The use of plastic scintillation microspheres in flow scintillation analysis.

This manuscript deals with the possible utilization of plastic microspheres for radiation detection. The aim was to determine the suitability of microspheres for this application, factors that affect detection efficiency, and based on the evaluation of current state technology to design and test a constructional solution suitable for this use. Three detection cell variations and their configurations, which utilize plastic microspheres, were tested for their response to selected militarily important radionuclides during a series of static measurements. Based on the results of static measurements, the most structurally suitable cell variation was subsequently tested for flow scintillation analysis. Among the cells designed for flow scintillation counting in 2π geometry, the highest achieved detection efficiency for 241Am was 13.1 ± 0.7% using Cell #5, for 90Sr/Y was 71.2 ± 3.9% using Cell #10 and for 3H was 3.9 ± 0.2% using Cell #5 respectively. Cell #10 was evaluated to perform universally the best despite achieving slightly lower detection efficiencies for 241Am and 3H than Cell #5, as the results were easily replicable and due to the cell constructional simplicity, its application was problem-free.

Methods for tentative determination of presence of artificial nuclides in air using NuRMS EGS air sampler and WIMP 120 gross alpha/beta counter.

The determination of the presence of artificial radionuclides in the air is mainly accomplished by using gamma spectrometry analysis of filter samples. This work suggests very fast, reliable and efficient methods for tentative quantitative determination of the activity of artificial nuclides such as transuranic elements, strontium, yttrium, etc. in the air based only on the gross alpha and beta volume activity. The main aspect of these methods is to provide information about approximate results for the gross alpha and beta activity of air filters, thus it is convenient as a triage technique. Unlike gamma spectrometry, the methods are not qualitative but it allows the preliminary estimation of the presence of non-natural radionuclides. The influence of increment of the dust layer on self-absorption of alpha/beta particles was also studied. The methods are particularly suitable for screening situations where radionuclide identification is not necessary.

Determination of the gross activity of uranium, plutonium, americium and strontium in environmental samples using solid-state scintillation.

Rapid determination of selected gross alpha and beta emitters in environmental matrices by solid-state scintillation technique is discussed. This method is based on sample treatment using microwave reactor and direct measurement of digested products using powder scintillator and alkaline solution as a substitute for traditional liquid scintillation cocktail. The selected group of radionuclides was chosen with respect to their use in nuclear industry, high radiotoxicity, and the possibility of potential misuse. The work aimed at verifying the connection of microwave decomposition using alkaline solution with solid-state scintillation using a powder scintillator YAP:Ce together with an alkaline medium.