Nuclear Fission & Fusion (AQA GCSE Physics)

Nuclear power stations use the fission of particular isotopes of uranium to generate electrical energy.

Burning coal that has been mined from the ground is another way of generating electrical energy.

Describe the advantages of nuclear power compared with the use of coal to generate electrical energy.

Name one element that is used in nuclear power stations.

Give its mass number.

Describe the process of nuclear fission.

The equation for the nuclear fission of uranium-235 is shown below.

Using information in the equation, describe the process of nuclear fission.

Explain what happens in the process of nuclear fusion.

Scientists in France are currently developing a nuclear fusion reactor called ITER for research into fusion technology.

Nuclear fusion uses isotopes of hydrogen called deuterium and tritium.

Deuterium can be reasonably easily extracted from seawater, and is naturally occurring.

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

Table 1 below shows the energy released from 1kg of deuterium and 1kg of uranium-235.

Table 1

Suggest two advantages from using a nuclear fusion reactor rather than a nuclear fission reactor.

Where does nuclear fusion happen naturally?

It is only possible to achieve nuclear fusion at very high temperatures and pressures, because the nuclei of the atoms which need to fuse repel each other.

Why is there a repulsive force between the nuclei?

Nuclear fission occurs in nuclear reactors.

An example of a nuclear reactor is shown in Figure 1

Explain what happens to the energy released. 

Explain how a chain reaction can occur in the reactor.

Figure 1 shows a neutron colliding with a nucleus of uranium-235, producing a number of products.

Figure

State the name of the process shown in the diagram.

Explain how the process shown in the diagram can lead to a chain reaction.

Explain the energy transfer taking place in this reaction.

 Figure 1 shows the fuel used in some nuclear reactors.

The fuel is contained inside spheres with a silicon carbide layer which is designed to contain the fission products for at least one million years.

Figure 1

Explain what is meant by the term fission products and give an example.

Explain why it is important to contain these fission products for such a long time.

Energy and mass can be converted using the equation: 

Fusion and fission are examples of when this conversion process occurs.

A particular fusion reaction that can occur is:

• Mass of reactants m_R = mass of helium−3 + mass of helium−4
• Mass of product m_P = mass of beryllium−7
• Energy is released

State and explain which quantity is greater, m_R or m_P.

The difference in mass of the reactants and products was found to be 2.8 × 10^–30 kg.

The speed of light is 3.00 × 10⁸ m/s.

Calculate the amount of energy released. Give the unit.