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Asakura, Toshihide; Kim, S.-Y.; Morita, Yasuji; Ozawa, Masaki*
Journal of Nuclear and Radiochemical Sciences, 6(3), p.267 - 269, 2005/12
An electrolytic extraction (EE) method, i.e. electro-reductive deposition, of Tc from nitric acid aqueous solution was studied for future reprocessing. After 30 min of constant potential electrolysis by carbon electrode at -0.3 V vs. SSE (Standard Silver Electrode), Tc concentration in 3 M nitric acid decreased to 93 % of the initial value, which corresponds to 7 % of deposition. With co-existence of Pd, the value reached to 15 % of deposition equivalent by electrolysis at 
0.0 V vs. SSE for 60 min. An acceleration effect of Pd on Tc deposition (promoter effect) was suggested. The concentration, however, increased to the initial value after further electrolysis and competing re-dissolution of deposited Tc was also suggested. In cyclic voltammetry measurements, it was found that the deposit from Tc-Pd-Ru-Rh solution dissolved easier than that from Pd-Ru-Rh did. In electrolyzed Tc solution, an absorption peak at 482 nm was found. It can be attributed to the complex with nitrite anion, and the complex formation is proposed as one possible mechanism of Tc re-dissolution.
Mineo, Hideaki; Isogai, Hikaru; Morita, Yasuji; Uchiyama, Gunzo*
Journal of Nuclear Science and Technology, 41(2), p.126 - 134, 2004/02
Times Cited Count：8 Percentile：48.24(Nuclear Science & Technology)A simple equation was proposed for the dissolution rate of spent LWR fuel, of which the change in the dissolution area was estimated by taking into account of the area of the cracks occurring due to thermal shrinkage of the pellets during irradiation. The applicability of proposed equation was examined using LWR fuel dissolution test results in the present study as well as the results obtained by other workers. The equation showed good agreements with the dissolution test results obtained from spent fuel pellets and pulverized spent fuel. It was indicated that the proposed equation was simple and would be useful for the prediction of dissolution of spent LWR fuels. However, the initial effective dissolution area, the parameter of the equation, was found to depend on the temperature, which could not be explained by the proposed equation. Further studies on the role of other factors affecting dissolution rate, such as nitrous acid, in the dissolution of spent fuel was required.
Mineo, Hideaki; Goto, Minoru; Iizuka, Masaru*; Fujisaki, Susumu; Hagiya, Hiromichi*; Uchiyama, Gunzo
Separation Science and Technology, 38(9), p.1981 - 2001, 2003/05
Times Cited Count：24 Percentile：65.18(Chemistry, Multidisciplinary)no abstracts in English
Working Group on Nuclear Criticality Satety Data
JAERI-Review 2001-028, 217 Pages, 2001/08
JAERI-Review-2001-028.pdf:10.04MB
no abstracts in English
Working Group on Nuclear Criticality Satety Data
JAERI 1340, 189 Pages, 1999/03
no abstracts in English
fuelNuclear Technology, 90, p.186 - 190, 1990/05
Times Cited Count：7 Percentile：60.66(Nuclear Science & Technology)no abstracts in English
; ; ;
Journal of Nuclear Science and Technology, 17(1), p.83 - 85, 1980/00
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)no abstracts in English
-radiation on a disposal of spent nuclear fuelKitamura, Akira
no journal, ,
The Japanese geological disposal program has started researching disposal of spent nuclear fuel (SF) in deep geological strata (hereafter "direct disposal of SF") as an alternative management option other reprocessing followed by vitrification and geological disposal of high-level radioactive waste. In the case of direct disposal of SF, specific examples of the possible effects of radiation include: generation of oxidizing chemical species in conjunction with decomposition of groundwater and accompanying oxidation of reducing groundwater; and increase in the dissolution rate of SF and the solubility of radionuclides. Focusing especially on the effects of -radiation in safety assessment, this study has reviewed research into the effects of -radiation on the spent nuclear fuel, canisters and environment outside the canisters, and safety assessments in countries other than Japan that are planning direct disposal of SF. It was found that the effects of -radiation on SF disposal are not significant due to suppression of water radiolysis by hydrogen gas generated from canister corrosion according to the latest research.
