ST3283 : Uskmouth Powerstation If I recall right this gets a chapter in a textbook on mechanical disasters as one of the turbines had a runaway and distributed itself round the inside of the turbine hall. It's 30 years since I read this but I think it was to do with problems with contamination of the oil system and "graphitic" corrosion of the governor valve control system, resulting in a failure of valve closure when it most mattered.