Soviet Russia was never overly concerned with nuclear waste disposal. For decades, the Soviets simply dumped radioactive materials into the Arctic Ocean or erected temporary storage facilities for such materials. Those facilities are now beginning to age, and are becoming a serious environmental problem. Frighteningly, one of these facilities may even be in danger of exploding.
Norwegian researchers have obtained an alarming report from Rosatom, the Russian nuclear agency, about a site on the Kola Peninsula, an ore-rich area near the northern border with Norway. Since 1982, 21,000 spent uranium fuel assemblies have been stored there in three concrete tanks right next to the coast. Inside the tanks, large metal pipes contain the rods. Unfortunately, the concrete has begun to leak and allow sea water in, corroding the metal tubes.
Leakage is a problem because spent rods contain many types of fissile isotopes, and salt water could cause them to disintegrate relatively quickly. Essentially, those fissile isotopes will dissolve in the water, creating a radioactive slurry inside the tubes.
This could be dangerous because, in the right conditions, enough fissile material concentrated in a small space creates a lot of heat—the same principle we exploit for nuclear power generation. Uncontrolled, this heat could cause steam to build up in the tubes, eventually leading them to explode. If concentrations of fissile material are high enough, dangerous chain reactions could occur, releasing more intense (and potentially explosive) "bursts of radiation and heat." The risk of such explosions is small— both Russian and Norwegian nuclear officials have accordingly "downplayed the danger"—but still significant given the potential for widespread fallout.
And while an actual atomic explosion is probably impossible in this situation, even steam explosions could send huge quantities of dangerously radioactive material into the environment. Rosatom claims there is no danger of that happening, but given the Russian track record on waste disposal, we should watch sites like this very carefully.