Valence separation of Fe and removal of Sn by solvent extraction as a potential method to determine Fe in glass containing Sn

Kanno, Naoki*; Nakase, Masahiko*; Saijo, Yoshitaka*; Matsumura, Daiju; Tsuji, Takuya; Takeshita, Kenji*; Tsukahara, Takehiko*

Progress in Nuclear Science and Technology (Internet), 7, p.154 - 160, 2025/03

https://doi.org/10.15669/pnst.7.154

Performance comparison of monoamides on U recovery by temperature swing extraction using Ce

Iwamoto, Toshihiro; Saito, Madoka*; Takahatake, Yoko; Watanabe, So; Watanabe, Masayuki; Naruse, Atsuki*; Tsukahara, Takehiko*

Mechanical Engineering Journal (Internet), 11(2), p.23-00444_1 - 23-00444_7, 2024/04

https://doi.org/10.1299/mej.23-00444

Treatment of U contaminated waste generated from nuclear fuel fabrication process, 1; Ce(IV) recovery by temperature swing extraction with monoamides

Iwamoto, Toshihiro; Saito, Madoka*; Takahatake, Yoko; Watanabe, So; Watanabe, Masayuki; Naruse, Atsuki*; Tsukahara, Takehiko*

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 4 Pages, 2023/05

Applicability of temperature swing extraction technology employing monoamides was examined for uranium contaminated waste treatment procedure. Separation experiments on simulated target solution with three kinds of monoamides with different structure showed that Ce(IV) in the solution was selectively recovered by the temperature swing extraction operation. Based on the experiments, an appropriate monoamide for the procedure was selected.

Determination of Cs/Cs isotopic ratio in soil collected near Fukushima Daiichi Nuclear Power Station through mass spectrometry

Shimada, Asako; Tsukahara, Takehiko*; Nomura, Masao*; Kim, M. S.*; Shimada, Taro; Takeda, Seiji; Yamaguchi, Tetsuji

Journal of Nuclear Science and Technology, 58(11), p.1184 - 1194, 2021/11

https://doi.org/10.1080/00223131.2021.1931520

Determining the completeness of nuclear reactor decommissioning is an important step in safely utilizing nuclear power. For example, Cs from the Fukushima Daiichi Nuclear Power Station (FDNPS) accident can be treated as background radioactivity, so determining the origin of Cs is essential. To accomplish this, measuring the Cs/Cs isotope ratio can be useful, so this study optimized a solvent extraction method, with calix[4]arene-bis(t-octylbenzo-crown-6) [BOBCalixC6] in 1-octanol, to purify radioactive Cs, radiocesium, from a solution of major environmental soil elements and mass spectrometry interference elements. This optimized method was applied to Cs purification in soil samples (40 g), and the final solutions contained a total of 10g/ml of the major soil elements and ng/ml concentrations at most of interfering elements. Soil samples collected near the FDNPS were then purified, and the Cs/Cs isotope ratios were measured, using both thermal ionization mass spectrometry (TIMS) and triple quadrupole induced coupled plasma mass spectrometry (ICP-QQQ). The results of each of these measurements were compared, and we found that Cs isotope ratios obtained by TIMS were more precise, by an order of magnitude, while the ICP-QQQ results possessed good abundance sensitivities. A slightly higher Cs/Cs ratio in the northwest area of the FDNPS was observed, while other areas exhibited similar values, all within the measurement error range, which indicated different origins of radiocesium. These results agreed with previously reported Cs/Cs activity distributions, suggesting that this ratio may be useful in identifying radiocesium origins for evaluating future nuclear reactor decommissions.

Direct temperature-swing extraction of rare-earth elements from acidic solution using the hydrophobic interactions of poly(-isopropylacrylamide) with diglycolamide-typed ligands

Saga, Kaname*; Suzuki, Hideya; Matsumura, Tatsuro; Tsukahara, Takehiko*

Analytical Sciences, 35(4), p.461 - 464, 2019/04

https://doi.org/10.2116/analsci.18N023

The phase transition-based gelification phenomenon of poly--isopropylacrylamide (PNIPAAm) in aqueous solutions has a great potential in developing new waste-free extraction processes of metal ions. By using hydrophobic diglycolamide-typed ligands in gelification extraction, a one-step complete extraction of all the RE ions from a nitric acid solution was successfully realized.

Local distribution and isotopic ratio of radiocesium in environment

Shimada, Asako; Tsukahara, Takehiko*; Nomura, Masao*; Takeda, Seiji

no journal, , 

Because of the accident at the Fukushima Daiichi Nuclear Power Station (1F), a large area of eastern Japan was contaminated by radiocesium. When radiocesium would be detected at the completion of their decommissioning in the site, estimation of the origin of which is from background originated 1F and fallout of atmospheric nuclear test or from decommissioned facilities will be important. Therefore, soils of 3 sites were collected by using U8 containers, and Cs radioactivity, Cs/Cs radioactivity ratios, Cs/Cs isotope ratios were determined. Cs radioactivity concentrations were varied in not only between sites but also in the same site, however, Cs/Cs radioactivity ratio was approximately constant in all sites. In case of highly contaminated soils, Cs/Cs isotope ratio was almost comparable to that for the soil collected at near the 1F. On the other hand, in case of lower contaminated soils, Cs/Cs isotope ratio was slightly higher than that for soil collected at near the 1F. It is possibly that fallout before the 1F accident contained Cs to increase the Cs/Cs isotope ratio.

First measurement of Cs/Cs isotope ratio in Japanese soil before the accident at the Fukushima Daiichi Nuclear Power Station

Shimada, Asako; Xu, J.*; Tsukahara, Takehiko*; Nomura, Masao*; Takeda, Seiji; Takahashi, Hiroaki*

no journal, , 

Cesium-137 concentration in environmental soil samples near and inside Tokai-mura was exceeded site release standard, 0.1 Bq/g, because of the accident at the Fukushima Daiichi Nuclear Power Station (1F). It is possibly to use the Cs/Cs isotope ratio to distinguish the Cs from the 1F and from decommissioned facility. However, radiocesium from global fallout is also contained in soil and it may be influenced on the Cs/Cs isotope ratio. There are no data of Cs/Cs isotope ratio before the 1F accident for soil samples collected in Japan. Therefore, Cs/Cs isotope ratio in soil samples collected in 2008 y at Tokai-mura was measured to be 2.610.28 agreed with the result for sampled collected in USA.

Development of chemical separation method for the measurement of Cs/Cs isotopic ratio in environmental samples

Shimada, Asako; Nomura, Masao*; Tsukahara, Takehiko*; Takeda, Seiji

no journal, , 

Although identification of radiocesium in environmental samples is commonly performed by using Cs/Cs radioactivity ratio, measurement of Cs will become challenge in a few decade ago because of short half-life (2 y). Instead of the measurement of Cs/Cs radioactivity ratio, the measurement of Cs/Cs isotopic ratio will be effective in future because of long half-life of Cs (133 My). In order to measure Cs/Cs isotopic ratio, Cs must be separated from the matrix of soil. Since 1 Bq of Cs is equal to 312.5 fg, large amount of soil have to be treated to extract Cs for the measurement. In the present study, we improved chemical separation method using BOBCalixC6 by optimizing extraction time and reuse of the organic phase. Finally, approximately 170 g of soil sampled at Toka-mura was dissolved and Cs was separate with the developed method to measure Cs/Cs isotopic ratio.

Development of temperature swing extraction apparatus for uranium waste treatment

Kai, Masao; Sato, Takanori*; Iwamoto, Toshihiro; Saito, Madoka*; Nakahara, Masaumi; Takahatake, Yoko; Watanabe, So; Nakamura, Masahiro; Naruse, Atsuki*; Itoda, Naokazu*; et al.

no journal, , 

The sludges containing uranium are generated in the nuclear fuel fabrication facilities. Uranium is planned to be selectively recovered from the sludge leachate. The temperature swing extraction method was selected for the selective recovery of uranium. In this study, a small-scale testing system was developed, and the performances of the agitation, the transportation of the gel-containing solution, and the separation of the gel were experimentally examined. Cerium(IV) was used instead of uranium, and agitator blades were selected to agitate the gel solution effectively. The gel solution was transferred through the self-feeding pump and was successfully separated into the gel and the solution using the spin dryer with a filter cloth.

Development of dose evaluation method for confirmation of completion of decommissioning, 2; Identification of radiocesium origin using Cs/Cs isotope ratio

Shimada, Asako; Tsukahara, Takehiko*; Nomura, Masao*; Kim, M. S.*; Shimada, Taro; Takeda, Seiji; Yamaguchi, Tetsuji

no journal, , 

Radiocesium from the Fukushima Daiichi Nuclear Power Station (1F) accident can be treated as background radioactivity at completion of decommissioning, so determining the origin of radiocesium is essential. Therefore, we studied identification of radiocesium origin using Cs/Cs isotope ratio. The ratio originated from 1F was 0.36280.0005. When the ratio originated from decommissioning facility was 0.050.2 larger than that originated from 1F, it is challenging to decrease the stand deviation less than 0.01 for 1 Bq/g of Cs because precision was decreased as decreasing the Cs concentration. If the ratio is able to be determined within the standard deviation of 0.0005 for 0.5 Bq/g of soil sample, the identification would be available.