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Sanada, Yukihisa; Abe, Tomohisa; Sasaki, Miyuki; Kanno, Marina*; Yamada, Tsutomu*; Nakasone, Takamasa*; Miyazaki, Nobuyuki*; Oshikiri, Keisuke*; Watabe, Hiroshi*
Journal of Nuclear Science and Technology, 10 Pages, 2023/00
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)The "treated water" from which the main radioactive materials were removed contains tritium, and stakeholders in Japan have been debating how to treat it. The amount of treated water stored in the facility has reached its limit, and the Japanese government has decided that the treatment method will be to discharge the water into the ocean by FY 2023 (FY: Fiscal Year). The present research developed a simple and practical tritium monitor for the Fukushima Daiichi Nuclear Power Station (FDNPS) tritiated water release. A simple and practical tritium monitor was developed for FDNPS tritiated water release based on thin plastic scintillator sheets. The developed devices were calibrated using standard tritium solutions and a method for calculating the minimum detectable activity. Fifteen 0.25 mm-thick scintillators can be placed in the 0.26 L flow cell where the sample water is fed, yielding an active surface area of 3,200 mm
. The efficiency of tritiated water with full water is 0.000035 cps Bq
. The minimum detectable activity under simple shielding conditions was 7,800 Bq L (Measurement time was 3,600 s).
Kato, Masato; Machida, Masahiko; Hirooka, Shun; Nakamichi, Shinya; Ikusawa, Yoshihisa; Nakamura, Hiroki; Kobayashi, Keita; Ozawa, Takayuki; Maeda, Koji; Sasaki, Shinji; et al.
Materials Science and Fuel Technologies of Uranium and Plutonium mixed Oxide, 171 Pages, 2022/10
Innovative and advanced nuclear reactors using plutonium fuel has been developed in each country. In order to develop a new nuclear fuel, irradiation tests are indispensable, and it is necessary to demonstrate the performance and safety of nuclear fuels. If we can develop a technology that accurately simulates irradiation behavior as a technology that complements the irradiation test, the cost, time, and labor involved in nuclear fuel research and development will be greatly reduced. And safety and reliability can be significantly improved through simulation of nuclear fuel irradiation behavior. In order to evaluate the performance of nuclear fuel, it is necessary to know the physical and chemical properties of the fuel at high temperatures. And it is indispensable to develop a behavior model that describes various phenomena that occur during irradiation. In previous research and development, empirical methods with fitting parameters have been used in many parts of model development. However, empirical techniques can give very different results in areas where there is no data. Therefore, the purpose of this study is to construct a scientific descriptive model that can extrapolate the basic characteristics of fuel to the composition and temperature, and to develop an irradiation behavior analysis code to which the model is applied.
Ohshima, Hiroyuki; Morishita, Masaki*; Aizawa, Kosuke; Ando, Masanori; Ashida, Takashi; Chikazawa, Yoshitaka; Doda, Norihiro; Enuma, Yasuhiro; Ezure, Toshiki; Fukano, Yoshitaka; et al.
Sodium-cooled Fast Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.3, 631 Pages, 2022/07
This book is a collection of the past experience of design, construction, and operation of two reactors, the latest knowledge and technology for SFR designs, and the future prospects of SFR development in Japan. It is intended to provide the perspective and the relevant knowledge to enable readers to become more familiar with SFR technology.
Bachrata, A.*; Gentet, D.*; Bertrand, F.*; Marie, N.*; Kubota, Ryuzaburo*; Sogabe, Joji; Sasaki, Keisuke; Kamiyama, Kenji; Yamano, Hidemasa; Kubo, Shigenobu
Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Sustainable Clean Energy for the Future (FR22) (Internet), 9 Pages, 2022/04
In the frame of France-Japan collaboration, one of the objectives is to define and assess the calculation methodologies, and to investigate the phenomenology and the consequences of severe accident scenarios in sodium fast reactors (SFRs). A methodology whose purpose is to assess the loadings of the structures induced by a Fuel Coolant Interaction (FCI) taking place in the sodium plenum of SFR has been defined in the frame of the collaboration between France and Japan during 2014-2019. The work progress will be spread over the period 2020-2024 and the main objectives and milestones will be introduced in the paper. The objective of studies is to comprehensively address the margin between the limit of integrity of the main vessel structures and the loadings resulting from severe accidents. For this purpose, the SIMMER mechanistic calculation code simulates core disruptive accident sequences in SFRs. A fluid structure dynamics tool evaluates this interaction i.e. EUROPLEXUS is used in CEA studies and AUTODYN tool is used in JAEA studies. In the paper, a benchmark study is described in order to illustrate the evaluation of vapour expansion phase in the hot plenum. To do that, joint input data are used on the basis of an ASTRID 1500 MWth core degraded state after the power excursion which leads to vapour expansion. The most penalizing case was evidenced in this study by suppressing the action of transfer tube in-core mitigation devices in SIMMER input deck and thus privileging the upward molten core ejection. Even if the most penalizing case was evidenced in this paper, no significant RV deformation was observed in both EUROPLEXUS and AUTODYN calculation results. The assumed mechanical energy was small for the core expansion phase.
Higuchi, Kyoko*; Kurita, Keisuke; Sakai, Takuro; Suzui, Nobuo*; Sasaki, Minori*; Katori, Maya*; Wakabayashi, Yuna*; Majima, Yuta*; Saito, Akihiro*; Oyama, Takuji*; et al.
Plants (Internet), 11(6), p.817_1 - 817_11, 2022/03
Times Cited Count：2 Percentile：37.57(Plant Sciences)Genetic diversity in the rate of Fe uptake by plants has not been broadly surveyed among plant species or genotypes, although plants have developed various Fe acquisition mechanisms. We adopted the "Live-autoradiography" technique with radioactive 
Fe to directly evaluate the uptake rate of Fe by barley cultivars from a nutrient solution containing a very low concentration of Fe. Our observations revealed that the ability to acquire Fe from the low Fe solution was not always the sole determinant of tolerance to Fe deficiency among the barley genotypes.
Sasaki, Yuji; Morita, Keisuke; Matsumiya, Masahiko*; Ono, Ryoma*; Shiroishi, Hidenobu*
JOM, 73(4), p.1037 - 1043, 2021/04
Times Cited Count：4 Percentile：34.69(Materials Science, Multidisciplinary)The separation of Dy from Nd is studied from the viewpoint of recycling Dy from Nd magnets. Both metals are lanthanide elements, which means their mutual separation is difficult because of their similar chemical behaviors. All lanthanide elements can be extracted easily by using tetradodecyl-diglycolamide (TDdDGA) extractants, and it has a relatively high separation factor (SF) between Dy and Nd (SF over 10). In the present study, by performing eight extraction steps with the organic phase (0.1M TDdDGA in dodecane), ten steps with an aqueous phase (0.7 M HNO
with metals), and six steps with another aqueous phase (0.7 M HNO without metals), approximately 99% Dy was recovered into the organic phase with 1% co-extraction of Nd.
Takeda, Tetsuaki*; Inagaki, Yoshiyuki; Aihara, Jun; Aoki, Takeshi; Fujiwara, Yusuke; Fukaya, Yuji; Goto, Minoru; Ho, H. Q.; Iigaki, Kazuhiko; Imai, Yoshiyuki; et al.
High Temperature Gas-Cooled Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.5, 464 Pages, 2021/02
As a general overview of the research and development of a High Temperature Gas-cooled Reactor (HTGR) in JAEA, this book describes the achievements by the High Temperature Engineering Test Reactor (HTTR) on the designs, key component technologies such as fuel, reactor internals, high temperature components, etc., and operational experience such as rise-to-power tests, high temperature operation at 950
C, safety demonstration tests, etc. In addition, based on the knowledge of the HTTR, the development of designs and component technologies such as high performance fuel, helium gas turbine and hydrogen production by IS process for commercial HTGRs are described. These results are very useful for the future development of HTGRs. This book is published as one of a series of technical books on fossil fuel and nuclear energy systems by the Power Energy Systems Division of the Japan Society of Mechanical Engineers.
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.
systemSasaki, Yuji; Morita, Keisuke; Matsumiya, Masahiko*; Nakase, Masahiko*
Radiochimica Acta, 108(9), p.689 - 699, 2020/09
Times Cited Count：9 Percentile：75.92(Chemistry, Inorganic & Nuclear)The simultaneous separation of Am and Cm from lanthanides is important for atomic energy fields. All lanthanides, Am, and Cm can be extracted by diglycolamide (DGA). In addition, relatively high separation factors between An and Ln were obtained by the extraction system of TODGA, DTPA (diethylenetriamine-pentaacetic acid) and HNO. In this work, DTPA-BA (diethylenetriamine-triacetic-bisamide), which is an improved version of DTPA, was employed for the separation of Ln and An. A relatively high separation factor (approximately 8) for actinides/lanthanides was obtained. Then, the multi-step extraction was performed. Thus, the recoveries of 94.7% for Nd and 4.7% for Am and Cm in organic phase, and 5.3% Nd and 95.3% for Am and Cm in aqueous phase were obtained.
Sasaki, Yuji; Ban, Yasutoshi; Morita, Keisuke; Matsumiya, Masahiko*; Ono, Ryoma*; Shiroishi, Hidenobu*
Solvent Extraction Research and Development, Japan, 27(1), p.63 - 67, 2020/00
Times Cited Count：6 Percentile：31.74(Chemistry, Multidisciplinary)Mutual separation technique of Dy and Nd in Nd magnet is studied. Dy is more valuable than Nd, then Dy might be isolated and reused. Lanthanide elements can be extracted thoroughly by diglycolamide (DGA) extractants, we use this reagent for the recovery and isolation of Dy. Tetradodecyl-DGA (TDdDGA) has relatively high separation factors(SF) between Dy and Nd (SF=17-18) in HNO extraction system, counter-current extraction using TDdDGA was applied for their mutual separation. From the present study, using the condition, four extraction stages, organic phase: 0.1M TDdDGA in n-dodecane, aqueous phase: 0.3M HNO, 92% Dy can be recovered with 0.7% co-extraction of Nd.
Sasaki, Yuji; Morita, Keisuke; Matsumiya, Masahiko*; Nakase, Masahiko*
Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.108 - 112, 2019/09
We attempted to separate An from Ln, and Am and Cm by the system including extractant and masking agent. The separation factor of Nd and Am was approximately 10 by TODGA-DTPA-BA and that of Am and Cm was over 3 by TODGA-DOODA(C2). Using these batch data, profiles of metal concentration with multi-step extractions proposed in this manuscript were demonstrated.
Sasaki, Yuji; Morita, Keisuke
Progress in Nuclear Science and Technology (Internet), 5, p.27 - 32, 2018/12
no abstracts in English
Sasaki, Yuji; Morita, Keisuke; Saeki, Morihisa*; Hisamatsu, Shugo*; Yoshizuka, Kazuharu*
Proceedings of 21st International Solvent Extraction Conference (ISEC 2017) (Internet), p.131 - 134, 2017/11
Three tridentate extractants including soft and hard donor has been developed and examined. The extractants are termed as 
-tetraoctyl-diglycolamide (TODGA), methylimino-
-dioctylacetamide (MIDOA) and -tetraoctyl-thiodiglycolamide (TDGA). The results of the present study show that TODGA can extract completely lanthanides and actinides, MIDOA can extract palladium, technetium, and rhenium, and TDGA can extract palladium, silver, and gold. We can compare the distribution ratios of these metals by TODGA, MIDOA, and TDGA. These results can be supported by some spectrometric studies, i.e., IR, NMR and UV, and calculations of metal complexes.
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.
Sasaki, Yuji; Morita, Keisuke; Saeki, Morihisa*; Hisamatsu, Shugo; Yoshizuka, Kazuharu*
Hydrometallurgy, 169, p.576 - 584, 2017/05
Times Cited Count：14 Percentile：56.4(Metallurgy & Metallurgical Engineering)The novel tridentate extractant including soft donor has developed and examined. The extractant, tetraoctyl-thiodiglycolamide (TDGA), is analogous structure to tetraoctyl-diglycolamide (TODGA) and methylimino-dioctylacetamide (MIDOA), but with sulfur donor instead of ether oxygen or nitrogen atoms of TODGA or MIDOA. From the present work, TDGA can extract silver, palladium, gold, and mercury from acidic solutions to n-dodecane. In addition to these results, the distribution ratios of hard and soft acid metals by using TDGA, TODGA, and MIDOA are compared, where the metal-complexations with each donor atom are investigated. 1H-NMR and IR studies for the metal-TDGA complexes indicate the role on donor atoms, S and N, of TDGA.
Suzuki, Tomoya; Morita, Keisuke; Sasaki, Yuji; Matsumura, Tatsuro
Separation Science and Technology, 51(17), p.2815 - 2822, 2016/09
Times Cited Count：7 Percentile：23.23(Chemistry, Multidisciplinary)To understand the adsorption properties of styrene-divinylbenzene copolymer functionalized with 
-trimethylglycine, AMP03, the adsorption behaviors for platinoid ions (Ru(III), Rh(III), and Pd(II)) were examined. Furthermore, we performed adsorption experiments using sample solutions with adding triethylamine, thiourea, and -trimethylglycine. Based on the adsorption data obtained in this study, we performed chromatographic experiments. The results indicated that all platinoid ions in the feed solution completely adsorbed on AMP03, and almost 80% of the adsorbed platinoid ions were recovered. These results show that AMP03 has the potential to recover Ru(III), Rh(III), and Pd(II) from high-level liquid waste.
-trimethylglycineSuzuki, Tomoya; Morita, Keisuke; Sasaki, Yuji; Matsumura, Tatsuro
Bulletin of the Chemical Society of Japan, 89(5), p.608 - 616, 2016/05
Times Cited Count：5 Percentile：16.1(Chemistry, Multidisciplinary)In a previous study, we found that AMP03 adsorbs Rh(III) from the HNO solution with pH = 1.7 - 2.2. In this study, to understand the Rh(III) adsorption properties of AMP03 and clarify conditions for efficient recovery, we investigated the adsorption behaviors of Rh(III) from the HNO solution. As a result, it was found that Rh(III) is effectively adsorbed from aqueous solution containing low H
and high NO
concentration. Considering the adsorption mechanism of Rh(III), we found that Rh
in aqueous solution is adsorbed with two betaine groups in AMP03 and three NO.
Sasaki, Yuji; Morita, Keisuke; Shimazaki, Shoma*; Tsubata, Yasuhiro; Ozawa, Masaki*
Solvent Extraction Research and Development, Japan, 23(2), p.161 - 174, 2016/05
We examined the masking effects of 16 water-miscible reagents, on the extraction of Mo, Re, Ru, and Pd. The extractants, methylimino-dioctylacetamide (MIDOA) and hexaoctyl-nitrilotriacetamide (NTAamide(C8)), show significantly high distribution ratios for these metals, were employed in this study. Masking effects were observed as a decrease of distribution ratio with an increase of masking agent concentration in these extraction systems. The results showed that Pd and Ru can be masked by similar reagents including N- or S- donor atoms, which suppressed the extraction into the organic phase. In contrast, distribution ratio of Mo was only slightly masked by the above mentioned reagents. The masking of Mo was achieved using complexing agents having a central N(CH
C(P)=O) framework that is important for this purpose. A masking agent for Re was not found in this study.
-tetraoctyl-thiodiglycolamideSasaki, Yuji; Suzuki, Tomoya; Morita, Keisuke; Yoshizuka, Kazuharu*
Hydrometallurgy, 159, p.107 - 109, 2016/01
Times Cited Count：5 Percentile：27.46(Metallurgy & Metallurgical Engineering)The novel tridentate extractant including soft donor has developed and examined. The extractant, tetraoctyl-thiodiglycolamide (S-DGA), is analogous structure to tetraoctyl-diglycolamide (TODGA), but with sulfur donor instead of ether oxygen of TODGA. S-DGA has unique property to extract silver from acidic solutions to n-dodecane with relatively high D values. We investigated the extraction behavior of Ag in various acids, HNO, HSO
, and HClO.
