HAZARDS AND WASTES: MET LAB AND OAK RIDGE

• Fuel and Target Fabrication
• Reactor Operations
• Chemical Separation
• Met Lab and Oak Ridge Hazards and Wastes
• Hanford Hazards and Wastes

Plutonium and enormous amounts of waste byproducts from the production and separation of plutonium comprised the vast majority of the total amount of radioactivity produced by the Manhattan Project. More potentially hazardous than uranium, plutonium and its man-made byproducts were much less widespread. Only in piles or reactors were significant amounts of plutonium created. Production of plutonium and its byproducts was minimal at CP-1, much greater at X-10 in Oak Ridge, and exponentially greater in the production reactors at Hanford. Plutonium was present at Los Alamos, but the volumes of waste and levels of radioactivity were considerably less than at Oak Ridge and Hanford.

The Manhattan Project's health physics and waste management programs began at the University of Chicago's Met Lab. Concern about radiation exposure arose immediately after the founding of the laboratory in early 1942 and focused primarily on the plutonium production process with its high levels of radioactivity and toxicity. At a major Met Lab chemistry conference in April, project scientists addressed issues of waste disposal, contamination of air and ground water, and radiation exposure and protection of workers from radiation effects. Met Lab Director Arthur Compton sought to build the first actual pile at a site in the Argonne Forest, about twenty-five miles southwest of Chicago, "where the hazards would be minimized." Labor and other difficulties, however, delayed construction at the Argonne site, and Compton, convinced by Enrico Fermi that calculations were reliable enough to preclude a catastrophic run-away chain reaction, authorized construction of the CP-1 pile on campus at Stagg Field. Fearing rejection, Compton sought approval for this decision from neither General Groves nor the University of Chicago administration. Precautions to protect both workers and the public were considerable. All workers in potentially hazardous areas received pocket monitoring devices. Special controls were developed for the chain-reacting pile. Control rods limited the reaction, with a principal safety rod, known as ZIP, which automatically engaged should radiation levels become dangerously high. On December 2, 1942, Fermi shut down the pile on its initial run, after only several minutes of operation and an energy release of less than one watt, because of an increase in radioactivity in the room. Sustained operations awaited removal to the Argonne site in February 1943.

Argonne also had been Compton's choice for a pilot production reactor and separations facility, with full-scale production reactors to be built at Oak Ridge. When calculations indicated that a pile meltdown might deposit radioactivity in "lethal concentration over an area of 5-mile radius," Compton agreed to construct the pilot facility at Oak Ridge. Potential hazards at the pilot facility posed more serious challenges than any encountered at the Met Lab. CP-1 operated at a power level of half a watt, with brief intervals at 200 watts. The X-10 reactor at Oak Ridge was designed for a power level of 1,000 kilowatts. In addition to the considerably greater power output, the X-10's irradiated fuel contained hundreds of different fission products, or radioactive isotopes, which had to be separated from the plutonium and residual uranium.

Releases into the environment, both inadvertent and intentional, were a concern from the earliest design stages. The X-10 cooling system consisted of outside air being pumped by a 50,000 cubic-feet-per-minute fan through the graphite pile and a filter system and out a 200-foot stack. A "substantial percentage" of the pile's fission activity would go up the stacks. A similar exhaust system existed for the separation facility, with radioactive xenon, iodine, and bromine being vented. Safety officials did not anticipate any major problems with these planned operational releases, with one official noting that "process catastrophe" seemed to be the "only means which would cause excessive activity to be unduly distributed in the atmosphere." Operational experience confirmed these expectations. No significant accidental releases occurred, and routine releases of gaseous effluents were closely monitored.

Safe disposal of the X-10 separation facility's liquid wastes, which contained most of the radioactivity produced at the site, proved more challenging. The DuPont Corporation built six underground concrete storage tanks to hold the anticipated high activity liquid wastes. Each of the 176,500-gallon tanks was lined on the inside with bituminous paint to protect against hairline cracks, with an additional concrete layer installed to protect the bituminous coat. High activity wastes consisted of "metal wastes" containing the residual uranium that had not been converted to plutonium and about 90 percent of overall waste radioactivity and non-metal or "chemical wastes" containing most of the remaining 10 percent. With the two types of waste held in separate tanks, officials had estimated that using the lanthanum-fluoride separation process one tank would hold 100 days' worth of metal wastes and a year's worth of chemical wastes, allowing for sufficient tank capacity for the intended one-year operation of X-10. The decision to use the bismuth-phosphate separation process, however, meant that anticipated chemical wastes increased about five times in volume and available tank space was now inadequate. As the tanks began to fill in early 1944, officials found that over 90 percent of the radioactivity in the chemical wastes precipitated out in the tanks, leaving a supernatant liquid containing only about .7 percent of the overall radioactivity involved in the separation process. They determined that 5,000 gallons per day of the liquid, properly diluted with wastewater, could be released to White Oak Creek and eventually the Clinch River via holding ponds. Higher-than-anticipated levels of radioactivity in mud on the bottom of White Oak Creek resulted in suspension of the releases for several months. Construction of an additional pond to be used as a settling basin helped ease concerns, and by late 1944 the handling of liquid wastes had become largely routine.

• Fuel and Target Fabrication
• Reactor Operations
• Chemical Separation
• Met Lab and Oak Ridge Hazards and Wastes
• Hanford Hazards and Wastes

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