Russia, with financial and technical assistance from America, Britain, Canada, Japan, Italy and Norway, has been dismantling about 20 retired nuclear submarines a year, and plans to have 191 dismantled by next year. Up through the early 1990s, Russia had built nearly 260 nuclear ships (nearly all submarines). The end of the Cold War in 1991, left the Russians unable to keep most of those subs in service. Russian nukes were expensive to maintain, and many were not worth keeping in service (too noisy, too old, too many other flaws).
Most of the submarine dismantling was paid for by the U.S., which spent over $15 billion to implement the 1993 Strategic Offense Arms Elimination Implementing Agreement with Russia. Britain, Canada, Japan, Italy and Norway also contributed cash and technical assistance to this effort.
Throughout the 1990s, Russia only decommissioned 2-4 nuclear subs a year. Many nuclear subs were taken out of service in the early 1990s, although lots of older boats were being decommissioned in the late 1980s, before the Cold War even ended. That's because Russians tend to keep old weapons in service long beyond the time it's worth it. By the end of the 1990s, Russia had 150 decommissioned nuclear subs waiting to be dismantled. Russia hoped to complete dismantling these submarines by 2007, but things went much slower than expected, because there was no money. However, by 2000, things really began to pick, as 18 subs were dismantled in that year.
It costs about $7 million to dismantle one submarine. The primary task is to safely take apart the nuclear reactor, and get the radioactive components to a secure storage facility. The foreign nations contributing to this effort are all maritime nations that were concerned about the old Soviet subs falling apart while still in the water. What got this aid program going was the discovery that the Soviets were just dumping some radioactive components into Arctic waters. Russia was more willing, than the Soviets, to do the right thing and is determined to safely dispose of all these old nuclear subs.