AbstractThe acquisition of a nuclear power reactor from the North American company Westinghouse in 1964 not only brought atomic practices and knowledge to Spain but also introduced new methods of industrial organization and management, as well as regulations created by organizations such as the US Atomic Energy Commission (US AEC) and the International Atomic Energy Agency (IAEA). This article analyzes the history of the knowledge, regulations and experimental practices relating to radiation safety and protection that traveled with this reactor to an industrial space: the Zorita nuclear power plant. Within this space, the appropriation, use, and coproduction of knowledge and practices were conditioned by political, economic, industrial and social factors, and by the engineers, researchers and other professionals who contributed expert knowledge. Material held in the Tecnatom Historical Archive—the engineering company that coordinated construction of the plant—is the main source for this work, which delves into the history of knowledge and atomic technologies and adds to the historiography of radiological protection in Spain.