Chemical wet maintenance method during shutdown of auxiliary boiler of nuclear power plant

Abstract

The invention belongs to the technical field of maintenance of auxiliary boilers of nuclear power plants, and particularly discloses a chemical wet maintenance method during shutdown of an auxiliary boiler of a nuclear power plant. The chemical wet maintenance method takes the auxiliary boiler and a water supply tank as maintenance objects and takes hydrazine concentration of 50-600ppm and pH (25DEG C) of 9.5-11.0 in the auxiliary boiler and the water supply tank as maintenance indexes. The chemical wet maintenance method specifically comprises the steps of system water feeding, medicine dispensing, medicine adding, circulation and sampling analysis, and regular monitoring. After hydrazine wet maintenance is carried out on the auxiliary boiler system, iron ions in boiler water are basically kept stable and are smaller than a control limit value in the operation period, and the problem of equipment corrosion in the shutdown process of the auxiliary boiler is effectively solved; a maintenance range, a maintenance mode and a monitoring means are defined to fully cover the auxiliary boiler system; maintenance acceptance criteria are defined, process control is strict, and maintenancequality is guaranteed; and moreover, the operation is simple, the cost is low and the risk is low.

Description

technical field [0001] The invention belongs to the field of nuclear power plant auxiliary boiler maintenance, and in particular relates to a chemical wet maintenance method during nuclear power plant auxiliary boiler outage. Background technique [0002] The nuclear power plant has a separate auxiliary boiler system designed to generate auxiliary steam to provide auxiliary steam for the steam turbine shaft seal system, deaerator, hot water heating system and laundry room in the site waste treatment facility when the main steam is not available. Most of the equipment in this system is made of carbon steel, which is prone to oxygen absorption corrosion. During the shutdown period of the boiler, if the equipment is not maintained, the corrosion of the equipment will be intensified. Scouring the boiler and related equipment will accelerate corrosion, affect the efficiency of the boiler, and affect the long-term stable operation of the unit. [0003] When the ambient humidity i...

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Problems solved by technology

[0004] Dry maintenance methods mainly include hot air drying method and nitrogen filling method, which have the following disadvantages: hot air drying requires hot air blowers to be arranged on site, and equipment manholes and related exhaust valves need to be opened. Check the temperature and humidity every day, and the daily supervision tasks are relatively heavy; the nitrogen filling method first drains the water inside the equipment before filling the nitrogen, uses the waste heat to dry the inner surface of the equipment, and then fills it with high-purity nitrogen at a certain pressure. High-purity nitrogen needs to be supplemented. Nitrogen maintenance has extremely strict requirements on the airtightness of the system. If there is a leak, the risk of suffocation of personnel in the plant will increase, and the maintenance cost will also increase.

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