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Matsumoto, Yoshinobu*; Do, Thi-Mai-Dung*; Inoue, Masao; Nagaishi, Ryuji; Ogawa, Toru
Journal of Nuclear Science and Technology, 52(10), p.1303 - 1307, 2015/10
Times Cited Count：4 Percentile：32.74(Nuclear Science & Technology)Effects of zirconium oxides and oxidation products of zircaloy-4 on water radiolysis were investigated to predict the hydrogen generation from the water-immersed debris after a severe accident of a nuclear power plant. Observed yields of hydrogen in water containing the oxides were measured as a function of their weight fractions. Assuming that energies of Co-60 
-ray deposited to water and the oxides brought about the water radiolysis to generate hydrogen independently, the radiolysis showed an additional term of hydrogen generation due to the energy deposition to the oxides. This term seemed to be dependent on the specific surface area or particle size of oxides, but not on the crystal structure of oxides in our experimental results. The oxides in distilled water gave the strong enhancement of term. The enhancement tended to saturate with increasing the weight fraction of oxides and was not apparent in the seawater.
Nagaishi, Ryuji; Inoue, Masao; Hino, Ryutaro; Ogawa, Toru
Proceedings of 2014 Nuclear Plant Chemistry Conference (NPC 2014) (USB Flash Drive), 9 Pages, 2014/10
Since seawater has been used as a coolant for reactors and spent fuel pools in broken reactor buildings at Fukushima Daiichi NPS accident, radioactive contaminated water emitted following the accident has contained salt content of seawater at high concentrations, different from that at TMI-2 accident. Radiolysis of seawater leading to hydrogen generation and corrosion has been simulated and reported by several groups. However, the proposed radiolysis models cannot be always applied to water radiolysis at the wide range of salt concentrations present in the NPS, mainly because primary yields of radiolysis products of water and radiation-induced reactions are dependent on the salt concentration. In this study, the radiolytic behavior in diluted and concentrated systems of seawater was considered on the basis of results in steady state and pulse radiolysis experiments, in which the above salt effects were demonstrated from the obtained results.
Nagaishi, Ryuji; Inoue, Masao; Hino, Ryutaro; Ogawa, Toru
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Nagaishi, Ryuji; Inoue, Masao; Hino, Ryutaro; Ogawa, Toru
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Nagaishi, Ryuji; Inoue, Masao; Endo, Keita*; Matsumura, Taichi; Ogawa, Toru
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Nagaishi, Ryuji; Inoue, Masao; Matsumura, Taichi; Yamagishi, Isao; Hino, Ryutaro; Ogawa, Toru
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Hydrogen gas generation in radiolysis of pure water or seawater coexisting with zeolite adsorbents has been investigated by using Co-60 -ray for hydrogen safety in decontamination of radioactive water after Fukushima Daiichi NPS accident. In this work, two types of void volumes present in the zeolite bed were paid attention microscopically, and the difference in water radiolysis between the volumes was considered. The oxygen generated by decomposition of hydrogen peroxide, as the counterpart of hydrogen molecule, contacting with the zeolites were also discussed.
Nagaishi, Ryuji; Motooka, Takafumi; Yamagishi, Isao; Inoue, Masao; Matsumura, Taichi
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Furukawahara, Ryo*; Ogawa, Toru; Inoue, Masao; Nagaishi, Ryuji
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Matsumoto, Yoshinobu*; Inoue, Masao; Nagaishi, Ryuji; Ogawa, Toru
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Nagaishi, Ryuji; Kondo, Takafumi*; Godo, Masao*; Yoshida, Yoichi*; Inoue, Masao
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-ray irradiationNagaishi, Ryuji; Motooka, Takafumi; Yamagishi, Isao; Inoue, Masao*; Matsumura, Taichi
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Matsumoto, Yoshinobu*; Inoue, Masao*; Nagaishi, Ryuji; Suzuki, Tatsuya*; Ogawa, Toru
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Nagaishi, Ryuji; Inoue, Masao*; Kondo, Takafumi*; Godo, Masao*; Yoshida, Yoichi*; Kuwano, Ryo*
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Matsumoto, Yoshinobu*; Inoue, Masao*; Nagaishi, Ryuji; Suzuki, Tatsuya*; Ogawa, Toru
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For hydrogen safety of post severe accident debris, radiolytic hydrogen generation with oxidized Zircaloy-4. The particle-size dependence of the hydrogen generation with oxidized Zircaloy-4 was investigated.
Nagaishi, Ryuji; Kuwano, Ryo*; Inoue, Masao*; Matsumura, Taichi
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in Reprocessing solutions, 6; Consideration on the temperature dependence of G value of H in plutonium nitrate solutionAbe, Yuma; Kumagai, Yuta; Hotoku, Shinobu; Inoue, Masao*; Suzuki, Sachiko*; Toigawa, Tomohiro; Watanabe, Masayuki; Nakano, Masanao*; Oyama, Kanichi*; Tamauchi, Yoshikazu*
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Hydrogen is generated from aqueous solutions containing radioactive materials through radiolysis of water. Because of the wide variety of solution properties treated in reprocessing plants and the difficulty of conducting experiments with radioactive materials, few studies have taken into account the properties of the solutions actually used. In particular, there are very few studies on the effects of agitation by bubbling, etc. and on temperature dependence. In this study, hydrogen generation was measured in Pu nitrate solution with and without agitation and at different temperatures, and G-values were calculated. Under the test conditions where the solution was agitated (bubbling agitation or boiling), the G-value increased by about 20 to 30% compared to that under static conditions at room temperature. Under the stirring condition, there was no clear trend of increase/decrease of G-values with increasing temperature. From these results, it is considered that the G-value of Pu nitrate solution increases with stirring and that there is no significant temperature dependence in the stirred condition. The reason for the observed temperature dependence of the hydrogen G-values in this study, which gives different from that of the nitric acid solution in the validation experiment, may be due to the difference in the composition and reaction behavior of the radicals produced by radiolysis between Co-60 gamma-rays and alpha-rays from Pu due to the difference in LET.
in Reprocessing Solutions, 7; Measurement of hydrogen generation test using high active liquid wasteHotoku, Shinobu; Fukaya, Hiroyuki; Kumagai, Yuta; Inoue, Masao*; Suzuki, Sachiko*; Ban, Yasutoshi; Kida, Takashi; Watanabe, Masayuki; Abe, Yuma*; Tamauchi, Yoshikazu*
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In order to evaluate the amount of hydrogen generated by radiolysis of water from the high active liquid waste in the reprocessing process, In this study a spent fuel solution was used and tests were conducted under the conditions of the solution temperature and the presence or absence of agitation and analyzed of the components in spent fuel solution. In this presentation, it is report on the outline of the test and the results obtained in the test.
