Pearson Edexcel · GCSE · Physics
Course version: 1PH0 · Version from Sept 2016
6.41P Describe how thermal (heat) energy from the chain reaction is used…
Full specification wording
Topic 6 – Radioactivity: 6.41P Describe how thermal (heat) energy from the chain reaction is used in the generation of electricity in a nuclear power station
In a nuclear power station, fission of uranium nuclei in the reactor core releases energy that heats the core.
Checked against the Pearson Edexcel 1PH0 specification (opens in a new tab) on .
- Point 37 of 42
Study notes
From the checked teaching notes for this specification point.
The idea
In a nuclear power station, fission of uranium nuclei in the reactor core releases energy that heats the core. A coolant, often water or carbon dioxide gas, is pumped through the core and carries the thermal energy away. This hot coolant passes through a heat exchanger, where it boils water in a separate circuit to make high-pressure steam. The steam is directed onto the blades of a turbine, making the turbine shaft spin. The spinning shaft turns a generator, and the generator converts the kinetic energy of rotation into electrical energy, which is fed to the grid via transformers. The steam then condenses and the water is returned to be heated again. The chain reaction itself is controlled by control rods and a moderator so that energy is released steadily.
What earns the marks
- Identifies that fission in the reactor core releases energy that heats the core and its coolant.
- States that the hot coolant transfers thermal energy to water in a heat exchanger to produce steam.
- Explains that the steam drives a turbine, whose rotation turns a generator to produce electricity.
- Recognises that the chain reaction is controlled so that thermal energy is released at a steady rate.
Common mistakes and how to put them right
Claims the reactor directly makes electricity.
Put it right by placing the turbine and generator between the heat source and the electrical output.
Says the coolant itself becomes the steam that turns the turbine in a single circuit.
Put it right by describing a heat exchanger separating the radioactive coolant from the steam circuit.
Assumes the chain reaction is uncontrolled.
Put it right by noting control rods absorb neutrons and keep the reaction steady.
Exam tips
- Learn the energy chain in order: fission energy, hot coolant, steam, turbine rotation, generator, electricity.
- Use the term heat exchanger and explain that it transfers energy without mixing the two water circuits.
- Link control rods to keeping the rate of fission, and so the thermal energy output, steady.
Try the lesson
The start of the Topic 6 – Radioactivity: 6.41P Describe how thermal (heat) energy from the chain reaction is used in the generation of electricity in a nuclear power station lesson, made from checked teaching notes for this specification point.
Have a go first
In a nuclear power station, what is the thermal energy released by the chain reaction used to do first?
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