Administrative data is data systematically generated and collected by administrative bodies or processes within a specific domain, such as information compiled on nuclear power reactors by international agencies for oversight purposes. This concept encompasses the study and utilization of such data, characterized by its origin in routine operations rather than primary research design, its potential for large-scale and longitudinal coverage, and its significance as an empirical resource for policy analysis, regulatory assessment, historical trends, and informing research questions within fields like nuclear energy management and safety.