For 15 years, two nuclear reactors in the city of Seversk in Russia have been producing plutonium. Not for war though - the plutonium is just a by-product of their present purpose.

While the reactors were once part of the Soviet Union's nuclear weapons program, they now only serve as a utility source of heat and power for the cold region along the Tomsk River.

If Russia had shut down the reactors, cities in that region - whose total population adds up to about 600,000 - will have to face temperatures that go down to below 40 degrees. For that reason, the reactors had to stay open - but not for long.

The plant has been refurbished enough for the reactors to be shut down. The first reactor will be shut down this Sunday, while the second reactor will be shut down sometime in June. The only other plutonium-producing plant in the country - located in Zheleznogorsk - is also planned to be replaced by a fossil-fuel plant in 2010.