Wet maintenance method during shutdown of secondary circuit of nuclear power plant

Abstract

The invention discloses a wet maintenance method during shutdown of a secondary circuit of a nuclear power plant. The wet maintenance method comprises the following steps of early-stage preparation, determination of the target concentration of a maintenance solution, determination of the addition amount and the addition duration of the maintenance solution, addition of the maintenance solution, circulation after addition of the maintenance solution, chemical sampling analysis, nitrogen filling, entering of a maintenance state and regular monitoring of the concentration of the maintenance solution. According to the wet maintenance method, the hydrazine solution with strong reducibility and water absorption is introduced into the secondary circuit equipment, a reduction environment is created, and the potential of the metal surface of the equipment is reduced, so that the purpose of maintaining the secondary circuit is achieved; according to the wet maintenance method, the unit design characteristics are combined, the maintenance range is defined, the maintenance mode and the monitoring means are determined, and the wet maintenance method covers all equipment of the secondary circuit; according to the method, through several times of verification of three-door nuclear power, a remarkable effect is achieved, and the flushing starting time is obviously shortened.

Description

technical field [0001] The invention relates to the field of equipment maintenance of the secondary circuit of a nuclear power plant, in particular to a wet maintenance method during the outage of the secondary circuit of the nuclear power plant. Background technique [0002] The secondary circuit system of a nuclear power plant is mainly composed of a saturated steam turbine, a generator, a condenser (or called a condenser), a condensate pump, a low-pressure heater, a deaerator, a feed water pump, a high-pressure heater, and an intermediate steam-water separation reheater and Corresponding instruments, valves and pipelines. The main function of the secondary circuit is to form a closed thermodynamic cycle, sending the steam generated by the nuclear steam supply system to the steam turbine for work, and the steam turbine drives the generator to convert mechanical energy into electrical energy; it is a conversion system of steam and power. The main working principle of the s...

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Problems solved by technology

At the same time, because the corrosion products delivered to the steam generator during start-up are more oxidative than those delivered during power operation, these oxidized corrosion products will increase the risk of corrosion cracking of the steam generator heat transfer tubes

On the other hand, if the equipment does not perform maintenance, it will affect the flushing progress of the unit after startup, and pose a challenge to the "shortest overhaul period" of the power station

[0005] The utility model patent with the publication number CN206345918U discloses an anti-corrosion device for the pipelines of important plant water systems in nuclear power plants. Corrosion and damage to the pipeline by seawater prolongs the service life of the pipeline and saves maintenance and management costs of the pipeline; however, the sacrificial anode method requires a separate sacrificial anode device, and its self-corrosion consumption leads to a lower current efficiency, and replacing spent anodes is difficult and expensive

[0006] So far, there are no public papers, patents and standards for the maintenance methods of secondary circuit equipment in nuclear power plants.

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