Pressurized water reactor having disconnectable two-piece drive rod

Abstract

Selectively and remotely disconnectable two-piece drive rod assemblies comprising elongated hub and drive rod portions interconnected by a selectively disconnectable coupling, connect rod clusters within the pressure vessel of a pressurized water reactor system to respectively corresponding drive means. The drive means are selectively operable, through the drive rod assemblies, to move the corresponding rod clusters between fully inserted positions within the lower barrel assembly of the pressure vessel, in telescoping relationship with fuel rod assemblies therein, and to a fully withdrawn position within an inner barrel assembly of the pressure vessel. The rods of each cluster are mounted to and supported by a respectively corresponding spider, in turn connected to the hub portion, the spider supporting the respective cluster on a support plate defining the lower elevation of the inner barrel assembly, in fully inserted positions of the corresponding rod clusters, and support the hubs in parallel axial relationship within the inner barrel assembly. The drive rod portions extend through the calandria and engage the couplings of the corresponding hub portions. The couplings are selectively disconnectable and, when disconnected, permit movement en masse of the calandria and drive rod portions during disassembly and assembly operations. Noninterchangeable couplings of first and second types corresponding to first and second types of rod clusters assure that incorrect couplings are not made in the assembly operations.