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Journal Articles

Theoretical elucidation of Am(III)/Cm(III) separation mechanism with diamide-type ligands using relativistic density functional theory calculation

Kaneko, Masashi; Suzuki, Hideya; Matsumura, Tatsuro

Inorganic Chemistry, 57(23), p.14513 - 14523, 2018/12

 Times Cited Count:10 Percentile:70.56(Chemistry, Inorganic & Nuclear)

We elucidated the separation mechanism between Am(III) and Cm(III) ions by using two different types of diamide ligands, diglycolamide (DGA) and alkylated diamide amine (ADAAM), by means of the density functional theory technique and electron density analysis. The molecular geometries and formation reactions of the metal-ligand complexes were modeled by using [M(DGA)$$_{3}$$]$$^{3+}$$ and [M(ADAAM)(NO$$_{3}$$)$$_{3}$$(H$$_{2}$$O)]. We successfully reproduced Cm(III) selectivity over Am(III) with DGA and Am(III) selectivity over Cm(III) with ADAAM. Furthermore, we analyzed the bonding properties between the metal ion and the diamide-type ligands by using model complexes, [M(DGA)$$_{3}$$]$$^{3+}$$ and [M(ADAAM)(NO$$_{3}$$)$$_{3}$$(H$$_{2}$$O)], and revealed the differences in terms of the bond dissociation energy and the metal 5f-orbital participation in the covalency between the Am(III) and the Cm(III) complexes. It was suggested that the differences were key factors to understand the Am(III)/Cm(III) selectivity.

Oral presentation

Current status of R&D of MA separation processes for P&T technology

Matsumura, Tatsuro; Ban, Yasutoshi; Suzuki, Hideya; Tsubata, Yasuhiro; Toigawa, Tomohiro; Tsutsui, Nao; Hotoku, Shinobu; Suzuki, Asuka

no journal, , 

no abstracts in English

Oral presentation

Current status of R&D on reprocessing and minor actinide separation process with CHON ligands in JAEA

Matsumura, Tatsuro; Ban, Yasutoshi; Suzuki, Hideya; Tsubata, Yasuhiro; Hotoku, Shinobu; Tsutsui, Nao; Suzuki, Asuka; Toigawa, Tomohiro; Kurosawa, Tatsuya*; Shibata, Mitsunobu*; et al.

no journal, , 

PUREX process was established for industrial scale reprocessing plant. TRUEX and the 4 group separation were developed for partitioning of minor actinides from HLW, and demonstrated using genuine HLW. Although the extractants for the processes have excellent performance, the molecules contain phosphorus which could be cause for the secondary waste from the solvent extraction processes. To minimize the radioactive waste, we have conducted research and development of the new reprocessing and MA separation processes using innovative extractants in accord with CHON principle. The extractants for reprocessing process are monoamides as alternative extractants for TBP. For An(III)+RE recovery process, we developed TDdDGA. HONTA and ADAAM were developed for An(III)/RE separation process and Am/Cm separation process respectively. The separation performances of the flowsheets were evaluated by continuous extraction tests using simulated and genuine spent fuel and high level liquid waste.

Oral presentation

Computational chemical study on separation mechanism of Am from Cm with diamide-type ligands

Kaneko, Masashi; Watanabe, Masayuki; Suzuki, Hideya; Matsumura, Tatsuro

no journal, , 

Japan Atomic Energy Agency has developed separation reagents between Am and Cm ions, which are minor actinides, to achieve partitioning and transmutation strategy. We aim to elucidate the Am/Cm separation mechanism by various reagents at a molecular level to design a novel extraction reagent. This study focused on the Am/Cm separation with diglycolamide (DGA) and alkyl-diacetoamidamine (ADAAM) reagents by using density functional theory. We modeled the complex formation reactions by referring to reported single crystal structures and solvent extraction experiments. As the result, we succeeded in reproducing the Am/Cm separation behaviors with DGA and ADAAM reagents. Moreover, the electronic state analyses of the extracted complexes indicated that a difference in chemical bonding property of 5f-electrons between Am and Cm differentiates the Am/Cm selectivity.

Oral presentation

Development on SELECT process for reprocessing and minor actinide separation in JAEA

Matsumura, Tatsuro; Ban, Yasutoshi; Suzuki, Hideya; Tsubata, Yasuhiro; Hotoku, Shinobu; Tsutsui, Nao; Toigawa, Tomohiro

no journal, , 

To minimize the radioactive waste from nuclear fuel cycle, we have conducted research and development of the new reprocessing and MA separation process, SELECT process (Solvent Extraction from Liquid-waste using Extractants of CHON-type for Transmutation), using innovative extractants. The extractants for each solvent extraction processes were developed in JAEA. The extractants for reprocessing process are monoamides as alternative extractants for TBP. For MA+RE recovery process, we developed TDdDGA which has very high performance to recover of MA from high level waste. HONTA and ADAAM were developed for MA/RE separation process and Am/Cm separation process respectively. All of the extractants consist of C, H, O, and N elements, and can be decomposed to gases by incineration. The demonstration tests using genuine spent fuel and high level liquid waste of the SELECT process have been conducted. Uranium solution and U+Pu mixed solution were separated from spent fuel, and MA, americium and curium, were recovered and separated from HLW effectively. The details of the extraction tests for each separation processes will be presented in correspond presentations in this conference.

Oral presentation

Development of a new extraction method for minor actinide separation

Suzuki, Hideya*; Ban, Yasutoshi; Tsubata, Yasuhiro; Hotoku, Shinobu; Tsutsui, Nao; Kurosawa, Tatsuya*; Shibata, Mitsunobu*; Kawasaki, Tomohiro*; Matsumura, Tatsuro

no journal, , 

A highly practical hybrid-type (soft ${it N}$-donor and hard ${it O}$-donor) extractant, which is an alkyldiamideamine (ADAAM), was investigated for the minor actinides (MA) separation. The new process aims at recovering americium (Am) alone from high-level waste liquid (HLLW) using an ADAAM. The principle of the process is based on the extraction of Am together with light lanthanides (La, Ce, Pr and Nd) and Mo having close values of distribution ratio, while curium, other lanthanides, and other fission products remain in the aqueous phase. The Am was subsequently selectively stripped from the light lanthanides and Mo using mixed solution (DTPA, malonic acid and ammonium nitrate). As a result, Am was directly separated from the simulated HLLW with high yield (95%).

Oral presentation

Development of new extraction methods for minor actinide separation

Suzuki, Hideya*; Ban, Yasutoshi; Tsubata, Yasuhiro; Tsutsui, Nao; Toigawa, Tomohiro; Kurosawa, Tatsuya*; Shibata, Mitsunobu*; Kawasaki, Tomohiro*; Matsumura, Tatsuro

no journal, , 

The Japan Atomic Energy Agency (JAEA) has been studying partitioning technology. Recently, JAEA proposed a new liquid-liquid extraction technology called SELECT process to separate minor actinide (MA) from high-level liquid waste for transmutation. In this process, new extractants (HONTA, ADAAM) with highly practical and high extraction ability for MA was developed. A mixed solvent of HONTA and ADAAM was tested for mutual separation of MA and rare earth elements (RE). In this test, separation of MA and RE was achieved with very high yield. Furthermore, Americium (Am) and Curium (Cm) were separated efficiently with high separation factor values.

Oral presentation

Development of a new extraction method for MA separation

Suzuki, Hideya*; Ban, Yasutoshi; Tsubata, Yasuhiro; Hotoku, Shinobu; Toigawa, Tomohiro; Tsutsui, Nao; Shibata, Mitsunobu*; Kurosawa, Tatsuya*; Kawasaki, Tomohiro*; Matsumura, Tatsuro

no journal, , 

The Japan Atomic Energy Agency has been studying partitioning and transmutation (P&T) systems. In the P&T, the separation of minor actinides (MAs) from the chemically similar lanthanides is the key step. After MAs are separated from high-level waste, the mutual separation of Am and Cm (Am/Cm separation) can be conducted. Therefore, the removal of the pyrogenic Cm nuclide would reduce the difficulties associated with MA-fuel fabrication. However, Am/Cm separation is very challenging because the two elements have similar chemical and physical properties. Highly practical a new reagent, called ADAAM have been developed. The Am is subsequently selectively stripped from the light lanthanides. As a result, Am was separated with high efficiency.

Oral presentation

Investigation of a new extraction method for americium separation from high-level liquid waste

Suzuki, Hideya*; Ban, Yasutoshi; Tsubata, Yasuhiro; Hotoku, Shinobu; Morita, Keisuke; Toigawa, Tomohiro; Tsutsui, Nao; Kurosawa, Tatsuya*; Shibata, Mitsunobu*; Kawasaki, Tomohiro*; et al.

no journal, , 

The Japan Atomic Energy Agency has been studying partitioning and transmutation (P&T) systems. In the P&T, the separation of minor actinide (MA) from the chemically similar lanthanides is the key step. After MAs are separated from high-level liquid waste (HLLW), the mutual separation of Am and Cm (Am/Cm separation) can be conducted. Therefore, the removal of the pyrogenic Cm nuclide would reduce the difficulties associated with MA-fuel fabrication. However, Am/Cm separation is very challenging because the two elements have similar chemical and physical properties. Highly practical new reagents, called HONTA and ADAAM have been developed. Solvent extraction tests were performed using a mixture of HONTA and ADAAM. As a result, the separation of Am from the simulated HLLW was achieved with high yield.

Oral presentation

Structural analysis on complexes of rare earths formed in the adsorbent impregnated with CHON type extractant for recovery of minor actinides

Okada, Makoto*; Watanabe, So; Nakase, Masahiko*; Ban, Yasutoshi; Shiwaku, Hideaki; Matsuura, Haruaki*

no journal, , 

no abstracts in English

Oral presentation

Development of a new extraction method for americium separation from high-level liquid waste, 2

Suzuki, Hideya*; Ban, Yasutoshi; Hotoku, Shinobu; Morita, Keisuke; Tsutsui, Nao; Kurosawa, Tatsuya*; Shibata, Mitsunobu*; Kawasaki, Tomohiro*; Matsumura, Tatsuro

no journal, , 

The Japan Atomic Energy Agency (JAEA) has been studying partitioning technology. Recently, JAEA proposed a new liquid-liquid extraction technology called SELECT (Solvent Extraction from Liquid-waste using Extractants of CHON-type for Transmutation) process to separate minor actinide (MA) from high-level liquid waste (HLLW) for transmutation. In this process, new extractants (HONTA, ADAAM) with highly practical and high extraction ability for MA was developed. In the present study, a new solvent extraction method using a mixture of HONTA and ADAAM was investigated. In the tests, it was found that the separation of Am from the simulated HLLW was achieved with very high yield.

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