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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.”
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A thermal-hydraulic field analysis code using the finite element method is developed to analyze the effects of anisotropic turbulent diffusion and secondary flow on turbulent mixing, which is essential to the nuclear fuel performance analysis.

In this study a new model of anisotropic eddy viscosity is developed. The representative value of the anisotropic factor is determined from the scale relation that is derived on the basis of the flow pulsation phenomenon. The spatial distribution is deduced qualitatively from well-known experiments. The flow fields calculated by this code are compared with experimental data and show good agreements, and the predicted turbulent mixing rates are successfully compared with the scale relation derived in the authors' previous work.

The results show that the isotropic eddy viscosity model underestimates the mixing rate and gives the reverse trend as the gap size reduces, and the secondary flow has a minor effect compared with the anisotropic eddy viscosity in the turbulent mixing process. Although the mixing phenomenon of the flow pulsation is a convective process, it can be simulated only by the anisotropic model.