Simplify the following text for a Grade 9 native English-speaking person.
Original: The most common nuclear fuels are uranium and plutonium but not all nuclear fuels are used in reactors .
Simplified: Any of the aforementioned fuels can be made with plutonium and other actinides as part of a closed nuclear fuel cycle . Metal fuels have been used in water reactors and liquid metal fast breeder reactors , such as EBR-II .