Design and radiation protection aspects for the PRIMA Cooling Plant

This work presents a description of the radiation protection issues impacting on Primary Cooling circuits of the MITICA (Megavolt ITER Injector Concept Advanced) experiment in Padova. MITICA represents the full scale Neutral Beam Injector of ITER; two Heating neutral Beams are planned to be used in Cadarache (F) to reach the plasma nuclear fusion conditions, in addition to other heating systems. Three actively cooled components will be installed in the MITICA Beam Line Vessel, and their surfaces will be impacted by high energy neutral particles produced by an RF Ion Source and accelerated up to 1 MV by a set of five acceleration grids. Ultrapure and deionized water will be used as an insulating coolant to guarantee high voltage holding. Due to the high velocity inside water channels and due to the components materials, the production of activated corrosion products is likely to pose safety concerns in MITICA facility. Considerations about this issue and technical solutions to be adopted for the Cooling Plant are described in this paper.