Seversk (Северск) is a town (since 1956) in Tomsk Oblast, Russia on the bank of Tom River. Population is 118,800 (2001). It is also known as Tomsk-7.
As is the tradition with Soviet towns containing secret facilities (Ozersk aka Chelyabinsk-40, Zheleznogorsk aka Atomgrad aka Krasnoyarsk-26, Sarov aka Arzamas-16), the name is actually a P.O. Box number and implies that the place is located some distance from the city of Tomsk (15 km to the NW, in fact).
Seversk is the site of Siberian Chemical Combine (Sibkhimkombinat), founded in 1954. It is comprised of several nuclear reactors and chemical plants for separation, enrichment and reprocessing of uranium and plutonium. Nuclear warheads were being produced and stored on the premises.
In 1993 an explosion occurred at the facility contaminating almost 120 kilometer2 of the surrounding province of Tomsk.
It was situated 15 km north west of the city of Tomsk with a population of 500,000.
A Tomsk based environmental group has detected cracks in the wells and the clay and sandstone put in place to prevent seepage to the surrounding ground and water systems.