Small nuclear reactor site boundary atmospheric dispersion factor analysis method and system

The invention belongs to the technical field of nuclear power plant design, and provides a small nuclear reactor site boundary atmospheric dispersion factor analysis method and system, and the method comprises the steps: calculating atmospheric dispersion factor values of all orientations in a plurality of standard time periods by adopting a first calculation method when the distances between all orientations and a reactor are greater than a preset distance; when the distances between one or more orientations and the reactor are not greater than the preset distance, if the release mode of the selected release source is ground release, calculating atmospheric dispersion factor values at all orientations in a plurality of standard time periods by adopting a second calculation method; if the release mode of the selected release source is elevated release, a first calculation method and a second calculation method are adopted to respectively calculate atmospheric dispersion factor values at all orientations in a