GENERATION IV NUCLEAR REACTORS: STRATEGY AND CHALLENGES OF RD PROGRAM FOR IMPROVING INSPECTION AND REPAIR OF SODIUM COOLED SYSTEMS

摘要

In the framework of the French law of the 28th of June 2006 about nuclear materials and wastemanagement, the CEA, EDF and AREVA French partners launched a coordinated research program onsodium cooled fast reactors (SFR). The SFR project has reached a pre conceptual design phase, with theobjective of improving safety, economical competitiveness and sustainability of such a reactor. Importantproject milestones will allow to select the main tracks and to confirm the potential of innovations by the endof2012.In order to meet the SFR project objectives, the improvement of the In Service Inspection and Repair (ISI&R)capabilities is considered as a key issue.Design activity is the preliminary step for improving ISI&R. On the one hand, the reactor global design hasto be selected so as to reduce ISI&R needs by minimizing potential risks of failure, which is facilitated by arobust design. On the other hand, the reactor design has to favor IS1 implementation with the help ofsufficient accessibility and a suitable positioning of areas to be inspected. Finally, the design has to dealwith repair operations by simplifying the structures and with replacement operations enabled by the use ofremovable components.In parallel an intensive program was launched to develop ISIR technologies. It is articulated around fourlevels including Continuous monitoring, Periodical examination, Special inspection in case of abnormalsituation, and Repair operations.Until now, technological progress has been mainly devoted to ultrasonic (US) techniques. Associated R&D istherefore focusing on US transducers immerged in liquid sodium. Several linked issues have to be solved,such as sodium acoustic coupling, diffraction phenomenon and surface wave propagation, US guided modesphenomenon, and design & manufacturing of liquid sodium proof transducers. Other alternative ultrasonictechniques are being studied so as to increase the failure detection capability and so as to make theexaminations easier.Some other developments dealing with robotic for carrier devices, and tools for repair operations, are alsoin progress.During the 2008-2012 period, R&D actions are as exhaustive as possible in order to avoid neglecting anypromising solution for innovation, therefore, to anticipate the future safety requirements and operationstandards.