Anthony Froggatt, IGov Team and Senior Research Fellow at Chatham House: 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.
IGov 9th May 2018 read more »
Cracks in the core of a Scottish nuclear reactor could signal that most of Britain’s ageing plants will not be able to supply the country with much needed power for as long as predicted. “These reactors are over 40 years old. This is a generic defect which cannot be fixed so it would not surprise me if the older plants would all need to close within the next few years,” said John Large, an independent nuclear engineering consultant. Britain’s electricity generation is under scrutiny due to a plan to close coal-fired power plants by 2025 and weak economic conditions for investment in new gas plants. There are also doubts about the timetable for EDF’s Hinkley Point C nuclear plant which is not expected to come online until the end of 2025, and the proposed Sizewell C plant, which is not even being built yet. French utility EDF said the Hunterston B shutdown was due to new cracks developing faster than expected in graphite bricks in one reactor’s core. These bricks are used in all 14 advanced gas-cooled nuclear reactors (AGRs) in Britain which drive seven out of eight of the country’s plants. “We believe that most of the AGRs will have their life limited by the progression of cracking,” Britain’s Office for Nuclear Regulation (ONR) says on its website, adding that this presents “unique challenges”. EDF Energy said the shutdown at the Hunterston B reactor would result in a forecast reduction of 3 terrawatt hours in its total nuclear output for this year. Based on current UK baseload power prices, that could equate to a loss of around 120 million pounds. The firm also says it has spent more than 100 million pounds in the last five years on graphite research. “The thing which will close (these reactors) down in the end will be the cost of ensuring safety. It is possible to make a safety case for a significant amount of cracked bricks but it takes time and costs money,” said Barry Marsden, professor of nuclear graphite technology at the University of Manchester.
Reuters 9th May 2018 read more »
