Nuclear energy

Nuclear energy is the energy released during nuclear reactions, either through fission (splitting heavy nuclei) or fusion (combining light nuclei). In the WJEC A-Level Physics syllabus, the focus is primarily on nuclear fission, which is used in nuclear power stations to generate electricity. You will study the structure of the nucleus, binding energy, mass defect, and the chain reaction that sustains fission. Understanding nuclear energy is crucial because it provides a low-carbon energy source, but it also involves risks such as radioactive waste and potential accidents. This topic connects to broader themes in physics, including energy conservation, radioactivity, and the strong nuclear force.

Nuclear reactions are governed by Einstein's famous equation E = mc², which shows that a small amount of mass can be converted into a huge amount of energy. In fission, a heavy nucleus like uranium-235 absorbs a neutron, becomes unstable, and splits into two smaller nuclei, releasing energy and more neutrons. These neutrons can then trigger further fissions, creating a chain reaction. In a nuclear reactor, control rods absorb excess neutrons to keep the reaction steady, while a coolant transfers heat to generate steam for turbines. You will also learn about the binding energy per nucleon curve, which explains why energy is released in both fission and fusion.

Mastering nuclear energy is essential for understanding modern energy debates and the physics behind nuclear power. It also lays the groundwork for topics like radioactive decay, half-life, and the use of radioisotopes in medicine and industry. In exams, you will be expected to calculate energy released from mass defect, explain how a chain reaction is controlled, and discuss the advantages and disadvantages of nuclear power. This topic is a key part of the 'Nuclear Physics' section of the WJEC A-Level, and it often appears in synoptic questions that link to other areas of physics.