The Hunterston B plant in Scotland comprises two 490 MWe AGR reactors - Reactors 3 and 4. Reactor 3 came online for the first time in February 1976, was initially expected to run for 25 years but had its generating lifespan increased to more than 45 years. The station's other unit, Reactor 4, started up in March 1977 and was taken offline in January this year.
Defuelling the plant involves removing more than 300 channels of fuel from each of the reactors. The fuel channels will be stripped and processed then taken to the on-site fuel storage pond to cool before being packaged into used fuel flasks and transported via rail to the Sellafield site in England.
Work to remove the used fuel from Reactor 3 began in May 2022 and has now been completed.
Work to defuel Reactor 4 is due to start shortly. EDF said the aim is to have the second reactor defueled and all used fuel sent to Sellafield by mid-2025, prior to transfer of site ownership to the Nuclear Decommissioning Authority (NDA) in 2026. The NDA's subsidiary, Magnox, is accountable for the long-term decommissioning of the AGRs and EDF is working closely with them on plans for the seamless transfer of Hunterston B in a timely manner.
"Now in defueling, Hunterston B is setting the standard for the rest of the fleet and demonstrating the nuclear industry can deliver, working closely with key partners like Sellafield who are so crucial to the success of the defueling programme," said EDF's Nuclear Decommissioning Director, Paul Morton. "Defueling the first of these reactors on time and on budget shows EDF's commitment to delivering on this contract, ensuring this site is ready for transfer to Magnox in 2026."
EDF had originally been responsible for total lifetime decommissioning of the seven AGR stations, which comprise Torness and Hunterston B in Scotland, Dungeness B in Kent, Hartlepool in Teesside, Heysham 1 and 2 in Lancashire and Hinkley Point B in Somerset. All these plants are scheduled to reach the end of their operational lives this decade.
However, in June 2021, the UK government and EDF agreed improved arrangements to safely and efficiently decommission the AGRs. Under the agreement, EDF will aim to shorten the time it takes to safely remove the fuel from the plants as they come offline, before working closely with the NDA to transfer ownership of the stations to the NDA.
Three of the seven AGR stations are currently in the defueling stage: Hunterston B, Hinkley Point B and Dungeness B. Four AGR plants are still in operation. Heysham 1 and Hartlepool are currently expected to operate until March 2026. Heysham 2 and Torness are currently due to generate until March 2028. However, EDF said it will "continue to review lifetimes to ensure the four generating stations can continue to support the UK's energy security for as long as it is safe and commercially viable to do so".
