Table of Contents
Reactor Fuel
In a Nuclear Reactor, nuclear fuel is “burnt” via nuclear fission; this creates heat which is ultimately used to produce steam that turns turbines to generate electricity.
What happens in the UK?
What happens in the UK?
What happens to spent nuclear fuel in a reactor?
- Spent fuel rods are removed with specially shielded flasks and transferred to cooling ponds for interim storage, allowing the radioactivity to decrease and the decay heat to cool.
- In an Advanced Gas-Cooled Reactor (AGR), fuel assemblies are replaced every few months (whilst the reactor is operating).
- In a Pressurised Water Reactor (PWR), fuel assemblies are replaced every 12-18 months (reactor is shut down for refuelling, which occurs with the facility flooded underwater – for cooling and as a biological shield).
Why can we no longer use spent fuel in a reactor?
Spent fuel still contains 96 % of its uranium, however the proportion of 235U (the fissile isotope) is now < 1 %, too low to sustain a chain reaction.
Of the remainder, 1 % is plutonium (Pu) and 3 % comprises fission products (actinide isotopes such as neptunium, americium and curium). The latter is high-level waste and continues to produce heat; it therefore must be actively cooled until it can be vitrified (safely encapsulated in glass for long-term storage).
Adam Piatt
Hartlepool Nuclear Power Station 2022, Wikimedia Commons – Licence CC BY-SA 4.0 DEED
Heysham Nuclear Power Stations, David Merrett – Licence CC BY 2.0 DEED
Torness Nuclear Power Station April 2016, Wikimedia Commons – Licence CC BY-SA 4.0 DEED
Sizewell B Power Station, Simon James – Licence CC BY-SA 2.0 DEED
