The Hellenic Centre for Marine Research (HCMR) presented the UnderSec Project at the RAP2025 International Conference, held from May 26th to 30th, 2025, through a dedicated poster session. The event brought together over 150 researchers and professionals from across the globe, focusing on the latest advancements in radiation applications for marine, environmental, and engineering sciences.

HCMR’s poster showcased the mini-KATERINA gamma-ray spectrometry system, a compact and innovative tool designed for underwater nuclear detection. Underwater in-situ gamma-ray spectrometry is recognized as a valuable method for identifying both naturally occurring and anthropogenic radionuclides in marine environments. The mini-KATERINA system stands out due to its small size, lightweight construction, low power consumption, and its ability to be easily integrated into robotic vehicles such as marine drones.

The poster detailed the sensor's design, calibration procedures using reference sources in air and water, and the successful reproduction of experimental data with simulation results. Field tests demonstrated the system’s stability and efficiency, with the mini-KATERINA integrated into a marine drone and deployed in real seawater conditions. Using a natural radioactive source of potassium chloride (KCl) as a simulant, the system effectively detected radioactivity both inside and outside ship hulls.

This technology marks a significant step forward for nuclear security, enabling early detection and classification of potential threats in underwater environments, especially in critical areas like ports. The strong interest and engagement from the conference’s research and academic stakeholders highlighted the importance and impact of HCMR’s work within the UnderSec Project.