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.
Vehicles with a smart-key system can disengage the immobiliser and activate the ignition without inserting a key in the ignition, provided the driver has the key inside the car. On most vehicles, this is done by pressing a starter button or twisting an ignition switch.