Short answers, pulled from the story.
The Obninsk Nuclear Power Plant connected to the Soviet power grid on the 27th of June 1954, making it the first grid-connected nuclear power plant in the world. Construction had begun on the 31st of December 1950, and the reactor first achieved criticality on the 2nd of May 1954.
The Obninsk Nuclear Power Plant is located in the city of Obninsk, Kaluga Oblast, about 110 kilometers southwest of Moscow, Russia. It was built within the Institute of Physics and Power Engineering.
The AM-1 reactor at Obninsk had a total electrical capacity of 6 megawatts and a net capacity of around 5 megawatts electric. Its thermal output was 30 megawatts. By commercial standards this was small, making it a pilot plant rather than a full-scale generating station.
The Obninsk plant ceased generating electricity for the grid in 2002 and was finally shut down on the 29th of April 2002. After that date it continued operating as a research and isotope production facility.
The Obninsk reactor, designated AM-1 (Atom Mirny, meaning Peaceful Atom), used a graphite moderator and water coolant with 5 percent enriched uranium. It was a prototype design and a direct forerunner of the Soviet RBMK reactor family.
The technology developed and refined at Obninsk was later applied on a much larger scale in the RBMK reactors. The plant ran 17 test loops that yielded experimental data used to design subsequent Soviet nuclear power stations, including Beloyarsk Unit 1, which came online in 1964 with a capacity of 100 megawatts electric.