2661 - 2666, 2011/10

 Times Cited Count:2 Percentile:20.43(Nuclear Science & Technology)

Novel concepts for effective utilization of molybdenum (Mo) from nuclear waste and magnesium silicates from hazardous asbestos wastes are proposed. A fast reactor cycle scheme that incorporates each material is described in the present paper. Basic studies on some fundamental technologies for the present cycle are given. Basic separation aspects for Mo by using LIX63 micro capsules and tertiary pyridine resin were investigated. A simple chemical synthesis route for Mo precursor powder from Mo containing HNO$$_{3}$$ solution was tested. Effects of impurities in recovered Mo on sintering behavior were experimentally investigated.

Journal Articles

High field magnetoresistance and de Haas-van Alphen effect in LaRu$$_2$$Al$$_{10}$$

Sakoda, Masahito*; Tanaka, Shuhei*; Matsuoka, Eiichi*; Sugawara, Hitoshi*; Harima, Hisatomo*; Honda, Fuminori*; Settai, Rikio*; Onuki, Yoshichika; Matsuda, Tatsuma; Haga, Yoshinori

Journal of the Physical Society of Japan, 80(8), p.084716_1 - 084716_5, 2011/08

 Times Cited Count:8 Percentile:53.36(Physics, Multidisciplinary)

Journal Articles

Generation of initial closed flux surface by ECH at a conventional aspect ratio of $$R$$/$$a$$ $$sim$$ 3; Experiments on the LATE device and JT-60U tokamak

Uchida, Masaki*; Maekawa, Takashi*; Tanaka, Hitoshi*; Ide, Shunsuke; Takase, Yuichi*; Watanabe, Fumitake*; Nishi, Seiji*

Nuclear Fusion, 51(6), p.063031_1 - 063031_9, 2011/06

 Times Cited Count:10 Percentile:45.15(Physics, Fluids & Plasmas)

Journal Articles

Extreme ultraviolet free electron laser seeded by high-order harmonic

Togashi, Tadashi*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; Sato, Takahiro*; Iwasaki, Atsushi*; Okino, Tomoya*; Yamanouchi, Kaoru*; Hara, Toru*; et al.

Proceedings of 2011 Conference on Lasers and Electro-Optics (CLEO 2011) (CD-ROM), p.1527 - 1528, 2011/05

We succeeded in generating the seeded free electron laser (FEL) with wavelengths of 61 nm at the SCSS test accelerator. The 13th (61 nm) harmonics generated by focusing the high peak power Ti:Sapphire laser to the Xe gas cell was directed to the undulator. This is first realization of the seeded FEL in extreme ultraviolet region.

68 (Records 1-20 displayed on this page)