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Ochs, M.*; Dolder, F.*; Tachi, Yukio
Applied Geochemistry, 136, p.105161_1 - 105161_11, 2022/01
Times Cited Count：4 Percentile：66.78(Geochemistry & Geophysics)Various types of radioactive wastes and environments contain organic substances that can stabilize the aqueous complexes with radionuclides and therefore lead to a decrease of sorption. The present study focuses on testing a methodology to quantify sorption reduction factors (SRFs) in the presence of organic ligands for cement systems. Three approaches for the estimation of SRFs; (1) analogy with solubility enhancement factors, (2) radionuclide speciation based on the thermodynamic calculations, and (3) experimental sorption data in ternary systems, were coupled and tested for the representative organic ligands (ISA and EDTA) and selected key radionuclides (actinides). Our approach allows to critically evaluate the dependence of SRFs for various systems on the chosen method of quantification, in accordance with the data availability for a given systems. The reliable SRFs can only be derived from the sorption measurements in ternary systems. SRF often need to be derived in the absence of such direct evidence, and estimations need to be made based on analogies and speciation information. However, such estimates may be subject to substantial uncertainties.
Kato, Takuma*; Nagaoka, Mika; Guo, H.*; Fujita, Hiroki; Aida, Taku*; Smith, R. L. Jr.*
Environmental Science and Pollution Research, 28(39), p.55725 - 55735, 2021/10
Times Cited Count：0 Percentile：0(Environmental Sciences)In this work, hydrothermal leaching was applied to simulated soils (clay minerals vermiculite, montmorillonite, kaolinite) and actual soils (Terunuma, Japan) to generate organic acids with the objective to develop an additive-free screening method for determination of Sr in soil. Stable strontium (SrCl
) was adsorbed onto soils for study and ten organic acids were evaluated for leaching Sr from simulated soils under hydrothermal conditions (120 to 200
C) at concentrations up to 0.3 M. For strontium-adsorbed vermiculite (Sr-V), 0.1 M citric acid was found to be effective for leaching Sr at 150C and 1 h treatment time. Based on these results, the formation of organic acids from organic matter in Terunuma soil was studied. Hydrothermal treatment of Terunuma soil produced a maximum amount of organic acids at 200C and 0.5 h reaction time. To confirm the possibility for leaching of Sr from Terunuma soil, strontium-adsorbed Terunuma soil (Sr-S) was studied. For Sr-S, hydrothermal treatment at 200C for 0.5 h reaction time allowed 40% of the Sr to be leached at room temperature, thus demonstrating an additive-free method for screening of Sr in soil. The additive-free hydrothermal leaching method avoids calcination of solids in the first step of chemical analysis and has application to both routine monitoring of metals in soils and to emergency situations.
Tachi, Yukio; Ochs, M.*
Progress in Nuclear Science and Technology (Internet), 5, p.229 - 232, 2018/11
Various types of post-accident radioactive waste have been generated from cleanup and decommissioning activities at the Fukushima Daiichi Nuclear Power Plant. For the disposal of these wastes, perturbation effects resulting from co-existing substances (e.g., organic substances, boron, and salts) are needed to be considered. Such co-existing substances may influence on the radionuclide sorption parameters for the safety assessment of the disposal systems. The present study focuses on developing the methodology to quantify sorption parameters by considering such perturbation effects and illustrating example calculations regarding the sorption reduction factors (SRFs) due to the presence of organic ligands (ISA) for cement systems. Three approaches for the derivations of SRFs for cement-Am-ISA case were compared. These options should be applied as a stepwise manner according to the data availability for the perturbation effects resulting from the co-existing substances.
Kojima, Takuji
Oyo Butsuri, 72(4), p.405 - 414, 2003/04
The advanced technologies are required to control pollutants e.g. dioxins in gas or water at extremely low concentration. The present paper introduces typical basic studies, developments of control technologies, and example of their industrial applications of electron beam technology having the features of oxidation, decomposition and detoxifying of such pollutants even at low concentration. It covers removal of SOx and NOx from coal-combustion flue gas, decomposition of gaseous volatile organic compound in off gas and dioxins in incineration flue-gas, purification of tap and wastewaters, and treatment of sewage/sludge.
Yamagishi, Isao
JAERI-Review 2001-027, 52 Pages, 2001/07
JAERI-Review-2001-027.pdf:3.59MB
The present study deals with the survey of inorganic ion-exchangers suitable for separation and immobilization of Sr and Cs contained in acidic high-level liquid waste. For separation and immobilization of Cs, crystalline silicotitanate seems to be the most promising exchanger. For selective separation of Sr, there is no promising exchanger up to now. Sintered ceramics are favorable waste forms of inorganic ion-exchangers. Their stabilities are largely influenced by composition of exchangers, qualities of ceramics and disposal scenario.
Uchiyama, Gunzo; Maeda, Mitsuru; Fujine, Sachio; *; *; *
Journal of Nuclear Science and Technology, 31(3), p.228 - 239, 1994/03
Times Cited Count：8 Percentile：60.22(Nuclear Science & Technology)no abstracts in English
Uchiyama, Gunzo; Maeda, Mitsuru; Fujine, Sachio; *; *
JAERI-M 93-213, 204 Pages, 1993/10
no abstracts in English
Uchiyama, Gunzo; Maeda, Mitsuru; Fujine, Sachio; *; *
JAERI-M 93-191, 58 Pages, 1993/10
no abstracts in English
Uchiyama, Gunzo; *; Fujine, Sachio; Maeda, Mitsuru
Proc. of Symp. on Solvent Extraction l991, p.243 - 250, 1991/00
no abstracts in English
Asanuma, Noriko*; Miyano, Riku*; Aihara, Haruka; Watanabe, So; Nomura, Kazunori
no journal, ,
