1.   John had described the do-it-yourself plutonium bomb as being shaped like the barrel of a small cannon.

2.   A plutonium bomb uses plutonium as the active material involved.

3.   In theory the uranium might have helped fuel the uranium bomb that leveled Hiroshima or the plutonium bomb that was dropped on Nagasaki.

4.   Plutonium bombs, in contrast, require more sophisticated detonation systems.

5.   In the latest wave, two men were arrested before dawn Friday, one carrying a semiautomatic handgun and another claiming he had a plutonium bomb in his car.