Obninsk Nuclear Power Plant (, "Obninskaja AES" []) was built in the "Science City" of Obninsk, Kaluga Oblast, about southwest of Moscow, Soviet Union. Connected to the power grid in June 1954, Obninsk was the first grid-connected nuclear power plant in the world, i.e. the first nuclear reactor that produced electricity industrially, albeit at small scale. It was located at the Institute of Physics and Power Engineering. The plant is also known as APS-1 Obninsk (Atomic Power Station 1 Obninsk). It remained in operation between 1954 and 2002, although its production of electricity for the grid ceased in 1959; thereafter it functioned as a research and isotope production plant only.