Novel Extraction Systems Based on Neutral and Cation-Exchange Extractants and Their Use for Decontamination of SNF and HLW Solutions from the Major Amount of Radioactivity

摘要

Novel extraction systems based on neutral [diphenyl-N,N-dibutylcarbamoylmethylphosphine oxide (CMPO), polyethylene glycol (PEG)] and cation-exchange [zirconium and hafnium salts of dibutyl hydrogen phosphate, chlorinated cobalt dicarbollilde (CCD)] extractants in a polar diluent and an aqueous solution of a complexone and HNO_(3) were developed for decontamination of solutions from the major amount of long-lived fission products (~(137)Cs, ~(90)Sr, ~(90)Y, ~(152,154)Eu) and actinides, including transplutonium elements (~(241)Am, ~(244)Cm). Stable and weakly radioactive fission and corrosion products (Zr, Mo, Mg, Pd, Ru, Rh, Si, Sb, Na, Fe, Cr, etc.) after such treatment remain in the solution and can be determined simultaneously by inductively coupled plasma atomic emission spectrometry and mass spectrometry. For example, in three extraction-washing operations, with a mixture of 0.005 M CCD with additions of PEG and CMPO in an o-chloronitrobenzene-CCl_(4) mixture as extractant and a solution of 0.05 M HNO_(3) and 1 g 1~(-1) H_(2)C_(2)O_(4) as aqueous washing solution, the radioactivity of the tested aqueous solution decreased by more than 6 orders of magnitude. In the process, the loss of the elements being analyzed with the extractant does not exceed 5percent.