On March 22, 1971, the General Shareholders of the GKT, decided to build an atomic power plant, with the contract going to Siemens.
The Zwentendorf atomic power plant was a hot water reactor with 723 MW's gross power and a net power of 692 MW. On April 4, 1972, the construction began. The energy plan for 1976 foresaw a construction of altogether three atomic power plants with a total power of 3300 MW in Austria. The second was nominated in St. Pantaleon-Erla on the border between Lower Austria and Upper Austria; altogether six atomic power plant sites were nominated.
The Zwentendorf power plant was to be operated by the Tullnerfeld Atomic Power Plant GmbH. (GKT), in which nearly all electric utilities had a share. (organisation with 50%, Tiwag 13.34%, EVN 10.83%, Steiermark Energy 10%, AG Upper Austria Energy 8.33%, Kelag 3.33%, Salzburg AG 2.5%, VKW 1.67%, current names of the companies).