Cracking in reactors should break open the debate on future electricity supply
Anthony Froggatt, IGov Team and Senior Research Fellow at Chatham House, 9th May 2018
The UK has one of the world’s oldest nuclear commercial fleet. In 2017 nuclear provided 63.9 TWh or 19.3 percent of electricity, down from a maximum of 26.9 percent in 1997. Across the UK 30 reactors have been permanently closed, the 12 first-generation Magnox plants, with 26 reactors, 2 fast reactors, an Advanced Gas-cooling reactor at Windscale and a Steam Generating Heavy Water Reactor (SGHWR) at Winfrith.
The remaining seven second-generation nuclear stations, each with two Advanced Gas Reactors (AGRs), are at or near the end of their operating lives. However, the owner EDF Energy is planning to keep them open and has agreements with the regulator to extend the operating lives for either seven years (Hinkley Pont B, Hunterson B, Heysham 2 and Torness) or ten years (Hartlepool, Heysham 1, Dungeness B). The country’s only PWR, at Sizewell B, is scheduled to close in 2035.
Life-extension has been an important strategy for the UK’s nuclear industry as its plans to build new reactors this decade has failed. The most advanced project at Hinkley Point C, which EDF said would be generating electricity this year, is still not even officially under construction, and therefore won’t generate any power before the mid-2020s at the earliest. In addition, the financial problems of both Hitachi and Toshiba/Westinghouse (the parent companies of NuGen and Horizon, the other proposed nuclear builders) mean that the completion of the other nuclear projects before the end of next decade is doubtful at best. Despite this press reports suggest that the Government is now willing to offer new financial support to Hitachi, in the form of loan guarantees, to stop the project being abandoned.
Managing reactors as they age is now a global concern and the AGRs are no exception. Most recently new keyway root cracks have been found in graphite bricks in the core of the Hunterston B reactor. These have been occurring at a rate slightly higher than had been predicted. This is a particular safety concern as this can lead to the degradation and therefore the efficient operation of the keying system, which houses the fuel and control rods and enable the cooling (Co2) to circulate A paper published by the IAEA warns that “Cracks that rapidly propagate are likely to cause a second key-way crack on the opposite side of the brick almost instantly – splitting the brick in two.” This issue may well become a life limiting factor for the AGRs, as it is not possible to replace the bricks and questions have been raised if the reactor in question will be able to restart. However, EDF Energy say that they expect the unit will return to service before the end of 2018.
As it currently stands the remaining 8.9 GW of nuclear capacity will close over a 12-year period, starting in 2023. However, rather than wondering if the AGRs could be given further life extensions, questions should now be asked about the supply implications if some, or all, of the AGRs are unable to operate as envisaged. With Brexit raising questions about the financing and schedules for some interconnections, government policies slowing down the deployment of onshore renewables despite their tumbling costs, and the existing plans for the closure of the remaining coal stations, urgent consideration must be given to ensure supply, energy efficiency and flexibility from now on.
Onshore and offshore renewables need to be at the heart of the future system. This would be good for the environment and competitiveness, as the last few years have seen a remarkable change in economics of renewable energy and it is now recognized that by 2020 electricity from renewables will be ‘within the fossil fuel-fired cost range, with most at the lower end or undercutting fossil fuels’ and are already significantly lower than the current prices offered for nuclear new build.