The advantages of nuclear energy are that it produces a large amount of useful energy from a very small amount of fuel and does not produce waste gases. However, it is very difficult to handle nuclear waste. There is always a chance where there can be a serious accident if something goes wrong. There are two primary methods of producing nuclear energy. The first is fission, which occurs when the heavy nucleus of a radioactive element like uranium or plutonium splits in two and the second is fusion, in which light nuclei are joined together as occurs in the Sun.
Atomic bombs are a perfect example of a nuclear reaction that causes massive destruction.
Atom bombs have a power equivalent to millions of tons of ordinary explosive. The temperatures of fusion nuclear explosions can go up into the millions of kelvin. Controlled fusion experiments can reach these temperatures. The temperature of this fission reaction was about 300,000 kelvin at the center and about 6000 kelvin on the ground below. Scientific Aspects of Nuclear Explosion Phenomena .