Individual quantification of 89Sr and 90Sr in nuclear reactor effluent

An analytical method utilizing ion chromatography, a non-radioactive strontium carrier, and liquid scintillation spectroscopy to individually quantify 89Sr and 90Sr in nuclear reactor effluent is presented. It is observed that this method is less time consuming than traditional procedures for quantifying radio-strontium, deals comprehensively with separation and subsequent isotopic quantification of strontium, and avoids difficulties reported in previous research. The equipment, solutions and operating conditions for the chromatographic separation of strontium in aqueous solution are identified, and the strontium fraction is shown to elute between 7 and 7.5 min after injection. The beta spectra of 90Sr, 89Sr and 90Y are obtained using liquid scintillation spectroscopy, and the effects of quenching are shown to be negligible. The positions of the liquid scintillation windows within the combined beta spectra facilitating isotopic analysis of 89Sr and 90Sr are identified, followed by the system of equations to quantify 89Sr and 90Sr within a sample. The performance of the method is evaluated using five solutions representing effluent containing radio-strontium at known concentrations. It is observed that when the 89Sr and 90Sr concentrations each are approximately 37 Bq mL(-1) or more, the method over-estimates the 89Sr activity by 15-20% and under-estimates the 90Sr activity by 10-30%, while yielding the total radio-strontium activity to within 1-4% of expected. The lower limit of detection of the system for either 89Sr or 90Sr is shown to be approximately 0.8 Bq mL(-1) of effluent.