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Journal Articles

Numerical simulation of laser welding different kinds of materials using a thermohydraulics computational science numerical simulation code SPLICE

Muramatsu, Toshiharu; Sato, Yuji; Kamei, Naomitsu; Aoyagi, Yuji*; Shobu, Takahisa

Nippon Kikai Gakkai Dai-13-Kai Seisan Kako, Kosaku Kikai Bumon Koenkai Koen Rombunshu (No.19-307) (Internet), p.157 - 160, 2019/10

no abstracts in English

Journal Articles

Front-loading for metal powder additive manufacturing processes with a computational science simulation code SPLICE

Muramatsu, Toshiharu; Aoyagi, Yuji*; Yoshiuji, Takahiro*

Nippon Kikai Gakkai 2017-Nendo Nenji Taikai Koen Rombunshu (DVD-ROM), 4 Pages, 2017/09

A general-purpose three-dimensional thermohydraulics numerical simulation code SPLICE was developed at Japan Atomic Energy Agency and designed to deal with gas-liquid-solid consolidated incompressible viscous flows with a phase change process in various laser applications, such as welding, coating, cutting, etc. The result obtained from metal powder laser additive manufacturing simulations is very encouraging in the sense that the SPLICE code would be used as one of efficient tools to provide the laser irradiation conditions.

JAEA Reports

Investigation and measures of abnormal events of helium refrigerator for cryogenic hydrogen system at J-PARC

Aso, Tomokazu; Teshigawara, Makoto; Hasegawa, Shoichi; Aoyagi, Katsuhiro*; Muto, Hideki*; Nomura, Kazutaka*; Takada, Hiroshi; Ikeda, Yujiro

JAEA-Technology 2017-021, 75 Pages, 2017/08

JAEA-Technology-2017-021.pdf:33.03MB

Liquid hydrogen is employed as a cold neutron moderator material at the spallation neutron source of Materials and Life science experimental Facility of Japan Proton Accelerator Research Complex (J-PARC). From January 2015, it became observable that the differential pressure between heat exchangers and an 80 K adsorber (ADS) in a helium refrigerator system increased with operating time. In November 2015, the differential pressure rise became more significant, leading to degrade the refrigerating performance in cooling liquid hydrogen. In order to investigate the cause of the abnormal differential pressure rise between the heat exchangers and the ADS, we carried out visual inspection inside the heat exchangers and analyzed the impurities contained in the helium gas. Unfortunately, we could not identify the impurities causing the performance degradation, but observed a trace of oil in the inlet piping of the heat exchanger. Based on investigations of the abnormal events occurred in the refrigerators with similar refrigerating capacity at other facilities, we took measures that cleaning the heat exchangers with Freon and replacing the ADS with new one. As a result, the differential pressure rise phenomenon was removed to recover the performance. We have detected oil from the Freon used for cleaning the heat exchangers and at a felt supporting charcoal packed in the ADS. In particular, oil was accumulated in membranous form onto the felt at the entrance side in the ADS. The amount of oil contained in the helium gas was about 10 ppb or so, less than the design value, in the helium refrigerator. However, the oil accumulated onto the felt in the ADS through long operating period may cause abnormal differential pressure rise, leading to the performance degradation of the helium refrigerator. Further study is needed to specify the cause more clearly.

JAEA Reports

Decommissioning activities and R&D of nuclear facilities in the second midterm plan

Terunuma, Akihiro; Mimura, Ryuji; Nagashima, Hisao; Aoyagi, Yoshitaka; Hirokawa, Katsunori*; Uta, Masato; Ishimori, Yuu; Kuwabara, Jun; Okamoto, Hisato; Kimura, Yasuhisa; et al.

JAEA-Review 2016-008, 98 Pages, 2016/07

JAEA-Review-2016-008.pdf:11.73MB

Japan Atomic Energy Agency formulated the plan to achieve the medium-term target in the period of April 2010 to March 2015(hereinafter referred to as "the second medium-term plan"). JAEA determined the plan for the business operations of each year (hereinafter referred to as "the year plan"). This report is that the Sector of Decommissioning and Radioactive Waste Management has summarized the results of the decommissioning technology development and decommissioning of nuclear facilities which were carried out in the second medium-term plan.

Journal Articles

Effective 3D data visualization in deep shaft construction

Inagaki, Daisuke*; Tsusaka, Kimikazu*; Aoyagi, Kazuhei; Nago, Makito*; Ijiri, Yuji*; Shigehiro, Michiko*

Proceedings of ITA-AITES World Tunnel Congress 2015 (WTC 2015)/41st General Assembly, 10 Pages, 2015/05

Journal Articles

Surface speciation of Eu$$^{3+}$$ adsorbed on kaolinite by time-resolved laser fluorescence spectroscopy (TRLFS) and parallel factor analysis (PARAFAC)

Ishida, Keisuke*; Saito, Takumi*; Aoyagi, Noboru; Kimura, Takaumi; Nagaishi, Ryuji; Nagasaki, Shinya*; Tanaka, Satoru*

Journal of Colloid and Interface Science, 374(1), p.258 - 266, 2012/05

 Times Cited Count:21 Percentile:46.2(Chemistry, Physical)

Journal Articles

Thermochromic properties of low-melting ionic uranyl isothiocyanate complexes

Aoyagi, Noboru; Shimojo, Kojiro; Brooks, N. R.*; Nagaishi, Ryuji; Naganawa, Hirochika; Van Hecke, K.*; Van Meervelt, L.*; Binnemans, K.*; Kimura, Takaumi

Chemical Communications, 47(15), p.4490 - 4492, 2011/04

 Times Cited Count:36 Percentile:28.33(Chemistry, Multidisciplinary)

Journal Articles

Basic and application studies on chemical responses to quantum beams in heterogeneous systems

Nagaishi, Ryuji; Yamada, Reiji; Aoyagi, Noboru; Sugo, Yumi

JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 161, 2008/03

From the standpoints of utilization of radioactive wastes, and of sophistication of separation process of spent fuels, we have been investigating promotion or inhibition of radiation-induced reactions in immiscible heterogeneous systems: solutions coexisting/contacting with solid oxides, solvent system with aqueous and organic phases, etc.. We have recently report that the reactions of reduction of metal ions and of hydrogen production in aqueous solution were promoted by adding oxide particles to the solution, and that the radiolysis of amides in n-dodecane was dependent on aqueous solution contacting with the n-dodecane. In this report, we illustrate recover of platinum-group elements from aqueous solution, and non-toxic treatment of chrysotile asbestos using ionizing radiations as the experimental results found in fiscal 2006.

Journal Articles

Hydrogen production and morphological change of chrysotile asbestos in the radiolysis of aqueous solutions

Aoyagi, Noboru; Nagaishi, Ryuji; Esaka, Fumitaka; Yamada, Reiji

Chemistry Letters, 36(7), p.890 - 891, 2007/07

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

A high yield of H$$_{2}$$ gas was unprecedentedly produced due to the radiolysis of water containing asbestos while the morphology of them turned fibrous bundles into non-fibrous particles in 0.40 M H$$_{2}$$SO$$_{4}$$ solution over 2.0 MGy dose of irradiation. In conclusion, irradiation against asbestos in solutions can promote the hydrogen gas production and cause the morphological change of chrysotile without providing heat or chemicals.

Journal Articles

Operation of circular dichroism measurements with periodic photon-helicity switching by an APPLE-2 type undulator at BL23SU at SPring-8

Agui, Akane; Yoshigoe, Akitaka; Nakatani, Takeshi; Matsushita, Tomohiro*; Saito, Yuji; Mizumaki, Masaichiro*; Yokoya, Akinari; Tanaka, Hitoshi*; Miyahara, Yoshikazu*; Shimada, Taihei; et al.

Hoshako, 14(5), p.339 - 348, 2001/11

no abstracts in English

Journal Articles

First operation of circular dichroism measurements with periodic photon-helicity switching by a variably polarizing undulator at BL23SU at SPring-8

Agui, Akane; Yoshigoe, Akitaka; Nakatani, Takeshi*; Matsushita, Tomohiro*; Saito, Yuji; Yokoya, Akinari; Tanaka, Hitoshi*; Miyahara, Yoshikazu*; Shimada, Taihei; Takeuchi, Masao*; et al.

Review of Scientific Instruments, 72(8), p.3191 - 3197, 2001/08

 Times Cited Count:21 Percentile:26.64(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Spent fuel reprocessing based on electrochemical extraction process(SREEP)

Yoshida, Zenko; Aoyagi, Hisao; ; Takeishi, Hideyo; Sasaki, Yuji; Uno, Seiichiro; Tachikawa, Enzo

Journal of Alloys and Compounds, 213-214, p.453 - 455, 1994/00

 Times Cited Count:7 Percentile:44.66(Chemistry, Physical)

no abstracts in English

Journal Articles

Determination of concentration and distribution of (CuO)$$^{+}$$ in high-T$$_{c}$$ superconducting La$$_{2-x}$$Sr$$_{x}$$CuO$$_{y}$$ pellet by flow-coulometry

Sasaki, Yuji; Aoyagi, Hisao; Takeishi, Hideyo; Yoshida, Zenko

Physica C, 191, p.347 - 353, 1992/00

 Times Cited Count:7 Percentile:55.21

no abstracts in English

Journal Articles

Chemical analysis of oxidation state of copper or oxygen and its distribution in superconducting La-Sr-Cu oxide

Sasaki, Yuji; Aoyagi, Hisao; Takeishi, Hideyo; Yoshida, Zenko

Analytical Sciences, 7(Suppl.), p.1201 - 1204, 1991/00

no abstracts in English

Oral presentation

Radiation-induced reduction of metal ions in aqueous solution systems and its application

Nagaishi, Ryuji; Aoyagi, Noboru; Yamada, Reiji; Hatano, Yoshihiko; Yoshida, Zenko

no journal, , 

Promotion of chemical reactions by adding oxide particles to aqueous solution under the irradiation of ionizing radiations has been paid attention especially from the practical viewpoint, so that hydrogen production and decomposition of toxic organic compounds studied. On the other hand, redox of metal ions has not been studied very much since successive reactions after the redox become complicated. In the present study, reduction behavior of metal ions in aqueous solution systems irradiated by $$gamma$$-ray and electron beam was measured, the reduced amount was compared with that by water radiolysis, and then the promotion of reduction by adding oxide particles was found out quantitatively. The application of reduction system to treatment of toxic substances in industry and environment, and to recovery of useful materials from high-level radioactive wastes (HLW), and the utilization of HLW as a radiation resource were also proposed.

Oral presentation

Studies of radiation-induced reactions in aqueous solution systems containing platinum group elements

Nagaishi, Ryuji; Aoyagi, Noboru; Yamada, Reiji

no journal, , 

Radiation-induced reductions of Pt group ions (Pd, Rh, Pt,..) were studied in aqueous solution systems by using Co-60 $$gamma$$-ray or electron beam. A small amount of oxide particles like Al$$_{2}$$O$$_{3}$$, SiO$$_{2}$$ or TiO$$_{2}$$ remarkably promoted the reduction of ions, which hardly proceed by ionizing radiations unless additives such as alcohol are present in solution. The promotion was discussed in terms of speciation of Pt group species, and of interaction between the species and the particles. Precipitates/adsorbents of Pt group elements on the particles formed during the reduction were also found to be involved in the further promotion of reduction of metal ions in aqueous solution.

Oral presentation

Promoted reaction of hydrogen gas generation and deformed morphology of chrysotile in aqueous solutions under irradiation

Aoyagi, Noboru; Nagaishi, Ryuji; Esaka, Fumitaka; Yamada, Reiji

no journal, , 

Interfacial reaction on chrysotile in acidic aqueous solutions which ispromoted by irradiation of $$^{60}$$Co $$gamma$$-ray or electron beam was studied by analyzing the production of hydrogen gas and morphological alteration of fibril structure. The amount of generated hydrogen gas was proportional to the dose of irradiation and larger than the other particles such as alumina or silica known as a reactive surface donor for radicals. An expedited reaction in which chrysotile fibrous structure fell apart and come into particles was found more in SEM-EDX measurementwith increasing the concentrations of sulfuric acid as 0.2M, 0.4M, 0.8M and 2.0M.

Oral presentation

Promoted reaction of hydrogen gas generation and deformed morphology of chrysotile in aqueous solutions under irradiation

Aoyagi, Noboru; Nagaishi, Ryuji; Esaka, Fumitaka; Yamada, Reiji

no journal, , 

Interfacial reaction on chrysotile in acidic aqueous solutions which is promoted by irradiation of $$^{60}$$Co $$gamma$$-ray or electron beam was studied by analyzing the production of hydrogen gas and morphological alteration offibril structure. The amount of generated hydrogen gas was proportional to the dose of irradiation and larger than the other particles such as alumina or silica known as a reactive surface donor for radicals. An expedited reaction in which chrysotile fibrous structure fell apart and come into particles was found more in SEM-EDX measurement with increasing the concentrations of sulfuric acid as 0.2M, 0.4M, 0.8M and 2.0M.

Oral presentation

Experimental studies on quantum beams-induced responses in binary heterogeneous systems

Nagaishi, Ryuji; Yamada, Reiji; Aoyagi, Noboru; Sugo, Yumi

no journal, , 

no abstracts in English

50 (Records 1-20 displayed on this page)