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Si us plau utilitzeu sempre aquest identificador per citar o enllaçar aquest document: https://hdl.handle.net/2445/113347
Development of Analytical Methodologies for Rapid Determination of Alpha and Beta Emitters by Liquid Scintillation Spectrometry in Water Samples
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[eng] In this thesis the development of different methodologies for the rapid determination of alpha and beta emitters by liquid scintillation spectrometry is described. The feasibility of PLS model construction for the decombolution of the spectra obtained with the proposed methodologies was studied. Finally, the developed methodologies together with multivariate calibration have been organized in a strategy for the quantification of the radionuclides included in the annex III of the directive 2013/51/EURATOM.
The methodologies developed in this thesis are; the simultaneous determination of gross alpha and gross beta by liquid scintillation spectrometry, and the determination of 226Ra, 228Ra and 210Pb using Radium RAD disk and liquid scintillation spectrometry.
The simultaneous determination of gross alpha and gross beta is based on a concentration of the sample by evaporation. The evaporated sample is measured by liquid scintillation spectrometry with the value of the instrumental parameter for α/β separation optimized using 236U as pure alpha emitter and 40K as pure beta emitter. Spectra obtained by means of this methodology are not just useful for quantify global alpha and beta activities but also for the quantification of specific radionuclides using the decombolution with PLS models.
The determination of 226Ra, 228Ra and 210Pb is based on the filtration of 1 L of the sample through a filter which selectively retains lead and radium isotopes. Lead isotopes, mainly 210Pb, are removed from the filter with a solution of di-hydrogen ammonium citrate (DHC). 210Pb is determined by liquid scintillation spectrometry from the eluted fraction while radium isotopes (226Ra and 228Ra) are determined directly from the RAD disk introducing it into a counting vial and measuring by liquid scintillation spectrometry. To avoid interferences in the quantification of the RAD disk is necessary to achieve an appropriate impregnation of the filter. For this aim the elapsed time between the sample preparation and the measure have to be eight hours at least. Alternatively, scintillation cocktail can be forced to pass through the RAD disk to ensure a correct impregnation.
The construction of PLS models for the analysis of liquid scintillation spectra requires from a data base of spectra which is constructed with the experimental work performed along this thesis.
Finally, a strategy for the determination of the radionuclides included in the annex III of the directive 2013/51/EURATOM using the developed methodologies and PLS models, is described. This strategy has been used total or partially for the determination of natural and artificial radionuclides with suitable results.
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FONS CASTELLS, Jordi. Development of Analytical Methodologies for Rapid Determination of Alpha and Beta Emitters by Liquid Scintillation Spectrometry in Water Samples. [consulta: 15 de desembre de 2025]. [Disponible a: https://hdl.handle.net/2445/113347]