Radiolysis and extraction properties of branched N,N-dialkylamides in -dodecane for U(VI) separation

ノルマルドデカン中におけるU(VI)分離のためのN,N-ジアルキルアミドの放射線劣化及び抽出特性

伴 康俊  ; Burdet, F.*; Cames, B.*; Caniffi, B.*; Hill, C.*; 森田 泰治  

Ban, Yasutoshi; Burdet, F.*; Cames, B.*; Caniffi, B.*; Hill, C.*; Morita, Yasuji

ノルマルドデカンで約2mol/dm(M)に希釈し、5M硝酸にて予備酸平衡を行ったN,N-di(2-ethylhexyl)butanamide, N,N-di(2-ethylhexyl)isobutanamide、及びN,N-di(2-ethylhexyl)dimethylpropanamideに対して、1040kGyを最大照射線量として線照射を行った。放射線劣化生成物の同定、及び放射線劣化させた3種類のモノアミドによる模擬核分裂生成物(Sr, Ba, Mo, Zr, Ru, Rh, Pd、及びNd)並びにU(VI)の抽出試験をそれぞれ実施した。本研究で用いた3種類のモノアミドは線照射に対して実質的に安定であり、これらのモノアミド及びそれらの劣化生成物はPd以外の模擬核分裂生成物とU(VI)との抽出分離に悪影響を及ぼさなかった。Pdに対する分配比は照射線量の増加とともに上昇したが、照射線量が300kGy未満の条件ではPdの分配比は1未満であった。一段階抽出によるモノアミドのU(VI)に対する抽出容量は約0.5Mであり、この抽出容量は照射線量が増加してもほとんど減少しなかった。

N,N-di(2-ethylhexyl)butanamide, N,N-di(2-ethylhexyl)isobutanamide, and N,N-di(2-ethylhexyl)dimethylpropanamide diluted to ca. 2 mol/dm(M) in dodecane pre-equilibrated with 5 M HNO were degraded by -ray up to the integrated dose of ca. 1040 kGy. Identification of degradation products, and extraction of simulated fission products (Sr, Ba, Zr, Mo, Ru, Rh, Pd, and Nd) and U(VI) by the three degraded monoamides were respectively carried out. The three monoamides were practically stable against -ray irradiation, and these monoamides and their degraded products hardly have detrimental effects on the extraction separation of U(VI). Although the distribution ratios toward Pd increased with increasing integrated dose, they were less than unity up to the integrated dose of ca. 300 kGy. The three irradiated monoamides conserve their loading capacities of ca. 0.5 M as single stage extraction of U(VI), and the loading capacities decrease little with increasing integrated dose.