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Sasaki, Yuji; Morita, Keisuke; Kitatsuji, Yoshihiro; Ito, Keisuke*; Yoshizuka, Kazuharu*
Solvent Extraction Research and Development, Japan, 28(2), p.121 - 131, 2021/00
Times Cited Count：2 Percentile：14.88(Chemistry, Multidisciplinary)High concentration of Cs is present in high-level radioactive waste. It is well-known that Cs is an alkali element and difficult to extract completely into an organic phase. Crown ether compounds are widely available for Cs extractants; DtBuDB18C6 (di-
-butyl-dibenzo-18crown6), was used in this study. Organic solvents used for the industrial applications, such as 
-dodecane and 1-octanol, have low solubility concerning the compound; other solvents were employed and tested. In this study, ketone-, ether-, and ester-type solvents showed high solubility for DtBuDB18C6 and DtBuDB18C6, when dissolved in ketones and alcohols, exhibited relatively high Cs distribution ratios (
(Cs)), closely to 10.
Sato, Satoshi*; Konno, Chikara; Nakashima, Hiroshi; Shionaga, Ryosuke*; Nose, Hiroyuki*; Ito, Yuji*; Hashimoto, Hirohide*
Journal of Nuclear Science and Technology, 55(4), p.410 - 417, 2018/04
Times Cited Count：1 Percentile：11.49(Nuclear Science & Technology)In order to enhance the neutron shielding performance, we developed concrete with boron of more than 10 wt%. We performed a neutron shielding experiment using the mockup of the newly developed boron-loaded concrete and DT neutrons at FNS in JAEA, and measured the reaction rates of the 
Nb(n,2n)
Nb and 
Au(n,
)
Au reactions in the mockup. The calculations were conducted by using MCNP-5.14 and FENDL-2.1. The calculation results agreed well with the measured ones, and we confirmed that the accuracy was very good on the atomic composition data of the boron-loaded concrete and their nuclear data. In addition, we calculated effective dose rates and reaction rates of the 
Co(n,)
Co and 
Eu(n,)
Eu reactions in the boron-loaded concrete and other concretes. It is concluded that the boron-loaded concrete has much better shielding performance for DT neutrons than other concretes.
Sasaki, Yuji; Morita, Keisuke; Ito, Keisuke; Suzuki, Shinichi; Shiwaku, Hideaki; Takahashi, Yuya*; Kaneko, Masaaki*; Omori, Takashi*; Asano, Kazuhito*
Proceedings of International Nuclear Fuel Cycle Conference (GLOBAL 2017) (USB Flash Drive), 4 Pages, 2017/09
no abstracts in English
Sasaki, Yuji; Morita, Keisuke; Suzuki, Shinichi; Shiwaku, Hideaki; Ito, Keisuke; Takahashi, Yuya*; Kaneko, Masaaki*
Solvent Extraction Research and Development, Japan, 24(2), p.113 - 122, 2017/06
The solvent extraction of Se, Zr, Pd, and Cs from nitric acid into 1-octanol (OC) and dodecane has been performed. These elements include long-lived radionuclides in spent nuclear fuels, so a simple separation method is indispensable for the development of the treatment of high-level liquid radioactive waste. It was found that Se can be extracted using phenylenediamine, Zr can be extracted using tetraoctyl diglycolamide and di-2-ethylhexyl phosphoric acid, and Pd can be extracted using (methylimino)bis(dioctylacetamide) and hexaoctylnitrilotriacetamide. These elements can be recovered in over 90% yield by these extractants from nitric acid into OC. A distribution ratio of Cs of greater than 1 can be obtained using di-t-butyldibenzo-18-crown-6. It is clear that 90% recovery of Cs can be achieved using an extraction solvent with ten times the volume of the aqueous phase.
Ito, Tatsuya*; Yamauchi, Yuji*; Hino, Tomoaki*; Shibayama, Tamaki*; Nobuta, Yuji*; Ezato, Koichiro; Suzuki, Satoshi; Akiba, Masato
Journal of Nuclear Materials, 417(1-3), p.1147 - 1149, 2011/10
Times Cited Count：13 Percentile：69.64(Materials Science, Multidisciplinary)Suzuki, Satoshi; Ito, Tatsuya*; Nobuta, Yuji*; Yamauchi, Yuji*; Hino, Tomoaki*; Ezato, Koichiro; Yokoyama, Kenji; Akiba, Masato
no journal, ,
A reduced activation ferritic-maternstic steel, F82H, is one of candidate structural materials for the first wall of fusion machines. For F82H, retention and desorption behavior of F82H has not been clarified though such behavior is considered to be significant from the plasma density control and safety points of view. In this study, F82H samples were irradiated by hydrogen ion in JAEA. In addition, these samples with surface defects were also irradiated by deuterium ion to investigate the retention and the desorption behavior based on its surface defects. As a result, while the amount of the deuterium retention has not been changed at a holding temperature below 550 K, it is significantly decreased at a holding temperature over 770 K.
Shionaga, Ryosuke*; Nose, Hiroyuki*; Ito, Yuji*; Kato, Hiroaki*; Hashimoto, Hirohide*; Sato, Satoshi
no journal, ,
In order to enhance the neutron shielding performance in nuclear power facilities, medical facilities and research facilities with large-scale accelerators, we have developed a new concrete with high concentration of boron of 10 weight %. Natural Colemanite minerals with a mass of boron were applied to the aggregates for the concrete. In addition, modification of the cement type and application of the special mixture material were performed to eliminate bad effects of the insufficient hardening and the strength degradation of the cement, and we successfully increased the boron concentration in the concrete up to 10 weight %. The flow rate in JIS flow test was about 150 mm before hardening of the material, which showed good flow property. We also confirmed that the compressive strength was about 40 N/mm
at the material age of 7 days. Based on the results, the block specimens were fabricated for the shielding experiment using DT neutrons.
Sasaki, Yuji; Morita, Keisuke; Suzuki, Shinichi; Shiwaku, Hideaki; Ito, Keisuke; Takahashi, Yuya*; Kaneko, Masaaki*
no journal, ,
Pd, Zr, Se, and Cs have very long lived radioactivities. These are the aimed elements to recover from high level radioactive waste and transmutated in order to reduce the environmental burden. All metals aimed show the different chemical behavior, so the different conditions for the recovery have to be set up. The solvent extractions of Se, Zr, Pd and Cs from nitric acid into 1-octanol are performed. It was found that Se, Zr and Pd can be extracted by phenylenediamine, TODGA, and NTAamide, respectively. In addition, Cs can be extracted up to 56% by di-t-butyl-dibenzo-18-crown-6.
Sasaki, Yuji; Morita, Keisuke; Suzuki, Shinichi; Shiwaku, Hideaki; Ito, Keisuke; Takahashi, Yuya*; Kaneko, Masaaki*
no journal, ,
no abstracts in English
Sasaki, Yuji; Suzuki, Shinichi; Shiwaku, Hideaki; Ito, Keisuke; Takahashi, Yuya*; Kaneko, Masaaki*; Omori, Takashi*; Asano, Kazuhito*
no journal, ,
no abstracts in English
Sasaki, Yuji; Morita, Keisuke; Suzuki, Shinichi; Shiwaku, Hideaki; Ito, Keisuke; Takahashi, Yuya*; Kaneko, Masaaki*; Asano, Kazuhito*
no journal, ,
no abstracts in English
Sasaki, Yuji; Suzuki, Shinichi; Kobayashi, Toru; Ito, Keisuke*; Takahashi, Yuya*; Kaneko, Masaaki*; Asano, Kazuhito*
no journal, ,
At ImPACT project, we investigate more safety and effect disposal method by using separation of long-lived radioactive nuclides and their transmutation from high-level radioactive waste (HLW). High concentration of Zr in simulated HLW is extracted by HDEHP or TODGA, so we study on properties of diluents instead of n-dodecane. Especially we study on the radiolysis. After irradiation of TODGA dissolved in different 5 diluents, we use these extraction solvents as solvent extraction of Nd. It is found that distribution ratio of Nd decrease with irradiation time.
