In March 2012, two of the big six power companies announced they would be pulling out of developing new nuclear power plants. The decision by RWE npower and E.ON followed uncertainty over nuclear energy following the Fukushima nuclear disaster, which had occurred the year before. Their decision followed a similar announcement by Scottish and Southern Electricity the previous year. Hitachi purchased the Horizon joint-venture, intending to build two or three 1350 MWe Advanced boiling water reactors (ABWR) at Oldbury and Wylfa.