Nuclear power uses the energy released when a uranium atom splits through a process called nuclear fission.
In MegaWatt, nuclear is a low environmental impact card with a high power capacity and high cost.
In a nuclear power station, uranium atoms in the fuel are split which releases a lot of energy and neutrons. The neutrons go on to split even more uranium atoms in the fuel, which is called a chain reaction. Controlling this chain reaction so that the number of neutrons stays the same means that a reactor is critical with a steady power that can be used to heat water to steam, with the steam driving a turbine to generate electricity.
Nuclear fuel is incredibly energy dense. 1 kg of natural uranium ore can be converted into fuel which generates 45,000 kWh of electricity. To generate the same amount of electricity using fossil fuels would need nearly 14,000 kg of coal. What's more, getting energy from nuclear fuel does not lead to carbon emissions once it's in the reactor.
Throughout a long lifetime (which could be over 60 years) nuclear power plants produce small volumes of spent fuel that need be reused or stored. However, nuclear power stations are costly to build and to decommission once they are no longer in operation.
Now for some stats from the UK grid in 2019.
15 nuclear reactors provided around 17.3% of the electricity generation (325 TWh), which is 2.3% less than the year before due to some longer pauses in generation at a couple of the power stations. These outages were for routine maintenance and inspections.
The majority of the current operating nuclear reactors in the UK are scheduled to be shut down by 2030. This will greatly reduce the nuclear power capacity in the UK. To make up for this reduction in nuclear capacity, 2 new reactors are currently being built at Hinkley Point C. They will provide around 7% of the UK's current electricity demand. The UK is pursuing further large-scale nuclear projects, such as Sizewell C, and other technologies such as Small and Advanced Modular Reactors.
We know that uranium atoms split into different atoms (called fission fragments) in a nuclear reactor to release energy. But what happens to the new atoms? Most fission fragments are radioactive which means that they split up again because they're not very stable. When this second split happens, some of them release electrons with a lot of energy (beta radiation). These electrons have enough energy to make water glow blue. This phenomena is called Cherenkov radiation and occurs when the electrons move faster than the speed of light in water. Take a look at the video below to see what this looks like!
https://www.world-nuclear-news.org/Articles/French-developed-SMR-design-unveiledIf you want to learn more, here are some examples of nuclear plants around the world.
Sizewell C is a proposed nuclear power plant that will be very similar to Hinkley Point C. Both power plants would have a capacity of approximately 3200 MW each. Since most existing UK nuclear power plants will be shut down by 2030, the addition of another large scale nuclear plant will mean nuclear could continue to supply a significant part of the energy mix in the UK.
Japan is home to the world's largest nuclear power station at Kashiwazaki-Kariwa with a massive capacity of 8212 MW from 7 boiling water reactors (closely followed by Kori in South Korea). Since the meltdowns at Fukushima in 2011, Japan has not been operating any of its nuclear reactors. In October 2020, the Tokyo Electric Power Company received approval from Japan's Nuclear Regulatory Authority to restart 2 of the 7 reactors.
Small Modular Reactors (SMRs) are a new way of building power plants to reduce the construction and finance costs associated with the bigger versions. Building lots of them as a fleet, and using factories to produce components and modules are some of the ideas that will help reduce the cost of the energy. The UK SMR programme lead by Rolls-Royce has announced plans to build 16 SMRs in the UK, NuScale and GE have plans too, in France an organisation is developing Nuward, and South Korea and Saudi Arabia are collaborating on the SMART reactor design.
Advanced Modular Reactors (AMRs) are those which use future technologies like new cooling systems or fuels, and could make it easier to carry out functions like generating hydrogen. The UK government has recently invested over £40m in AMR research and development.
All of the numbers we used for the UK statistics can be found in the Digest of United Kingdom Energy Statistics 2020 which is from the Department for Business, Energy & Industrial Strategy (the people in government who look after our energy policy).