The cost of decommissioning the UK’s 20th-century nuclear waste could rise to £260bn as the aged and degrading sites present growing challenges, according to analysis presented to an international group of experts. As the government pursues nuclear energy with the promise of a new generation of reactors, the cost of safely cleaning up waste from previous generations of power stations is soaring. Degrading nuclear facilities are presenting increasingly hazardous and challenging problems. Ageing equipment and electrical systems at Sellafield, which is storing much of the country’s nuclear waste and is one of the most hazardous sites in the world, are increasing the risk of fire, according to the Nuclear Decommissioning Authority. They require increasing maintenance and present growing risk. Last October a faulty light fitting started a blaze at a Sellafield facility which led to its closure for several weeks. Analysis by Stephen Thomas, a professor of energy policy at the University of Greenwich, estimates the total bill for decommissioning the UK’s nuclear waste mountain will grow to £260bn. Thomas told a conference of international experts the cost of decommissioning Sellafield had risen from to £110bn, according to freedom of information requests. Other sites that need decommissioning are the 11 Magnox power stations, built between the 1950s and 1970s, including Dungeness A in Kent, Hinkley Point A in Somerset and Trawsfynydd in north Wales, and seven advanced gas-cooled reactors built in the 1990s, including Dungeness B, which closed last year, Hinkley Point B and Heysham 1 and 2 in Lancashire. Deterioration of one of the Magnox stations, Trawsfynydd, which shut down in 1991, is such that substantial work is needed to make it safe, according to the NDA. “Work that would then need to be undone to complete reactor dismantling,” the agency said. Thomas told the International Nuclear Risk Assessment Group similar problems are expected at other Magnox sites. The timetable for decommissioning the old nuclear power stations has been abandoned, with no new timescale yet published. The Nuclear Waste Service has said deferring decommissioning for 85 years from shutdown, which was previous policy, is not suitable for all the reactors because of their different ages and physical conditions. Decommissioning of some Magnox stations will have to be brought forward, the NWS has said. Attempts to speed up the decommissioning would only add to the growing bill, Thomas said, which he estimated had increased to £34bn. In 2005, the cost for decommissioning and disposing of the radioactive waste from nuclear power stations built in the 1950s, 70s and 90s was put at £51bn. Last year the NDA estimates rose to £131bn, and its latest annual report said £149bn was needed to pay for the clear up. But Thomas said rising costs meant the total bill was on track to reach £260bn. Part of the soaring increase is the cost of building a large underground nuclear waste dump or geological deposit facility (GDF) to safely store the 700,000 cubic metres of radioactive waste – roughly the volume of 6,000 double decker buses – from the country’s past nuclear programme. The mammoth engineering project was initially predicted to cost £11bn but the bill is now estimated to be up to £53bn because of uncertainty about where the site will be located, and the need to provide space for an unspecified amount of waste from the new generation of nuclear reactors which the government wants to build. Four areas of the country are being considered for the GDF but no decision on where it will be located has yet been made. “While we are clear about the current legacy of waste which already exists, a GDF would have to handle additional waste from new facilities being developed,” the NWService said. “The actual cost will … depend on the number of new nuclear projects that the UK develops in future and any additional waste from those stations.” The cleanup of past nuclear waste will take more than 100 years, the NDA has said. Highlighting the challenges of the degrading and hazardous facilities, the authority said in its annual report that robots and drones were increasingly being used to carry out site inspections.