Rapid separation of uranium and plutonium by extraction chromatography for determination by thermal ionisation mass spectrometry

A rapid method based upon extraction chromatography was developed for the separation of U and Pu from solutions of spent nuclear fuel for thermal ionization mass spectrometry. The method involves retention of Pu(iv) and U(vi) on a UTEVA column, thereby accomplishing a separation of these actinides from fission products. A separation of Pu from U was then achieved by selective elution of Pu. Two approaches for accomplishing this selective elution were investigated: (a) competitive complexation using oxalic acid and (b) reduction of Pu(iv) to Pu(iii) using ascorbic acid. The latter method yielded a purer isolate as the former method yielded a Pu isolate that was contaminated with an unacceptable amount of U. The UTEVA separation was 3–5 times more rapid than the existing separation and was considered to be more suitable for automation.