How we generate nuclear electricity
We take a look at how we can create low carbon electricity from nuclear power
It all starts with uranium
Uranium is the naturally-occurring element at the heart of all nuclear power stations. Far from rare, it is found in abundance around the world.
It’s mined from the ground at sites in Australia, Canada and Kazakhstan. The abundance of uranium, and the stable nature of the regions it is found in, are two of the reasons that we believe nuclear power is such a strong option for the UK’s energy mix.
Once mined, the raw uranium ore is then ‘enriched’, which basically means it’s prepared for use as fuel for power stations. The end result is small fuel pellets. One small pellet, which is about the size of a peanut, is capable of generating as much power as 800kg of coal. The pellets are then loaded into fuel pins, hundreds of fuel pins make up each fuel element, and thousands of fuel elements make up each fuel assembly. Which means an incredible 5.5 million uranium pellets sit at the core of each nuclear reactor.
Power from our people
Behind the doors of our nuclear power stations are teams of highly skilled and experienced engineers. They work around the clock to produce low carbon electricity for the UK. Around 750 people at each of our stations carry the responsibility of generating this power safely and effectively.
The engineering roles within the station are diverse. From Reactor Engineers who are responsible for keeping the reactors working from the control room, to Environmental Safety Engineers who make sure we minimise the impact of our activites on the environment around us.
This huge team is the driving force behind our nuclear power generation. It’s their dedication and skill, combined with uranium and our power stations that generate enough electricity to power more than 14 million homes in the UK.
The power generation process
All power stations generate electricity in a very similar way – it’s just the source of the heat that varies: coal, oil or nuclear. This is how a nuclear PWR (Pressurised Water Reactor) station works...
The nuclear reaction is triggered
The reactor vessel is a tough steel capsule that houses fuel elements – sealed metal cylinders containing uranium. Neutrons are fired at the uranium atoms, causing them to split and release more neutrons. These then hit other atoms, causing more splits, and so the chain reaction continues. It’s this chain reaction that generates the huge amount of heat needed for the next stage.
Water is heated
Water is passed through the reactor vessel, where the chain reaction heats it to around 300°C. The water needs to stay in liquid form for the power station to work, so the pressuriser applies around 155 times atmospheric pressure, to stop it from boiling and evaporating.
Hot water is circulated
A coolant pump then circulates the hot, pressurised water from the reactor vessel through to a steam generator.
Steam is created
This hot, pressurised water flows through thousands of looped pipes while a second stream of water flows around the outside of the pipes. This water is under much less pressure, so the heat from the pipes boils it into steam.
Steam energy is converted to electrical energy
The steam passes through a series of turbines, and causes them to spin. This converts the steam’s heat energy into mechanical energy. A shaft connects the turbines, which are spinning at 3000 revs per minute, to a generator. The generator then uses an electromagnetic field to convert this mechanical energy into electrical energy.
Electrical energy is passed to national grid
A transformer converts the electrical energy to the high voltage needed by the national grid.
Electricity is sent through power lines to homes
The national grid uses high voltages to transmit electricity efficiently through the power lines. And at the end of the power lines are the homes, businesses and services that use the electricity. Here, other transformers reduce the voltage back down to a usable level.
The steam is cooled and recycled
Once the steam has done its job in the generator, it needs to be cooled. It is passed over pipes full of cold water pumped in from the sea. These cool the steam and condense it back into water. It’s then piped back into the steam generator, where it can be reheated turned into steam again, keeping the turbines turning and the electricity generation going.
The final step – dealing with the waste
Nuclear power produces radioactive waste that gives off a lot of heat and needs to be carefully and safely managed. Most of this radioactive waste is low-level – this means its radioactivity is short-lived and the waste can be incinerated or buried in shallow ground.
A very small amount of high-level waste is produced, from the substances left over after the nuclear reaction. This waste needs to be shielded from people and the environment for many years. Stored for 50 to 60 years in robust, designated storage facilities allows it to cool enough and reduces radioactivity enough to make it safe.