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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.”
A. Tsechanski, M. Segev, G. Shani
Nuclear Science and Engineering | Volume 84 | Number 3 | July 1983 | Pages 226-233
Technical Paper | doi.org/10.13182/NSE83-A17791
Articles are hosted by Taylor and Francis Online.
Integral experiments with a large graphite stack and fast neutron spectra calculations are described. A well-collimated beam of (14.75 ± 0.05) MeV (D,T) neutrons from a generator incident on the graphite resulted in a neutron spectrum that strongly correlated with the fine structure of the carbon nuclei, including anisotropy of elastic and inelastic scattering to first levels. This experimental approach is easier and more straightforward from the calculational point of view than one with a neutron source inside of a stack. The neutron spectrum measurement was performed by an NE-213 liquid scintillator using a pulse-shape discrimination technique to reject gamma-ray counts. The unfolding of the proton recoil spectrum was done by the FORIST code. The calculations were performed using the DOT 3.5 two-dimensional discrete ordinates neutron transport code incorporating the ENDF/B-IV cross-section library with the ETOG III group cross-section generating code. Comparison between measured and calculated spectra showed a reasonable agreement in the 1- to 8-MeV energy range. On the other hand, great discrepancies (up to an order of magnitude) are revealed in the range from 8 to 10.5 MeV. It was found that these discrepancies are due to the fact that the ETOG III program does not take into consideration the angle/energy correlation in inelastic scattering. Including the angle/energy correlation in inelastic scattering drastically improved the agreement between measurements and calculations in the inelastic scattering range to the first level of the carbon. The calculated spectrum in the 7- to 10.5-MeV range, i.e., in the inelastic scattering range, was found to be very sensitive to the anisotropy distribution of inelastic scattering to the first level. Therefore, these kinds of integral experiments (with a monoenergetic collimated neutron beam introduced from outside) supply direct data on the anisotropy of both inelastic and elastic scattering.