PRIMER DOZA 2025

F-2 department, ELME and SVPIS, with the assistance of the Ljubljana Oncology Institute and the sponsorship of the Slovenian Nuclear Safety Administration, organized comparative measurements of ionizing radiation dose rates as part of the PRIMER DOZA exercise on Wednesday, 19 November 2025, at the IJS Reactor Centre. The purpose of the exercise was to allow organizations and individuals from Slovenia and abroad - who use dose-rate meters for various measurements (e.g., in radiation protection, research, etc.) - to test their knowledge and equipment in different tasks related to the detection of radioactive sources, to exchange experience, and, through comparison of results, to upgrade their knowledge and working procedures.

• The first task set involved dose-rate measurements in the field of a Cs-137 source with an activity of approx. 2 GBq. Participants carried out measurements with handheld meters at various distances from the source, as well as background radiation measurements. Participants with vehicles equipped with dose-rate meters could also perform measurements at three additional measurement points dedicated exclusively to vehicles.
• The second task set involved searching for sources hidden in barrels.
• The third task set involved dose-rate mapping at designated measurement points within a marked area where sources were buried underground.
• The fourth task set consisted of calculating thyroid iodine activity by measuring the dose rate on a phantom containing an I-131 source.
• In the fifth task set, participants first had to determine the position of an unknown source inside a horizontal pipe based on dose-rate measurements, and then, using additional measurements with a lead plate for shielding, estimate which source it was. The large number of tasks, ranging from simple to difficult, required intensive and focused work from the participants, as well as a degree of improvisation.

In recent years, interest in participating in such measurements has steadily increased. Therefore, for the first time, the comparative dose-rate measurements were organized separately from the comparative gamma-spectrometry measurements of radioactive source activity. More than 90 representatives from 28 different organizations from Slovenia, Austria, Bosnia and Herzegovina, Croatia, the Czech Republic, and Italy took part. The following organizations participated in the exercise: IJS, ARAO, NEK, GB Ljubljana, GB Maribor, GB Koper, GARS Kranj, GARS Jesenice, PGE Celje, PGD Radlje ob Dravi, PIGD Kovinoplastika Lož, KNM UKC Ljubljana, OI Ljubljana, Special Police Unit, Police Aviation Unit, Slovenian Armed Forces, RKB Celje, Civil protection EHI CBRN unit, URSJV, URSVS, Landespolizeidirektion Kärnten (Austria), EKOTEH Mostar (Bosnia and Herzegovina), EKOTEH, IMI and IRB (Croatia), SURO (Czech Republic), and Comando VV.F. di Udine (Italy).

Photos: Klara Poiškruh