Power systems developer Rolls-Royce has bagged a bumper contract with the Ministry of Defence (MoD) to supply reactor cores for the UK's nuclear-powered submarine fleet.In a deal worth more than £1bn the UK engineering colossus will also undertake to spruce up the current Rolls-Royce submarine reactor core manufacturing facility in Derby.Rolls-Royce will continue to maintain and operate its existing reactor core manufacturing facility in Derby, while at the same time completing a phased rebuild to provide a leading-edge manufacturing facility to support future MoD programmeneeds.Shares in Rolls-Royce were 6p higher at 828p after two hours of trading on the day the contract win was announced.