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Simonnet, M.; Muller, L.*; Sittel, T.*; Wessling, P.*; Mullich, U.*; Geist, A.*
no journal, ,
Reaching a sustainable nuclear waste management is one of the major challenges to gain public acceptance. The most commonly accepted solution is to process the spent fuel to recover useful isotopes, along with removing the highest heat emitters. Several processes were designed to achieve the separation of the actinides to be potentially re-used as nuclear fuel, and of Sr and Cs to decrease the heat load of the final nuclear waste to be disposed of. Most of these processes consist in a step-by-step methodology, requiring the use of many stages, except for the UNEX process that aimed at co-extracting An(III), Ln(III), Cs(I) and Sr(II) from the PUREX raffinate. Unfortunately, none of the extractants are CHON-compatible, nor the diluent that is also toxic. The present study shows the feasibility of a CHON-UNEX process, where An(III), Ln(III), Cs(I) and Sr(II) are co-extracted and then selectively stripped, allowing to merge several processes into one.
Simonnet, M.; 小林 徹; 横山 啓一; 矢板 毅
no journal, ,
Lanthanides are especially difficult to separate from each other due to their similar chemical behavior. However, ensuring high elemental purity is necessary for most industrial applications. 1,10-phenanthroline carboxamide compounds showed good results towards selective lanthanide separation in nitric acid medium. Here, we report the change in selectivity that occurs when modifying the counterion.
坂本 淳志; 佐藤 武彦; 佐野 雄一; 竹内 正行
no journal, ,
現在、使用済核燃料の再処理工場ではPUREX法が多く採用されているが、PUREX法では、使用済核燃料溶解液中から溶媒抽出法によりウランとプルトニウムを個々に分離するため、核不拡散上の懸念を有する。原子力機構では、核拡散抵抗性の向上を目指した新プロセスとして、プルトニウムをウランと共に回収するコプロセッシング法の開発を進めている。本研究では、使用済核燃料の実溶解液によるコプロセッシング法試験の実施に向けて、遠心抽出器システムによるウラン抽出挙動の評価を行った。また、テクネチウムの代替物質としてレニウム、及びジルコニウムを用いた除染性能の向上に関する評価を実施した。
solution; Comparison with a conventional organic phosphate上田 祐生; Micheau, C.; 徳永 紘平; 杉田 剛; 阿久津 和宏*; 元川 竜平
no journal, ,
The extraction of Zr(IV) from aqueous HNO solutions have been investigated extensively because the presence of Zr in the tri-n-butyl phosphate (TBP)-based PUREX process for reprocessing spent nuclear fuel is problematic. We have recently shown that a Zr-loaded organic phase from solvent extraction with TBP shows hierarchical aggregation behaviors of Zr(NO)
(TBP)
complexes, which self-assemble into primary clusters that coalesce further to form superclusters. This supercluster formation portends the formation of the third phase. Fluorous solvents have excellent chemical properties and immiscibility with both water and organic solutions. Considering these properties, the hierarchical aggregating behaviors of Zr(IV) and the highly hydrophobic fluorous extractant should be different from that of Zr(IV) with TBP. We investigated the extraction performance of a fluoroalkylated phosphate of Zr(IV) from HNO solutions into perfluorohexane and compared them with the TBP in n-hexane.
Micheau, C.; 上田 祐生; 元川 竜平; Moussaoui, S.*; Makombe, E.*; Daniel, M.*; Berthon, L.*; Bourgeois, D.*; 阿久津 和宏*
no journal, ,
The DIAMEX process aims to separate minor f-elements using malonamide as extractant molecules such as N,N'-dimethyl-N,N'-dibutyl-tetradecyl-malonamide (DBMA). Recently, Poirot studied the effect of n-heptane and toluene on the selectivity of DBMA between Pd and Nd and have conclude that Pd extraction is driven by coordination whereas Nd extraction is driven by extractant aggregation. More recently, a specific study on tetrahexylmalonamide (THMA) in toluene demonstrated a superior selectivity for Pd compared to DBMA. THMA molecular structure suggests poor aptitude for aggregation compared with DBMA, and has been much less characterized. Supramolecular features of two different solvent extraction systems based on malonamide extractants, THMA in toluene and DBMA in heptane, have been studied using characterization techniques dedicated to bulk organic phase organisation, ie. small angle X-ray scattering, and to interface characterization, ie. neutron reflectivity and interfacial tension.