What is nuclear fission?

Nuclear fission is the splitting up of a large and unstable nucleus, into smaller nuclei.


This releases energy.

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Where is nuclear fission carried out on earth?

In nuclear power stations.

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What is spontaneous fission?

Spontaneous fission is when the fission is unforced, and the atom splits by itself.


This is very rare.

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How do boron control rods reduce the risk of nuclear meltdown?

Boron control rods can be lowered into the nuclear reactor to absorb neutrons and slow the chain reaction.


This prevents it from getting out of control and leading to a meltdown. 

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Why must the walls of a nuclear reactor be very thick concrete?

To stop the gamma radiation from passing out of the reactor, where it could harm the workers. 

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Give 3 advantages of nuclear power.

  1. Nuclear power plants can reliably produce large amounts of electricity.
  2. Nuclear power does not produce any greenhouse gas.
  3. Although not renewable, there are very large quantities of the uranium and plutonium fuel.

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Give 4 disadvantages of nuclear power.

  1. Nuclear power stations are very expensive to build.
  2. It produces radioactive nuclear waste, so it must be stored safely - this is expensive because it must be stored in thick underground bunkers for a very long time.
  3. There is a risk of the nuclear chain reaction getting out of control and causing a nuclear meltdown.
  4. The fuel is not renewable.

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What are the steps in a nuclear fission chain reaction?

  1. A neutron is fired at an unstable nucleus (e.g. uranium-235), causing it to split apart.
  2. The unstable nucleus splits into 2 daughter nuclei and 2 or 3 neutrons. It also emits a large amount of energy as gamma radiation.
  3. The 2 or 3 neutrons that were released are then absorbed by other unstable nuclei and this repeats the process from the previous step.
  4. This process then occurs over and over again in what we call a chain reaction.

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How do nuclear power stations generate electricity?

  1. Whenever unstable nuclei (e.g. uranium-235) split apart they release lots of gamma radiation.
  2. This gamma radiation is then used to heat liquid water into steam (gaseous water).
  3. As the steam rises it turns turbines, and the kinetic energy of those turbine is converted into electrical energy by a generator. 

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