Separation of Yttrium-90 from Strontium-90 by Extraction Chromatography Using Combined Sr Resin and RE Resin

Abstract

Yittrium-90 (Y-90) is a radioisotope having half-life 64 hour and emitting strong energy beta radiation at 2.28 MeV. It is one of the radionuclides suitable to the applications in targeted therapy. Y-90 can be generated from radioactive decay of strontium-90 (Sr-90), which is one of the fission products of uranium fuel in the nuclear reactor. Y-90 must be highly pure and free form Sr-90 and other metal ions to get high efficient uses. In this study, process for separation of Y from Sr in 4-7M HNO3 with extraction chromatography technique has been investigated using column of Sr resin, column of RE resin and combined columns of both resins. Most feed solutions used in the study contained Y and Sr at the concentration ratio of Y: Sr around 0.18: 756 to simulate the equilibrium composition ratio of their radionuclides, Y-90 and Sr-90. It was found that a series of 3 columns packed with 0.35g Sr resin each was required to adsorb Sr up to 4mg from 4mL feed in 4M HNO3 and Y was barely adsorbed by Sr resin. A column packed with 0.25g of RE resin could be used to continuously purify Y in effluent from Sr column by selectively adsorb Sr. The adsorbed species could be eluted with dilute nitric acid, 0.05-0.1M. Feed solution spiked with trace of Sr-90/Y-90 was also used to determine the purity of the obtained Y product and it was found that the activity ratio of Sr-90 to Y-90 was in the order of 10-4. This process was found to be simple to operate continuously and the recovery of Y-90 was higher than 80%.