Method for replacing thermocouple column of pressure vessel reactor core of nuclear power station

Abstract

The invention discloses a method for replacing a thermocouple column of a pressure vessel reactor core of a nuclear power station, which comprises the following steps of: 1) dismounting a thermocoupleseal of a thermocouple conduit sealing seat, and pulling out a thermocouple by using a thermocouple plugging tool or a sling; 2) cutting a weld joint connecting the upper conduit section and the lower conduit section of the thermocouple conduit sealing seat, and taking down the upper conduit section of the thermocouple column conduit sealing seat; (3) introducing a new upper conduit section of the thermocouple column conduit sealing seat, welding the new upper conduit section with the lower conduit section after installation and positioning, and carrying out nondestructive testing and a go-gauge test of a top channel; and 4) inserting a new thermocouple by using the thermocouple plugging tool, and carrying out performance test. According to the method, under the condition that a top coverof the pressure vessel is not opened, the weld joint of the upper conduit section and the lower conduit section of the thermocouple conduit sealing seat is cut and welding is then performed again, sothat the problems of leakage, unavailability and the like of a broken thermocouple channel are solved, and a guarantee is provided for safe operation of the nuclear power station.

Description

technical field [0001] The invention belongs to the technical field of nuclear power, and more specifically, the invention relates to a method for replacing a core thermocouple column of a nuclear power plant pressure vessel. Background technique [0002] During the operation of a nuclear power plant, it is necessary to closely monitor the temperature change of the core through the core temperature measurement subsystem. If there is an abnormal temperature, a nuclear power plant safety accident may occur. In the event of an accident, the core temperature measurement subsystem also needs to be able to perform continuous temperature measurement so that the operator can follow the trend of core temperature and core subcooling during and after the accident. [0003] The core temperature measurement subsystem generally includes a thermocouple column and thermocouples located in the thermocouple column. A common reactor has a total of 40 thermocouples, which are divided into four...

AI Technical Summary

Problems solved by technology

Although this treatment technology can effectively block the conduit and cause water leakage in the primary circuit, it makes the thermocouple channel unusable, and the temperature at the corresponding position of the core cannot be measured. It is necessary to conduct a safety assessment of the operation of the nuclear power plant

In addition, this treatment technology can only be used as an emergency treatment plan for emergencies, and the unavailability of a single thermocouple has no major impact on the safe operation of the nuclear power plant. However, if the same problem occurs with other thermocouple conduits, the same problem cannot be used. to solve

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