Nuclear reactor coolant pump and passive stopping seal assembly thereof

Abstract

The invention discloses a nuclear reactor coolant pump and a passive stopping seal assembly thereof. The passive stopping seal assembly comprises a seal ring, a tightening-up ring and a meltable support block. The seal ring is an opening ring. In a normal working condition, a pump shaft is surrounded by the seal ring and a space is kept between the seal ring and the pump shaft. The outer circumferential wall of the seal ring is encircled by the tightening-up ring. In a working condition that power failure happens to a whole plant, the tightening-up ring provides the seal ring with sufficiently big holding-tightly force to drive the seal ring to close to hold the pump shaft tightly. The meltable support block is inlayed in an opening of the seal ring or of the tightening-up ring. In the normal working condition, the meltable support block prevents the ring where the meltable support block is located from being closed and it is ensured that the seal ring is in an opening state. In addition, in the working condition that power failure happens to the whole plant, the meltable support block melts and loses efficacy, so that the seal ring is closed under the action of the tightening-up ring. Compared with the prior art, the passive stopping seal assembly is only provided with the three elements; not only can the integrity requirement of a shaft seal be met under the condition that an emergency shaft seal injection system is not relied on in the working condition that power failure happens to the whole plant, but also the passive stopping seal assembly has the advantages of being simple in structure and firm in seal.

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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