Virtual Reality: a way to prepare and optimize operations in decommissioning projects
Résumé
After having operated numerous nuclear facilities to do experiments and define nuclear fuel life cycle processes since the 1950s, the CEA must now manage the clean-up and dismantling of those which have reached the end of their lifetime. These high priority actions have led to the creation of an R&D dismantling division which aims at providing innovative tools, including in situ radiological characterization, remote handling and cutting, and intervention scenario simulation. The latter involves running defined scenarios and verifying their suitability for the environment. Simulation is a good means of visualizing and therefore knowing highly radioactive environments where humans cannot enter, of testing different technical alternatives, and of training workers prior to interventions. This paper describes an application using Virtual Reality (VR) technologies: dismantling a blind cell at Marcoule (France) by a remote handling system. A VR simulation can be defined as an interactive and immersive simulation that enables the user to interact with a computer-simulated environment. VR environments, mostly based on visual immersion displayed through stereoscopic devices, can also include additional sensory information, such as sound or touch. Our application, based on audio, tactile and visual immersion, provides a useful support to verify defined scenarios and to design alternative solutions if necessary: thanks to a stereoscopic visualization, users are immersed in a virtual world, where they can hear virtual sounds when there is a collision, and can manipulate virtual objects and touch them via a haptic interface. This article first describes the application case: MAR200 blind cell decommissioning is presented, as well as the nuclear environment and the remote handling system used for dismantling. Secondly, the data preparation is focused, especially the 3D model reconstruction and the simulation configuration (detection collision, force feedback and interactivity) with its constraints and limits. Accessibility, operational trajectories and maintainability on the remote handling system have then been verified: problems have been found, which have meant modifications and updates of the final scenario to guarantee the system will work properly. Next, lessons learnt from this application case are described, especially the applicability of Virtual Reality on decommissioning projects: before beginning the actual operations, such a set of tools is well adapted to simulating remote handling systems, designing new equipment and validating scenarios, to training operators and ensuring they are aware of the risks they could be exposed to, to communicating and sharing information during project reviews. Strong points of such technologies remain in speed in testing, user-friendliness, reactivity and usefulness on complex dismantling operations. Finally, the perspectives for the application are mentioned, especially radioactive dose rate and virtual human simulation.