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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.”
W. O. Doggett, Fred A. Bryan, Jr.
Nuclear Science and Engineering | Volume 39 | Number 1 | January 1970 | Pages 92-104
Technical Paper | doi.org/10.13182/NSE70-1
Articles are hosted by Taylor and Francis Online.
Berger et al. of the National Bureau of Standards have utilized the Monte Carlo method to calculate total scatter differential dose transmission and reflection coefficients for plane unidirectional gamma rays incident on concrete barriers of finite thickness. These calculations were performed for source energies of 0.2, 0.4, 0.66, 1.25, 5.0, and 10.0 MeV with incident obliquity angles cos θ0 = 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.01; emergent obliquity angles cos θd = 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.01; emergent azimuthal angles relative to the ongoing incident ray = 0, 30, 60, 90, 120, 150, and 180 degrees; and slab thicknesses of 0.25, 0.5, 0.75, 1, 2, 3, and 4 mean-free-paths. These data are used herein to compute dose rate slant penetration and reflection probabilities for a detector located adjacent to a barrier. The total scatter contribution was calculated by numerically integrating the Monte Carlo data of Berger et al. over the 2π solid angle subtended by the barrier relative to the detector location. In addition to results for the above listed thicknesses, energies, and incident obliquities, slant penetration and reflection probabilities are computed for the 1.12 h unfractionated fission spectrum by interpolating and weighting the Monte Carlo data at appropriate energies and thicknesses. The probabilities obtained herein compare favorably with those obtained by the Spencer-Fano moments method for an infinite medium, with other Monte Carlo studies, and with experimental data.