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Members are devoted to applying nuclear science and engineering technologies involving isotopes, radiation applications, and associated equipment in scientific research, development, and industrial processes. Their interests lie primarily in education, industrial uses, biology, medicine, and health physics. Division committees include Analytical Applications of Isotopes and Radiation, Biology and Medicine, Radiation Applications, Radiation Sources and Detection, and Thermal Power Sources.
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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.”
D. D. B. van Bragt, Rizwan-uddin, T. H. J. J. van der Hagen
Nuclear Science and Engineering | Volume 131 | Number 1 | January 1999 | Pages 23-44
Technical Paper | doi.org/10.13182/NSE99-A2016
Articles are hosted by Taylor and Francis Online.
A dynamic model of natural circulation boiling water reactors (BWRs) is analyzed using a bifurcation code and numerical simulations. The two fundamental bifurcation types relevant to BWRs, the supercritical and the subcritical Hopf bifurcations, are first studied in natural circulation systems without nuclear feedback. The effect of nodalization approximation in the riser on stability and bifurcation characteristics of the system is determined. The strong effect of the nuclear-thermohydraulic interaction on the nonlinear characteristics of a natural circulation BWR is then explored in a parametric study. Supercritical bifurcations become dominant in the (high-power) Type-II region for small values of the subcooling number and a strong nuclear-thermohydraulic coupling. A cascade of period-doubling pitchfork bifurcations (deep in the unstable region) is also predicted by the model under these conditions. Subcritical bifurcations in the Type-II instability region were found for larger values of the subcooling number. Both Hopf-bifurcation modes were also encountered in the Type-I instability region (low power or high power/high subcooling). Finally, the nonlinear reactor model was validated successfully compared with nonlinear power oscillations measured in a natural circulation BWR.