Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 413

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Study on optimizing microwave heating denitration method and powder characteristics of uranium trioxide

Segawa, Tomoomi; Kawaguchi, Koichi; Kato, Yoshiyuki; Ishii, Katsunori; Suzuki, Masahiro; Fujita, Shunya*; Kobayashi, Shohei*; Abe, Yutaka*; Kaneko, Akiko*; Yuasa, Tomohisa*

Proceedings of 2019 International Congress on Advances in Nuclear Power Plants (ICAPP 2019) (Internet), 9 Pages, 2019/05

A solution of plutonium nitrate and uranyl nitrate is converted into a mixed oxide by microwave heating denitration method. In the present study, for improving the efficiency of microwave heating and achieving high-temperature uniformity to produce homogeneous UO$$_{3}$$ powder, the microwave heating test of potassium chloride and uranyl nitrate solution, and numerical simulation analysis were conducted. The potassium chloride agar was adjusted to the dielectric loss, which is close to that of the uranyl nitrate solution and the optimum support table height was estimated to be 50 mm for denitration of the uranyl nitrate solution by microwave heating. The adiabator improved the efficiency of microwave heating denitration. Moreover, the powder yield was improved by using the adiabator owing to ease of scraping of the denitration product from the bottom of the denitration vessel.

Journal Articles

Visualized measurement of extremely high-speed droplets in Venturi scrubber

Horiguchi, Naoki; Yoshida, Hiroyuki; Abe, Yutaka*

Journal of Nuclear Science and Technology, 56(3), p.278 - 290, 2019/03

 Percentile:100(Nuclear Science & Technology)

Venturi scrubber (VS) has been installed in NPPs as one of the components of filtered venting systems. It can eliminate fine aerosol particles including fission products from polluted gas. Under extremely high-velocity conditions during severe accident, the data related to the droplet in the VS, which affects decontamination performance, is insufficient. This objective is to obtain the diameter of the extremely high-speed droplets and clarify an applicability of the existing correlations for the diameter. To visualize the extremely high-velocity droplet, an optical system with high frame rate and high resolution was developed. Visualization experiment using the VS under air-water condition was conducted, and droplet diameter distributions and Sauter mean diameter (SMD) were obtained. By comparing experimental data with values evaluated by existing correlations, it was clarified that the Nukiyama-Tanasawa equation can evaluate the SMD with good accuracy in the gas velocity range 82-250 m/s.

Journal Articles

Mechanism of flashing phenomena by microwave heating and influence of high dielectric constant solution

Fujita, Shunya*; Abe, Yutaka*; Kaneko, Akiko*; Yuasa, Tomohisa*; Segawa, Tomoomi; Kato, Yoshiyuki; Kawaguchi, Koichi; Ishii, Katsunori

Proceedings of 11th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-11) (Internet), 7 Pages, 2018/11

Mixed uranium oxide and plutonium oxide powder is produced from uranyl nitrate and plutonium nitrate mixed solution by the microwave heating denitration method in the spent fuel reprocessing process. Since the microwave heating method is accompanied by a boiling phenomenon, it is necessary to fully grasp the operating conditions in order to avoid flashing and spilling in the mass production of denitrification technology for the future. In this research, it was clarified that the heat transfer coefficient became lower as the dielectric constant increased. The dominant factor of the blowing up phenomena is supposed to be generation of the innumerable bubble rather than bubble's growth.

Journal Articles

Mechanism of flashing phenomena induced by microwave heating

Fujita, Shunya*; Abe, Yutaka*; Kaneko, Akiko*; Yuasa, Tomohisa*; Segawa, Tomoomi; Yamada, Yoshikazu; Kato, Yoshiyuki; Ishii, Katsunori

Proceedings of 26th International Conference on Nuclear Engineering (ICONE-26) (Internet), 8 Pages, 2018/07

Mixed uranium oxide and plutonium oxide powder is produced from uranyl nitrate and plutonium nitrate mixed solution by the microwave heating denitration method in the spent fuel reprocessing process. Since the microwave heating method is accompanied by a boiling phenomenon, it is necessary to fully grasp the operating conditions in order to avoid flashing and spilling in the mass production of denitrification technology for the future. In this research, it was confirmed that a potassium chloride aqueous solution as a simulant of uranyl nitrate aqueous solution with high dielectric loss cause loss of microwave at the solution surface as the dielectric loss increased with the increase of KCl concentration by experimental and electromagnetic field analysis, and revealed that the change in the heating condition affects the generation of flushing.

Journal Articles

Visualization study on droplet-entrainment in a high-speed gas jet into a liquid pool

Sugimoto, Taro*; Saito, Shimpei*; Kaneko, Akiko*; Abe, Yutaka*; Uchibori, Akihiro; Ohshima, Hiroyuki

Proceedings of 26th International Conference on Nuclear Engineering (ICONE-26) (Internet), 7 Pages, 2018/07

A computational fluid dynamics code for a sodium-water reaction phenomenon in a steam generator of sodium-cooled fast reactors has been developed. In order to provide the data for validation of this code, the visualization experiment on liquid droplet entrainment in the high-pressure air jet submerged in the water pool was carried out. The experiment successfully elucidated the behavior, such as atomization of the relatively large diameter liquid droplet generated from the gas-liquid interface.

Journal Articles

First direct mass measurements of nuclides around $$Z$$ = 100 with a multireflection time-of-flight mass spectrograph

Ito, Yuta*; Schury, P.*; Wada, Michiharu*; Arai, Fumiya*; Haba, Hiromitsu*; Hirayama, Yoshikazu*; Ishizawa, Satoshi*; Kaji, Daiya*; Kimura, Sota*; Koura, Hiroyuki; et al.

Physical Review Letters, 120(15), p.152501_1 - 152501_6, 2018/04

 Times Cited Count:11 Percentile:3.78(Physics, Multidisciplinary)

Masses of $$^{246}$$Es, $$^{251}$$Fm and the transfermium nuclei $$^{249-252}$$Md, and $$^{254}$$No, produced by hot- and cold-fusion reactions, in the vicinity of the deformed $$N=152$$ neutron shell closure, have been directly measured using a multi-reflection time-of-flight mass spectrograph. The masses of $$^{246}$$Es and $$^{249,250,252}$$Md were measured for the first time. Using the masses of $$^{249,250}$$Md as anchor points for $$alpha$$ decay chains, the masses of heavier nuclei, up to $$^{261}$$Bh and $$^{266}$$Mt, were determined. These new masses were compared with theoretical global mass models and demonstrated to be in good agreement with macroscopic-microscopic models in this region. The empirical shell gap parameter $$delta_{2n}$$ derived from three isotopic masses was updated with the new masses and corroborate the existence of the deformed $$N=152$$ neutron shell closure for Md and Lr.

Journal Articles

Flushing phenomena and flow structure by microwave heating

Fujita, Shunya*; Abe, Yutaka*; Kaneko, Akiko*; Chonan, Fuminori*; Yuasa, Tomohisa*; Yamaki, Tatsunori*; Segawa, Tomoomi; Yamada, Yoshikazu

Proceedings of 25th International Conference on Nuclear Engineering (ICONE-25) (CD-ROM), 8 Pages, 2017/07

From the observation results, in the process of flushing, the behaviors leading to flushing were classified divided into three types. First type is that first generation bubble from heating leads to flushing. Second type is that nucleate boiling continues during heating and stop, finally single bubble generates and leads to flushing. Third type is defined that gradual evaporation occurs without bubbles. It was revealed that the total quantities of heat released by flushing are approximately equal when assuming the flushing mechanism, it can be triggered that a large amount of micro bubbles are instantaneously generated and grew.

Journal Articles

Prediction and evaluation of decontamination performance of venturi scrubber in actual environments

Horiguchi, Naoki; Yoshida, Hiroyuki; Uesawa, Shinichiro; Abe, Yutaka*

Dai-22-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (USB Flash Drive), 4 Pages, 2017/06

Venturi scrubber is installed in nuclear power plant as a component of filtered venting system and used to remove small aerosols with fission products. There is, however, no method to estimate its decontamination performance in the assumed operating pressure range. In this study, we establish a method to estimate the decontamination performance based on mechanistic thermal hydrodynamic simulation code and report simulated results of the thermal hydrodynamics and decontamination performance in the pressure range in the pressure range in actual environments. With decrease in inlet pressure of the Venturi scrubber, gas flow velocity at the throat of it is suppressed, liquid flow velocity in a hole of it by self-priming changes and the decontamination factor changes were obtained. Also, with larger the aerosol diameter, the decontamination factor become larger was obtained.

Journal Articles

Observation of doubly-charged ions of francium isotopes extracted from a gas cell

Schury, P.*; Wada, Michiharu*; Ito, Yuta*; Kaji, Daiya*; Haba, Hiromitsu*; Hirayama, Yoshikazu*; Kimura, Sota*; Koura, Hiroyuki; MacCormick, M.*; Miyatake, Hiroari*; et al.

Nuclear Instruments and Methods in Physics Research B, 407, p.160 - 165, 2017/06

 Times Cited Count:3 Percentile:27.27(Instruments & Instrumentation)

Various isotopes of Ac, Ra, Fr, and Rn were produced by fusion-evaporation reactions using a $$^{48}$$Ca beam. The energetic ions were stopped in and extracted from a helium gas cell. The extracted ions were identified using a multi-reflection time-of-fight mass spectrograph. In all cases, it was observed that the predominant charge state for the extracted ions, including the alkali Fr, was 2+.

Journal Articles

Monte Carlo shell model studies with massively parallel supercomputers

Shimizu, Noritaka*; Abe, Takashi*; Homma, Michio*; Otsuka, Takaharu*; Togashi, Tomoaki*; Tsunoda, Yusuke*; Utsuno, Yutaka; Yoshida, Toru*

Physica Scripta, 92(6), p.063001_1 - 063001_19, 2017/06

 Times Cited Count:5 Percentile:26.6(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

New measurement of the $$^{8}$$Li($$alpha$$,n)$$^{11}$$B reaction in a lower-energy region below the Coulomb barrier

Das, S. K.*; Fukuda, Tomokazu*; Mizoi, Yutaka*; Ishiyama, Hironobu*; Miyatake, Hiroari*; Watanabe, Yutaka*; Hirayama, Yoshikazu*; Jeong, S. C.*; Ikezoe, Hiroshi*; Matsuda, Makoto; et al.

Physical Review C, 95(5), p.055805_1 - 055805_4, 2017/05

 Percentile:100(Physics, Nuclear)

Journal Articles

Numerical simulation of two-phase flow behavior in Venturi scrubber by interface tracking method

Horiguchi, Naoki; Yoshida, Hiroyuki; Abe, Yutaka*

Nuclear Engineering and Design, 310, p.580 - 586, 2016/12

 Times Cited Count:3 Percentile:42.29(Nuclear Science & Technology)

Journal Articles

Development of evaluation method for hydraulic behavior in venturi scrubber for filtered venting

Horiguchi, Naoki; Yoshida, Hiroyuki; Nakao, Yasuhiro*; Kaneko, Akiko*; Abe, Yutaka*

Proceedings of 10th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-10) (USB Flash Drive), 7 Pages, 2016/11

Journal Articles

Direct measurement of nanoscale lithium diffusion in solid battery materials using radioactive tracer of $$^{8}$$Li

Ishiyama, Hironobu*; Jeong, S.-C.*; Watanabe, Yutaka*; Hirayama, Yoshikazu*; Imai, Nobuaki*; Jung, H. S.*; Miyatake, Hiroari*; Oyaizu, Mitsuhiro*; Osa, Akihiko; Otokawa, Yoshinori; et al.

Nuclear Instruments and Methods in Physics Research B, 376, p.379 - 381, 2016/06

 Times Cited Count:2 Percentile:57.25(Instruments & Instrumentation)

Journal Articles

Large-scale shell-model analysis of the neutrinoless $$betabeta$$ decay of $$^{48}$$Ca

Iwata, Yoritaka*; Shimizu, Noritaka*; Otsuka, Takaharu*; Utsuno, Yutaka; Men$'e$ndez, J.*; Homma, Michio*; Abe, Takashi*

Physical Review Letters, 116(11), p.112502_1 - 112502_6, 2016/03

AA2015-0865.pdf:0.45MB

 Times Cited Count:30 Percentile:5.78(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Breakup and fragmentation behavior of molten material jet in multi-channel of BWR lower plenum

Saito, Ryusuke*; Abe, Yutaka*; Yoshida, Hiroyuki

Journal of Nuclear Science and Technology, 53(2), p.147 - 160, 2016/02

 Times Cited Count:4 Percentile:31.55(Nuclear Science & Technology)

Journal Articles

Influence of linear energy transfer on the scintillation decay behavior in a lithium glass scintillator

Koshimizu, Masanori*; Iwamatsu, Kazuhiro*; Taguchi, Mitsumasa; Kurashima, Satoshi; Kimura, Atsushi; Yanagida, Takayuki*; Fujimoto, Yutaka*; Watanabe, Kenichi*; Asai, Keisuke*

Journal of Luminescence, 169(Part B), p.678 - 681, 2016/01

We analyzed the effects of linear energy transfer (LET) on the scintillation properties of a Li glass scintillator, GS20. The scintillation time profiles were measured by using pulsed ion beams having different LETs. The rise in the scintillation time profiles was faster for higher LET, whereas the decay part was not significantly different for largely different LETs. The LET effects in the rise was ascribed to the effects of excited states interaction during the energy transfer process from the host glass to the luminescent centers, Ce$$^{3+}$$ ions. Supposing that the light yield decreases with LET, the fast rise at high LET was explained in terms of the competition between the energy transfer and the quenching due to the excited states interaction.

Journal Articles

Large-scale shell-model studies for exotic nuclei; Probing shell evolution

Utsuno, Yutaka; Otsuka, Takaharu*; Shimizu, Noritaka*; Tsunoda, Yusuke*; Homma, Michio*; Abe, Takashi*; Mizusaki, Takahiro*; Togashi, Tomoaki*; Brown, B. A.*

Proceedings of International Conference on Nuclear Theory in the Supercomputing Era 2014 (NTSE 2014), p.29 - 34, 2016/00

no abstracts in English

Journal Articles

Nuclear structure of $$^{37,38}$$Si investigated by decay spectroscopy of $$^{37,38}$$Al

Steiger, K.*; Nishimura, Shunji*; Li, Z.*; Gernh$"a$user, R.*; Utsuno, Yutaka; Chen, R.*; Faestermann, T.*; Hinke, C.*; Kr$"u$cken, R.*; Nishimura, Mitsuki*; et al.

European Physical Journal A, 51(9), p.117_1 - 117_9, 2015/09

 Times Cited Count:5 Percentile:45.25(Physics, Nuclear)

no abstracts in English

Journal Articles

New AESJ thermal-hydraulics roadmap for LWR safety improvement and development after Fukushima accident

Nakamura, Hideo; Arai, Kenji*; Oikawa, Hirohide*; Fujii, Tadashi*; Umezawa, Shigemitsu*; Abe, Yutaka*; Sugimoto, Jun*; Koshizuka, Seiichi*; Yamaguchi, Akira*

Proceedings of 16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-16) (USB Flash Drive), p.5353 - 5366, 2015/08

413 (Records 1-20 displayed on this page)