Celmes drill Drones D1-Olen: Overview of the measurement results

In the frame of a CELMES drill, measurements were performed at the Umicore D1 site in Olen. Different drone (type DJI F550 and M600 Pro) - detector (AD-b plastic scintillator, Geiger-Muller and RadDetecTIF CsI scintillator) combinations were used to perform airborne measurements. These measurements were complemented with ground measurements (walking and car-borne, respectively AD-b and AGS large NaI scintillator measurements) on and around the site of D1. This measurement campaign was mainly organised to show the potential of novel techniques for measuring environmental radioactive contamination. Emphasis was mostly on airborne measurements, using rather small detectors of different types,carried by small unmanned aerial vehicles. Two types of multicopter-drones were used. Through the measurement campaign,practical experience was gained and a unique dataset collected. All planned flights/measurements could be successfully executed in an excellent cooperation between various players which are the Belgian Federal Agency for Nuclear Control (FANC), the Civil Protection operational drone units, the Belgian Nuclear Research Centre (SCK CEN) and Umicore, the owner of the D1 site. The measurements largely confirmed the well-known radiological situation of the site and the results of former measurement campaigns since the early nineties. Elevated dose-rates and enhanced radium-226 (Ra-226) concentrations could be detected within the enclosure of the site, with a distinct maximum just south west of the centre of the site. The values found are in line with observations from the past. The drill demonstrated that radiological monitoring with standard multicopter drones is a powerful way for assessing radioactive contaminations in detail in difficult to access locations of moderate size, typically from a few hectares up to say the order of 1 km². For some of the deployed methods, preliminary results are immediately available, live, during the measurement campaign, hence allowing an instant quick evaluation of the levels and type of radioactive contamination. All methods require further post processing of the data for more detailed quantitative information and evaluation.