# Nuclear power II

On the Nuclear power page we covered all of the components of a nuclear fission reactor. This page demonstrates the key ideas in action.

Key Concepts

In a chain reaction, more neutrons are produced by a nuclear fission reaction than are needed to react. This is a good thing - it is essential that the nuclear reaction rate is maintained for ongoing electricity generation.

An uncontrolled chain reaction is used in nuclear weaponry.

Essentials

Neutron absorption

When a neutron is absorbed by a uranium nucleus, it's binding energy per nucleon increases. This makes the nucleus too unstable and so it splits to release this energy.

Moderation

Fast neutrons will not be absorbed by the nuclei. A moderator is used to slow them down.

Critical mass

If the mass of fuel is insufficient, the neutrons will escape without causing further reactions.

Fuel enrichment

Natural uranium contains mainly 238U, which does not split when it absorbs neutrons. The fuel is enriched with 235U to increase the likelihood of a successful reaction.

Nuclear waste

Fission products have too many neutrons so are unstable. This makes them radioactive (producing alpha, beta and gamma radiation).

Summary

A reactor simulation

Nuclear energy (fuel)  → thermal energy (steam) → mechanical energy (turbine) → electrical energy (generator)

Test Yourself

Use quizzes to practise application of theory.

Exam-style Questions