Nuclear power plant valve membrane maintenance method

The invention relates to the field of nuclear power plant auxiliary cooling water systems, and discloses a nuclear power plant valve membrane maintenance method. The method comprises the steps of isolating the area, with pipelines to be maintained, of a nuclear power plant, wherein the area with the pipelines to be maintained comprises a main pipeline, a plurality of branch pipelines and operatingpoint pipelines, the branch pipelines communicate with the main pipeline, the operating point pipelines communicate with the main pipeline, and operating point valves are arranged on the operating point pipelines; opening some operating point valve, and judging whether the water outlet quantity of the opened operating point valve is smaller than a preset water outlet threshold or not; and if thewater outlet quantity of the operating point valve is smaller than the preset water outlet threshold, carrying out maintenance on a valve membrane of an appointed valve in the area with the pipelinesto be maintained according