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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.”
Yimeng Chan, Sicong Xiao
Nuclear Science and Engineering | Volume 194 | Number 7 | July 2020 | Pages 554-571
Technical Paper | doi.org/10.1080/00295639.2020.1752045
Articles are hosted by Taylor and Francis Online.
The recently developed linear prolongation Coarse Mesh Finite Difference (lpCMFD) acceleration scheme, which employs a linear additive approach to update the scalar flux, has been shown to be more stable and effective than the conventional scaling-based Coarse Mesh Finite Difference (CMFD) method for accelerating the discrete ordinates (SN) neutron transport calculation using spatial finite difference discretization. In this paper, we study and extend the application of lpCMFD to accelerate the SN neutron transport calculation with spatial discretization using the Discontinuous Galerkin Finite Element Method (DGFEM), which generally involves linear- or higher-order space expansion functions. A function space mapping operator is proposed in this paper to project the lpCMFD linear-order correction flux to an arbitrary-order DGFEM basis function, which is implemented and tested on a one-dimensional (1-D) in-house–developed DGFEM-based SN code. The consistency between the lpCMFD accelerated results and the pure SN results is naturally guaranteed by employing upwind current information from DGFEM-based SN transport calculation to evaluate the drift coefficient. It was found from our numerical testing with the CMFD and the lpCMFD acceleration schemes on single-group fixed-source and k-eigenvalue problems that both acceleration schemes can reproduce the unaccelerated scalar flux and keff, respectively. Further numerical testing on a more realistic case is performed on a 1-D slice multi-energy-group problem based on the three-dimensional C5G7 mixed oxide (MOX) benchmark. It was found that by using the function space projector proposed in this paper, lpCMFD was stable and effective to accelerate the DGFEM-based SN neutron transport calculation for all coarse mesh sizes tested while CMFD diverged for large optical thickness.
