Pressure vessel for boiling water reactor has dividing plates - between high and low pressure zones around core with annular expansion cap at plate periphery

摘要

A reactor pressure vessel for a boiling water reactor has an annular gap between the vessel and the core tank or wall surrounding the core. The annular gap is bridged by a horizontal dividing plate, separating the suction and the pressure sides of a circulating pump mounted in an aperture in the dividing plate. The dividing plate is firmly welded to the core retaining tank and has a slight gap at its outer periphery in the cold state of the reactor. This gap is of such dimension that when the reactor runs hot it is fully closed. The pump casing fits into the aperture with a gap all around. This gap is closed by a rigid sealing element. More specifically, the rigid sealing element may be a ring seated in a groove around the periphery of the casing. A simple and inexpensive arrangement. The completely flat dividing plate is absolutely leak-tight in the hot running state. The actual radial stress in the plate is determined by the relationship between the size of the gap and the thermal expansion of the plate in the radical direction.