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GCSE Questions: Energy Sources

Q15. Many countries use nuclear power stations to generate electricity. Nuclear power stations use the process of nuclear fission to release energy.

(a)

(i) What is nuclear fission?

The splitting of a(n atomic) nucleus

You got no marks for saying 'splitting an atom'!

[1 mark]

(ii) Plutonium-239 is one substance used as a fuel in a nuclear reactor.

For nuclear fission to happen, the nucleus must absorb a particle. What type of particle must be absorbed?

A neutron

[1 mark]

(b) Nuclear fusion also releases energy.

Nuclear fusion happens at very high temperatures. A high temperature is needed to overcome the repulsion force between the nuclei.

(i) Why is there a repulsion force between the nuclei of atoms?

Because all nuclei have the same (positive) charge and like charges repel.

[1 mark]

(ii) Where does nuclear fusion happen naturally?

Within a (main sequence) star.

[1 mark]

(c) In 1991, scientists produced the first controlled release of energy from an experimental nuclear fusion reactor.

This was achieved by fusing the hydrogen isotopes, deuterium and tritium. Deuterium is naturally occurring and can easily be extracted from seawater.

Tritium can be produced from lithium. Lithium is also found in seawater.

The table below gives the energy released from 1 kg of fusion fuel and from 1 kg of fission fuel.

Type of fuel
Energy released from 1 kg of fuel/J
Fusion fuel
3.4 × 1014
Fission fuel
8.8 × 1013

 

(i) Suggest two advantages of the fuel used in a fusion reactor compared with plutonium and the other substances used as fuel in a fission reactor.

Any two from:

easy to obtain / extract

available in (very) large amounts

releases more energy (per kg)

produces little/no radioactive waste

Saying it is 'naturally occurring' or 'seawater is renewable' was considered insufficient to get you a mark, as was saying it involves 'less cost'.

[2 marks]

(ii) Some scientists think that by the year 2050 a nuclear fusion power station capable of generating electricity on a large scale will have been developed. Suggest one important consequence of developing nuclear fusion power stations to generate electricity.

Any one from:

makes another source of energy available

increases supply of electricity

able to meet global demand

less environmental damage

reduces amount of other fuels used

[1 mark]

(d) Tritium is radioactive. After 36 years, only 10 g of tritium remains from an original sample of 80 g. Calculate the half-life of tritium. Show clearly how you work out your answer.

80g to 40g in one half life

40g to 20g in the next half life

20g to 10g in the third half life.

36 = 3 half lives

so, the half life is 36/3 = 12 years

[2 marks]

(Total 9 marks)