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General Kenneth Nichols and the Manhattan Project
Nichols
The Oak Ridger has published the latest in a series of articles about General Kenneth D. Nichols, the Manhattan Project, and the 1954 Atomic Energy Act. The series has been produced by Nichols’ grandniece Barbara Rogers Scollin and Oak Ridge (Tenn.) city historian David Ray Smith. Gen. Nichols (1907–2000) was the district engineer for the Manhattan Engineer District during the Manhattan Project.
As Smith and Scollin explain, Nichols “had supervision of the research and development connected with, and the design, construction, and operation of, all plants required to produce plutonium-239 and uranium-235, including the construction of the towns of Oak Ridge, Tennessee, and Richland, Washington. The responsibility of his position was massive as he oversaw a workforce of both military and civilian personnel of approximately 125,000; his Oak Ridge office became the center of the wartime atomic energy’s activities.”
Timothy S. Roth, A. Biancheria
Nuclear Technology | Volume 77 | Number 1 | April 1987 | Pages 50-59
Technical Paper | Material | doi.org/10.13182/NT87-A33951
Articles are hosted by Taylor and Francis Online.
A computer graphics technique was used to measure cracks and other features of mixed-oxide fuel ceramographs to provide information useful for the modeling of fuel cracking and fragment movement. These measurements provided qualitative and quantitative information in several areas: crack formation and fuel-fragment movement, fuel-cladding gap size, crack size, crack orientation, radial distribution of crack porosity, and change in fuel volume (referred to as total fuel swelling) as a function of oxygen-to-metal ratio (O/M) and burnup. Examination of the ceramographs indicated that a crack starts on a free surface and propogates until it reaches another free surface. Thus, the first crack extends from one side of the fuel to the other, and succeeding cracks terminate on existing cracks or on the fuel surface. While crack formation was found to be independent of O/M, differences in crack healing at moderate power (19 kW/m) and high burnup (12 at.%) lead to a predominance of radial cracks for high O/M (∼1.96) fuel and both radial and circumferential cracks for low O/M (∼1.92) fuel. The different effects of circumferential and radial cracks on fuel behavior produce smaller postirradiation fuel-cladding gaps and larger cracks in the lower O/M fuel pins. Fuel swelling at intermediate burnup (∼8 at. %) is independent of O/M, but at high burnup (∼12 at. Vo) lower O/M fuel swells more. This swelling behavior may be related to a similar O/M dependence of retained fission gas.