Analysis of those factors at a site that could affect the safety of a facility or activity on that site. This includes site characterization, consideration of factors that could affect safety features of the facility or activity so as to result in a release of radioactive material and/or could affect the dispersion of such material in the environment, as well as population and access issues relevant to safety (for example, feasibility of evacuation, location of people and resources). The analysis of the origins of external events for a site that could give rise to hazards with potential consequences for the safety of a nuclear power plant constructed on that site. (The definition in NS-G-3.1 had ‘sources’ instead of ‘origins’.) For a nuclear power plant, site evaluation typically involves the following stages: Site selection stage. One or more preferred candidate sites are selected after the investigation of a large region, the rejection of unsuitable sites, and screening and comparison of the remaining sites. Site characterization stage. This stage is further subdivided into: Site verification, in which the suitability of the site to host a nuclear power plant is verified mainly according to predefined site exclusion criteria; Site confirmation, in which the characteristics of the site necessary for the purposes of analysis and detailed design are determined.(a) Pre-operational stage. Studies and investigations begun in the previous stages are continued after the start of construction and before the start of operation of the plant to complete and refine the assessment of site characteristics. The site data obtained allow a final assessment of the simulation models used in the final design.(b) Operational stage. Appropriate safety related site evaluation activities are carried out throughout the lifetime of the facility, mainly by means of monitoring and periodic safety review