These four lightbulbs augured a future with nuclear power. Argonne National Laboratory via FlickrFlickrDeep in the sagebrush steppe of southeast Idaho on December 20, 1951, a team of nuclear physicists gathered around four 200-watt lightbulbs dangling from a slack wire. Then, Harold Lichtenberger, the project manager, flipped a switch. The bulbs lit up. Most of the time, flipping a light switch doesnt need an audience. The team of scientists was reportedly nonchalant, too. This is it, one scientist said when the bulbs illuminated, according to Rick Michal in Nuclear News.But this was no mere flick of the finger: For the first time in history, a nuclear reaction had generated a significant amount of electricity.For the time being, it only powered four bulbs. But the future looked bright from the small brick building outside of Arco, Idaho.Development of the Experimental Breeder Reactor-I, as the reactor that powered the lightbulbs was known, began in the late 1940s, as the United States government sought to develop a nuclear reaction process that would extend its finite supply of uranium.Uranium-238 is uraniums most relatively abundant isotope, making up 99 percent of the naturally occurring form of the element. However, unlike the scarce and radioactive uranium-235 isotope, uranium-238 is stable and nonfissionable without high-energy neutrons.A breeder reactor, like the one scientists in Idaho were trying to build, converts uranium-238s nonfissionable material into fissionable material more rapidly than the nuclear fuel is consumed, Popular Mechanics explained in 1952, a process that would contribute to expansion of our atomic program.As scientists initiate the process of artificial nuclear decay, uranium-238 atoms absorb neutrons in the reactor core, becoming relatively more fissionable plutonium-239 atoms. When a plutonium nucleus in a breeder reactor is hit with a high-energy neutron, it splits, releasing heat and more neutrons. The process becomes a self-sustaining source of energy, in the form of heat, as the reaction continues.A secret 1949 government feasibility report written by Lichtenberger, Walter Zinn and Aaron Novickall veterans of the United States top-secret Manhattan Project that furthered nuclear research and created the worlds first nuclear weaponsconcluded that from the nuclear point of view there is much attraction toward a fast neutron reactor for breeding.Experiments with EBR-I began in early 1951. In the compact brick building, a complex process of nuclear reactions took place leading up to the moment when Lichtenberger flipped that switch.First, a liquid metal coolant consisting of an alloy of sodium and potassium flowed through the reactor core, where it absorbed heat from the artificial decay process. As it returned back to its supply tank, it transferred its heat to a secondary liquid metal coolant, which was pumped to a boiler, transferring heat to water and generating enough steam to turn a turbine.At 1:50 p.m. on December 20, as Lichtenberger flipped the switch, the first electricity generated from nuclear energy flowed from the turbines into the four lightbulbs.When I turned the switch, Lichtenberger later told The Idaho Statesman, I guess I was more interested in how the circuit breakers would function than I was in the significance of the test.In fact, power production, Atomic Energy Commission officials told the Statesman, was merely incidental to the experiments main goals: measuring the efficacy of the breeder process and converting nonfissionable material into fissionable material. The generation of electricity was simply a side project.The next day, the EBR-Is output reached 100 kilowatts, powering all the electronics in the building, another promising indication of the development of nuclear power.Interest in breeder reactors waned after the 1960s as the available global uranium supply increased and scientists developed more efficient enrichment methods. But the little brick building near Arco still proudly calls itself the Worlds First Nuclear Power Plant. Get the latest stories in your inbox every weekday.Filed Under: Electricity, Environment, Nuclear Power, On This Day in History, Physics, Sustainability