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Journal Articles

Study on evaluation method of kernel migration of TRISO fuel for High Temperature Gas-cooled Reactor

Fukaya, Yuji; Okita, Shoichiro; Sasaki, Koei; Ueta, Shohei; Goto, Minoru; Ohashi, Hirofumi; Yan, X.

Nuclear Engineering and Design, 399, p.112033_1 - 112033_9, 2022/12

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

Kernel migration of TRi-structural ISOtropic (TRISO) fuel for High Temperature Gas-cooled Reactor (HTGR) has been analyzed to investigate the potential dominating effects. Kernel migration is a major fuel failure mode and dominant to determine the lifetime of the fuel for High Temperature engineering Test Reactor (HTTR). However, this study shows that the result and reliability depend on the evaluation method. The evaluation method used in this study takes into account of actual distribution of Coated Fuel Particles (CFPs) and the resulting heterogeneous fuel temperature calculation with such distribution. The result shows that the Kernel Migration Rate (KMR) is predicted to be about 10% less compared with the most conservative evaluation.

Journal Articles

Computed tomography neutron detector system to observe power distribution in a core with long neutron flight path

Fukaya, Yuji; Okita, Shoichiro; Nakagawa, Shigeaki; Goto, Minoru; Ohashi, Hirofumi

Annals of Nuclear Energy, 168, p.108911_1 - 108911_7, 2022/04

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

A power distribution monitoring system by using a moving detector for a core with a long neutron flight path has been proposed. High Temperature Gas-cooled Reactor (HTGR) and Fast Reactor (FR) has a long neutron flight path and the neutrons reach to detector far from fuel assembly in the center of the core unlike Light Water Reactor (LWR). By using the feature, power distribution can be observed with a few detectors by moving the detector and computed tomography technology similar to X-ray Computed Tomography (CT). For a small-sized core, the power distribution can be evaluated only by an ex-core neutron detector. For a large-sized core with inner detectors, the power distribution can be observed with a small number of in-core detectors even if the deployment is limited due to material integrity conditions such as temperature environment. The feasibility is numerically confirmed by simulations of the HTGR core and its detector response. It is expected to observe the power distribution in the core of HTGR and FR, which is difficult continuously to deploy in-core detectors because of high temperature and/or high irradiation damage.

Journal Articles

Studies on the extraction of soft acid metal species using MIDOA and analogous compounds

Sasaki, Yuji; Saeki, Morihisa; Sugo, Yumi; Ikeda, Yasuhisa*; Kawasaki, Takeshi*; Suzuki, Tomoya*; Ohashi, Akira*

Solvent Extraction Research and Development, Japan, 22(1), p.37 - 45, 2015/05

 Times Cited Count:13 Percentile:43.15(Chemistry, Multidisciplinary)

An extractant, methylimino-bis-${it N,N'}$-dioctylacetamide (MIDOA), was used for the extraction of soft acid metals. It was found that MIDOA can extract not only Cr(VI), Mo(VI), W(VI), Tc(VII) and Re(VII), whose metals can form the oxonium anions due to their high oxidation states, but also other metal cations, like Nb(V), Ta(V) and Pd(II). Analogous compounds, imino-bis-${it N,N'}$-dioctylacetamide (IDOA) and methylimino-bis-${it N,N'}$-di-2-ethylhexylacetamide (MIDEHA), are synthesized and compared for their extractability. It is clear that these extractants have almost same or lower $$D$$ values than those for MIDOA. In order to examine the effect on extractability with different donor atoms, TODGA (${it N,N,N',N'}$-tetraoctyl-diglycolamide) and TDGA (${it N,N,N',N'}$-tetraoctyl-tyiodiglycolamide) having oxygen and sulfur donor are employed. The comparison of their extractabilities suggests that the trend of Pd and Re extraction is N $$>$$ S $$>$$ O and N $$>$$ O $$>$$ S, respectively.

Journal Articles

Comprehensive extraction study using $$N$$,$$N$$-dioctyldiglycolamic acid

Shimojo, Kojiro; Nakai, Ayaka*; Okamura, Hiroyuki; Saito, Takumi*; Ohashi, Akira*; Naganawa, Hirochika

Analytical Sciences, 30(4), p.513 - 517, 2014/04

 Times Cited Count:13 Percentile:48.79(Chemistry, Analytical)

Journal Articles

Extraction behavior and selective separation of lead(II) using $$N$$,$$N$$-dioctyldiglycol amic acid

Shimojo, Kojiro; Nakai, Ayaka; Okamura, Hiroyuki; Ohashi, Akira*; Naganawa, Hirochika

Analytical Sciences, 29(1), p.147 - 150, 2013/01

 Times Cited Count:13 Percentile:43.01(Chemistry, Analytical)

Journal Articles

Structural study on 2,2'-(methylimino)bis($$N$$,$$N$$-dioctylacetamide) complex with Re(VII)O$$_{4}$$$$^{-}$$ and Tc(VII)O$$_{4}$$$$^{-}$$ by $$^{1}$$H-NMR, EXAFS and IR spectroscopy

Saeki, Morihisa; Sasaki, Yuji; Nakai, Ayaka*; Ohashi, Akira*; Banerjee, D.*; Scheinost, A. C.*; Foerstendorf, H.*

Inorganic Chemistry, 51(10), p.5814 - 5821, 2012/05

 Times Cited Count:23 Percentile:70.08(Chemistry, Inorganic & Nuclear)

The structures of the complex of 2,2'-(methylimino)bis($$N$$,$$N$$-dioctylacetamide) (MIDOA) with M(VII)O$$_{4}$$$$^{-}$$ (M=Re and Tc), which were prepared by liquid-liquid solvent extraction, were investigated by using $$^{1}$$H-NMR, EXAFS and IR spectroscopy. The results from $$^{1}$$H-NMR and EXAFS provide therefore evidence of M(VII)O$$_{4}$$$$^{-}$$...H$$^{+}$$MIDOA complex formation in the organic solution. The IR spectra of Re(VII)O$$_{4}$$$$^{-}$$...H$$^{+}$$MIDOA and Tc(VII)O$$_{4}$$$$^{-}$$...H$$^{+}$$MIDOA were analyzed based on the structures and the IR spectra calculated at the B3LYP/cc-pVDZ level. Comparison of the observed and calculated IR spectra demonstrates that an intramolecular hydrogen bond is formed in H$$^{+}$$MIDOA and the M(VII)O$$_{4}$$$$^{-}$$ ion interact with H$$^{+}$$MIDOA through multiple C-H$$_{n}$$...O hydrogen bonds.

Journal Articles

Technetium(VII) and rhenium(VII) extraction by a new diamide reagent, 2,2'-(Imino)bis(${it N,N}$-dialkylacetamide) (IDAA)

Sasaki, Yuji; Sugo, Yumi; Saeki, Morihisa; Morita, Yasuji; Ohashi, Akira*

Solvent Extraction Research and Development, Japan, 18, p.69 - 74, 2011/00

The new diamide-type extractant, 2,2-(Imino)bis(${it N,N}$-dialkylacetamide) (IDAA), was developed for Tc recovery. IDAA has a nitrogen donor atom introduced into the center of backbone and shows the tridentate feature by hybrid donor atoms of two carbonyl oxygen and a nitrogen. 2,2-(Methylimino)bis(${it N,N}$-Dioctylacetamide) (MIDOA), 2,2-(Methylimino)bis(${it N,N}$-Didodecylacetamide) (MIDDA), and 2,2-(Imino)bis(${it N,N}$-Didodecylacetamide) (IDDA), the IDAA derivatives, can be dissolved well in n-dodecane, and are readily used in the solvent extraction. In addition to Tc(VII) and Re(VII), Cr(VI), Mo(VI), W(VI), Pd(II) and Pu(IV) can be extracted from nitric acid to n-dodecane by these extractants, therefore IDAA has high extractability with some oxonium anions. The extraction capacity for Re(VII) was measured and more than 37 mM Re(VII) can be extracted by 0.1 M MIDOA.

Journal Articles

Neutron diffraction analysis of deuterium transfer in chiral $$beta$$-thiolactam formation in the crystalline state

Hosoya, Takaaki*; Uekusa, Hidehiro*; Ohashi, Yuji*; Ohara, Takashi; Tanaka, Ichiro*; Niimura, Nobuo*

Acta Crystallographica Section B; Structural Science, Crystal Engineering and Materials (Internet), 62(1), p.153 - 160, 2006/02

 Times Cited Count:5 Percentile:48.77(Chemistry, Multidisciplinary)

Since N,N-dibenzyl-1-cyclohexenecarbothioamide is photoisomerized to the optically active $$beta$$-thiolactam with the retention of the single-crystal form, the mechanism of chirality induction was identified by X-ray crystal structure analyses during the process of the reaction. In order to clarify the mechanism of hydrogen transfer in the reaction, the H atomsof the benzyl groups were replaced with deuterium atoms. The crystal structure after photoisomerization was analyzed by neutron diffraction. One of four deuterium atoms of the two benzyl groups is transferred to the C atom of the cyclohexene ring. The absolute configuration of the -C$$^{*}$$HD- group(chiral methylene) in the photoproduct r-thiolactam revealed that the deuterium atom occupies the equatorial position. This suggests that the deuterium atom is not transferred from the benzyl group of a neighbouring molecule, but from one of the benzyl groups within the molecule.

Journal Articles

Beamline for surface and interface structures at SPring-8

Sakata, Osami*; Furukawa, Yukito*; Goto, Shunji*; Mochizuki, Tetsuro*; Uruga, Tomoya*; Takeshita, Kunikazu*; Ohashi, Haruhiko*; Ohata, Toru*; Matsushita, Tomohiro*; Takahashi, Sunao*; et al.

Surface Review and Letters, 10(2&3), p.543 - 547, 2003/04

 Times Cited Count:140 Percentile:96.39(Chemistry, Physical)

The main components of a new beamline for surface and interface crystal structure determination at SPring-8 are briefly described. Stages for the beamline monochromator are modified for making an incident X-ray intensity more stable for surface X-ray experiments. Absolute photon flux densities were measured with an incident photon energy. A new ultrahigh vacuum system is introduced with preliminary X-ray measurements from an ordered oxygen on Pt(111) surface.

Journal Articles

Study of the performance of the commercial scale steam reformer using HTGR

Fumizawa, Motoo; Inaba, Yoshitomo; *; *; *; Takenaka, Yutaka*

Nihon Kikai Gakkai Dai-6-Kai Doryoku, Enerugi Gijutsu Shimpojiumu '98 Koen Rombunshu, p.100 - 105, 1998/00

no abstracts in English

Journal Articles

The Thermal expansion coefficient and Gruneisen parameter of InP crystal low temperatures

Haruna, K.*; Maeta, Hiroshi; Ohashi, K.*; Koike, T.*

J. Phys., C, 20(32), p.5275 - 5279, 1987/11

The thermal expansion of the lattice constante of InP crystal has been measured in the rage 4.2-300 K by the Bond method and teh rsults are shown graphically.

Oral presentation

Extraction of technetium(VII) and rhenium(VII) by the new reagent, 2-(Imino)bis(N,N-dialkylacetamide) (IDAA)

Sasaki, Yuji; Sugo, Yumi; Saeki, Morihisa; Morita, Yasuji; Ohashi, Akira*

no journal, , 

The new diamide-type extractant, (Imino)bis(N,N-dialkylacetamide) (IDAA), was developed for Tc recovery. IDAA has a nitrogen donor atom introduced into the center of backbone and shows the tridentate feature by hybrid donor atoms of two carbonyl oxygen and a nitrogen. (Methylimino)bis(N,N-Dioctylacetamide) (MIDOA) and (Imino)bis(N,N-Dioctylacetamide) (IDOA), the IDAA derivatives, can be dissolved well in n-dodecane, and are readily used in the solvent extraction. In addition to Tc(VII) and Re(VII), Cr(VI), Mo(VI), W(VI), Pd(II) and Pu(IV) can be extracted from nitric acid to n-dodecane by MIDOA, therefore IDAA has high extractability with some oxonium anions. The extraction capacity for Re(VII) was measured and more than 37 mM Re(VII) can be extracted by 0.1M MIDOA.

Oral presentation

Extraction and separation of cadmium(II) from process residue of scallop by "emulsion flow"

Ishioka, Minami; Yanase, Nobuyuki; Nagano, Tetsushi; Mitamura, Hisayoshi; Ohashi, Akira*; Yamaguchi, Akira*; Kim, H.-B.*; Naganawa, Hirochika

no journal, , 

no abstracts in English

Oral presentation

2-(Imino)bis(N,N-dialkylacetamide) (IDAA), a novel complexing agent for Palladiumu(II), technetium(VII) and rhenium(VII)

Sasaki, Yuji; Saeki, Morihisa; Sugo, Yumi; Morita, Yasuji; Ohashi, Akira*; Oriyama, Takeshi*; Ikeda, Yasuhisa*; Ali, M.*

no journal, , 

no abstracts in English

Oral presentation

Extraction of lanthanoids with diglycol amic acid extractant

Nakai, Ayaka; Okamura, Hiroyuki; Shimojo, Kojiro; Ohashi, Akira*; Naganawa, Hirochika

no journal, , 

no abstracts in English

Oral presentation

Highly efficient extraction separation of lead(II) using a diglycol amic acid extractant

Shimojo, Kojiro; Nakai, Ayaka; Okamura, Hiroyuki; Ohashi, Akira*; Naganawa, Hirochika

no journal, , 

no abstracts in English

Oral presentation

One-pot synthesis of ligand-immobilized gold nanoparticles using gold-binding peptide and colorimetric analysis of mercury ions

Shimojo, Kojiro; Nakai, Ayaka; Ohashi, Akira*; Naganawa, Hirochika

no journal, , 

no abstracts in English

Oral presentation

One-pot fabrication of Hg(II)-responsive gold nanoparticles with ligand bearing gold-binding peptide

Shimojo, Kojiro; Nakai, Ayaka*; Ohashi, Akira*; Naganawa, Hirochika

no journal, , 

no abstracts in English

Oral presentation

Colorimetric detection of mercury ions using gold nanoparticles decorated with peptide-fused diglycolamic acid ligand

Shimojo, Kojiro; Nakai, Ayaka*; Ohashi, Akira*; Naganawa, Hirochika

no journal, , 

no abstracts in English

Oral presentation

Lanthanide extraction using novel extractant calix[4]arene diglycolamic acid derivative

Yabe, Makoto; Okamura, Hiroyuki; Ohashi, Akira*; Naganawa, Hirochika; Shimojo, Kojiro

no journal, , 

no abstracts in English

33 (Records 1-20 displayed on this page)