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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.”
Jeffrey A. Favorite
Nuclear Science and Engineering | Volume 155 | Number 2 | February 2007 | Pages 321-329
Technical Paper | Mathematics and Computation, Supercomputing, Reactor Physics and Nuclear and Biological Applications | doi.org/10.13182/NSE07-A2666
Articles are hosted by Taylor and Francis Online.
Standard variational estimates for perturbations in inhomogeneous transport problems were applied to internal-interface perturbations in coupled neutron-photon problems. Absolute gamma-ray line leakages and ratios of line leakages were the quantities of interest. Gamma-ray spectroscopy using the deterministic multigroup discrete-ordinates code PARTISN was accomplished with a 130-group neutron library and a 120-group photon library with narrow bins centered around gamma lines of interest. Perturbed integrals were evaluated using a volume and a surface formulation, and issues involving negative fluxes (required in the adjoint calculation for line ratios) were addressed. Numerical test problems used a 252Cf source surrounded by a material containing nitrogen and hydrogen; the thickness of this material was perturbed ±86%. The ratios of the 1.8848-, 2.2246-, and 5.2692-MeV thermal neutron capture lines were very well estimated using the variational estimates, even for macroscopic-size perturbations of internal interface locations; the volume-integral formulation for the perturbed integrals was generally more accurate than the surface-integral formulation for estimating ratios. For estimating absolute leakages, the Roussopolos functional in the surface-integral formulation was clearly superior when the gamma-producing shell was thickened, but it produced negative estimates when the shell was thinned.