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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.”
M. T. Pigni, M. Herman, P. Oblozinsky
Nuclear Science and Engineering | Volume 162 | Number 1 | May 2009 | Pages 25-40
Technical Paper | doi.org/10.13182/NSE162-25
Articles are hosted by Taylor and Francis Online.
We generated, for the first time, a very comprehensive set of estimates of cross-section covariance data in the neutron energy range of 5 keV to 20 MeV. The covariance matrices were obtained for 307 materials, from 19F to 209Bi, covering structural materials, fission products, and heavy nonfissile nuclei. These results offer model-based, consistent assessments of covariance data for nuclear criticality safety applications. The evaluation methodology combines the nuclear reaction model code EMPIRE, which calculates the sensitivity of the cross sections to nuclear reaction model parameters, and the Bayesian code KALMAN, which propagates uncertainties of the model parameters to these cross sections. Taking into account the large number of materials studied, we refer only marginally to experimental data. The covariances were derived from the perturbation of several key model parameters selected by the sensitivity analysis. These parameters refer to the optical model potential, the level densities, and the strength of the preequilibrium emission. Our work represents the first attempt to generate neutron cross-section covariances on such a large scale.