Evaluation of interferences on measurements of ~(90)Sr/~(90)Y by TDCR Cherenkov counting technique

摘要

A study to evaluate conditions affecting the determination of ~(90)Sr/~(90)Y activities in liquid samples by the triple-to-double coincidence ratio (TDCR) Cherenkov counting technique was conducted. The Cherenkov radiation produced by the ~(90)Y beta decay was determined using a commercially available Hidex 300 SL liquid scintillation counter. The interferences of sample geometry, including sample counting vial type and volume composition, and sample colour on the TDCR were investigated. The effects of potentially interfering beta and mixed beta–gamma emitters on the TDCR Cherenkov counting of ~(90)Sr/~(90)Y activities were also examined. The TDCR values were used to quantify counting efficiencies of ~(90)Y under different experimental conditions. The results demonstrated that the Cherenkov counting efficiency of ~(90)Y is independent of sample volume and counting vial size. The effect of colour quenching was examined using yellow and brown foodgrade dyes. The TDCR correction for colour quenching was found to be effective. An evaluation of counting efficiency of different beta-emitting radionuclides demonstrated that strong gamma emissions can contribute to the Cherenkov counting efficiency. Overall, measured radioactivity values deviated from reference values by ≤7.5 %, which is acceptable for screening applications in emergency situations.