Ozyorsk is a town (from 1954) in Russia, the administrative center of Ozyorsk urban district (from 2005), in Chelyabinsk Region.

Ozyorsk was a closed administrative-territorial entity and was not mentioned on maps till 1990.

The population of Ozyorsk is 82.3 thousand people as of 2010.

History of Ozyorsk

Ozyorsk was founded on the shore of Lake Irtyash in 1945. For a long time it was marked with the code name Chelyabinsk – 40. It became known due to its main enterprise – the chemical plant Mayak, where combative charges for the first nuclear bombs were made - and the participation in its creation of the outstanding scientist I.V. Kurchatov, who was the principal investigator of the uranium project.

In 1957 a container with radioactive waste exploded at the Mayak plant, the accident resulting in contamination of the area of 23 thousand sq. km in 217 settlements of Sverdlovsk, Chelyabinsk and Tyumen Regions. People were resettled from the most contaminated areas and the East Ural State Reserve was formed there. Presently wild animals and rare birds inhabit the reserve in spite of the high level of background radiation. The contaminated area is now called the East Ural Radioactive Track.

The town of Chelyabinsk-40 itself escaped radioactive contamination and became the town of Ozyorsk in 1994.