Recent advances in the treatment of nuclear wastes by the use of diamide and picolinadmide extractants

In the framework of the SPIN(ACTINEX) program for the partitioning and transmutation of actinides contained in effluents generated during the nuclear fuel reprocessing cycle, diamides and picolinamides, extractants which have the common characteristic of being totally combustible, were evaluated. Among the diamides, N,N'-dimethyl N,N'-dibutyl tetradecyl malonadmide (DMDBTDMA) was chosen as the reference extractant. It has been shown that actinides(III) may be extracted from concentrated nitric acid effluent; the actinides(III) may be readily stripped from the loaded solvent. There is restricted third-phase formation. Long alkyl groups (R double-prime) and different R and R' on the amide nitrogen limit the extent of third-phase formation. The second class of extractants studies, the picolinamides, seem to have potential for the separation of An(III)/Ln(III)