5.3 Nuclear Energy and Power Generation

The Principle of Nuclear Fission

**Nuclear fission** is a process in which the nucleus of a heavy atom, such as Uranium-235 (\(^{235}\)U), is split into smaller nuclei. This is typically initiated by a neutron striking the nucleus. The fission process releases a tremendous amount of energy and also produces more neutrons, which can go on to cause further fissions, leading to a **chain reaction**.

The energy released from a single fission event is millions of times greater than the energy released in a chemical reaction, such as burning fossil fuels.

The Role of a Nuclear Reactor

A **nuclear reactor** is the core component of a nuclear power plant, designed to safely control the nuclear chain reaction. The main components include:

• Fuel: Uranium-235 is the most common fuel. It is arranged in fuel rods within the reactor core.
• Moderator: A material (e.g., water, heavy water, graphite) that slows down fast neutrons released during fission, making them more likely to cause further fissions and sustain the chain reaction.
• Control Rods: Rods made of neutron-absorbing material (e.g., Cadmium, Boron) that are inserted into the reactor core to control the rate of fission. They can be raised or lowered to increase or decrease the reactor's power output.
• Coolant: A fluid (e.g., water) that transfers the heat generated by fission away from the reactor core.

Generating Electricity

The heat produced by the controlled chain reaction in the reactor core is used to boil water, creating high-pressure steam. This steam drives a turbine, which is connected to an electrical generator. The generator then converts the mechanical energy from the spinning turbine into electrical energy, which is distributed to homes and businesses.