IMPROVED RADIOCHEMICAL METHOD FOR THE ISOLATION OF URANIUM FROM OTHER ACTINIDES IN URINE.

The Bioassay Laboratory at CRNL (Chalk River Nuclear Laboratories) estimates uranium in urine by extraction with TBP (Tributyl Phosphate) and alpha counting. Studies performed on this method revealed several disadvantages: other actinides follow uranium and the overall recovery of uranium is not high. Cross-contamination studies showed that plutonium-239, neptunium-237, thorium-natural and curium-244 were all present in the final uranium source (Pu-239, 64%; Np-237, 48%, Th-nat, 40%, Cm-244, 15%). The overall uranium recovery was about 60%. The method has since been modified to improve the uranium recovery to 85 plus or minus 5% and completely eliminate actinide cross-contamination by the inclusion of some selective co-precipitation steps after the TBP extractions have been carried out.