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Journal Articles

Prediction of stability constants for novel chelates design in minor actinides partitioning over lanthanides using density functional theory calculation

Kaneko, Masashi; Sasaki, Yuji; Wada, Eriko*; Nakase, Masahiko*; Takeshita, Kenji*

Chemistry Letters, 50(10), p.1765 - 1769, 2021/10

 Times Cited Count:0

Density functional theory calculation is applied to predict the stability constants for Eu$$^{3+}$$ and Am$$^{3+}$$ complexes in aqueous solution for molecular modelling of novel separation agents for minor actinides over lanthanides. Logarithm of experimental stability constants correlates with calculated complex formation enthalpies with high reproducibility (R$$^{2}$$ $$>$$ 0.98). Prediction of stability constants of novel chelates is demonstrated and indicates a potential availability of the derivatives of diethylenetriaminepentaacetic acid type chelate in acidic condition and enhancement of Am$$^{3+}$$ selectivity over Eu$$^{3+}$$.

Journal Articles

Density functional modeling of Am$$^{3+}$$/Eu$$^{3+}$$ selectivity with diethylenetriaminepentaacetic acid and its bisamide chelates.

Kaneko, Masashi; Sasaki, Yuji; Matsumiya, Masahiko*; Nakase, Masahiko*; Takeshita, Kenji*

Journal of Nuclear Science and Technology, 58(5), p.515 - 526, 2021/05

 Times Cited Count:1 Percentile:39.17(Nuclear Science & Technology)

Density-functional theory calculations were applied to molecular structure and complex formation reaction modelings of metal ion complexes with diethylenetriaminepentaacetic acid (DTPA) and its bisamide (DTPABA) chelates to understand the metal ions selectivity between Am$$^{3+}$$ and Eu$$^{3+}$$. The calculated complexes with DTPA and DTPABA chelates reproduced the coordination geometries of experimental crystal structures. Calculated Gibbs free energies of the complex formation reactions indicated that Am$$^{3+}$$ ion forms higher stable complexes with both chelates than Eu$$^{3+}$$ ion, being consistent with the experimental results. The higher Am$$^{3+}$$ selectivity over Eu$$^{3+}$$ was suggested to originate in the larger bond overlap between Am$$^{3+}$$ 5f-orbital and N 2s, 2p-orbital. This mean that the covalent contribution between metal ion and donor atoms differentiates the complex formation stabilities, leading to the Am$$^{3+}$$/Eu$$^{3+}$$ selectivity. We expect that this study contributes to systematize the origin of metal ions selectivity and to accelerate novel ligands exploration.

Journal Articles

Mechanistic study on the removal of Cs from contaminated soil by rapid ion exchange in subcritical water

Fukuda, Tatsuya*; Takahashi, Ryo*; Hara, Takuhi*; Ohara, Koji*; Kato, Kazuo*; Matsumura, Daiju; Inaba, Yusuke*; Nakase, Masahiko*; Takeshita, Kenji*

Journal of Nuclear Science and Technology, 58(4), p.399 - 404, 2021/04

 Times Cited Count:1 Percentile:0.01(Nuclear Science & Technology)

JAEA Reports

Selection of nuclides for mass-balance analysis of fission products

Okamura, Tomohiro*; Oizumi, Akito; Nishihara, Kenji; Nakase, Masahiko*; Takeshita, Kenji*

JAEA-Data/Code 2020-023, 32 Pages, 2021/03

JAEA-Data-Code-2020-023.pdf:1.67MB

Nuclear Material Balance code (NMB code) have been developed in Japan Atomic Energy Agency. The NMB code will be updated with the function of mass balance analysis at the backend process such as reprocessing, vitrification and geological disposal. In order to perform its analysis with high accuracy, it is necessary to expand the number of FP nuclides calculated in the NMB code. In this study, depletion calculation by ORIGEN code was performed under 3 different burn-up conditions such as spent uranium fuel from light water reactor, and nuclides were selected from 5 evaluation indexes such as mass and heat generation. In addition, the FP nuclides required to configure a simple burnup chain with the same calculation accuracy as ORIGEN in the NMB code was selected. As the result, two lists with different number of nuclides, such as "Detailed list" and a "Simplified list", were created.

Journal Articles

Effects of diluents on the separation of minor actinides from lanthanides with tetradodecyl-1,10-phenanthroline-2,9-diamide from nitric acid medium

Tsutsui, Nao; Ban, Yasutoshi; Suzuki, Hideya*; Nakase, Masahiko*; Ito, Sayumi*; Inaba, Yusuke*; Matsumura, Tatsuro; Takeshita, Kenji*

Analytical Sciences, 36(2), p.241 - 246, 2020/02

 Times Cited Count:5 Percentile:41.67(Chemistry, Analytical)

To investigate the effective separation of actinides (Ans) from lanthanides (Lns), single-stage batch extraction experiments were performed with a novel extractant, tetradodecyl-1,10-phenanthroline-2,9-diamide (TDdPTDA) with various diluents such as 3-nitrobenzotrifluoride (F-3), nitrobenzene, and ${it n}$-dodecane for Am, Cm, and Lns. The extraction kinetics with TDdPTDA was rapid enough to perform the actual extraction flow sheet. The slopes of the distribution ratio versus TDdPTDA concentration and the distribution ratio versus nitric acid concentration were similar for F-3 and nitrobenzene systems but different from ${it n}$-dodecane system. These differences were attributed to the characteristics of the diluents. This study reveals high distribution ratios of Am (${it D}$ $$_{Am}$$) and Cm (${it D}$ $$_{Cm}$$) for TDdPTDA, with the high separation factors (${it SF}$s) of Am from Lns enough for their separation.

Journal Articles

Complexation properties and structural character of lanthanides complexes of $$O,N$$-hetero donor ligand BIZA

Kobayashi, Toru; Akutsu, Kazuhiro*; Nakase, Masahiko*; Suzuki, Shinichi; Shiwaku, Hideaki; Yaita, Tsuyoshi

Separation Science and Technology, 54(13), p.2077 - 2083, 2019/02

 Times Cited Count:2 Percentile:20.54(Chemistry, Multidisciplinary)

Development of separation reagent, which can efficiently separate lanthanides, is of increasing importance because it concerns establishment of purification and recycle techniques rare-earth elements. In our research group, several hetero donor type ligands, which have both oxygen and heterocyclic nitrogen atoms as donor atoms, were developed and revealed that this type of ligands show the selective complexation with specific lanthanide. In this paper, we will discuss the lanthaides complexation properties of the hetero donor type ligand containing benzimidazole group as nitrogen donor ($$N$$-methyl-$$N$$-phenyl-2-(1$$H$$-benzimidazol-2-yl)-pyridine-6-carboxamide) based on structural investigation by crystallography.

Journal Articles

Extended X-ray absorption fine structure study on gel/liquid extraction of f-block elements

Nakase, Masahiko*; Kobayashi, Toru; Shiwaku, Hideaki; Kawamura, Takuya*; Takeshita, Kenji*; Yamamura, Tomoo*; Yaita, Tsuyoshi

Progress in Nuclear Science and Technology (Internet), 5, p.56 - 60, 2018/11

Gel/liquid extraction was investigated to achieve selective separation of trivalent actinides over lanthanides. In this study, thermosensitive hydrogel including N,N,N',N'-tetraallylpyridine-2,6-dicarboxamine (PDA) was synthesized, and its complexation with lanthanide was investigated by extended X-ray absorption fine structure experiments at SPring-8. The radial structure functions (RSF) of solution with gels with and without ligands at different temperatures showed slight differences. As the temperature increased, the RSF decreased owing to the increase in thermal vibration, but PDA-gel showed a shift in the first peak toward the shorter direction. This shift was attributed to the change in stoichiometry of PDA-Ln(III) complexes or coordination number of water molecules affected by the change of conformation of polymer chains and the hydrophilic/hydrophobic properties in the hydrogel.

Journal Articles

Structure and complexation studies on 2,2'-bipyridyl and trivalent lanthanides

Nakase, Masahiko*; Takeshita, Kenji*; Kobayashi, Toru; Shiwaku, Hideaki; Yaita, Tsuyoshi

Separation Science and Technology, 50, p.2832 - 2835, 2015/05

 Times Cited Count:1 Percentile:6.11(Chemistry, Multidisciplinary)

Separation of trivalent lanthanides (Ln) and trivalent actinides (An) is important task in reprocessing high-level liquid waste. In this study, the relationship between structures of complexes of 2,2'-bipyridyl (Bpy) and Ln and coordination strengths were investigated by X-ray diffraction and UV titration. With the decrease in ionic radius from Nd to Er, the N(Bpy)-Ln distance and N(Bpy)-Ln-N(Bpy) angle decreased, the dihedral angle of the Bpy pyridines increased, and the stability constant increased. This information about structure and coordination strength is important for designing better ligands for separating Ln and An ions.

Oral presentation

Estimation of higher-order eigenvalues from residual of power iteration

Nakase, Masahiko*; Chiba, Go; Saito, Masaki*

no journal, , 

Higher-order eigenvalues can be useful indices for reactor core stability. Usually, higher-order eiganvalues are calculated with the subtraction method in which several numerical techniques are necessary. In this present study, we develop a simple method to estimate higher-order eigenvalues from a residual of power iteration. Through numerical calculations with the IAEA benchmark problem, the present method estimates higher-order eigenvalues up to the 5th order quite well.

Oral presentation

Matal-complexation using N donor-included amide compounds

Sasaki, Yuji; Sugo, Yumi; Kawasaki, Takeshi*; Suzuki, Tomoya*; Ikeda, Yasuyuki*; Nakase, Masahiko*; Takeshita, Kenji*

no journal, , 

no abstracts in English

Oral presentation

Extraction property of tetradodecyl-1,10-phenanthroline-2,9-diamide toward effective separation of minor actinides and lanthanides

Tsutsui, Nao; Nakase, Masahiko*; Ito, Sayumi*; Matsumura, Tatsuro; Takeshita, Kenji*

no journal, , 

To separate minor acitinides from lanthanides in nitric acid, we focused on 1,10-phenanthroline-2,9-diamides (PTDAs) which consist of both soft and hard donor atoms. The present study employed a PTDA having dodecyl groups in N atoms of amides groups, TDdPTDA, and its extraction property toward Am, Cm, and Eu was studied.

Oral presentation

Extraction of minor actinides and lanthanides with novel soft-hard hybrid donor ligand, 2,9-diamides-1,10-phenanthroline

Ito, Sayumi*; Tsutsui, Nao; Nakase, Masahiko*; Matsumura, Tatsuro; Takeshita, Kenji*

no journal, , 

We focused on 1,10-phenanthroline-2,9-diamides (PTDAs) for mutual separation of minor actinides (MAs) from lanthanides (Lns). PTDAs are hybrid-type ligands which consist of both soft N and hard O donors and show high extraction selectivity for MAs over Lns. They also have the symmetrical structures, and thus they are easy to synthesize. Furthermore, PTDAs have little detrimental effect on environment when they are incinerated. In this study, we synthesized novel PTDAs having phenyl groups and alkyl groups on the amide groups. The effectiveness of the novel PTDAs was evaluated from the viewpoint of extraction and separation properties of Lns and MAs.

Oral presentation

Rare earth pattern leading the mutual separation of lanthanides and actinides at the extraction using DGA compound

Sasaki, Yuji; Ban, Yasutoshi; Morita, Keisuke; Matsumiya, Masahiko*; Nakase, Masahiko*

no journal, , 

We focus on the development of simply mutual separation method of trivalent lanthanide (Ln) and actinides (An). The extraction system using extractant and masking agent in both aqueous and organic phases may change the lanthanide pattern greatly, which leads the high separation factor not only Ln and An but also Am and Cm. In this presentation, the results obtained by several extraction system will be discussed.

Oral presentation

Extraction of minor actinides and lanthanides by novel soft-hard hybrid donor ligand, 2,9-diamides-1,10-phenanthroline with long alkyl chains

Ito, Sayumi*; Nakase, Masahiko*; Tsutsui, Nao; Matsumura, Tatsuro; Takeshita, Kenji*

no journal, , 

no abstracts in English

Oral presentation

Extraction separation of minor actinides and lanthanides by 1,10-phenanthroline-2,9-diamide with phenyl group in nitric acid systems

Tsutsui, Nao; Nakase, Masahiko*; Ito, Sayumi*; Ban, Yasutoshi; Matsumura, Tatsuro; Takeshita, Kenji*

no journal, , 

The extraction properties of three 1,10-phenanthroline-2,9-diamide derivatives (${it N}$ $$^{2}$$,${it N}$ $$^{9}$$-diethly-${it N}$ $$^{2}$$,${it N}$ $$^{9}$$-bis(4-ethylphenyl)-1,10-phenanthroline-2,9-dicarboxamide (Et(EtPh)PTDA), ${it N}$ $$^{2}$$,${it N}$ $$^{9}$$-dihexyl-${it N}$ $$^{2}$$, ${it N}$ $$^{9}$$-bis(4-hexylphenyl)-1,10-phenanthroline-2,9-dicarboxamide (Hex(HexPh)PTDA), and ${it N}$ $$^{2}$$, ${it N}$ $$^{9}$$-didodecyl-${it N}$ $$^{2}$$, ${it N}$ $$^{9}$$-bis(4-dodecylphenyl)-1,10-phenanthroline-2,9-dicarboxamide (Dd(DdPh)PTDA)) were studied for the separation of minor actinides (Am and Cm) and lanthanide (Eu) using single-stage batch methods. The results demonstrated that the PTDA derivatives extracted Am more efficiently than Eu or Cm. Furthermore, PTDA functionalized with short alkyl chains exhibited higher distribution ratios toward Eu, Am, and Cm when compared with those exhibited with longer chains. It was also revealed that the separation factor of Am with respect to Eu was relatively large, and that the alkyl chain length did not affect the separation factor when the same concentration of PTDA was used.

Oral presentation

Adsorption study on PGM elements by AlHCF from nitric acid solution

Mishima, Ria; Tachioka, Sotaro*; Inaba, Yusuke*; Harigai, Miki*; Matsumura, Tatsuro; Watanabe, Shinta*; Onoe, Jun*; Nakase, Masahiko*; Takeshita, Kenji*

no journal, , 

In Japan, the final disposal of high level liquid waste (HLLW) will be done after vitrification into borosilicate glass and then disposed into deep underground. In this vitrification process, there are some concerns. The first concern is precipitation of platinum group metals (PGMs) in the melter due to their low solubility into borosilicate glass. The second concern is the formation of yellow phase caused by Mo content. The final concern is the generation of huge number of vitrified glasses and the requirement of wide space needed for final disposal. Among many kinds of extractants and adsorbents for separation of such metal ions, metal hexacyanoferrate (HCFs) were reported to have an ability to adsorb PGMs. The objective of this study is to elucidate the adsorption behavior of aluminum hexacyanoferrate (AlHCF) for various metal ions and understand the relation between elution and adsorption. The effect of synthetic and workup conditions on PGM and Mo adsorption from simulated HLLW (sHLLW) was surveyed. Also, the relationship between adsorption of metal ions and elution of the AlHCF was studied. The synthesized AlHCF showed adsorption performance for PGMs and Mo in simulated HLLW. As a result of an adsorption test with a Pd single component solution to investigate the adsorption mechanism, the eluted element ratio was Fe:Al = 1:4 in the Pd adsorption test. However, the element ratio was Fe:Al = 3:4 in the original AlHCF. Therefore, it was suggested the existence of not only Pd adsorption, but also resorption and stabilization mechanisms.

Oral presentation

Development of cyano-group bridge-type coordination polymer with a high sorption characteristic of platinum-group elements for high quality and volume reduction of vitrified objects containing high-level radioactive nuclear wastes, 10; Platinum-group elements sorption studies of aluminum ferrocyanide

Mishima, Ria; Tachioka, Sotaro*; Inaba, Yusuke*; Harigai, Miki*; Matsumura, Tatsuro; Watanabe, Shinta*; Onoe, Jun*; Nakase, Masahiko*; Takeshita, Kenji*

no journal, , 

In Japan, the final disposal of high level liquid waste (HLLW) will be done after vitrification into borosilicate glass and then disposed into deep underground. In this vitrification process, there are some concerns. The first concern is precipitation of platinum group metals (PGMs) in the melter due to their low solubility into borosilicate glass. The second concern is the formation of yellow phase caused by Mo content. The final concern is the generation of huge number of vitrified glasses and the requirement of wide space needed for final disposal. Among many kinds of extractants and adsorbents for separation of such metal ions, metal hexacyanoferrate (HCFs) were reported to have an ability to adsorb PGMs. The objective of this study is to elucidate the adsorption behavior of aluminum hexacyanoferrate (AlHCF) for various metal ions and understand the relation between elution and adsorption. The effect of synthetic and workup conditions on PGM and Mo adsorption from simulated HLLW (sHLLW) was surveyed. Also, the relationship between adsorption of metal ions and elution of the AlHCF was studied. The synthesized AlHCF showed adsorption performance for PGMs and Mo in simulated HLLW. As a result of an adsorption test with a Pd single component solution to investigate the adsorption mechanism, the eluted element ratio was Fe:Al = 1:4 in the Pd adsorption test. However, the element ratio was Fe:Al = 3:4 in the original AlHCF. Therefore, it was suggested the existence of not only Pd adsorption, but also resorption and stabilization mechanisms.

Oral presentation

Development of DGA compounds and their mutual separations of trivalent lanthanide and actinides

Sasaki, Yuji; Matsumiya, Masahiko*; Nakase, Masahiko*

no journal, , 

We will show the background how to prepare DGA compounds that we develop initially and the results of their extraction abilities. In addition, as an example of utility of DGA compounds for the mutual separation of lanthanides and actinides, the results of the batchwise multi-step extraction for Nd and Dy separation will be shown.

Oral presentation

Development of DGA compound and separation of trivalent actinides from lanthanides using organic acid with DTPA-BA

Sasaki, Yuji; Kaneko, Masashi; Matsumiya, Masahiko*; Nakase, Masahiko*; Takeshita, Kenji*

no journal, , 

The history of development of DGA compounds in our laboratory and their extraction ability will be mentioned. In addition, it is effective to separate An from Ln by back-extraction after lumping together extractions of An + Ln, and we can use various aqueous phase in the back-extraction. In this case we use organic acid, thus the results of separation of An and Ln using DTPA-BA dissolved in organic acid will be discussed.

Oral presentation

Development of stable solidification technique of ALPS sediment wastes by apatite ceramics, 1; General plan

Takeshita, Kenji*; Nakase, Masahiko*; Kanagawa, Shun*; Hijikata, Takatoshi*; Koma, Yoshikazu

no journal, , 

no abstracts in English

29 (Records 1-20 displayed on this page)