The basic principle of creating nuclear power is that of splitting an atom by bombarding it with neutrons.
In the early 20th century, Albert Einstein formulated an equation which related Energy to Matter. This famous equation, know by many but understood by few, states in simple terms that Energy is equal to Mass multiplied by the Speed of Light squared - E=MC2.
When an atom is split in two by Nuclear Fission, two new atoms are created, however these two new atoms do not weight the same (combined), as the original. The remainder mass is converted into energy! However the amount of energy released is HUGE! It is 2.997 * 108 squared or 8.98 * 1016 times larger than the mass!
When the atom is split, as well as huge amounts of energy being released, more neutrons can also be released. This causes more atoms to be split, and yet more energy and neutrons to be released! The process goes on an on, and even more energy is released.
This is known as a Chain Reaction!
Chain reactions are practically unstopable, and give rise to what most people associate with the word nuclear - The mushroom cloud.
