 The breeders were designed to create more fissile material than they consumed.By 1948, he had become convinced that it would be unwise to build large experimental reactors near Chicago, and the AEC acquired land around Arco, Idaho, which became an outpost of Argonne.The Experimental Breeder Reactor I (EBR-I, but known at Argonne as "ZIP" — Zinn's Infernal Pile) was the first reactor to be cooled by liquid metal, and the first to produce electricity.