COVER STORY | DEFUELING AGRS Defueling AGRs


On 13 January EDFE announced that defueling had been completed at Hinkley Point B, following a similar milestone at Hunterston. The key project was completed on time and on budget. How was this achieved?


THIS YEAR MARKS A HALF-CENTURY since the UK started up the first of its fleet of advanced gas-cooled reactors (AGRs), which have been owned and operated since 1999 by EDF Energy (EDFE). Three of the stations have already closed – Hinkley Point B, Hunterston B and Dungeness – while the remainder are in their final years. Now they will move into the storage and decommissioning phase, which will eventually mean their ownership will transfer to the government-owned Nuclear Decommissioning Authority (NDA), for decommissioning. But the first stage, defueling the reactors, remains the responsibility of EDFE. The cost of decommissioning the reactors is largely borne by the public, so the UK’s independent public spending watchdog, the National Audit Office, published its view on some of the risks in a report, ‘The decommissioning of the AGR nuclear power stations’, published in January 2022. A key aspect of the overall cost to decommission the AGRs is the speed at which fuel – representing the vast majority of the radiological load – can be removed from the reactors. EDFE estimated that the annual fixed costs to manage and


maintain a station that is not generating electricity drops from around £140m (US$188m) per year before defueling to £25-30m (US$33-40m) once the fuel has been removed. The costs are to be borne by the Nuclear Liabilities


Fund, which meets the costs of decommissioning the AGRs. These costs are therefore very dependent on how soon defueling begins once a station ceases electricity generation and how quickly fuel can be removed. The NAO said: “Accelerated defueling will test the capacity of EDFE to remove the fuel, and then the NDA to transport and store the fuel safely at Sellafield. A bottleneck at any point in this process could have repercussions across


the defueling programme”. EDFE estimated in 2021 that the cost of defueling the AGR fleet could be £3.1–£8.0bn (US$4.2-10.7bn) depending on when it begins and how quickly it is completed. In 2015, the Department, EDFE and the NDA established the


AGR Operating Programme (AGROP) and Defueling Steering Panel to provide management and oversight of the defueling of the AGR fleet. The accelerated defueling programme aimed to reduce the defueling period for each AGR station from eight years to three and a half years. The NAO report noted that to achieve this a whole series of actions need to be taken by EDFE and the NDA across the end-to-end defueling, transport and storage process, including plant modifications required to handle the increase in volume and rate of defueling, sourcing of critical spares, removal from across the AGR fleet of sufficiently cooled fuel to reduce overall pond fuel stocks, and the NDA ensuring that it has adequate capacity for the transportation and dismantling of fuel. Successful accelerated defueling will require Sellafield to receive, dismantle and store increased rates of fuel from the AGR stations, up from 200 tonnes of fuel to 300 tonnes annually. It said: “Experience gained from defueling the NDA- owned Magnox stations suggests that despite significant effort it was difficult to increase the rate from one to three flasks per week and it took several years to achieve the required performance.” According to the NAO report, all the parties (EDFE, NDA and


the government) agreed that, given its existing knowledge of the AGR stations and the sites, EDFE was best placed to take forward defueling. It said that: “We saw no evidence to suggest that transferring the stations prior to defueling


Right: New Heavy Goods Vehicle flask transporters are used to transport the fuel to the rail head for the journey to Sellafield.


22 | January 2026 | www.neimagazine.com


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