OPTIMIZATION AND DEVELOPMENT OF THE MANUFACTURING PROCESS OF HEXAGONAL WRAPPER TUBES FOR ASTRID FIRST CORE SUB-ASSEMBLIES

摘要

The CEA has designed an innovative fast sodium reactor, whose ASTRID is the prototype. The main different objectives are to reduce investment costs, operating costs and fuel cycle costs, to induce better management of accidents, and to be able to withstand the risk of proliferation. Among core components under study, the hexagonal wrapper tube is a major element of the shell of sub-assembly. Based on accumulated experience regarding the significant feedback on Phenix and SuperPhenix French reactors, the improvement of the ASTRID first core design involves producing hexagonal tubes with novel geometrical and dimensional characteristics. Particularly, the objective is to provide longer hexagonal tubes with a larger distance across flats, compared to hexagonal tubes produced for Phenix sub-assemblies. In the framework of the industrial development of the production, some critical points concerning manufacturing processes have been identified and induce questions concerning the industrial feasibility of hexagonal tubes with specified geometry and dimensions. Indeed, the route designed for Phenix and SuperPhenix hexagonal tubes is no longer available, due to the modifications or the dismantling of some historic manufacturing facilities. Feasibility studies are necessary to determine whether present-day equipment capacities are suitable to produce tubes with required geometry and dimensions. Moreover, some environmental standards have been tightened up and induce consequently an adaptation or a development of innovative processes, particularly for the lubrication technology applied during cold working process. Finally, the development of new methods of nondestructive tests is required in order to ensure the quality of the final tube with hexagonal shape.