Remote Handling Refurbishment Process for the European IFMIF Target Assembly: Concept Design, Simulation and Validation in Virtual Environment

The remote handling (RH) maintenance of components of International Fusion Materials Irradiation Facility (IFMIF) is one of the most challenging activities to be performed to guarantee the required high level of IFMIF plant availability. Among these components, the maintenance of the target assembly (TA) system appears to be critical, because it is located in the most severe region of neutron irradiation. The present European TA design is based on the so-called replaceable backplate (BP) bayonet concept. It was developed with the objective to reduce the waste material and to simplify the procedures for the target and BP replacement, thus reducing the intervention time for their substitution. The RH maintenance activity for the TA comprises a number of in situ refurbishment tasks, such as the removal of the BP, cleaning of surfaces from lithium solid deposition, inspection of the target body, installation of a new BP, and testing of the assembled system. However, there is also the possibility to replace the entire TA and to perform these refurbishment tasks offline in a dedicated hot cell. To accomplish all the refurbishment operations for the TA within the expected time for maintenance, the annual preventive maintenance period for IFMIF has been fixed in 20 days; several 3-D kinematic simulations in virtual reality environment and experimental activities aimed at developing and validating the implemented maintenance procedures for this component were carried out, in collaboration with the IDEAinVR Laboratory of CREATE/University of Naples Federico II, at the research center at ENEA Brasimone, Italy. The in situ refurbishment processes and the target replacement were simulated and tested and the feasibility of each maintenance operation was proved. In this paper, a description of the simulations and the validation activities carried out together with the main outcomes obtained are given.