Pressurised nuclear equipment in research reactors

The research reactors in CEA [France) are specifically designed facilities for research, radionuclide production and other applications. The Nuclear Pressure Equipments (ESPN) are also specifically designed. For the most important of them, their pressure barrier must have two antinomic characteristics: to be enough tough to sustain the pressure and to be transparent to neutrons and so to have the use of the most important possible flux trough the experimental devices. The consequence is a limited choice of materials for example the aluminium and the zirconium alloys. To illustrate the particularities of Nuclear Pressure Equipments installed in research reactors, we give four examples: - Osiris Reactor: divergence in 1966 and 'Jules Horowitz' Reactor, commissioning planned in 2014, are irradiation reactors intended to materials research and irradiated fuels; - CABRI, intended to studies of phenomenon resulting from fast power transients, corresponding to hypothetical accidental conditions, and driving to severe accidents; - ORPHEE, divergence en 1980, intended to produce neutron beams, for fundamental research for knowledge of materials. They contain some Nuclear Pressure Equipments, submitted to 12 December order, most of them were not submitted to regulation before the 99-1046 decree relating to Pressure Equipments. (authors)