Built in total secrecy between 1946 and 1948, the Mayak plant was the first reactor used to create plutonium for the Soviet atomic bomb project. In accordance with Stalinist procedure and supervised by NKVD Chief Lavrenti Beria, it was the utmost priority to produce enough weapons-grade material to match the U.S. nuclear superiority following the atomic bombings of Hiroshima and Nagasaki. Little to no consideration was paid to worker safety or responsible disposal of waste materials, and the reactors all were optimized for plutonium production, producing many tons of contaminated materials and utilizing open-cycle cooling systems which directly contaminated every liter of the thousands of liters of cooling water the reactors used every day.