Candu Reactor : Darlington The Canadian Candu had its origins in the Manhattan Project. It fissions unenriched uranium in a moderator of heavy water to produce heat, steam, electricity--and plutonium. It produces plutonium more efficiently than any other reactor except the breeder. Canadians themselves refer to the Candu as a « near-breeder. » The Candu is used for peaceful purposes, but the plutonium in the bomb that India built came from a copy of the first Canadian heavy-watermoderated reactor. Pakistan, Argentina, and South Korea have operating Candu reactors.