Nuclear power plants operate in much the same way as traditional power stations.
Traditional power plants burn coal, oil and natural gas, and use them to boil water into steam. The steam is used to turn turbines – and that produces electricity.
Nuclear power plants follow the same process, but they don’t burn anything; instead they split uranium atoms inside a reactor in a process called fission. The heat created in this process is used to produce steam, the steam turns the turbines, and so on.
The uranium is formed into small, hard ceramic pellets that are packed into 12-foot long vertical tubes, or ‘fuel rods’, arranged in bundles known as ‘fuel assemblies’. Each tiny pellet can produce the same amount of energy as 150 gallons of oil.
There are several types of uranium, but it’s uranium-235 (U-235) that’s most important in the production of nuclear power. When U-235 is exposed to radiation it throws off an ‘alpha particle’, composed of two neutrons and two protons bound together. When a free neutron is fired at this nucleus, the nucleus will absorb the neutron, become unstable and split immediately, releasing around 200 million electron volts and a considerable amount of heat.
Within the centre of the nuclear reactor, known as its ‘core’, the bundles of uranium are submerged in water inside a pressure vessel, which acts as coolant (left to its own devices the uranium would overheat and melt) and which is then turned into steam by the heat. This is known as a ‘chain reaction’.
The steam turns huge turbine blades, which in turn drive generators to make electricity. The steam is then turned back into water and cooled in a cooling tower so it can be used again.
Nuclear power has one of the smallest carbon footprints of any energy source. Most of the carbon dioxide (CO2) emissions created by nuclear power plants are actually released while they’re being built or while they’re processing fuel – not while they’re generating electricity.
This makes nuclear power the most affordable way for the UK to generate significant amounts of low-carbon electricity. This will help the UK meet its carbon-reduction commitments; in fact, without the use of nuclear energy the targets would be virtually impossible.
The Government’s Overarching National Policy Statement for Energy, published in July 2011, concludes that:
“For the UK to meet its energy and climate change objectives, the Government believes that there is an urgent need for new electricity generation plant, including new nuclear power. Nuclear power generation is a low carbon, proven technology, which is anticipated to play an increasingly important role as we move to diversify and decarbonise our sources of electricity.”
In fact, according to the Committee on Climate Change, by the year 2030 nuclear power might provide around 40% of the UK’s energy mix.
Because of its low carbon footprint, nuclear energy is considered a clean-air source of power, but it’s not counted as a renewable power source as there’s not an unlimited supply of uranium on Earth. Instead, it’s often called a sustainable energy source because there’s enough uranium in the world to fuel reactors for 100 years or longer.
Nuclear power stations are very expensive to build, but they last for a long time – the next generation should last for around 60 years, and they are also designed to be quicker and easier to dismantle and decommission. Nuclear plants have relatively low running costs, while uranium is an abundant resource, which helps to keep prices down. Overall, nuclear power is one of the most cost-effective ways to generate low-carbon electricity.
Nuclear power plants take safety very seriously, and the industry works within a culture of continually striving for improvement. However, while accidents are extremely unusual, they can happen, resulting in environmental damage and sickness from radiation poisoning.
Nuclear energy is one of the most fiercely regulated industries in the UK. It is controlled by a wide range of laws covering the storage, transport and use of nuclear materials. On the rare occasions when there has been an accident at a nuclear facility, governing bodies across the world have immediately introduced greater regulation and cooperation, nationally and often internationally.
One of the most recent accidents was caused by the tsunami that hit Japan in March 2011 after the Tōhoku earthquake. It flooded the reactors at the Fukushima 1 nuclear power plant, causing a loss of coolant followed by nuclear meltdowns and the escape of radioactive materials.
Several lessons were learned from the incident, and since then there has been renewed focus on the safety of nuclear power stations. The UK government commissioned a thorough review of nuclear power in the UK.
Nuclear waste is classified as high level, intermediate or low level, depending on how much residual radioactivity is left in it, and must be dealt with according to its defined level. It is usually transported by rail or sea in steel containers that are purpose built for radioactive materials. They can stand up to extremes of temperature and pressure, whether they’re ultimately buried on land or dropped in the ocean.
There have never been any instances of damage to health or the environment caused by transporting nuclear waste.