Design concepts for reactor assembly components of 500 MWe future FRs

It is planned to construct four 500 MWe SFRs, as the logical followup of 500 MWe Prototype Fast Breeder Reactor (PFBR), with improved economy and enhanced safety. Among many measures to achieve economy, reduction of reactor assembly dimensions, component wall thicknesses and manufacturing cost is the main activity undertaken. Conceptual designs of reactor assembly components of various SFRs are critically looked at taking into account design and construction experiences. This exercise has yielded an innovative reactor assembly design, which is presented in the paper. The improved design concepts are compact and symmetric welded grid plate without fuel transfer post, inner vessel integrated with fuel transfer post, thick plate rotatable plug, control plug integrated with small rotatable plug, torus roof slab, simplified fuel handling scheme with elimination of inclined fuel transfer machine, conical support skirt for reactor assembly with optimum support location to minimize the seismic moments and safety vessel made of carbon steel integrated with reactor vault liner. The improved design concepts have indicated significant economic advantages. To confirm the design, detailed thermal hydraulics and structural mechanics analyses are carried out and optimum dimensions and structural wall thicknesses are arrived at, to comply the design code RCC-MR (2007). The paper discusses the basis of conceptual designs giving due considerations for emerging design concepts, analysis backups and further R and D required