May 17, 2001; Although Russia planning to raise their nuclear sub the Kursk this Summer, they already have a backup plan if the Kursk operation fails. In the late 1980s, they developed a biological gel for sealing the reactors of sunk nuclear subs. While the stuff is very expensive, the Russians claim it lasts 500 years. They first used the gel on the Komsomolets, a nuclear sub that went down in 1989. The gel appears to be working, so far. Meanwhile, Russia plans to have the Kursk raised by this September.