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Gewählte Doctoral Thesis:

Hannah Wiedner (2019): Development of innovative methods in radionuclide metrology for applications in natural resources and life sciences.
Doctoral Thesis - Institut für Bodenforschung (IBF), BOKU-Universität für Bodenkultur, pp 126. UB BOKU obvsg FullText

Abstract:

This thesis focuses on the development of innovative methods in radionuclide metrology for applications in natural resources and life science research. It gives an overview over current state of the art techniques for the evaluation of activity concentration in naturally occurring radioactive materials (NORM). An extensive study of particular problems arising in γ-ray spectrometry of NORM samples has been conducted. Common challenges and problematic γ-lines are highlighted, and a best practice recommendation on the evaluation of naturally occurring radionuclides is given. Special attention is given to the evaluation of radon tightness of used sample containers. The general demand in industry and science for NORM reference materials for instrument calibration and method verication led to the preparation and characterization of a traceable NORM material and its use in a prociency test of nine European laboratories concerned with radioactivity measurements and environmental monitoring by γ-ray spectrometry. Both the preparation and characterization process of a new NORM material and the results of the prociency test are presented in this thesis. As an alternative to classical γ-ray spectrometry, the application of articial neural networks (ANNs) has been tested in a feasibility study. An ANN that is able to decide from the raw γ-spectrum, whether the activity concentrations in a sample are above or below the exemption limits was trained. Furthermore, a comparison of two ionization chamber measurement techniques was conducted using water samples of drinking water quality. It was shown, that the results and uncertainties of an old and inexpensive, self-built ionization chamber are in good agreement with the results of a commercially available AlphaGUARD radon monitor. The results of this work give the scientic basis for practical solutions concerning the implementation of the European Radiation Protection Directive in the eld of NORM.

Betreuer: Maringer Franz Josef

1. Berater: Gerzabek Martin