Selection of materials for prototype fast breeder reactor

This paper discusses the rationale behind the selection of materials for the different components of the 500 MWe sodium cooled Prototype Fast Breeder Reactor (PFBR). The major factors considered in the selection of materials include operating conditions, availability of design data in nuclear codes, ease of fabrication, international experience and cost. Attempt has been made to minimise the number of materials and welding consumables in order to avoid mix up of materials during fabrication, and to reduce the cost of Research and Development on materials development and characterisation. From consideration of radiation damage, 20% cold worked Alloy D9 (15Cr-15Ni-Mo- Ti-Si) has been chosen for the initial core of the PFBR. Type 316L(N) stainless steel (SS) has been chosen for structural components of reactor assembly, other than the core components, operating at temperatures above 700 K while 304L(N) SS is the choice for components operating at lower temperatures. Modified 9Cr-1Mo steel is the choice for steam generator while carbon steel has been chosen for top shield components of the reactor assembly. Stringent specifications for chemical compositions and other mechanical properties have been drawn for PFBR materials with the view to improve reliability of components.