An electrifying visit to Sizewell B

Natalie Gomez, AF Energy Supply Management Specialist

Nuclear power has been the subject of widespread debate in the ‘green’ energy arena.  It is a divisive topic and whilst critics say it is too expensive, creates radioactive waste and poses a security risk, supporters argue its reliability and efficiency make it the way forward.

To learn more about this key source of power, electricity supplier EDF gave your AF Energy team an educational tour of Sizewell B nuclear power station on the Suffolk coast in February 2022.  

Getting past security

For security reasons we all underwent background checks before we could visit Sizewell B.  When we arrived, we passed through airline style security and had to ensure that we left everything in the car, even phones and fitness watches.

Once we were in the building our guide Claire settled us in a classroom to complete some essential health and safety paperwork.  By this stage we were all starting to realise the magnitude of what was happening at Sizewell.   Paperwork completed and safety instructions issued, the educational part of the day began. 

A physics lesson

The tour started with Claire giving us an explanation of what the nuclear reactor is and how it works.

Sizewell B’s reactor is fuelled by uranium pellets. The reactor can hold over 18 million pellets, with each one containing the same amount of energy as 800kg of coal.  It generates nuclear power by using radioactivity to split uranium atoms in a process called fission.  Nuclear fission is based on natural processes such as the biological fission of living cells. Nuclear fission creates a huge amount of heat and this is used to power Sizewell B. 

The next stage in the process is that water is heated using the power from the nuclear fission to create steam.  This steam is transported through Sizewell’s network of pipes that in turn heat up and cool the steam as it travels. Water from the North Sea is used for this cooling process.  Eventually the steam enters two enormous turbines.   A high temperature  of 282 degrees Celsius creates the right amount of steam at the right pressure to turn the turbines.  Each turbine uses over 1 tonne of steam per second to generate 630 megawatts of electricity. 

The whole process uses 3 million litres of water every minute. Sizewell B has 3 completely separate water loops:

  • The 1st loop is kept under extreme pressure to allow the boiling point to be increased.  This is heated up using the heat of the reactor to create a large “kettle”.  This water is so purified that it would be harmful to drink as it nutrients from your body.
  • The 2nd water loop from the kettle is turned into steam to move the turbines then converted back into water. Again this water is as purified as the 1st loop. 
  • The 3rd loop is pumped form the cold North Sea to cool the steam. It is returned to the ocean after being filtered for any radioactivity.

Out of the classroom 

We were issued with PPE including a hard hat, ear defenders, safety glasses, gloves and a hi vis jacket.  We were relieved that they weren’t taking any chances!

We visited the buildings where different parts of the power generating process took place.  We also met the teams that worked on each stage and were taken into the turbine hall where we were allowed to see and touch the outside casing of the turbines.  The noise from the rotating blades was deafening and we were glad of the ear defenders.

We were fascinated to learn about all safety procedures that are in place:

  • 4 separate engines to power the cooling system for the reactor in case of an emergency;
  • a 1.5 metre thick concrete wall lined with a steel mesh to protect the reactor from any external attack;
  • the permanent presence of firefighters as well as armed police, medical and mental health staff;
  • an additional team of staff located a few miles away from site with vehicles capable of reaching Sizewell across the surrounding fields in case of an emergency.

We were left in no doubt as to how tightly regulated, managed and secured this nuclear power station is.  

The radioactive topic of waste

Radioactive waste, a by-product of the nuclear power process, is one of the most controversial topics.  What we didn’t know before the tour was that virtually all of Sizewell’s waste is processed on site. Because it is so dangerous, it is kept in a fuel storage point for a number of years before being transferred to casks.  It is then kept on site for a further 100 years before being moved to an underground repository. 

Some final fascinating facts

  • Sizewell B first synchronised with the National Grid on 14th February 1995.
  • In 2020, it produced enough electricity to power 2.3 million homes.  That’s enough to power all of Norfolk, Suffolk, Essex and part of Cambridgeshire or take 1.3 million cars of the road for a year.
  • The turbines rotate at twice the speed of sound.
  • There are over £55 million of spare parts on site at any time.
  • The site has a deluge system, not a sprinkler system. It can deliver 8,000 litres of water in case of a fire.
  • The process of drawing water from the North Sea means fish are caught. 87% of these are returned live to the sea. 

The visit was extremely educational and it was a fantastic opportunity for us to learn more about how our Members’ power is produced. 


Would you like to talk to us about your energy requirements?  Get in touch with your AF Energy team by emailing or call 01603 881910.