Detection of Simulated Fukushima Daichii Fuel Debris using a Remotely Operated Vehicle at the Naraha Test Facility

The use of robotics in harsh environments, such as nuclear decommissioning, has increased in recent years. Events such as the Fukushima Daiichi accident in 2011, also highlight the need for robotic systems capable of deployment in hazardous environments unsafe for human workers. To characterise these environments, it is important to develop robust and accurate localization
systems that can be combined with mapping techniques to create 3D reconstructions of the unknown environment. This paper describes the development and experimental verification of a localization system for an underwater robot, which enabled the collection of sonar data to create 3D images of submerged simulated fuel debris. The system has been demonstrated at the Naraha test facility, Fukushima prefecture, Japan. Using a camera with a bird’s-eye view of the simulated pressure containment vessel. The 3D pose of the robot was obtained using coloured LED markers (active markers) on the robot, landmarks on the test-rig (passive markers) and a depth sensor on the robot. The successful reconstruction of a 3D image has been created through use of a Robot Operating System (ROS) node in real-time.