Nuclear power plant start secondary circuit flushing method

Abstract

A nuclear power plant start secondary circuit flushing method comprises the steps of small cycle flushing, medium cycle flushing and large cycle flushing started in sequence. After the small cycle flushing is completed, a condensate polishing system for purifying circulating water is put into operation, and the medium cycle flushing and the large cycle flushing are established, wherein the requirement after the small cycle flushing is that the concentration of Fe is less than 500 ppb; the requirement after the medium cycle flushing is that the turbidity is less than 1 ppm; and the requirementafter the large cycle flushing is that the peak turbidity value is less than 1 ppm. According to the flushing method, a flushing path is standardized, flushing indicators at each stage are clarified,and the process is strictly controlled to achieve the effect of refinement treatment; after the small cycle is established, a polishing bed body can be put into operation, flushing water is purified through polishing, and in a subsequent path flushing process, the flushing water consumption is effectively reduced, and the flushing efficiency is improved.

Description

technical field [0001] The invention belongs to the technical field of nuclear power engineering construction and debugging, and in particular relates to a method for flushing a secondary circuit of a nuclear power plant. Background technique [0002] Before starting the primary loop of a nuclear power plant, the system pipelines and equipment need to be flushed to remove foreign matter, impurities and corrosion products introduced into the system equipment during equipment manufacturing, installation and commissioning, so as to ensure the water quality of downstream users (steam generators) Meet the specification requirements as soon as possible, maintain a good water chemical environment of the steam generator, and inhibit or delay the corrosion of the steam generator. [0003] Most of the domestic nuclear power plants start-up secondary circuit flushing adopts the method of integral water intake and circular flushing. This method has the following disadvantages: (1) The ...

AI Technical Summary

Problems solved by technology

This method has the following disadvantages: (1) The flushing effect is not good: in the traditional flushing method, the acceptance index is few and broad, resulting in incomplete flushing

It takes 2-3 months for the purification time of the same power plant to start after the first loading, and the sewage quality can reach the WANO-CPI median value; after the overhaul starts, it takes about a week of purification time, and the sewage quality can reach the WANO-CPI median value Requirements, long-term unqualified chemical indicators have brought great challenges to the realization of excellent performance goals of power plants

(2) The consumption of flushing water is large: In the traditional flushing method, the method of changing the water as a whole after water intake is adopted. Generally, the water needs to be changed 2-3 times, and the amount of water changed is close to 4000-5000t before the condensate polishing treatment can be put into operation. , coupled with the consumption of subsequent filling and discharging, the flushing water consumption of the secondary circuit will reach 7000-8000t. Excessive consumption of flushing water will affect the goal of "cost leaning" of the power station and bring pressure to the operation

(3) Long flushing time: In the traditional flushing method, the process control is loose, resulting in uncontrolled flushing time

[0005] However, in this flushing scheme, as the cleaning of the low-pressure water supply system and the high-pressure water supply system is carried out step by step, the route of the cleaning pipeline is getting longer and longer, and based on the overall large-flow flushing scheme, the water volume of the entire line needs to be 1175.28 cubic meters at a time , and generally need to go through 2~3 cycles to reach the standard, each time a new desalinated water needs to be injected, and there is a great demand for desalinated water required for cleaning; in addition, with the continuous flow of large flow flushing, the internal adhesion of equipment pipes is relatively The tight corrosion products are washed out again and brought into the subsequent equipment, which makes the required cleaning time longer

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