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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.”
Ken Nakajima, Masanori Akai
Nuclear Technology | Volume 113 | Number 3 | March 1996 | Pages 375-379
Technical Note | Fission Reactor | doi.org/10.13182/NT96-A35217
Articles are hosted by Taylor and Francis Online.
To investigate the accuracy of the neutronic calculations in various neutron spectra, the modified conversion ratios [(MCR): ratio of 238U capture rate-to-total fission rate] of four kinds of light water-moderated UO2 fuel lattices were measured. In the measurements, the relative reaction rates of 238U capture and total fission were obtained from the nondestructive gamma-ray spectrometry of 239Np and 143 Ce, respectively, which accumulated in the fuel rod irradiated at the Tank-Type Critical Assembly. The moderator-to-fuel volume ratios Vm/Vf of the measured lattices were 1.50 (undermoderate) to 3.00 (overmoderate). The measured MCRs were 0.477 ± 0.014(Vm/Vf = 1.50), 0.434 ± 0.013(1.83), 0.383 ± 0.011(2.48), and 0.356 ± 0.011(3.00), respectively. The Monte Carlo calculation employing the JENDL-3 library showed good agreement with the experiments for all the cores, although they showed a tendency of overestimation for larger values of MCR, as shown in the case of UO2 tight lattices. Therefore, it was concluded that, for the cores investigated, the accuracy of the neutronic calculation method currently used was very good.
