5 1951 Light from Nuclear Energy On Dec. 20, 1951, Experimental Breeder Reactor No. 1 produced enough electricity to power four lightbulbs. From this modest start, the civilian application of nuclear energy became a reality. EBR-I achieved full-power operation the next day.The liquid metal sodium-potassium alloy (NaK) used as coolant produced a high-temperature low-pressure operation, both conducive to efficient power production. In 1953, EBR-I proved that a nuclear reactor designed to operate in the high-energy neutron range could create more fuel than it consumed (“breeding”). “ Electricity flows from atomic energy. Rough estimate indicates 45 kw.” — Walter Zinn’s entry in the EBR-I logbook at 1:23 p.m. on Dec. 20, 1951