Shaft sealing water injection system of main pump of nuclear power station

Abstract

The invention discloses a shaft sealing water injection system of a main pump of a nuclear power station. The shaft sealing water injection system comprises an injection pump, a high-pressure cooler, a hydrocyclone, valves and a main connecting pipeline that are arranged at the exterior of the main pump, as well as an auxiliary pump and an internal runner that arranged in the main pump; the internal runner of the main pump is connected with an external runner of the main pump through a shaft sealing water injection hole and a high temperature water drainage hole that are formed in a main flange; and the injection pump, the high-pressure cooler and the hydrocyclone are sequentially arranged on the main connecting pipeline. The shaft sealing water injection system further comprises a bypass pipeline connected with the injection pump, the high-pressure cooler and the hydrocyclone in parallel; the main connecting pipeline is provided with a normally open main pipeline isolating valve at each of the two ends of a parallel connection section connected with the bypass pipeline in parallel; and the bypass pipeline allows low temperature upward filling water of a RCV system to be able to bypass the injection pump, the high-pressure cooler and the hydrocyclone and to directly enter the shaft sealing water injection hole of the main flange. Compared with the prior art, through redundancy design, and optimization of a system structure and control, the safety and the reliability of system operation and the maintainability of the shaft sealing water injection system are ensured.

Description

technical field [0001] The invention belongs to the field of nuclear power, and more specifically, the invention relates to a water injection system for a shaft seal of a main pump of a nuclear power plant. Background technique [0002] The reactor coolant pump is referred to as "main pump" for short, and it is one of the key equipment of the primary circuit system of the pressurized water reactor nuclear power plant. Only when the main pump operates reliably can the continuous and safe operation of the nuclear power plant be ensured. see figure 1 , The shaft-sealed main pump is provided with a water-lubricated radial bearing 10 and a shaft-seal assembly 11 on the pump body. The water-lubricated radial bearing 10 is mainly responsible for the radial force of the main pump; and the shaft seal assembly 11 ensures that the unit is under normal operating conditions and design basis accident conditions to prevent the reactor coolant from flowing along the pump shaft 12 in a cont...

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Problems solved by technology

[0005] but, figure 2 and image 3 The shown shaft seal water injection system has at least the following defects: first, it cannot achieve effective exhaust, and cannot guarantee the normal operation of the system; second, two auxiliary pumps 24 and 25 need to be installed in the main pump, which increases the The complexity of the internal structure; third, when it is necessary to overhaul the jet pump 20, hydrocyclone 21 and high-pressure cooler 22, the reactor coolant cannot be effectively isolated; fourth, there is no corresponding monitoring instrument on the system loop, and it is impossible to System status is monitored; fifth, when the high-pressure cooler 22 fails, the main pump must be shut down

[0007] but, Figure 4 and Figure 5 The shaft seal water injection system shown has at least the following defects: first, the control of the shaft seal water injection system during operation is complicated, and valves 39 and 40 need to be frequently operated; second, during the main pump outage process, if At the same time, the loss of water filling on the RCV may fail to establish natural circulation, and there is a risk that the shaft seal cannot be injected with water; third, when the high-pressure cooler 31 and jet pump 30 fail, the main pump must be shut down; fourth, the valve 36 is located on the connecting pipe 33 in front of the shaft seal water injection hole of the main flange 14a. If this valve 36 fails, it will affect the normal operation of the shaft seal water injection system

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