Britain must build 14 new nuclear plants, setting aside fears over radiation leaks, because that is the cheapest way of meeting compulsory carbon reduction targets, according to the Government's climate change watchdog. The number of offshore wind turbines planned for 2020 should be cut by up to third, because they are too expensive. The Committee on Climate Change says heavy reliance on offshore wind could result in unacceptable increases in fuel bills.  The committee today delivers recommendations on how to meet Britain's EU obligation to increase the share of energy from renewable sources from 3 per cent to 15 per cent by 2020. It will also dismiss concerns over safety raised by the leaks from the tsunamihit Fukushima reactors in Japan. It says nuclear power, which produces no carbon dioxide, should play a central role in meeting its recommended target of cutting emissions by 60 per cent by 2030. The cost of meeting the target is expected to add at least ?50 to the average household's annual energy bills in the next ten years.  The watchdog's intervention comes amid nuclear industry fears that Japan's disaster could result in a delay in the approval of new reactors and an escalation in the cost of safety systems.  Dr Mike Weightman, the Health and Safety Executive's chief nuclear inspector, is due to deliver an interim report commissioned to review safety in the wake of the Fukushima leaks.  The committee expects him to concur with its own conclusion that "the likelihood of natural disasters of this type and scale occurring in the UK is extremely small". It adds that the reactor designs proposed in Britain "have benefited from considerable technological improvement since the 1960s Boiling Water Reactors used at Fukushima, including the incorporation of secondary backup and passive cooling facilities".  The committee's r