Nuclear Power

Nuclear Power

So, what is nuclear power?

Today, over 400 nuclear power plants around the world produce 400 GW (gigawatts) of electricity – enough to power 400 million households for the year!

Nuclear Power Plant: Explanation and Diagram

Before we learn how a nuclear power plant works, let's recap the concept of radioactive decay.

All elements have the same number of positively charged protons and negatively charged electrons. But they may have different numbers of neutrons.

Sometimes, these isotopes are unstable. These atoms will decay by releasing fission products (a package of subatomic particles) and a burst of ionising radiation to change into a smaller, more stable element.

Isotopes that undergo more than one step of decay are the most useful for generating nuclear power.

Fission Power Plants

A nuclear power plant (also known as a nuclear reactor) is a series of machines that control nuclear fission to produce electricity. Most power plants use uranium as a fuel – in particular, the isotope uranium-235.

Alternatively, an isotope of plutonium is used (plutonium-239).

Atoms of the nuclear fuel are forced to break apart. As they split, the atoms release fission products. These induce nearby atoms to split, starting a chain reaction.

As the atoms split apart, they release energy in the form of heat:

• The heat is used to convert water into steam.

• The steam drives turbines (converting heat → kinetic energy)

• The movement of the turbines drives a generator (converting kinetic energy → electrical energy)

To stop the chain reactions from getting out of control, nuclear power plants contain boron control rods. These rods absorb neutrons, stopping them from splitting more uranium atoms. Raising the rods speeds up the rate of decay, while lowering them slows it down.

Uranium Mining Techniques

How is uranium extracted from Earth's crust?

• Open pit mining: drilling and blasting create a large hole in the ground, exposing the ore. Then, the ore is mined using blasting and excavation techniques.

• Underground mining: underground ores are extracted using blasting, pneumatic drilling, picks, and shovels. This mining technique exposes workers to harmful radon gas.

• In-situ leaching: chemicals are used to separate the uranium from surrounding rock. The chemicals are mostly sulfuric acid or sodium bicarbonate. In-situ leaching is the predominant method of uranium mining.

Thorium Reactors

Thorium-based nuclear reactors have been suggested as an alternative to uranium-based reactors. The reactors would be molten salt reactors, with the thorium remaining as a liquid fuel; safer than uranium-based reactors. Thorium reactors would generate less radioactive waste. Furthermore, thorium is approximately three times more abundant than uranium.

However, molten salt reactors are difficult and highly expensive to develop. A commercial thorium reactor is decades away.

Complications of Nuclear Energy Density

Earlier, we learned that nuclear fuels have an enormous energy density – far greater than any other fuel.

If there's so much energy in nuclear fuel, why don't we have more electricity than we could ever need? Well, we need to consider a few factors:

• Enrichment: only a small fraction of mined material is used in power plants

• Fuel consumption: only 6% of the fuel's energy is extracted in traditional power plants

• Thermal efficiency: nuclear power plants can only convert 33% of heat to electricity

Despite these reductions in effective energy density, nuclear fission remains an effective and useful tool for generating electricity.

Fusion Power Plants

Nuclear fusion occurs when the nuclei of two light elements are forced together to form one nucleus of a heavier element. Nuclear fusion takes place in the Sun, providing so much energy that it can heat Earth from millions of kilometres away.

Fusion reactions are estimated to produce four times as much energy as fission reactions, without radioactive waste! Thus, fusion power plants could be groundbreaking – but scientists are struggling to develop suitable technology. Nuclear fusion requires temperatures of over 100,000,000ºC; difficult to create on Earth.

Researchers are focusing on hydrogen fusion reactions, using heavy isotopes deuterium and tritium. When combined, they produce helium nuclei. The process releases large amounts of energy, and occurs at lower temperatures than other elements.

Toroidal Reactors

Some experimental fusion power plants use a machine called a tokamak. It confines a plasma using a magnetic field, creating a doughnut shape called a torus.

Magnetic coils generate an intense 'toroidal field'. In the centre of the torus, another magnet creates a 'poloidal field'. These magnetic fields work together, confining particles in the plasma and creating the conditions needed for nuclear fusion.

Laser Fusion

During laser fusion, deuterium and tritium are added to a blast chamber and compressed to high densities using an intense laser beam. The high density and heat from compression provides the conditions required for nuclear fusion.

A disadvantage of laser fusion techniques is that lasers are relatively inefficient at converting electrical energy into light energy. Plus, some laser light is reflected or scattered away.

Countries that Use Nuclear Power

Over 30 countries use nuclear power to generate electricity. Who are the top ten biggest producers?

Nuclear Power in the UK

The UK is home to six operational nuclear power plants:

• Dungeness B, Kent
• Hartlepool, County Durham
• Heysham 1, Lancashire
• Heysham 2, Lancashire
• Sizewell B, Suffolk
• Torness, East Lothian

In 2021, nuclear power generated 14.8% of the country's electricity.

Advantages of Nuclear Power

What gives nuclear power an edge over fossil fuels?

Disadvantages of Nuclear Power

It's important to recognise that no energy resource is perfect. So, what are the disadvantages of nuclear power?

I hope that this article has explained nuclear power for you. Remember that it is electricity generated using nuclear reactions. Nuclear power produces vast amounts of electricity without carbon emissions or pollutants, but does create radioactive waste that must be stored carefully.

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