<p>U disertaciji je izvr&scaron;ena optimizacija detektorskog IZ&nbsp;&nbsp; sistema Quantulus 1220^TM radi razvoja metoda za određivanje pojedinačnih radionuklida ³H,²²²Rn i⁹⁰Sr, kao i ukupne alfa/beta aktivnosti u vodama. Predstavljeni su eksperimenti u svrhu kalibracije sistema, istraživanja uticaja relevantnih parametara na rezultate određivanja aktivnosti alfa i beta emitera, i pode&scaron;avanja optimalnih vrednosti ovih parametara.&nbsp;Posebna pažnja je posvećena variranju&nbsp; PSA diskriminatora, odnosno pode&scaron;avanju analizatora oblika impulsa na optimalnu vrednost u svrhu optimalnog razdvajanja alfa od beta događaja, kao i ispitivanju efekata prigu&scaron;enja u uzorcima i metodama&nbsp;njihove korekcije.&nbsp; Predstavljene razvijene metode su brze, efikasne i jednostavne, &scaron;to je naročito važno u slučaju radijacionog akcidenta, kada je potrebno brzo odrediti sadržaj radionuklida u&nbsp; uzorcima vode, a njihova validnost je pokazana u okviru međunarodnih<br />i međulaboratorijskih interkomparacija.</p> / <p>Dissertation involves optimization of detector AB&nbsp;&nbsp; system&nbsp; Quantulus 1220^TM for development of methods for determination of individual radionuclides ³H, ²²²Rn and ⁹⁰Sr, as well as gross alpha/beta activity in waters. Presented experiments had purpose of calibration of the system,&nbsp; investigation&nbsp; of&nbsp; relevant parameters&nbsp; influence&nbsp; on&nbsp; activity&nbsp; measurements&nbsp; of alpha and beta emitters, as well as&nbsp; setting the optimum values of&nbsp; these parameters. Special attention&nbsp; was devoted to&nbsp; PSA&nbsp; discriminator value&nbsp; setting, i.e. adjusting the pulse shape analyzer level at optimum value for an optimal separation of alpha from beta events, as well as testing the effects of quenching in the samples and methods for quench&nbsp; correction. Presented developed methods are fast, efficient and simple, which is especially important in the case of a radiation accident, when there is a need to quickly determine the content of radionuclides in water samples, and their validity has been demonstrated within the framework of international and inter-laboratory&nbsp; ntercomparison measurements.</p>

The aim of the research study was to evaluate the levels of 14C and 3H radionuclides in Hartbeespoort Dam water and to determine if these radionuclides are within regulatory concerns. Water samples from Hartbeespoort Dam were prepared using the Sample Oxidiser Method and measurements of selected radionuclides were done using Liquid Scintillation Counter Quantulus 1220. The results evaluated suggest that water from Hartbeespoort Dam contains levels of 14C and 3H radionuclides that are within regulatory limits. The highest average concentration for 14C measured was 3.77E+01 (+/-2.47E-01) Bq/L, whereas the highest average concentration measured for 3H was 2.74E+01 (+/- 2.30E-01) Bq/L. The observations made regarding the impacts of climate on the 14C radionuclide were that, the concentration levels were higher during winter season when there was a rain than during rainy seasons. Tritium results showed that the climate conditions did not have any significant impacts on the concentration levels. When the concentrations of these radionuclides are above regulatory levels (14C is 100 Bq/L and 3H is10000 Bq/L), their impacts may cause harm to public`s health and the environment. Therefore, Necsa as a nuclear facility owner and National Nuclear Regulator (NNR) as a regulator are responsible for ensuring the public protection from radioactive effluents that contain not just 3H and 14C, but any radionuclide which may cause harm to public`s health. / Environmental Sciences / M. Sc. (Environmental Science)