Experimental Study of Materials Radiation Resistance in Reactor Mixed Fields for the construction of the SPES Facility at LNL

The Selective Production of Exotic Species (SPES) facility, now under construction at Legnaro National Laboratories of INFN, is a second-generation accelerator for the production of neutron-rich ion beams. the radioactive nuclear species are produced by fission of a 238U target, on which a 200 uA primary proton beam of 40 MeV energy impinges. Materials and components constituting the Target and Ion Source assembly and the Front-End supporting structure are subjected to serious radioactive damage due to intense neutron and photon fields present under operating conditions. In the framework of the SPES project, experimental campaigns aimed at testing the radiation hardness of critical materials and components of potential use in the construction were started. Irradiations were conducted in a reactor neutron and photon mixed field in order to reproduce, as close as possible, the actual environmental service conditions. Results obtained for different types of elastomeric materials used for construction of vacuum O-rings, as well as preliminary results obtained for lubricating oils and greases, are presented. Materials under consideration are both conventional ones as well as materials specifically developed for applications in the presence of ionizing radiation. The latter materials were previously tested mainly in gamma fields.