Nuclear reactor coolant pump and its passive shutdown seal assembly

Abstract

Disclosed is a passive stopping seal assembly (30) of a nuclear reactor coolant pump, comprising a sealing ring (40), a tightening ring (60) and a fusible support block (50). The sealing ring (40) is an opening ring, and in a normal operating condition, the sealing ring (40) surrounds, in an opening state, a pump shaft (18) and keeps a clearance from the pump shaft (18). The tightening ring (60) encircles an outer peripheral wall of the sealing ring (40) to provide, when the plant is in an outage, a clasping force great enough on the sealing ring (40) such that the sealing ring (40) is driven to tightly clasp the pump shaft (18). The fusible support block (50) is embedded in the opening of the sealing ring (40) or the tightening ring (60). In a normal operating condition, the block prevents the ring, within which the block is located, from closing so as to ensure that the sealing ring (40) is in an open state, and when the plant is in an outage, the block is fused so to become ineffective such that the sealing ring (40) is closed under the action of the tightening ring (60). Further disclosed is a nuclear reactor coolant pump comprising this type of stopping seal assembly (30). This type of passive stopping seal assembly has only three components but is capable of satisfying the requirement of a complete shaft seal when the plant is in an outage without depending on an emergency shaft seal injection system, and has a simple structure and tight sealing.

Description

technical field [0001] The invention belongs to the field of nuclear power, and more specifically, the invention relates to a nuclear reactor coolant pump and a passive shutdown sealing assembly thereof. Background technique [0002] In pressurized water reactor nuclear power plants, the reactor coolant pump is usually called the main pump, and the hydrostatic shaft-sealed main pump is a single-stage, single-suction, vertical mixed-flow pump driven by a three-phase induction motor. figure 1 It is a structural schematic diagram of an existing nuclear reactor coolant pump, which is composed of a motor 10, a hydrostatic shaft seal assembly 12 and a hydraulic component 14 from top to bottom, and the pump shaft runs through the center of the entire main pump; the reactor coolant is installed in a The impeller at the lower end of the pump shaft pumps, which is sucked in through the bottom of the pump casing and flows up through the impeller, and then discharged through the guide v...

AI Technical Summary

Problems solved by technology

However, most of the existing passive parking seal assemblies 24 have many components and complex assembly, which not only makes the manufacture of the shaft seal assembly difficult and expensive, but also tends to cause seal failure due to failure of one or more components.

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