From a news paper:
In addition to the primary nuclear capsule, the bomb also harbored a secondary nuclear explosive, or sparkplug, designed to make it go thermo. This is a hollow plug about an inch in diameter made of either plutonium or highly enriched uranium (the Pentagon has never said which) that is filled with fusion fuel, most likely lithium-6 deuteride. Lithium is highly reactive in water. The plutonium in the bomb was manufactured at the Hanford Nuclear Site in Washington State and would be the oldest in the United States. That's bad news: Plutonium gets more dangerous as it ages. In addition, the bomb would contain other radioactive materials, such as uranium and beryllium.
The bomb is also charged with 400 pounds of TNT, designed to cause the plutonium trigger to implode and thus start the nuclear explosion. As the years go by, those high explosives are becoming flaky, brittle and sensitive. The bomb is most likely now buried in 5 to 15 feet of sand and slowly leaking radioactivity into the rich crabbing grounds of the Wassaw Slough. If the Pentagon can't find the Tybee Island bomb, others might. That's the conclusion of Bert Soleau, a former CIA officer who now works with ASSURE, the salvage company. Soleau, a chemical engineer, said that it wouldn't be hard for terrorists to locate the weapon and recover the lithium, beryllium and enriched uranium, "the essential building blocks of nuclear weapons." What to do? Coastal residents want the weapon located and removed. "Plutonium is a nightmare and their own people know it," said Pam O'Brien, an anti-nuke organizer from Douglassville, Georgia. "It can get in everything--your eyes, your bones, your go------