The defuelling of the first reactor at the UK’s Hunterston B NPP has been completed, on time and on budget, EDF Energy reported. Reactor 3 was defuelled in 16 months and work is due to start shortly on Reactor 4.

Hunterston B plant comprises two 490 MWe advanced gas-cooled reactors (AGRs) – reactors 3 and 4. Reactor 3 began operating in 1976 with an original lifespan of 25 years. However, its operating life was extended to more than 45 years. Reactor 4 started up in 1977 and was taken offline with reactor 3 in January.

EDF Energy said the aim is to have the second reactor defuelled and all used fuel sent to Sellafield by mid-2025, before transferring site ownership to the Nuclear Decommissioning Authority (NDA) in 2026. NDA subsidiary Magnox is responsible for the long-term decommissioning of the AGRs and EDF said it is working closely with Magnox on plans for the seamless transfer of Hunterston B in a timely manner.

Hunterston B’s Station Director, Joe Struthers, said: “Since the station stopped generating in January 2022 the team has been completely focused on doing this job safely and efficiently, providing value for money for the UK taxpayer…. While defuelling is similar to the refuelling we carried out here for 46 years, the team at Hunterston B should be proud of the way they have adapted to our new mission, finding a whole new rhythm of working.”

EDF’s Nuclear Decommissioning Director, Paul Morton, said: EDF has invested more than £7bn ($8/6bn) in the UK nuclear fleet since acquisition in 2009. “That investment has helped secure life extensions for these sites and maximise nuclear’s contribution to energy security,” he noted. “Now in defuelling, 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.”

The AGR stations are currently expected to stop generating in 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.

Over the last 50 years, the seven AGR power stations have generated more than 1,800TWh electricity, enough to power every UK home for more than 16 years. The carbon avoided by using nuclear instead of gas stations is equal to nine years of UK car emissions. Tens of thousands of jobs have been supported and communities across the UK have benefitted.

Three of the seven AGR stations are currently undergoing defuelling – Hunterston B, Hinkley Point B in Somerset and Dungeness B in Kent. The other four AGR stations are still operating. Heysham 1 and Hartlepool are currently forecast to generate until March 2026. Heysham 2 and Torness are due to generate until March 2028.

The decommissioning of the AGR fleet is funded by the Nuclear Liabilities Fund, which was established in 1996 and has received contributions for its shareholding of British Energy, from operators (British Energy and EDF) and from UK Government.

Defuelling involves removing all the used nuclear fuel from the plant site. EDF will be supported by the internal and external independent regulators – Independent Nuclear Assurance (INA) and, the Office for Nuclear Regulation (ONR) – in confirming when all the fuel has been removed. This is Fuel Free Verification (FFV).

EDF took responsibility for managing the UK’s AGR fleet in 2009 and signed a contract with the UK Government in June 2021 to defuel all seven AGR stations (14 reactors) as well as Sizewell B, the UK’s only pressurised water reactor. Sizewell B is due to operate until 2035 with preparations under way for a 20-year life extension.

Image: Hunterston B (courtesy of EDF)