Horizon Nuclear Power, the UK subsidiary of Hitachi Ltd, said today it was joining forces with Exelon Generation as Horizon develops its "expertise and capability" to operate a new nuclear power plant at Wylfa Newydd on the Isle of Anglesey. Exelon Generation operates the biggest fleet of nuclear power plants in the USA, with 19,460 megawatts of capacity from 22 units, eight of which are boiling water reactors. The Wylfa Newydd project will deploy two Advanced Boiling Water Reactors.