4.4.4 Nuclear fission and fusion

What is nuclear fission?

The splitting of a large and unstable nucleus into two smaller nuclei, releasing energy and neutrons

What are the products of a fission reaction?

Two smaller nuclei, energy, two or three neutrons

What can the neutrons released in fission do?

They can start a chain reaction by causing more nuclei to undergo fission

How is nuclear fission used in power stations?

The energy released by fission heats water to produce steam, which turns turbines to generate electricity

What is a chain reaction?

A self-sustaining series of reactions where where the neutrons from one fission cause further fission reactions

How is a chain reaction controlled in a nuclear reactor?

Control rods absorb excess neutrons to slow down or stop the chain reaction

What is nuclear fusion?

The process where two light atomic nuclei combine to form a heavier nucleus, releasing energy

Where does nuclear fusion naturally occur?

Stars, including the sun

Why is nuclear fusion difficult to achieve on earth?

It requires extremely high temperatures and pressures to overcome the electrostatic repulsion between nuclei

Which releases more energy per reaction: fusion or fission?

Fusion

What are the advantages of fusion over fission?

Fusion produces less radioactive waste and uses abundant fuel like hydrogen isotopes

What isotopes are commonly used in fusion experiments?

Deuterium and tritium (isotopes of hydrogen)