Closed city of Sverdlovsk-45 / Lesnoy

The closed city of Sverdlovsk-45, currently Lesnoy, was established in 1947 as a home to the Plant 418 – an electromagnetic separation (calutron) facility to produce HEU. An industrial-scale separation facility, SU-20, was completed at the Plant 418 simultaneously with the Soviet first gaseous diffusion plant D-1 in Sverdlovsk-44. Initially, the SU-20 facility was used to increase the level of enrichment of uranium received from the D-1 plant from 70 to 90 percent uranium-235. Improvements in the gaseous diffusion technology have subsequently eliminated the need in electromagnetic separation of uranium isotopes and the SU-20 facility was redirected to enrich non-uranium isotopes.

In the late 1950s, a portion of the Plant 418 was adopted to house a nuclear warhead assembly/disassembly facility – the Combine "Electrochimpribor." The Combine was established to duplicate the Electro-Mechanical Plant "Avangard" in Arzamas-16 in assembling physics packages and nuclear warheads. Eventually, it has become Russia’s largest warhead assembly complex.

Sverdlovsk-45 is located near Nizhnyaya Tura, approximately 160 km north of Yekaterinburg. Its population is 58,000. Approximately 10,000 work at the warhead production complex.

The warhead assembly/disassembly plant is located north-west of the residential area. The production complex is supported by two large national warhead stockpile storage sites, the nearest of which is located approximately 10 km west of the main production area.