The rapid radiochemical separation of radioactive praseodymium from radioactive cerium

IN ORDER to determine the half life, the decay scheme and other characteristics of a radioactive nuclide, it is important to obtain a sample of very high radiochemical purity. The time interval from the end of irradiation to the beginning of counting is very important, especially in the measurement of the decay constants of short lived radionuclides. In order to obtain pureshort-lived radioactive cerium and pure short-lived radioactive praseodymium from a praseodymium metal target (99.9 per cent pure) irradiated at the NBS Linac, the following two requirements must be met: (1) the rapid transfer of the target material ; (2) the rapid dissolution and separation of cerium from praseodymium. A procedure was developed to rapidly transfer and separate praseodymium and cerium. The praseodymium metal is dissolved in nitric acid and this solution is then divided into at least two aliquots. Fraction one is used to precipitate cerium (IV) iodate, giving an aqueous phase free of cerium radioactivity. A second fraction is extracted with a 0.7 M solution of hydrogen di-(2 ethylhexyl) orthophosphoric acid (HDEHP) . The cerium (IV) in the organic phase is free of praseodymium radioactivity. The total time of transfer is 5 rain and the time required for the separations is 5 rain. Figure 1 shows the scheme for separating cerium and praseodymium. 147 EXPERIMENTAL