Method for replacing unit first-loop pressure boundary pipeline of nuclear power station

The invention relates to the technical field of a unit first-loop pressure boundary pipeline of a nuclear power station and discloses a method for replacing the unit first-loop pressure boundary pipeline of the nuclear power station. The method comprises the following steps of: 1, fixing the first-loop pressure boundary pipeline to be replaced; 2, cutting the old unit first-loop pressure boundary pipeline and carrying out opening breaking machining on a new unit first-loop pressure boundary pipeline; 3, carrying out hydrostatic test on a new pipeline spare part of the new unit first-loop pressure boundary pipeline before delivery; and 4, carrying out manual priming and automatic welding filling to respectively weld both ends of the new pipeline spare part to two connecting pipelines and checking weld joints. According to the invention, the normalized method is adopted; various technologies are adopted; the technical problems of welding and fixing of the unit first-loop pressure boundary pipeline are solved; the equipment defects of the nuclear power station unit are eliminated; replacement on the unit first-loop pressure boundary pipeline of the nuclear power station is guaranteed to be safely completed under high quality; and the phenomena of retarding the construction period and the like cannot be generated.