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Journal Articles

Separation and recovery of long-lived fission products from high level radioactive waste using electrochemical technique

Kanamura, Shohei*; Takahashi, Yuya*; Omori, Takashi*; Nohira, Toshiyuki*; Sakamura, Yoshiharu*; Matsumura, Tatsuro

Denki Kagaku, 88(3), p.289 - 290, 2020/09

no abstracts in English

Journal Articles

Zr separation from high-level liquid waste with a novel hydroxyacetoamide type extractant

Morita, Keisuke; Suzuki, Hideya; Matsumura, Tatsuro; Takahashi, Yuya*; Omori, Takashi*; Kaneko, Masaaki*; Asano, Kazuhito*

Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.464 - 468, 2019/09

High level liquid waste (HLLW) contains several radionuclides with half-lives longer than 10$$^{6}$$ year. For reduce environmental burden of waste disposal, minor actinoids and long-lived fission products will to be partitioned and transmuted. JAEA and Toshiba developed process for recovering Se, Zr, Pd and Cs from HLLW. Solvent extraction for Zr with novel extractant, ${it N,N}$-didodecyl-2-hydroxyacetoamide (HAA) was detailed. The HAA system showed high selectivity for Zr, as indicated by the extraction order of Zr $$>$$ Mo $$>$$ Pd $$>$$ Ag $$approx$$ Sb $$>$$ Sn $$>$$ Lns $$>$$ Fe. The extracted species was determined as Zr(HAA)$$_{3}$$(NO$$_{3}$$)$$_{4}$$(HNO$$_{3}$$)$$_{x}$$. A continuous countercurrent extraction with HAA was applied to a simulated, concentrated HLLW after Pd, Se, and Cs removal, where the quantitative extraction of Zr and Mo was effectively demonstrated.

Journal Articles

A Failure investigation of the beam collimator system in the J-PARC 3 GeV rapid cycling synchrotron

Okabe, Kota; Yamamoto, Kazami; Kamiya, Junichiro; Takayanagi, Tomohiro; Yamamoto, Masanobu; Yoshimoto, Masahiro; Takeda, Osamu*; Horino, Koki*; Ueno, Tomoaki*; Yanagibashi, Toru*; et al.

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.853 - 857, 2017/12

The most important issue is to reduce the uncontrolled beam loss in the high intensity hadron accelerator such as J-PARC proton accelerators. The J-PARC 3 GeV Synchrotron (RCS) has a collimator system which narrows a high intensity beam in the RCS. After startup of RCS in 2007, the collimator system of the RCS worked well. However, in April 2016, vacuum leakage at the collimator system occurred during the maintenance operation. To investigate a cause of the failure, we took apart iron shields of the collimator reducing exposed dose of operators. As a result of inspection, we succeeded to identify the cause of the vacuum leakage failure. In this presentation, we report the failure investigation of the beam collimator system in the RCS.

Journal Articles

Reduction and resource recycling of high-level radioactive wastes through nuclear transmutation; Isolation techniques of Pd, Zr, Se and Cs in simulated high level radioactive waste using solvent extraction

Sasaki, Yuji; Morita, Keisuke; Ito, Keisuke; Suzuki, Shinichi; Shiwaku, Hideaki; Takahashi, Yuya*; Kaneko, Masaaki*; Omori, Takashi*; Asano, Kazuhito*

Proceedings of International Nuclear Fuel Cycle Conference (GLOBAL 2017) (USB Flash Drive), 4 Pages, 2017/09

no abstracts in English

Journal Articles

Extraction and separation of Se, Zr, Pd, and Cs including long-lived radionuclides

Sasaki, Yuji; Morita, Keisuke; Suzuki, Shinichi; Shiwaku, Hideaki; Ito, Keisuke; Takahashi, Yuya*; Kaneko, Masaaki*

Solvent Extraction Research and Development, Japan, 24(2), p.113 - 122, 2017/06

The solvent extraction of Se, Zr, Pd, and Cs from nitric acid into 1-octanol (OC) and dodecane has been performed. These elements include long-lived radionuclides in spent nuclear fuels, so a simple separation method is indispensable for the development of the treatment of high-level liquid radioactive waste. It was found that Se can be extracted using phenylenediamine, Zr can be extracted using tetraoctyl diglycolamide and di-2-ethylhexyl phosphoric acid, and Pd can be extracted using (methylimino)bis(dioctylacetamide) and hexaoctylnitrilotriacetamide. These elements can be recovered in over 90% yield by these extractants from nitric acid into OC. A distribution ratio of Cs of greater than 1 can be obtained using di-t-butyldibenzo-18-crown-6. It is clear that 90% recovery of Cs can be achieved using an extraction solvent with ten times the volume of the aqueous phase.

Journal Articles

Progress of divertor simulation research toward the realization of detached plasma using a large tandem mirror device

Nakashima, Yosuke*; Takeda, Hisahito*; Ichimura, Kazuya*; Hosoi, Katsuhiro*; Oki, Kensuke*; Sakamoto, Mizuki*; Hirata, Mafumi*; Ichimura, Makoto*; Ikezoe, Ryuya*; Imai, Tsuyoshi*; et al.

Journal of Nuclear Materials, 463, p.537 - 540, 2015/08

 Times Cited Count:17 Percentile:88.2(Materials Science, Multidisciplinary)

Journal Articles

Development of function-graded proton exchange membrane for PEFC using heavy ion beam irradiation

Shiraki, Fumiya*; Yoshikawa, Taeko*; Oshima, Akihiro*; Oshima, Yuji*; Takasawa, Yuya*; Fukutake, Naoyuki*; Oyama, Tomoko*; Urakawa, Tatsuya*; Fujita, Hajime*; Takahashi, Tomohiro*; et al.

Nuclear Instruments and Methods in Physics Research B, 269(15), p.1777 - 1781, 2011/08

 Times Cited Count:7 Percentile:53.57(Instruments & Instrumentation)

The graded energy deposition of heavy ion beam irradiation to polymeric materials was utilized to synthesize a novel proton exchange membrane (PEM) with the graded density of sulfonic acid groups toward the thickness direction. Stacked Poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) films were irradiated by Xe$$^{54+}$$ ion beam with the energy of 6 MeV/u under a vacuum condition. Irradiated films were grafted with styrene monomer and then sulfonated. The membrane electrode assembly (MEA) fabricated by the function graded PEM showed improved fuel cell performance in terms of voltage stability. It was expected that the function-graded PEM could control the graded concentration of sulfonic acid groups in PEM.

Journal Articles

A One-dimensional propagation of shock wave supported by atmospheric millimeter-wave plasma

Oda, Yasuhisa; Yamaguchi, Toshikazu*; Shiraishi, Yuya*; Komurasaki, Kimiya*; Kajiwara, Ken; Takahashi, Koji; Kasugai, Atsushi; Sakamoto, Keishi

Journal of Infrared, Millimeter, and Terahertz Waves, 32(6), p.877 - 882, 2011/06

 Times Cited Count:8 Percentile:47.07(Engineering, Electrical & Electronic)

Journal Articles

Micro-fabrication of biodegradable polymers using focused ion beam

Okubo, Satoshi*; Takahashi, Tomohiro*; Takasawa, Yuya*; Gowa, Tomoko*; Sasaki, Takashi*; Nagasawa, Naotsugu; Tamada, Masao; Oshima, Akihiro*; Tagawa, Seiichi*; Washio, Masakazu*

Journal of Photopolymer Science and Technology, 23(3), p.393 - 397, 2010/11

 Times Cited Count:4 Percentile:15.4(Polymer Science)

Microfabrication of biodegradable polymers such as poly(butylene succinate-${it co}$-adipate) (PBSA) and poly($$varepsilon$$-caprolactone) (PCL) were demonstrated using focused ion beam (FIB) with maskless direct etching. As the result, the micro structures of PBSA and PCL were obtained. The etching depth of both PBSA and PCL were increased with increasing FIB fluence, and the etching rates were estimated to be about 1.3 $$times$$ 10$$^{-18}$$ $$mu$$m/(ions cm$$^{-2}$$) and 1.2 $$times$$ 10$$^{-18}$$ $$mu$$m/(ions cm$$^{-2}$$), respectively. Moreover, very thin films of PBSA and PCL were made by spin-coating method. The thicknesses of the spin-coated samples were about 200 nm, and the surface roughness was less than 10 nm (RMS). The fine structures such as micro-gear of PBSA and PCL were obtained without solid debris. The line width of the fabricated structure was about 250 nm.

Journal Articles

SR-PES and STM observation of metastable chemisorption state of oxygen on Si(110)-16$$times$$2 surface

Yamamoto, Yoshihisa*; Togashi, Hideaki*; Kato, Atsushi*; Takahashi, Yuya*; Konno, Atsushi*; Teraoka, Yuden; Yoshigoe, Akitaka; Asaoka, Hidehito; Suemitsu, Maki*

Applied Surface Science, 254(19), p.6232 - 6234, 2008/07

 Times Cited Count:4 Percentile:23.21(Chemistry, Physical)

The room temperature adsorbed state of oxygen molecules on Si(110)-16$$times$$2 surface and the structural change after a mild annealing has been investigated by synchrotron radiation photoemission spectroscopy. As a result, despite the very small dosage of oxygen, Si$$^{2+}$$ and Si$$^{3+}$$ components already appear in addition to Si$$^{1+}$$. This is likely to be caused by a selective adsorption of O$$_{2}$$ molecules into the vicinity of already oxidized sites. After annealing, we found that binding energy of Si$$^{2+}$$ and Si$$^{3+}$$ increase and approach to their corresponding peak positions of a thermally-grown oxide, and this increase indicates relaxation of the Si-O bond length and Si-O-Si bond angle of metastable oxygen atoms.

Journal Articles

Observation of initial oxidation on Si(110)-16$$times$$2 surface by scanning tunneling microscopy

Togashi, Hideaki*; Takahashi, Yuya*; Kato, Atsushi*; Konno, Atsushi*; Asaoka, Hidehito; Suemitsu, Maki*

Japanese Journal of Applied Physics, Part 1, 46(5B), p.3239 - 3243, 2007/05

 Times Cited Count:13 Percentile:48.98(Physics, Applied)

On Si(110) surface, the hole mobility is enhanced as compared with that on Si(001) surface. This surface is also to be used in the next-generation three-dimensional devices. We conducted scanning-tunneling-microscopy (STM) observation on the initial oxidation of Si(110)-16$$times$$2 surface. The present result suggests less occurrence of etching under the oxidation condition. There is a possibility to form an abrupt oxide/Si interface on the Si(110) surface.

Journal Articles

XPS and STM studies on initial oxidation of Si(110)-16$$times$$2

Suemitsu, Maki*; Togashi, Hideaki*; Kato, Atsushi*; Takahashi, Yuya*; Konno, Atsushi*; Yamamoto, Yoshihisa*; Teraoka, Yuden; Yoshigoe, Akitaka; Asaoka, Hidehito

Materials Research Society Symposium Proceedings, Vol.996, p.19 - 25, 2007/00

From its high hole mobility, as well as its inevitable usage as an active layer in multi-gated FETs, Si(110) surface is expected to play a crucial role in the next generation CMOS devices. We have investigated the initial oxidation of Si(110) surface by using SR-XPS and STM. Reflecting its atomistic structure of the 16$$times$$2 reconstruction, initial oxidation of Si(110) surface shows a unique behavior which is not observed on other surfaces like (111) and (001).

Oral presentation

Observation of initial oxidation process on Si(110)-16$$times$$2 by real-time photoemission spectroscopy, 1

Togashi, Hideaki*; Kato, Atsushi*; Yamamoto, Yoshihisa*; Konno, Atsushi*; Narita, Yuzuru*; Suemitsu, Maki*; Teraoka, Yuden; Yoshigoe, Akitaka; Takahashi, Yuya*; Asaoka, Hidehito

no journal, , 

no abstracts in English

Oral presentation

Observation of initial oxidation process on Si(110)-16$$times$$2 by real-time photoemission spectroscopy, 2

Kato, Atsushi*; Togashi, Hideaki*; Yamamoto, Yoshihisa*; Konno, Atsushi*; Narita, Yuzuru*; Suemitsu, Maki*; Teraoka, Yuden; Yoshigoe, Akitaka; Takahashi, Yuya*; Asaoka, Hidehito

no journal, , 

no abstracts in English

Oral presentation

Analysis of initial oxidation on Si(110)-16$$times$$2 surface using synchrotron radiation photoelectron spectroscopy

Kato, Atsushi*; Togashi, Hideaki*; Yamamoto, Yoshihisa*; Konno, Atsushi*; Narita, Yuzuru*; Suemitsu, Maki*; Teraoka, Yuden; Yoshigoe, Akitaka; Takahashi, Yuya*; Asaoka, Hidehito

no journal, , 

no abstracts in English

Oral presentation

Scanning tunneling microscope observation on initial oxidization at Si surfaces

Takahashi, Yuya*; Togashi, Hideaki*; Kato, Atsushi*; Asaoka, Hidehito; Konno, Atsushi*; Suemitsu, Maki*

no journal, , 

no abstracts in English

Oral presentation

Scanning-tunneling-microscope observation on initial oxidization at Si surfaces

Takahashi, Yuya*; Togashi, Hideaki*; Kato, Atsushi*; Asaoka, Hidehito; Konno, Atsushi*; Suemitsu, Maki*; Teraoka, Yuden; Yoshigoe, Akitaka

no journal, , 

no abstracts in English

Oral presentation

Temperature dependence of Si(110)-16$$times$$2 reconstruction

Takahashi, Yuya*; Togashi, Hideaki*; Kato, Atsushi*; Asaoka, Hidehito; Konno, Atsushi*; Suemitsu, Maki*

no journal, , 

no abstracts in English

Oral presentation

Synchrotron radiation photoemission spectroscopy for initial oxidation processes at Si(110)-16$$times$$2 surface

Togashi, Hideaki*; Yamamoto, Yoshihisa*; Goto, Seiichi*; Takahashi, Yuya*; Nakano, Takuya*; Kato, Atsushi*; Hasegawa, Satoshi*; Konno, Atsushi*; Suemitsu, Maki*; Asaoka, Hidehito; et al.

no journal, , 

no abstracts in English

Oral presentation

STM and SR-XPS observation on RT adsorption of oxygen molecules at Si(110)-16$$times$$2 surfaces

Togashi, Hideaki*; Takahashi, Yuya*; Kato, Atsushi*; Konno, Atsushi*; Suemitsu, Maki*; Asaoka, Hidehito; Yoshigoe, Akitaka; Teraoka, Yuden

no journal, , 

no abstracts in English

40 (Records 1-20 displayed on this page)