From Single Platforms Towards Coordinated Fleets: Safety- and Security-Bounded Autonomous Multi-Robot Systems for Nuclear Decommissioning in Europe

Europe’s ageing nuclear fleet creates a growing need for repeated radiological characterisation of contaminated, GPS-denied facilities where human access must be kept to a minimum. However, most deployed robotic systems remain limited to a single platform with a narrow task range. Methods: Building on two earlier conference papers by the authors, this article presents the design, safety engineering and initial field evaluation of the EURATOM project XS-ABILITY, tracing how previous European projects shaped its architecture. The system combines legged, wheeled, rail-based and caged aerial robots equipped with gamma/neutron and beta/gamma instruments. The platforms are coordinated through a ROS 2 architecture supporting distributed SLAM, energy-aware task allocation, risk-aware navigation and a radiological digital twin. A safety and conformity framework consolidates machinery, radiation protection, aviation, cybersecurity and AI regulations, with constraints enforced by a supervisory controller. Results: A campaign at the BR1 and BR3 facilities of SCK CEN, Belgium, in April 2026 evaluated a single wheeled ground platform against criteria fixed before deployment. Radiological and pose streams were paired with a median offset of −8.6 ms and no detectable message loss; LiDAR-only localisation was maintained over a 76 m traverse with the accumulated trajectory error bounded at 0.15 m; and repeat passes agreed to a cloud-to-cloud dispersion of 1.1 cm. Fleet-level coordination, communication reliability, radiation endurance and metrological registration accuracy were not evaluated. Conclusions: The demonstrated capability is integrated single-platform operation at TRL 4–5; coordinated fleet operation remains designed but unvalidated. The forthcoming Ignalina campaign is the next validation step, while supervisory human–robot interaction remains a priority for development.