Fission and Fusion

The splitting up of the nucleus is known as nuclear __________. Nuclear reactors generally use uranium 235 as a fuel, but one third use plutonium 239. Plutonium 239 is also used in nuclear warheads. For fission to occur the uranium 235 or plutonium 239 nucleus must first absorb a __________.

The nucleus undergoing fission splits into two smaller nuclei and 2 or 3 neutrons and energy is released. The neutrons may go on to start a chain reaction.

There is also a process known as nuclear __________ which occurs naturally under the huge gravity conditions within a __________. During fusion two __________ nuclei are forced together forming a __________ one which also releases energy.


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