Obninsk Nuclear Power Plant (Russian: Обнинская АЭС, romanized: Obninskaya AES; ) was built in the "Science City" of Obninsk, Kaluga Oblast, about 110 km (68 mi) 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. Its production of electricity for the grid ceased in 2002; thereafter it functioned as a research and isotope production plant only.
According to Lev Kotchetkov, who was there at the time: "Although utilisation of generated heat was going on, and production of isotopes was even enhanced, the main task was to carry out experimental studies on 17 test loops installed in the reactor." The technology perfected in the Obninsk pilot plant was later employed on a much larger scale in the RBMK reactors.