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Journal Articles

Evaluation of oxidation efficiency of hydrophobic palladium catalyst for $$^{3}$$H monitoring in radioactive gaseous waste

Furutani, Misa; Kometani, Tatsunari; Nakagawa, Masahiro; Ueno, Yumi; Sato, Junya; Iwai, Yasunori*

Hoken Butsuri (Internet), 55(2), p.97 - 101, 2020/06

Herein, an oxidation catalyst was introduced after heating it to 600$$^{circ}$$C to oxidize tritium gas (HT) existing in exhaust into tritiated water vapor (HTO). This study aims to establish a safer $$^{3}$$H monitoring system by lowering the heating temperature required for the catalyst. In these experiments, which were conducted in the Nuclear Science Research Institute, Japan Atomic Energy Agency, cupric oxide, hydrophobic palladium/silicon dioxide (Pd/SiO$$_{2}$$), and platinum/aluminum oxide (Pt/Al$$_{2}$$O$$_{3}$$) catalysts were ventilated using standard hydrogen gas. After comparing the oxidation efficiency of each catalyst at different temperatures, we found that the hydrophobic Pd/SiO$$_{2}$$ and Pt/Al$$_{2}$$O$$_{3}$$ catalysts could oxidize HT into HTO at 25$$^{circ}$$C.

Journal Articles

Validation of measured microwave absorption and temperature change for development of a single-mode-type microwave heating thermogravimetry apparatus

Karisma, A. D.*; Hamaba, Taishu*; Fukasawa, Tomonori*; Huang, A.-N.*; Segawa, Tomomi; Fukui, Kunihiro*

Review of Scientific Instruments, 88(2), p.024101_1 - 024101_8, 2017/02

 Times Cited Count:3 Percentile:23.36(Instruments & Instrumentation)

Microwave heating direct denitration method is used in the nuclear fuel reprocessing process. In order to develop a single-mode-type microwave heating thermogravimetry apparatus which can perform detailed analysis of the characteristics of microwave heating, the temperature dependence of microwave absorption is verified. The temperature distribution, microwave absorption efficiency, and dielectric properties of a CuO pellet that was heated by the microwave irradiation were investigated. The temperature distribution in the CuO pellet due to one-way travel of the microwave in the apparatus was accurately reproduced by a three-dimensional numerical simulation of the electromagnetic field. The numerically determined temperature dependency of the CuO absorption efficiency was found to be in very good agreement with published data.

JAEA Reports

Development of active control technology for impurities in coolant helium using High Temperature Engineering Test Reactor (HTTR)

Hamamoto, Shimpei; Nemoto, Takahiro; Sekita, Kenji; Saito, Kenji

JAEA-Technology 2015-048, 62 Pages, 2016/03

JAEA-Technology-2015-048.pdf:2.58MB

The decarburization may take place depending on the chemical impurity composition in helium gas used as the primary coolant in High-Temperature Gas-cooled Reactors, and will significantly reduce the strength of the alloy. The ability to remove impurities by a helium purification system was designed according to the predicted generation rate of impurities so as to make the coolant become the carburizing atmosphere. It has been confirmed that the coolant becomes the carburizing atmosphere during the operation period of the High Temperature engineering Test Reactor (HTTR). However, it is necessary to consider changes of generation rates of impurities since lifetime of commercial reactor is longer than the life of the HTTR. To avoid the influence of the change of generation rate, the control of removal efficiency of impurity in the helium purification system was considered in this study. To reform the decarburizing into the carburizing atmosphere, it is effective to increase the H$$_{2}$$ and CO concentration in the coolant helium. By controlling the efficiency of the Cooper Oxide Trap (CuOT), it is possible to increase the H$$_{2}$$ and CO concentrations. Therefore, an experiment was carried out by injecting the gas mixture of H$$_{2}$$ and CO into the existing purification system of HTTR to investigate the dependencies of temperature and impurity concentration on the removal efficiency of CuOT. The experimental results are described as the following, (1) By adjusting the temperature of helium at the CuOT within a range from 110$$^{circ}$$C to 50$$^{circ}$$C, it is possible to reduce the removal efficiency of H$$_{2}$$ sufficiently. (2) Temperature change of helium gas in the CuOT is sufficiently reduced by the cooler located at the downstream of the CuOT, which does not affect the primary cooling system of HTTR. As the results, the applicability of removal efficiency control of CuOT was verified to improve the decarburizing atmosphere for the actual HTGR system.

Journal Articles

Evaluation of oxidation efficiency of hydrophobic palladium catalyst for $$^{14}$$C monitoring in gaseous radioactive waste

Ueno, Yumi; Nakagawa, Masahiro; Sato, Junya; Iwai, Yasunori

Hoken Butsuri, 51(1), p.7 - 11, 2016/03

In the Nuclear Science Research Institute, Japan Atomic Energy Agency (JAEA), in order to oxidize $$^{14}$$C, which exists in various chemical forms in exhaust, into $$^{14}$$CO$$_{2}$$, a copper oxide (CuO) catalyst is introduced after heating to 600$$^{circ}$$C. Our goal was to establish a safer $$^{14}$$C monitoring system by lowering the heating temperature required for the catalyst; therefore, we developed a new hydrophobic palladium/silicon dioxide (Pd/SiO$$_{2}$$) catalyst that makes the carrier's surface hydrophobic. In these experiments, catalysts CuO, platinum/aluminum oxide (Pt/Al$$_{2}$$O$$_{3}$$), palladium/zirconium dioxide (Pd/ZrO$$_{2}$$), hydrophobic Pd/SiO$$_{2}$$, and hydrophilic Pd/SiO$$_{2}$$ were ventilated with standard methane gas, and we compared the oxidation efficiency of each catalyst at different temperatures. As a result, we determined that the hydrophobic Pd/SiO$$_{2}$$ catalyst had the best oxidation efficiency. By substituting the currently used CuO catalyst with the hydrophobic Pd/SiO$$_{2}$$ catalyst, we will be able to lower the working temperature from 600$$^{circ}$$C to 300$$^{circ}$$C and improve the safety of the monitoring process.

Journal Articles

Doping dependence of softening in the bond-stretching phonon mode of La$$_{2-x}$$Sr$$_x$$CuO$$_4$$ (0$$leq x leq$$0.29)

Fukuda, Tatsuo; Mizuki, Junichiro; Ikeuchi, Kazuhiko*; Yamada, Kazuyoshi*; Baron, A. Q. R.*; Tsutsui, Satoshi*

Physical Review B, 71(6), p.060501_1 - 060501_4, 2005/02

 Times Cited Count:56 Percentile:86.82(Materials Science, Multidisciplinary)

Phonons along the [100] direction, in particular the highest energy Cu-O bond-stretching LO mode, of La$$_{2-x}$$Sr$$_x$$CuO$$_4$$ have been studied by inelastic X-ray scattering experiments. The LO phonon mode in the $$x$$ = 0.12 sample shows significant softening similar to early neutron studies. We show here a recovery of the softening was found in the $$x$$ = 0.29 sample, where superconductivity degrades and normal metallic conductivity dominates. The results suggest one-to-one correspondence between the softening of this LO phonon and the superconductivity.

Journal Articles

Analysis of resonant inelastic X-ray scattering in La$$_2$$CuO$$_4$$

Nomura, Takuji; Igarashi, Junichi*

Physical Review B, 71(3), p.035110_1 - 035110_5, 2005/01

 Times Cited Count:45 Percentile:83.01(Materials Science, Multidisciplinary)

The experimental result of resonant inelastic X-ray scattering in La$$_2$$CuO$$_4$$ is theoretically analyzed. The ground state of the system is described within the Hartree-Fock approximation, and the electronic excitation processes are taken account of within the random phase approximation. In the experiment, the spectral shape shows a strong dependence on the transferred momentum of the photon. We have succeeded in reproducing theoretically this dependence quantitatively.

Journal Articles

Theoretical study on resonant inelastic X-ray scattering in quasi-one-dimensional cuprates

Nomura, Takuji; Igarashi, Junichi*

Journal of the Physical Society of Japan, 73(7), p.1677 - 1680, 2004/07

 Times Cited Count:26 Percentile:74.84(Physics, Multidisciplinary)

We study theoretically the resonant inelastic X-ray scattering in quasi-one-dimensional insulating copper oxides, where the incident photon energy is tuned to the Cu1$$s$$-4$$p$$ absorption energy. Our attention is focused particularly on the strong momentum-transfer dependence of the spectral shape observed in recent experiments. We describe the antiferromagnetic ground state within the Hartree-Fock theory, and consider charge excitations from the ground state within the random phase approximation. By taking account of the electron correlation effects perturbatively, we obtain detailed momentum-transfer dependence of the spectra in a semiquantitative agreement with the experiments.

Journal Articles

Magnetic field effects and magnetic anisotropy in lightly doped La$$_{2-x}$$Sr$$_{x}$$CuO$$_{4}$$

Matsuda, Masaaki; Fujita, Masaki*; Yamada, Kazuyoshi*; Birgeneau, R. J.*; Endo, Yasuo*; Shirane, Gen*

Physical Review B, 66(17), p.174508_1 - 174508_6, 2002/11

 Times Cited Count:11 Percentile:51.99(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Electronic phase separation in lightly doped La$$_{2-x}$$Sr$$_{x}$$CuO$$_{4}$$

Matsuda, Masaaki; Fujita, Masaki*; Yamada, Kazuyoshi*; Birgeneau, R. J.*; Endo, Yasuo*; Shirane, Gen*

Physical Review B, 65(13), p.134515_1 - 134515_6, 2002/04

 Times Cited Count:137 Percentile:96.78(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Neutron scattering studies on lightly-doped La$$_{2-x}$$Sr$$_{x}$$CuO$$_{4}$$

Matsuda, Masaaki; Birgeneau, R. J.*; Endo, Yasuo*; Fujita, Masaki*; Hiraka, Haruhiro*; Kastner, M. A.*; Shirane, Gen*; Wakimoto, Shuichi*; Yamada, Kazuyoshi*

Journal of the Physical Society of Japan, Vol.70, Supplement A, p.46 - 48, 2001/05

no abstracts in English

Journal Articles

Enhancement of static antiferromagnetic correlations by magnetic field in a superconductor La$$_{2-x}$$Sr$$_{x}$$CuO$$_{4}$$ with x=0.12

Katano, Susumu; Sato, Masugu*; Yamada, Kazuyoshi*; Suzuki, Takao*; Fukase, Tetsuo*; Yamada, Kazuyoshi*

Physical Review B, 62(22), p.R14677 - R14680, 2000/12

 Times Cited Count:141 Percentile:97.32(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Chemical effect on X-ray spectra induced by multiple inner-shell ionization, 2

Kawatsura, Kiyoshi*; Takeshima, Naoki*; Terazawa, Norihisa*; Aoki, Yasushi; Yamamoto, Shunya; Nashiyama, Isamu; Narumi, Kazumasa; Naramoto, Hiroshi

JAERI-Review 99-025, TIARA Annual Report 1998, p.188 - 190, 1999/10

no abstracts in English

Journal Articles

Determination of depth profile of CuO$$^{+}$$ and Cu$$^{+}$$ in superconductors by a wet-chemical method using flow-coulometry

Sasaki, Yuji

Analytical Sciences, 15, p.421 - 425, 1999/05

 Times Cited Count:0 Percentile:0.01(Chemistry, Analytical)

no abstracts in English

Journal Articles

Determination of oxidation state of electrolyzed La$$_{2}$$CuO$$_{y}$$ by flow-coulometry

Sasaki, Yuji

Electrochimica Acta, 42(12), p.1915 - 1920, 1997/00

 Times Cited Count:2 Percentile:12.6(Electrochemistry)

no abstracts in English

Journal Articles

Characterization of superconducting oxides, La$$_{2-x}$$M$$_{x}$$CuO$$_{y}$$ (M=alkali metals), synthesized in MOH molten salts

Sasaki, Yuji; Wuryanto*; Takeishi, Hideyo

Analytical Sciences, 12, p.499 - 501, 1996/06

 Times Cited Count:1 Percentile:6.06(Chemistry, Analytical)

no abstracts in English

Journal Articles

In-plane microwave conductivity and quasiparticle scattering rate of superconducting high-Tc cuprates

*; *; Maeda, A.*; Asaoka, Hidehito; Takei, Humihiko*; *; *; *; *; *; et al.

Journal of the Physical Society of Japan, 65(10), p.3266 - 3273, 1996/00

 Times Cited Count:16 Percentile:72.01(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Nonlinear meissner effect in double layered high-Tc cuprates investigated by measurement of the penetration depth

Maeda, A.*; *; *; *; *; *; *; Asaoka, Hidehito; *; *; et al.

Journal of the Physical Society of Japan, 65(11), p.3638 - 3645, 1996/00

 Times Cited Count:21 Percentile:76.5(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Correlation between superconductivity, electronic state and crystal structure in La$$_{2-y-x}$$Bi$$_{y}$$Ba$$_{x}$$CuO$$_{4}$$

*; *; Katano, Susumu; *; *; *; *

Physica C, 263(1-4), p.298 - 301, 1996/00

 Times Cited Count:4 Percentile:29.7(Physics, Applied)

no abstracts in English

Journal Articles

A Dual character of twin boundaries in YBa$$_{2}$$Cu$$_{3}$$O$$_{7}$$ single crystal

Ishida, Takekazu*; Okuda, Kiichi*; Asaoka, Hidehito; *; Noda, Kenji; *

Proc. of 8th Int. Workshop on Critical Currents in Superconductors, 0, p.313 - 316, 1996/00

no abstracts in English

Journal Articles

Distribution of CuO$$^{+}$$ in La$$_{2}$$CuO$$_{y}$$ and La$$_{1.85}$$Sr$$_{0.15}$$CuO$$_{y}$$ pellets and their superconducting properties

Sasaki, Yuji

Analytical Sciences, 11, p.1005 - 1008, 1995/12

 Times Cited Count:1 Percentile:7.68(Chemistry, Analytical)

no abstracts in English

48 (Records 1-20 displayed on this page)