CHAPTER 4
Sitting in the warehouse for two full years, the Staten Island northshore site became fully contaminated. The uranium cache was finally sold by Belgian importer Edgar Sengiere, to Colonel Kenneth Nichols of the US Army for $1.35 per pound (September 1942). This uranium ore was reduced to solid metal in Bloomfield, New Jersey; a process which exposed uranyl nitrate to sunlight in opened rooftop evaporating tanks. Metallic uranium powder was obtained by electrolyzing the resulting green salts. Pressed into briquettes and melted in vacuum into 1 inch-diameter wafers, the discs were priced at $2000 each. The factory produced a little more than 1 pound uranium metal per month. In upscaled production, the sunlight process produced 65 tons of uranium metal at the original New Jersey site.
On Boston’s northshore, industrial chemists melted a mixture of uranium ore with calcium compounds. Hundreds of pounds uranium powder were produced by this method. The highly reactive metal powder, capable of bursting into flames in air, was packed around with crushed dry ice. These were each shipped in one gallon dry ice covered containers to MTT for vacuum melting. This method was much improved by the mixing of uranium tetrafluo-ride salt with pure calcium. The resultant product produced 6 parts pure uranium metal for every 10 parts tetrafluoride salt. Vacuum melted, these castings measured 2 inches in diameter and 5 inches long. Each casting weighed 11 pounds. Later magnesium was mixed with uranium tetrafluoride and melted, a process which produced 100 pounds pure uranium metal weekly. Mallinckrodt, in St. Louis, developed an ether purification process which produced one daily ton of uranium metal. Every vessel, every accoutrement, every bit of ground, or laboratory table, shipping room floor, or workmen’s aprons…everything was contaminated with the radioactive poison. The dust lingered for years in locations which merely shipped the dust Hapless machinists, mere cogs in the radioactive machine, were later given highly purified uranium castings for tooling. The flakes which fell from lathes, yet hopelessly contaminated with the poisoning, exploded into smoky flames. Now what of those innocent souls who held castings and tools together, breathing radioactive smoke, and who stooped to pick up each burning flaie?
The developmental problem was not now one which lacked for high grade uranium metal, but for high grade fissile uranium. Now the problem was to obtain the highly purified U-235 isotope, a natural rarity, and produce it in large quantities. Only the nuclei of neutron-emitting U-235 atoms could be made to ring like a bell and split into neat fragments. This was “bomb material”. This would only happen when the nuclei were made to absorb more neutrons. But U-235 percentages in metallic uranium were low, a weak 0.7 percent of the supply. Furthermore, the separation of fissile U-235 from natural U-238 was problematic on several engineering levels. The other possible material was plutonium, another fissile element altogether. Theory taught that smaller amounts of plutonium would produce more violent fissile energies than the now-precious uranium-235.
Thermal diffusion, directed by Philip Abelson at the NRL, was pioneered in Nazi Germany. Thermal diffusion separated isotopes by placing thermal gradients across isotope rich solutions, mass differences separating the isotopes. A thermal diffusion pilot plant was managed by Naval Authority in Philadelphia. Gaseous diffusion, directed by John Dunning of Columbia University, required greatest care, an engineering nightmare. Heated until it became a caustic radioactive gas, uranium isotopic mixtures were pressured through an extensive baffle of filters. Diflusion separated the relatively light U-238 nuclei from those slightly heavier U-235 nuclei. Both of these processes were time consuming and dangerous, a chemical engineering nightmare. The gaseous diffusion method was the most hazardous method, provoking a great deal of concern. There would be no permissible accidental oversights. The nature of these unnaturally concentrated elements was found not to be a forgiving one. Enrico Fermi successfully designed a workable atomic “reactor” (December 2, 1942). Chain reactor conversion, pioneered by Dr. Fermi, irradiated uranium slugs with neutrons, gradually building plutonium over a period of months. Magnetic separation, a method proposed by Nobel Laureate, Dr. Ernest Lawrence, seemed to be the quickest means for separating uranium isotopes. His miniature models at Berkeley successfully produced milligrams of 30 percent pure U-235. Larger systems would separate and purify isotopes with speed and in quantity.
Government authority stepped into highest gear now, allocating funds and lands which dwarfed all the previous expenditures. Two work sites were chosen, each for their remoteness and proximity to hydroelectric energy sources. One site was constructed in Hanford, Washington. Hanford was built around three Chain Reactors, B, D, and F, for the production of plutonium, and a large adjacent separation plant. The other site, in Clinton, Tennessee, became popularly known as Oakridge. This was the site of several different isotope separation systems. The 2 Megawatt Chain Reactor (X-10), gaseous diffusion plant (the “gasworks”, Project K-25), thermal diffusion plant (the “fox farm”, Project S-50), and the magnetic separator (the “racetrack”, Project Y-12). It is quite obvious that government bureaucracy was given full authority to engage all possible means for producing fissile materials at any cost. So great was the fear that hostile others would appropriate the knowledge and loose the terror first. Save in the D-Day Invasive Force, where lives and machines flooded the seas, never before in history had such unlimited funding been expended.
The first plant to begin production was the Y-12 of Dr. Lawrence. The device required to rapidly manufacture this material had to be many times more powerful than any cyclotron in existence. Calculated at 12,000 times the combined acceleration and volume transport of any existing cyclotron, twelve of these huge magnetic separation systems (CALUTRONS) were constructed. Each such system required tons of iron core material and equivalent tonnages of silver magnet wire. Nearly 400 million dollars worth of pure silver was convoyed from West Point to Bayway, New Jersey, where it was formed by Phelps Dodge. This wire was then trucked in convoy to Milwaukee, where the thick silver ribbon was wrapped around massive iron cores. These gigantic magnet sections were shipped to Clinton on opened flatbed trucks, a total of 14 thousand tons of silver ribbon (see figure).