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Journal Articles

Solvent extraction of selenium in nitric acid; Evaluation of multiple extractants and proposal of a novel separation process

Ito, Kengo*; Kawakami, Takahiro*; Kato, Chizu*; Fukutani, Satoshi*; Matsumura, Tatsuro; Fujii, Toshiyuki*

Journal of Radioanalytical and Nuclear Chemistry, 333(10), p.5183 - 5189, 2024/10

https://doi.org/10.1007/s10967-024-09681-6

Times Cited Count：1 Percentile：27.40(Chemistry, Analytical)

Solvent extraction behaviors of Se (VI) from nitric acid solutions were investigated with multiple extractants used for uranium, plutonium, minor actinides, and rare earthelements separation processes from high-level liquid waste. During the processes, Se remained in the residual aqueous solutions, as all extractants showed distributionratios 1. In contrast, Se showed distribution ratios 1 with -phenylenediamine in dilute nitric acid ( 2 M HNO $_{3}$ ), octanol as the organic phase, and concentrated nitric acid (8 M HNO $_{3}$ ) for back extraction, suggesting a potential new single separation process and recovery of Se.

Journal Articles

Effective removal of selenite and selenate ions from aqueous solution by barite

Tokunaga, Kohei*; Takahashi, Yoshio*

Environmental Science & Technology, 51(16), p.9194 - 9201, 2017/08

https://doi.org/10.1021/acs.est.7b01219

Times Cited Count：53 Percentile：81.06(Engineering, Environmental)

In the present study, we explore a new application of barite (BaSO $_{4}$ ) as a sequestering phase for selenite (Se(IV)) and selenate (Se(VI)) ions from aqueous solutions due to the low solubility and high stability of barite. The uptake of Se(IV) and Se(VI) during coprecipitation with barite was investigated through batch experiments to understand the factors controlling effective removal of Se(IV) and Se(VI) from polluted water to barite. The uptake of Se(IV) by barite is dependent on pH, coexistent calcium ion, and sulfate concentration in the initial solution, possibly due to their effects on the chemical affinity and structural similarity. On the other hand, the uptake of Se(VI) by barite was strongly dependent on sulfate concentration in the initial solution, which is only related to the structural similarity. This study provides a good estimate of its ability to effectively remove Se(IV) and Se(VI) from aqueous solutions (more than 80%) under optimized experimental parameters.

Journal Articles

X-ray diffraction measurements for expanded fluid Se using synchrotron radiation up to the dense vapor region

Inui, Masanori*; Hong, X.*; Matsusaka, Tetsuya*; Ishikawa, Daisuke*; Kazi, M. H.*; Tamura, Kozaburo*; Funakoshi, Kenichi*; Utsumi, Wataru

Journal of Non-Crystalline Solids, 312-314, p.274 - 278, 2002/10

https://doi.org/10.1016/S0022-3093(02)01683-6

Times Cited Count：2 Percentile：29.95(Materials Science, Ceramics)

no abstracts in English

JAEA Reports

The Sorption database of radionuclides for cementitious materials

Kato, Hiroshige*; Mine, Tatsuya*; Mihara, Morihiro; Oi, Takao; Honda, Akira

JNC TN8400 2001-029, 63 Pages, 2002/01

JNC-TN8400-2001-029.pdf:1.81MB

Cementitious materials will be used for the TRU waste repository as a component of engineered barrier system. The distribution coefficients which represent the retardation of radionuclides migration for the cementitious materials would be one of the important parameter for the safety assessment. The much information of radionuclide sorption onto the cementitious materials has been accumulated through the study in the world. Therefore it is necessary to compile the information and Kd of the radionuclides reported in previous studies. In this report, the Kd of the important radionuclides, such as C, Ni, Se, Sr, Zr, Nb, Mo, Tc, Sn, I, Cs, Sm, Pb, Ra, Ac, Th, Pa, U, Np, Pu, Am, Cm, for the cementitious materials were compiled as the Sorption Database (SDB). For radionuclides to be sensitive to the redox potential, e.g. Se, Tc, Pa, U, Pu and Np, some Kds measured under the controlled atmosphere had been reported, and few Kds measured under the controlled redox potential had been reported. For Se, Mo, Sm, Cm and Ac, the distribution coefficients had not been reported, therefore distribution coefficients of Se and Mo for OPC (Ordinary Portland Cement) pastes were measured by batch sorption experiments and these data were added into the SDB.

Journal Articles

XAFS study on liquid selenium under high pressure

Katayama, Yoshinori

Journal of Synchrotron Radiation, 8(Part2), p.182 - 185, 2001/03

no abstracts in English

Journal Articles

X-ray diffraction study on structural change in liquid selenium under high pressure

Katayama, Yoshinori; Mizutani, Takeshi; Utsumi, Wataru; Shimomura, Osamu; Tsuji, Kazuhiko*

Physica Status Solidi (B), 223(2), p.401 - 404, 2001/01

https://doi.org/10.1002/1521-3951(200101)223:2<401::AID-PSSB401>3.0.CO;2-L

Times Cited Count：18 Percentile：66.81(Physics, Condensed Matter)

no abstracts in English

Journal Articles

The Solubility of metallic selenium under anoxic conditions

Iida, Yoshihisa; Yamaguchi, Tetsuji; Nakayama, Shinichi; ; Sakamoto, Yoshiaki

Materials Research Society Symposium Proceedings, Vol.663, p.1143 - 1149, 2001/00

no abstracts in English

Journal Articles

High pressure XAFS

Katayama, Yoshinori

Hoshako, 13(5), p.385 - 387, 2000/11

http://ci.nii.ac.jp/naid/10005304553

no abstracts in English

JAEA Reports

Investigation of equilibrium core by recycling MA and LLFP in fast reactor cycle (II) -lnvestigation of LLFP confined in Equilibrium core with element separation-

Mizutani, Akihiko; ;

JNC TN9400 2000-013, 66 Pages, 2000/02

JNC-TN9400-2000-013.pdf:1.97MB

Feasibility study on a self-consistent fuel cycle system has been performed in the nuclear fuel recycle system with fast reactors. ln this system, the self-generated MAs (Minor Actinides) and LLFPs (Long-Lived Fission Products) are confined and incinerated in the fast reactor, which is called the "Equilibrium Core" concept. However, as the isotope separations for selected LLFPs have been assumed in this cycle system, it seems that this assumption is far from realistic one from the viewpoint of economy with respect to the fuel cycle system. ln this study, the possibility for realization of the "Equilibrium Core" concept is evaluated for three fuel types such as oxide, nitride and metallic fuels, provided that the isotopic separation of LLFPs is changed to the element one. This study provides, that is to say, how many LLFP elements can be confined in the "Equilibrium Core" with element separation. This report examines the nuclear properties of the "Equilibrium Core" for various combinations of LLFP incineration schemes from the viewpoints of the risk of geological disposal and the limit in confinable quantity of LLFPs. From the viewpoint of the risk of geological disposal estimated by the retardation factor, it is possible to confine with element separation for T $_{c}$ , I and Se even in the oxide fueled core. From the standpoint of the limit of confinable amounts of LLFPs, on the other hand, T $_{c}$ , I, S $_{e}$ , S $_{n}$ and Cs can be confined with element separation in case that the nitride fuel is chosen.

JAEA Reports

Radionuclide migration analysis in porous rock

Ijiri, Yuji; ; ; Watari, Shingo; K.E.Web*; ;

JNC TN8400 99-092, 91 Pages, 1999/11

JNC-TN8400-99-092.pdf:8.72MB

JNC has been developed the performance assessment approaches for both fractured rock and porous rock. An equivalent continuum model is incorporated for solving the radionuclide migration in porous rock, while a discrete fracture network model is incorporated for solving the radionuclide migration in fractured rock (see more detail in Sawada et al. [1999]). This report describes the methodology, the data and the results of the performance assessment of porous rock. From the results of radionuclide migration analyses that were based on the hydrogeological properties obtained from the Neogene sedimentaly rock at the Tono mine, it was found that the release rate of selenium-79 and cesium-135 are dominant in porous rock. The sensitivity analyses using one-dimensional porous model revealed that hydraulic conductivity has more influences on the results than porosity does. In addition, it was found that smaller distribution coefficients of sandstone yield higher release rate than mudstone and tuff, and smaller distribution coefficients of saline water conditions yield higher release rate than fresh water conditions. The radionuclide migration in Neogene sedimentaly rock, where flow in rock matrix as well as in fractures are significant, was evaluated by superposing the results of porous model and fracture model. Since fracture model tends to yield more conservative results than porous model, it is obvious that the performance of Neogene sedimentary rock can be conservatively assessed by fracture model alone. The nuclide migration analyses performed in this report were based on the hydrogeological properties obtained at the depth between 20 meters and 200 meters frrom the ground surface. Therefore, it should be noted that the release rate at the depth of a future repository in Neogene sedimentary rock, 500 m, will be smaller than that shown in this report due to peemeability decrease from 200 m to 500 m.

Journal Articles

Structure of liquids under high-pressure and high-temperature studied by synchrotron radiation

Katayama, Yoshinori

Hoshako, 12(5), p.375 - 383, 1999/11

http://ci.nii.ac.jp/naid/40006420952

By combining large volume presses and synchrotron radiation, it is now possible to study structure of liquids under high-pressure and high-temperature. In addition to the X-ray diffraction method, EXAFS is also now applicable to samples under high-pressure. We have also developed a new method for density measurements under high-pressure. These methods are used to study structural change in liquid selenium that is associated with a semiconductor-to-metal transition. X-ray diffraction study on liquid phosphorus reveals that there are two distinct liquid forms in phosphorus.

JAEA Reports

Acquisitions of effective diffusion coefficients (De) for Ni(II), Am(III), Sm(III) and Se(IV) in bentonite by through-diffusion method

Sato, Haruo

JNC TN8400 99-062, 16 Pages, 1999/10

JNC-TN8400-99-062.pdf:0.81MB

Effective diffusion coefficients (De) for Ni $^{2+}$ , Sm $^{3+}$ , Am $^{3+}$ and SeO $_{3}^{2-}$ were measured as a function of the ionic charge of diffusion species to quantitatively evaluate the effect of ionic charge in compacted bentonite. The De measurements for Ni $^{2+}$ and Sm $^{3+}$ were carried out for a bentonite dry density of 1.8 Mgm $^{-3}$ with a simulated porewater condition of pH56 by through-diffusion method. The De values for SeO $_{3}^{2-}$ were measured for a bentonite dry density of 1.8 Mgm $^{-3}$ with a simulated porewater condition of pH11. The De measurements for Am $^{3+}$ were carried out for the dry densities of 0.8, 1.4 and l.8 Mgm $^{-3}$ with a porewater condition of pH2 in order to check cation exclusion. Sodium bentonite, Kunigel-V1 was used for those measurements. For the measurements of Am, H-typed Kunigel-V1 which interlayer ion (Na $^{+}$ ) was exchanged with H $^{+}$ was used, because the experiments are carried out for a low pH range. The order of obtained De values was Sm $^{3+}$ Ni $^{2+}$ Am $^{3+}$ SeO $_{3}^{2-}$ . These De values were compared to those reported to date. Consequently, the order of De values was Cs $^{+}$ Sm $^{3+}$ HTO Ni $^{2+}$ anions (I $^{-}$ , Cl $^{-}$ , CO $_{3}^{2-}$ , SeO $_{3}^{2-}$ TcO $_{4}^{-}$ , NpO $_{2}$ CO $_{3}^{-}$ , UO $_{2}$ (CO $_{3}$ ) $_{3}^{4-}$ ), showing a tendency of cations HTO anions. Only the De values of Am $^{3+}$ were approximately the same degree as those of anions. The reason that the De of Ni $^{2+}$ was lower than that of HTO may be because the free water diffusion coefficient (Do) of Ni $^{2+}$ is about 1/3 of that of HTO. The cause that the De of Am $^{3+}$ was approximately the same degee as those of anions may be because the Do of Am $^{3+}$ is about 1/3 of that of HTO and that Am $^{3+}$ was electrostatically repulsed from the surface of bentonite by cation exclusion. The formation factors (FF), calculated normalizing Do, were in the ...

JAEA Reports

Measurements of Apparent Diffusion Coefficients (Da)for Ca(I), Ni(II)and Se(IV) in Bentonite with Silica Sand

Sato, Haruo

JNC TN8400 99-060, 12 Pages, 1999/10

JNC-TN8400-99-060.pdf:0.55MB

Apparent diffusion coefficients(Da) of Cs(Cs $^{+}$ ), Ni(Ni $^{2+}$ ) and Se(SeO $_{3}$ $^{2-}$ ) in a Na-bentonite (Kunigel-V1) were measured for a dry density of 1.8 Mgm $^{-3}$ with silica sand of 30 wt% at room temperature by in-diffusion method to evaluate the effect of the mixture of silica sand on Da in bentonite. The experiments for Cs and Ni were carried out under aerobic condition, but those for Se which is redox sensitive were carried out in an Ar glove-box (O $_{2}$ concentration 0.1 ppm). Consequently, no significant effect of silica sand mixture to the bentonite on Da values of Cs and Se was found, and the obtained Da values were approximately the same as those in the system without silica sand reported so far. On the other hand, Da values of Ni in bentonite with silica sand were 2 orders of magnitude lower than those in bentonite without silica sand obtained to date. The Da values of Ni reported so far were obtained using stable isotopic tracer and a tracer solution with fairly high Ni concentration compared with concentration used in this study was introduced. Additionally, it is known that distribution coefficient (Kd) of Ni on Na-montmorillonite which is the major constituent clay mineral of Kunigel-V1 decreases with increasing Ni concentration. Based on this, the abrupt decrease in Da values of Ni for bentonite with silica sand is considered to be due to the difference of sorption caused by the difference of Ni concentration in the porewater of bentonite.