In-situ characterization master student

To assess the (potential) radiological impact on humans and non-human biota and/or to plan the remediation of a historically contaminated site with increased radioactive concentrations, the radiological characterization of the site is an essential first step. This can be done via sampling followed by laboratory analyses. However, for gamma-emitting radionuclides, in-situ measurements provide a powerful alternative. These techniques range from rapid dose rate surveys and drone-based aerial mapping to high-resolution HPGe spectrometry and depth profiling, efficient, real-time spatial analysis of large or difficult-to-access areas, with the ultimate goal of determining contamination levels.

The objective of the master thesis is to characterize a radiation field from a historically contaminated site and to contribute to a detailed understanding of this radiation field. For the contaminated site of interest, dose rate surveys at ground level and drone-borne in-flight gamma spectroscopy measurements are available, supplemented with some specific in-situ HPGe measurements at 1 m height. However, additional measurements will be set up to improve the characterization of the site.

Challenges include the heterogeneity of the site, the background radiation field (including contributions from radon daughters in the air), and factors originating from the way the measurements are performed (different heights, speeds, acquisition times, …). The aim is to reconstruct the radiation field using both dose rate measurement equipment and spectroscopic devices performing measurements at ground level, and by additionally analyzing gamma spectroscopic data acquired with a drone. The research challenge is to combine all radiological data into a consistent picture of the radiation field. Also, the assessment of potential changes in the radiation field under study due to external environmental factors can be an interesting additional research problem to investigate.

The master thesis is part of a larger project in which research is performed on the robust quantification of radiological data acquired with UAVs (drones) in different radiological exposure situations, a PhD project (Jonas Jacobs) in collaboration between SCK CEN and UHasselt, and a research on in-situ gamma-ray spectroscopy at SCK CEN.

Specific research objectives are:

• set-up of a measurement data plan, considering existing data;
• collection of data (apart from the radiological data, accurate location data coupled to the radiation data should be collected). The measurement campaign will typically span around 5 days, with repetitions of measurements under different environmental circumstances to assess potential differences in the influence of parameters such as moisture content and background radiation;
• analysis of the data with the main goal to discriminate between potential differences and components in the radiation field as a function of measurement set-up, location, and time;
• study of potential changes in the radiation field due to environmental changes;
• comparison of the results with similar experimental or theoretical studies published in the literature;
• interpretation of the results in terms of potential external radiation exposure of humans.

Candidates should have an interest in performing experimental work in the outdoor environment using radiation detectors and auxiliary equipment, and should like even more analyzing the data, including the scientific visualization and interpretation of the results.