| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1737911 | Journal of Environmental Radioactivity | 2015 | 6 Pages |
•Thorough study on influence of relevant factors on optimal PSA level in gross alpha/beta measurements in waters is presented.•Experiments were performed on liquid scintillation counter Quantulus 1220™ according to recommendations in ASTM method.•Influence of calibration radionuclide, its activity and LS cocktails used on optimal PSA adjustment has been investigated.•The manner in which various chemical and color quenchers change PSA/spillover factor in two LS cocktails was compared.•Application of PSA vs. SQP(E) correlation for color quench correction on gross alpha/beta activities has been demonstrated.
Gross alpha/beta measurements in drinking waters enable radiochemical composition analysis in environmental studies providing efficient screening method that can indicate whether water contains elevated levels of any radionuclide. Routine gross alpha/beta activity monitoring in drinking waters has been carried out for a few years in laboratory for low-level radioactivity measurements in Novi Sad according to ASTM method, performing measurements on liquid scintillation counter Quantulus 1220 which can simultaneously generate alpha/beta spectra of samples by Pulse Shape Analysis (PSA circuit). In this paper, PSA discriminator impact was investigated to ensure obtaining of accurate and reliable alpha/beta activities. One novelty of presented work is PSA parameter setup with two combinations of radionuclides (241Am, 226Ra and 90Sr/90Y) with varying activity concentrations. Performed experiments also make contribution to investigations on the manner in which chemical and color quench affect optimal PSA parameter setting and further on, their altogether influence on gross alpha/beta activity measurements. Nitromethane, 15.8 M nitric acid and water, as well as yellow and yellow-orange dye, were used as quenching agents in order to test PSA/interference factor behavior in the presence of quenchers with different quenching strengths. Variation of PSA setting in quenched samples with two different commercially available cocktails (Ultima Gold LLT and OptiPhase HiSafe 3) was also tested. Lastly, application i.e. assessment of obtained PSA-SQP(E) correlation on the obtained results of activity concentrations of few artesian well water samples and colored spiked samples, based on the measured SQP(E) value of samples, has been demonstrated.
