Steam generator upper support having thermal displacement compensation

Abstract

A steam generator upper support arrangement provides restraint to the steam generator during operating and non-operating conditions, for loading forces resulting from seismic and postulated accident conditions, while allowing for free thermal expansion of the steam generator in the radial, lateral, and vertical directions. Four embodiments of the present invention are described. In a first embodiment, inclined bumpers are placed at predetermined angles with respect to the load path, such that as the steam generator is thermally displaced the placement and incline angles of the bumpers will compensate for the expansion and maintain a nominal gap therebetween. In a second embodiment, the variable shim mechanism comprised of cams, bumper rods, and a pivoted linkage between the steam generator and the building structure maintains the nominal gap for the required support. In the third embodiment, a single small snubber is utilized. A pair of opposed, pivotally mounted rigid links arranged in a V-shaped manner are connected between the steam generator and the building structure, their respective apexes joined by the ends of the snubber to resist the loading forces. In the fourth embodiment, a pair of frustoconical sliding shims are disposed between support blocks which are correspondingly slanted to provide a tapered opening for the sliding shims. The shims are pivotally connected to a driveshaft also pivotally connected to the steam generator such that the mechanism maintains a nominal gap between the generator support and the building structure at all times.