ROBBE-autonomous robot-aided coating removal and decontamination of assemblies in nuclear dismantling: development and operational evaluation

ROBBE is the first autonomous robotic system to combine real-time 3D perception, digital-twin trajectory planning, and ultra-high-pressure (UHD) waterjet technology for coating removal and decontamination of variant-rich steel components in nuclear dismantling. Conceived to replace ergonomically demanding and radiologically relevant manual work, the system scans previously unknown geometries, computes collision-free tool paths that honor process physics and robot kinematics, and executes coating removal and decontamination in a closed cabin without personnel exposure. The end-effector integrates a sealed laser-triangulation scanner behind a protective shutter with a high-performance rotating UHD nozzle; all media and signals are routed through a humidity-resistant 7-axis industrial robot. The planning stack fuses scan data, fixture separation, and a digital twin of robot, table, part, and cell environment to optimize nozzle distance, angle, and feed speed within experimentally derived efficacy windows. An IMU-based module is available for robust pose tracking during manual re-clamping, though most parts are efficiently processed using a “clean upper half + flip” strategy with selective re-cleaning. Development progressed from a full-scale prototype outside the controlled area (RWE01) to an integrated operational cell in the Biblis dismantling plant (RWE02). The UHD process runs at 2,200-2,400 bar (rated 2,500 bar) and 24 l/min; removal performance peaks at approximately 50-60 mm stand-off, and feed is adapted online to reachability constraints. 12 months of operational testing on representative part classes (pipe sections and shells, vessel plates, profiles, machine and device components with free-form surfaces, undercuts, and bores) verified autonomy, repeatability, and robustness. ROBBE achieved ≥ 90 % decontamination on > 90 % of parts, with net Scan + UHD times < 12 min per part and total part times typically < 30 min including manual handling. No collisions occurred; arm, hoses, and rotary feedthroughs operated without failure over 390 h of arm-power-on. For aged, multi-layer coating systems with pronounced thermal hardening, decontamination and full coating removal were reliably achieved by lowering feed rates, applying multiple passes, and, where appropriate, using chemical pre-treatment. The integrated cabin enables continuous UHD operation without operator presence, improving safety (ALARA) and process consistency compared with manual methods that are limited by noise exposure and operator fatigue. Lessons learned emphasize the benefit of a dedicated robotic cell (optimized robot-to-table layout, servo-driven round table, automatic part feed), consolidated control and HMI (single GUI for all parameters), and targeted use of the IMU for complex re-clamping only. With a demonstrated technology readiness of TRL 7-8, ROBBE is ready for broader deployment across nuclear dismantling sites and is being extended in the ARRIVE project to laser ablation and integrated radiological pre-/free measurement for an end-to-end autonomous decontamination and documentation chain.