The ENRICH hackathon is a international robotics competition organized by Fraunhofer FKIE and the Austrian Military. Held biennially at the Zwentendorf Nuclear Power Plant in Lower Austria, it attracts over fifteen teams from around the world, including from as far away as Canada. But what makes ENRICH so special? The answer lies in the venue itself. Zwentendorf is the only nuclear power plant in the world that was completed but never turned on. It remains fully intact, making it an ideal and realistic testbed for robotic systems facing extreme and rough conditions, without the hazards associated with an active facility.

The Challenges

Participants compete in four main challenges: Radiation Mapping, 3D Mapping, Manipulation, and Search and Rescue. The Radiation Mapping task is mandatory for all teams, as it builds the foundation of the competition, and yes, real radioactive sources are used. These sources, placed in the environment by the Austrian Military, are only accessible by robots, creating a high-stakes scenario for locating and mapping their position and radiation intensity. In the 3D Mapping category, teams must create detailed spatial maps of the power plant using autonomous systems. This year marked a significant milestone: for the first time, both ground robots and aerial drones operated in the same environment. Some areas, however, were only accessible to aerial robots, creating unique navigation challenges. Meanwhile, in the Manipulation and Search and Rescue tasks, ground robots were tasked with opening/closing valves and rescuing human- sized dummies weighing up to 70 kg.

Team FlyBy

Team FlyBy comprises Leo Pichelbauer and Stefan Schmikal (students at HTL Wiener Neustadt), Sebastian Kawicher (Bachelor’s student at TU Munich), and Joel Klimont (PhD student under Prof. Radu Grosu, Head of the Cyber-Physical Systems research unit at TU Wien Informatics). The team shares a common background at HTL Wiener Neustadt and active membership in the robotics club robo4you.at.

Figure: Team FlyBy

Flying a Drone in a Nuclear Power Plant

Operating a drone inside a nuclear power plant presents unique technical challenges. Team FlyBy brought valuable experience to ENRICH 2025, having already participated in the 2023 edition, where they received the ”Best Young Team” award. This year, the competition was more demanding, as both aerial and ground robots shared the same dynamic and complex environment.

Figure: The 18-meter ascent into the turbine hall

The mission involved flying a drone through narrow corridors with multiple turns, then ascending 18 meters into the turbine hall to continue mapping and identifying radiation sources. The 5.5 kg drone was able to fly for up to 30 minutes per mission.

To ensure precise and safe navigation, the team developed custom control software that combined human inputs with onboard autonomy. The operator selected waypoints, and the drone autonomously navigated to them while avoiding obstacles, collecting radiation data, and building the 3D map in real time. Reliable communication was key to success. Due to the thick concrete walls, highbandwidth transmission was impossible. The team tackled this with a highly efficient software module that cached, compressed, and prioritized data before transmission. This included strongly compressed video streams and lean updates of the 3D map. Depending on the use case, they reduced bandwidth needs only about 1 Mbps for two video feeds or as low as 50 kbps when transmitting only essential mapping data.

Figure: Comparison: Hand-taken image vs. 3D LiDAR map

Conclusion

Team FlyBy was the only team to successfully complete a full autonomous flight through the entire environment while generating a high-quality 3D map. Their performance earned them the Best 3D Mapping award at ENRICH 2025. We extend our thanks to Prof. Radu Grosu (TU Wien) and Dr. Michael Stifter (robo4you) for their continuous support. We are also deeply grateful to Dr. Frank E. Schneider (Fraunhofer FKIE) and his team for organizing this exceptional event, and to Brigadier Janisch (Director of the Defence Technology Agency, Austrian Military) for his support and making our participation possible.

Figure: 3D LiDAR map of the corridor and turbine hall during flight