SECOND ONLY TO CHERNOBYL
An underground tank at the Tomsk-7 Plutonium Reprocessing Plant in Siberia blew up on April 6, 1993. The explosion released a clous of radioactive gas, and contaminated about 14 square miles of land with low levels of plutonium, but the Russians weren't too concerned at the time. The exact circumstances of the accident are unclear.
The reactor was located near Seversk, the site of the Siberian Group of Chemical Enterprises, founded in 1954. It comprises several nuclear reactors and chemical plants for separation, enrichment, and reprocessing of uranium and plutonium. Following an agreement in March 2003 between Russia and the United States to shut down Russia's three remaining plutonium-producing reactors, two of the three plutonium producing reactors (the two that are sited at Seversk) have now been shut down.
Despite a 1992 order removing Seversk's secret status, the city still remains closed to non-residents. The city has six checkpoints where visitors must show entry documents. Permission to visit to the city may only be granted by the appropriate authorities through the institution being visited, or through a private party such as a close relative.
