Why Queen Elizabeth-class carriers are conventionally powered

The Queen Elizabeth class uses diesel and gas machinery to combine economical worldwide cruising with high speed when required. Nuclear propulsion would require certification of the home ports intended to receive the ships, with cost and local approval forming part of that decision. Conventional machinery also makes foreign port visits and access to dry docks easier. It preserves the option of selling the ships after British service. A CATOBAR carrier of the same size brings a different argument for nuclear power, with oil-fired steam raised as the conventional alternative.