Investigation of fast screening LSC method for monitoring 14C activity in wastewater samples. (February 2019)

• Record Type: Journal Article
• Authors: Stojković, Ivana; Todorović, Nataša; Nikolov, Jovana; Krajcar Bronić, Ines; Bátor, Gergő; Kovács, Tibor
• Is Part Of: Radiation measurements. Volume 121(2019:Feb.)
• Page Start: 1
• Page End: 9
• Publication Date: 2019-02
• Subjects: 14C in water -- Liquid Scintillation Counting (LSC) -- Optimization -- Screening test; Nuclear emulsions -- Periodicals; Particle tracks (Nuclear physics) -- Periodicals; Thermoluminescence -- Periodicals; Cosmic rays -- Periodicals; Radiation -- Measurement -- Periodicals; Radiometry -- Periodicals; Radiation Monitoring -- Periodicals; Émulsions nucléaires -- Périodiques; Particules (Physique nucléaire) -- Traces -- Périodiques; Thermoluminescence -- Périodiques; Rayonnement cosmique -- Périodiques; Radiométrie -- Périodiques; 539.77
• DOI: 10.1016/j.radmeas.2018.12.004
• Languages: English
• ISSNs: 1350-4487

Abstract

Abstract: This paper explores the possibility of a direct measurement of 14 C activity concentration in wastewater without chemical pretreatment of samples, which would provide the advantages such as rapidity, low-cost, and simplicity of radioanalysis that is desirable in the case of nuclear emergencies. A method via Liquid Scintillation Counting (LSC) technique has been implemented and optimized. The method assumes mixing of the water sample with a scintillation cocktail (Permafluor E+ and Ultima Gold AB cocktails were tested). Measurements were performed on Ultra Low Level Liquid Scintillation Spectrometer Wallac 1220 Quantulus. Optimization of the method included optimal water:cocktail volume ratio, optimal counting window selection, PAC (Pulse Amplitude Comparator) parameter adjustment, based on the highest FOM (Figure of Merit) value achieved, as well as detection efficiency and detection limit evaluation. The main problem in such an approach, interference with other beta emitters that are often present in wastewater samples, has been discussed. The possibility to eliminate low-energy counts that would be generated from 3 H, and to estimate the contribution of other high-energy beta emitters to obtained results of 14 C content is presented as well. Method's constraints, its accuracy, and precision have been considered from the obtained results of measurements of wastewater samples. Its application is limited only to 14 C screening of samples with much higher 14 C activities than those of the environmental (surface and ground) waters. Presented results could be used as guiding principles of development, optimization, and implementation of the fast 14 C screening method in other laboratories. Highlights: Screening test for high 14 C activities in water was investigated and optimized. Optimal sample/cocktail ratio, ROI and PAC were determined for two scintillators. Best features:Ultima Gold AB, 9:11 ratio, efficiency 62%, detection limit 0.9 Bql −1 . Real samples with high 14 C and 3 H activities revealed constraints of direct method. This method is rapid, simple, effective for 14 C monitoring in nuclear emergencies.