OSIRIS. Refurbishment and management of ageing effects

OSIRIS, one of the French CEA research reactors (Saclay, France), achieved criticality for the first time on July 1966. During the 29 running years OSIRIS was mainly devoted to production and technological irradiations. To satisfy these objectives, OSIRIS is equipped by different test facilities allowing: the long time irradiation of different material including fuel rods, reactor vessel materials, fusion reactor components; the power ramps of fuel rods; the activation analysis; the neutron-radiography of materials and test sections... All the foreseen irradiation programmes will only be possible if safety and high performances of the reactor are guaranteed. That is why a continuous maintenance and improvement programme has taken place during the whole life of the reactor. This paper gives an overview of this programme, mainly about the part conducted during the last years. Details about characteristics of the reactor, history of experiments, maintenance programme, instrumentation and control system, electrotechnical low voltage supply network, decay tanks and water purification system are summarized. The paper focuses on the refurbishment or the replacement of the main components connected to the continuous maintenance programme to guarantee the reliability, the safety and the high performances of the reactor. (J.S.). 2 refs., 8 figs., 2 tabs