Isolation of iron and strontium from liquid samples and determination of 55Fe and 89,90Sr in liquid radioactive waste

This paper describes the method of isolating iron and strontium from liquid samples with a low concentration of ions that enables simple and rapid determination of 55Fe and 89,90Sr. The method consists of binding (concentrating) Fe and Sr at the cation exchanger Amberlite IR-120, their elution from cation exchanger with 4 M HCl or 8 M HNO3, isolating Fe on the TRU extraction chromatographic column with 4 M HCl or 8 M HNO3, and isolating Sr on the Sr.spec column with the mixture of 8 M HNO3+2 M HCl or 5 M HNO3. After the isolation, 55Fe is determined by liquid scintillation counting with scintillation solution, while activity of 89,90Sr is obtained by Cherenkov counting in 5 M HNO3. It was shown that successive counting can be used for simultaneous determination of 89,90Sr activity. The activity ratio of 89Sr/90Sr (up to 20:1) and vice versa does not impact the determination. 55Fe is also determined immediately after isolation. The measurements in (alpha),(beta) mode can be used to verify any presence of (alpha)-emitter (americium) in the fraction of iron and to correct the result. The method was tested by determining 55Fe and 89,90Sr in model samples and radioactive waste samples. The paper also shows that Fe and Zn can be bound to the TEVA and TRU resins from the solutions of HCl, HNO3, and mixture of HCl+HNO3. The binding strength depends on the type of resin and the concentration of the acid or the concentration of acids in the mixture. These resin and acids can be used for mutual separation of Fe and Zn and their separation from other elements.