Guide tube insert assembly for use in a nuclear reactor

Abstract

A guide tube insert assembly for receiving and guiding a control rod assembly through mutually aligned apertures formed in an upper support plate and an upper core plate of a nuclear reactor is disclosed. The guide tube insert assembly includes a plurality of guide plates with each guide plate including a plurality of bores with respective bores of each of the guide plates being axially aligned with one another so as to form a plurality of axial passages for conducting rodlets of the control rod assembly into and out of the fuel rod assemblies of a nuclear reactor. A plurality of tie rods are provided and extend between an uppermost guide plate and a lowermost guide plate, the tie rods being concentrically surrounded by a plurality of spacer sleeves of a predetermined length, with the spacer sleeves being positioned between adjacent guide plates so as to space the guide plates a predetermined distance from one another. The guide tube insert assembly further includes nuts which threadingly engage opposing ends of the tie rods so as to generate a compressive force between the lowermost and the uppermost guide plates to maintain the guide plates in their predetermined positions with respect to one another. The tie rods thereby maintain the predetermined spacing between each of the plurality of guide plates and allow the plurality of guide plates to be simultaneously removed from within a guide tube extending between the upper core plate and the upper support plate within the upper internals of a nuclear reactor.