Separate the Boys from the Men





College 10


11.5.99





Uranium-235 and Plutonium-239 ensured both inspiration and heartache for all on the frontlines. Purely on a scientific level, the propensity, potential and dense complications of the two were sure to plague, drive and crush the souls of many. These two isotopes were the only source that could give way to the construction of nuclear weapons. Because the elements had so much potential unprecedented power and presented clarity in murky manic wartime, the pressure to develop them quickly went beyond profound. The Manhattan Project presented an industrious diagram of how to manufacture these bombs in time to affect the outcome of the war. Two separate simultaneous projects were implemented to derive substantial amounts of the isotopes to produce nuclear weapons. The trajectories were different as were their consequent embodiments: Fat Man and Little Boy.


Obviously, one of the main difficulties in the production of P239 was extracting it sufficiently from uranium. Separating uranium in a chain-reacting pile gave the garden. But the plutonium had to be weeded out substantially. The massive production piles created the element at a maximum concentration in the uranium of about 250 parts per million. This number could have been disheartening, a vehicle had to be used to propel enough uranium to engender plutonium. A few methods were proposed, their voices being heard in a two day conference on Wednesday April 23rd, 1942. The scientists discussed seven different ways to extract plutonium from uranium. All seven projects underwent examination. The prospect of chemical separation was overwhelming. The piles were so heavy with radioactivity, all but the final chemical processing had to be carried out by remote control behind thick shielding. The pile production plants posed a burden of danger; for safety the separate plants around Hanford went up behind Gable mountain ten miles southwest of the riverside piles. The mere construction of a plant was an arduous feat.


Assembly of the implosion bomb was extremely arduous. There were numerous difficulties in the construction. The high explosive castings had to be machined in order to turn out the necessary molds. George B. Kistiakowsky, in finishing castings by machining, found the molds to be the largest problem for the HE components of the bomb totaled: “something in the nature of a hundred or so pieces, which had to fit together to within a precision of a few thousandths of an inch or a total size of five feet and make a sphere. So we had to have very precise molds.” Molds at hand casting HE was a whole other complicated process being understood as they went along. This was not a field that had been explored, there was no blueprint, the blueprint for assembly was being created in the assembly. The time factor than was beyond frustrating. The castings required specific kinds of cooling so as to guarantee implosions. If not, air bubbles in the middle or separations of solids and liquids would prevent implosion. These are just a few of the taxing levels in the channeling of plutonium into the assembly of Fat Man.


Electromagnetic isotope separation plants and gaseous diffusion plants, were what separated U-235 from U-238. With the development of these vehicles as a means to sufficiently quantify enough material for an atom bomb, it is fully realized the necessity of two independent projects. The method of electromagnetic separation was inherently problematic and difficult. As Ernest Lawrence’s staff put it: “depends on the fact that an electrically charged atom traveling through a magnetic field moves in a circle whose radius is determined by mass”-essentially light U235 atoms would travel a narrower arc than heavier U238 atoms. Upon arriving a collection pocket would pose to catch the ions and isolate them. What this meant was a long microscopically tiered process:”Lawrence was proposing to separate uranium atom by individual atom.” Berkeley summer study group had estimated 30 kilograms of U235 for an efficient atomic bomb (inexorably fatal), the formula was 2000 calutrons separating 100 grams a day to ensure a viable bomb core every 300 days. The lengthy time was a gamble on a system that had not proved itself reliable. The confiden ce in this mode of production of uranium made no claim of material support, an insured difficulty was the theoretical