b'P ROVING THE P RINCIPLEuranium, because now the abundantMaking Enriched Ura n i u m non-fissioning isotope could becomefuel. More profoundly, it would providea revolutionary abundance of energy ina world constantly craving more. That aT hroughout the Cold War, gaseous diffusion was a fuel could replace itself in the veryreliable way to make enriched uranium. The first process of consuming itself, perhapsstep was to change the solid urani- breed even more than the originalum oxide into a gas called uranium amount, was a fabulous possibility.hexafluoride. The gas was then circu-lated thousands of times through fine General Groves approved Zinns pro-filters with tiny openings. The lighter posal, observing that independentU-235 atoms passed through the fil- reviewers would have to agree the reac-ters slightly more easily than U-238. tor could safely operate near Chicago.As it turned out, the decision would notGradually the percentage of U-235 in be Groves to make, and Zinns ideathe gas increased, and it was said to along with many othershad to wait abe enriched. The gas was then con- few years while Congress rearrangedverted back to a solid form and the nuclear enterprise as a peace-timeshaped into rods or pellets. These institution. Those years brought a morewere placed in tubes made of alu- U.S Department of Energy 094 054 001 pessimistic outlook for world peace andminum, zirconium, or stainless steel. many other changes, but none of themThese cladding metals do not inter- challenged Zinns logic. Uraniumfere with the passage of neutrons, but remained costly, and the breeder projectthey do protect the uranium from air remained high on any list of proposedand water corrosion and provide a experiments. 10path for the heat to leave the fuel.Congress passed the Atomic EnergyDepending on its intended use, urani- Act in August 1946. The governmentum can be enriched to any percentage continued to monopolize uranium anddesired. The uranium in bombs is one plutonium. The military handed controlhundred percent enriched. Test reac- of atomic weapons factories and labora-tors, which require a rich flow of Oak Ridge National Laboratory tories to a new civilian agency, theneutrons, need uranium enriched up to ninety-five per- Above. Worker holding Atomic Energy Commission (AEC),cent. Uranium in commercial power reactors is typical- simulated nuclear fuel headed by five commissioners.ly two percent to four percent enriched.pellets. Below. Exterior of Advisory committees assured that thethe Gaseous Diffusion military would influence the distribu-Plant in Oak Ridge, tion of uranium for defense purposesTennessee. and help decide on the allocation ofresources for defense research.2 4'