Sealing mechanism for overhaul of reactor coolant pump or coolant fan

Abstract

The invention relates to a sealing mechanism for the overhaul of a reactor coolant pump or a coolant fan, comprising a shell of a nuclear main pump or main fan; a main shaft penetrates through a central hole of the shell; an impeller is arranged on the lower end of the main shaft; a gap is retained between the main shaft and the central hole of the shell; a second-level piston is configured in the central hole of the shell; a shaft seal system is configured between the second-level piston and the main shaft and is arranged on the main shaft; a first-level piston is configured between the second-level piston and the main shaft and is sleeved in the second-level piston; a first-level sealing ring is arranged at the inner side of the lower end surface of the first-level piston, and a resetting spring is configured below the outer side of lower end surface of the first-level piston; the upper end surface of the first-level piston is connected with the second-level piston and is provided with a high-pressure air cavity; a first-level sealing surface is configured below the first-level piston; a second-level sealing ring is arranged on the upper surface of an inner cavity of the shell; and a second-level sealing surface is positioned in the inner cavity of the shell. The invention decreases the overhaul processes and reduces the overhaul cost through the cooperating usage of a first-level independent sealing structure and a second-level independent sealing structure and has the advantage of effectively ensuring the sealing safety of the overhauling process.

Description

technical field [0001] The invention relates to a sealing structure, in particular to a sealing mechanism used for maintenance of reactor coolant pumps or coolant blowers. Background technique [0002] One of the key equipment of the PWR nuclear power plant is the primary circuit coolant circulation pump, referred to as the nuclear main pump. The shaft seal generally adopts mechanical seal. Due to the need of sealing performance, the mechanical seal of the main pump is generally replaced every two to three years. Carry out an overhaul including checking the friction and wear of the seal, and replace the necessary sealing elements and components. The working pressure in the chamber is reduced to normal pressure. This process is generally called pressure relief. After maintenance, it needs to be re-pressurized. Pressure relief increases the complexity of the maintenance process and also causes a waste of energy. Similar to the sub-aqueous nuclear reactor, the primary circuit ...

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