top of page

How does a Nuclear Reactor work?

Updated: Dec 5, 2022

A nuclear reactor works in a very similar way to a coal power plant. In that fuel is used to heat water, to generate steam, which powers a generator to produce electricity.

Just like a big kettle, really!

A Look into Nuclear Reactor Technology: How It Works, Its History and What's to Come

In this day and age, nuclear energy has become an increasingly popular source of electricity. The discovery of nuclear power has changed how we live, offering a virtually limitless power source that is more cost-effective than other forms of energy.

But how does nuclear power actually work, and what is its history?

At its core, a nuclear reactor is a device that uses the energy released through nuclear fission. In this process, neutrons are fired at a uranium or plutonium core, causing the atoms to break apart and release energy in the form of heat. This heat is then used to raise the temperature of the water, which is channelled through pipes to a turbine generator, where it is converted into electricity.

The history of nuclear power dates back to the early 20th century when scientists first began researching the potential of nuclear fission. In 1954, the world's first commercial nuclear reactor went online in Obninsk, Russia. Since then, more than 450 reactors have been operational across the globe — with many more in the planning stages.

The technology behind nuclear reactors has also been improved and refined over time, enabling them to be safer and more efficient than ever. Reactors are now built with multiple layers of safety systems that keep the fuel from overheating or releasing radiation.

In addition, advancements in nuclear materials science have allowed engineers to design reactors that can produce more energy with less fuel, making them even more cost-effective.

Looking to the future, nuclear power is expected to remain a major energy source. Researchers are currently exploring ways to make nuclear reactors even smarter and more efficient — such as developing new materials that can withstand higher temperatures or exploring the potential of alternative fuels.

Additionally, engineers are devising ways to reduce the amount of radioactive waste produced by nuclear reactors, such as using thorium instead of uranium.

Nuclear reactor technology has been an invaluable source of electricity for decades and will continue to be a key part of our energy future. With its vast potential and ever-improving safety systems, nuclear power is poised to become even more prominent in the years ahead.

This is a great way to generate a consistent baseload of clean, carbon-free energy as part of a nation's energy mix.

Keeping It Simple

You can find many resources explaining how an atom is split to release the energy that produces heat. For some reason, the nuclear industry feels the need to explain its inner workings.

However, does anyone ever concern themselves with the science of how coal burns?

You set it on fire, and it produces heat.

Or, how do solar panels work?

When exposed to the sun, they generate electricity.

Likewise, all you need to know is that uranium, or any fissionable nuclear material, gets hot in certain environments. This heat can be used to turn water into steam.

Some scientists would maybe like to string us up, but this is all you need to know.

If you are an Investigator and want to find information on nuclear reactors in much more detail, check out our pages available via our nuclear definition page. Find out more about nuclear fission, nuclear fusion, nuclear energy, nuclear power plant, and nuclear waste.

Now back to our big kettle...


Before you read on - we have created an email course to guide you through the process of defining your career path into the nuclear industry. Check it out below:

FREE Six-Steps To Get Into Nuclear


Baseload, Clean Energy

With a household kettle, you flick a switch and go from zero to boiling in a couple of minutes. With a nuclear reactor, you want to reach a particular heat or output and stay there until there is a need to change.

The operator controls the output by increasing and decreasing the reactor's output using control rods. The operator can turn the kettle up to produce more steam, the kettle down to produce less steam or take it into shutdown, where the water is allowed to cool.

The heat from the kettle (nuclear reactor) generates steam. The steam drives a turbine that produces electricity.

This is a great way to generate a consistent baseload of clean, carbon-free energy as part of a nation's energy mix.

Don't Believe Me, Just Watch!

[sorry Bruno Mars fans]

We have included a couple of videos below to help you find out more:

Firstly, we have a video from Urenco which answers the question of how uranium is made into nuclear fuel.

And secondly, we have a video tour of Sizewell B, a nuclear power plant in Somerset, UK. This is one of our favourite videos for several reasons.

  • The presentation from Poppy of EDF is fantastic,

  • it showcases the wide range of jobs involved in operating a nuclear power plant,

  • and it is an excellent insight into the workings of a nuclear power station.


What Now?

Well, now that we have an understanding of the workings of a nuclear reactor, you can find out more below about the following:

UK Nuclear Industry

Types of Jobs in Nuclear

Career Stories of Nuclear Workers

Definitions of Nuclear

Live Nuclear Jobs