In a gun-type bomb, Uranium-235 is the fuel. In an implosion bomb, Plutonium-239 is the fuel. A fusion-boosted atomic bomb uses the implosion design, with the addition of gaseous tritium (Hydrogen-3). Producing the appropriate amounts of fuel for bombs is expensive, time-consuming, and difficult.
What does an inhibitor switch do? An inhibitor switch basically tells your vehicle whether its in motion or in park. It can tell the car to park or to go into first gear etc.
A car's ignition switch serves several purposes. First, it allows you to control the power to many of the car's accessories, preventing accessories from running down the car's battery when the car is parked for a long period of time.