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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.

JAEA Reports

Separation of $$^{14}$$C from irradiated graphite materials, 1; Oxidation behaviors and the changes in pore structure of Q1 and IG-110 graphite due to the air reaction (Joint research)

Fujii, Kimio

JAERI-Tech 2005-048, 108 Pages, 2005/09

JAERI-Tech-2005-048.pdf:25.05MB

The graphite-moderated power reactor was shut down in 1998 and its decommissioning program is being planned. Various graphites are used in the core of magnox-type reactors and HTTR as core-support structural materials and moderating materials of fast neutrons. For the nuclear graphite disposal, it is necessary to determine especially the treatment of long-lived nuclides, such as $$^{14}$$C which are generated in the graphite components during reactor operation. As a research, which solves the problem of the $$^{14}$$C concentration, the cooperative research is concluded between JAERI and Japan Nuclear Power Corp. in 1999, and the research for the basic data acquisition has been advanced up to the present. To find the optimum conditions for $$^{14}$$C reduction, basic data on oxidation reaction and the structure of graphite materials are indispensable. In the present experiment, we measure the air oxidation characteristics in the temperature range 450$$sim$$800$$^{circ}$$C in Quality1 graphite and IG-110 graphite. Changes in pore diameter and pore size distribution due to air oxidation are discussed.

Journal Articles

Measurement of depth distributions of $$^{3}$$H and $$^{14}$$C induced in concrete shielding of an electron accelerator facility

Endo, Akira; Harada, Yasunori; Kawasaki, Katsuya; Kikuchi, Masamitsu

Applied Radiation and Isotopes, 60(6), p.955 - 958, 2004/06

 Times Cited Count:5 Percentile:36.97(Chemistry, Inorganic & Nuclear)

no abstracts in English

Journal Articles

Status on Tandetron AMS in JAERI-Mutsu

Kitamura, Toshikatsu; Kabuto, Shoji*; Suzuki, Takashi; Togawa, Orihiko; Kitada, Yoshinobu*; Watanabe, Yukiya*

Dai-16-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.27 - 31, 2004/02

no abstracts in English

Journal Articles

Status on tandetron AMS in JAERI Mutsu

Kitamura, Toshikatsu; Togawa, Orihiko; Aramaki, Takafumi; Suzuki, Takashi; Kabuto, Shoji*

Dai-15-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.1 - 6, 2003/03

no abstracts in English

Journal Articles

Variation of $$^{14}$$C, $$^{137}$$Cs and stable carbon composition in forest soil and its implications

Guo, J.; Atarashi-Andoh, Mariko; Amano, Hikaru

Journal of Radioanalytical and Nuclear Chemistry, 255(1), p.223 - 229, 2003/01

 Times Cited Count:7 Percentile:47.54(Chemistry, Analytical)

Soil organic matter content, $$delta$$$$^{13}$$C, $$^{14}$$C and $$^{137}$$Cs radioactivity were determined in 3 undisturbed forest soil profiles in Ibaraki prefecture, Japan to estimate $$^{14}$$C migration in surface environment. The $$^{137}$$Cs data illustrate that no disturbance has occurred during past years in 3 soil profiles. The peak values are observed in the top 10 cm of the soil profiles. $$^{14}$$C activities were determined with fast bomb combustion-liquid scintillation counting method. $$^{14}$$C determination shows that $$^{14}$$C also has peak values in the top 10 cm of the soil profiles ascribed to the highest bomb $$^{14}$$C level in 1960's.$$delta$$$$^{13}$$C values continuously decreased with increasing soil depth. Enrichment of deeper soils in isotope ratio probably results from discrimination against $$^{13}$$C during mineralization and loss of isotopically lighter carbon from soils due to root uptake, leaching etc.It shows that $$delta$$$$^{13}$$C is an excellent indicator of soil carbon turnover and belowground process.

Journal Articles

Estimation of $$^{14}$$CO$$_{2}$$ flux at soil-atmosphere interface and distribution of $$^{14}$$C in forest ecosystem

Koarashi, Jun; Amano, Hikaru; Atarashi-Andoh, Mariko; Iida, Takao*; Moriizumi, Jun*

Journal of Environmental Radioactivity, 60(3), p.249 - 261, 2002/06

 Times Cited Count:15 Percentile:36.2(Environmental Sciences)

no abstracts in English

Journal Articles

The AMS facility at the Japan Atomic Energy Research Institute (JAERI)

Aramaki, Takafumi; Mizushima, Toshihiko; Mizutani, Yoshihiko*; Yamamoto, Tadatoshi; Togawa, Orihiko; Kabuto, Shoji*; Kuji, Tomoyuki*; Gottdang, A.*; Klein, M.*; Mous, D. J. W.*

Nuclear Instruments and Methods in Physics Research B, 172(1-4), p.18 - 23, 2000/10

 Times Cited Count:26 Percentile:83.97(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Decompositions of carbon dioxide, carbon monoxide and gaseous water by microwave discharge

Sakurai, Tsutomu*; Yokoyama, Atsushi

Journal of Nuclear Science and Technology, 37(9), p.814 - 820, 2000/09

no abstracts in English

Journal Articles

New AMS system at the JAERI-Mutsu

Aramaki, Takafumi; Togawa, Orihiko; Kitamura, Toshikatsu

Proceedings of the International Workshop on Distribution and Speciation of Radionuclides in the Environment, p.350 - 353, 2000/00

no abstracts in English

Journal Articles

Measurements of tritium and $$^{14}$$C production cross sections for 14.7-MeV neutrons on $$^{17}$$O and $$^{18}$$O

Y.M.Verzilov*; Ikeda, Yujiro; Maekawa, Fujio; Oyama, Yukio; D.L.Smith*

Nuclear Science and Engineering, 129(1), p.81 - 87, 1998/00

 Times Cited Count:1 Percentile:15.58(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Migration behavior of carbonate-$$^{14}$$C in tuffaceous soil

Nagao, Seiya;

Materials Research Society Symposium Proceedings, Vol.353, 0, p.1093 - 1100, 1995/00

no abstracts in English

Journal Articles

Adsorption of carbon-14 on mortar

Matsumoto, Junko; Bamba, Tsunetaka; Muraoka, Susumu

Materials Research Society Symposium Proceedings, Vol.353, 0, p.1029 - 1035, 1995/00

no abstracts in English

Journal Articles

Production of carbon-14 and preparation of some key precursors for labeling organic molecules

; Motoishi, Shoji

Proc. of the 3rd Asian Symp. on Research Reactor, 8 Pages, 1991/00

no abstracts in English

Oral presentation

Carbon-14 measurements of PM$$_{2.5}$$ from Noto peninsular in Kanazawa, Japan

Yamada, Reina*; Ikemori, Fumikazu*; Nakamura, Toshio*; Minami, Masayo*; Watanabe, Takahiro; Kinouchi, Kento*; Matsuki, Atsushi*

no journal, , 

PM$$_{2.5}$$ is becoming the focus of international attention, particularly in eastern Asia, because of air pollution and the health risks. Carbon is one of the major components in aerosol. Therefore, sources of the carbon compound should be known for the understanding material cycles and mechanism of the rise. Radiocarbon analysis is unique and useful techniques for estimation of carbon sources in environmental samples including aerosol. Hence half-life of radiocarbon is 5730 years, percent modern carbon (pMC) value based on radiocarbon concentration of fossil fuels are negligible. Therefore, pMC value can reveal the components of carbon in aerosol (biomass carbon versus fossil fuel). In this study, aerosol samples were taken at Noto Peninsula in Ishikawa pref., Japan, in order to estimate contribution rate of biomass carbon and/or fossil fuel in PM$$_{2.5}$$. The pMC values of PM$$_{2.5}$$ at Noto were more than 70 in the summer of 2014. These results show that biomass contribution is relative high in the area.

Oral presentation

Oral presentation

Design of a proportional counter for $$^{14}$$C detection in the downsized AMS system

Matsubara, Akihiro; Fujita, Natsuko; Kimura, Kenji

no journal, , 

no abstracts in English

Oral presentation

Holocene crustal movements recorded in fossil calcareous assemblages around the Cape Hane, Shikoku, Southwestern Japan

Tsukahara, Yuzuko; Kanno, Mizuho; Goto, Akira; Fujita, Natsuko; Komatsu, Tetsuya; Maemoku, Hideaki*

no journal, , 

Holocene crustal movements are recorded as fossil calcareous assemblages on rocky coast. It is possible to reconstruct crustal movements by summarizing these heights, structures and $$^{14}$$C ages. In this study, to clarify crustal movements, we collected calcareous assemblages and dated them using the $$^{14}$$C at Cape Hane. $$^{14}$$C ages show forming period of the lowest wave-cut-bench. However, it is difficult to determine the history of emerged events in a short cycle. To reconstruct the crustal movement history precisely, it is necessary to identify obvious multi-layer structures or discontinuous surfaces with time interval.

18 (Records 1-18 displayed on this page)
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