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Division Spotlight
Thermal Hydraulics
The division provides a forum for focused technical dialogue on thermal hydraulic technology in the nuclear industry. Specifically, this will include heat transfer and fluid mechanics involved in the utilization of nuclear energy. It is intended to attract the highest quality of theoretical and experimental work to ANS, including research on basic phenomena and application to nuclear system design.
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ANS Student Conference 2025
April 3–5, 2025
Albuquerque, NM|The University of New Mexico
Standards Program
The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
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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.”
Henry A. Sandmeier
Nuclear Science and Engineering | Volume 9 | Number 2 | February 1961 | Pages 260-270
doi.org/10.13182/NSE61-A15608
Articles are hosted by Taylor and Francis Online.
To test reactor fuel elements for their content of fissionable material and poison, it is desirable to have an assembly which has maximum sensitivity to a perturbation of fissionable absorber in the axial center line of the reactor. For normal sizes of thermal power reactor fuel elements, a graphite-moderated reactor is a suitable choice. The change in reactivity measured is the difference between the effect of changes in the fission and absorption parameters. For a bare core and uniform fuel distribution, maximum sensitivity to a fission-parameter-perturbation is obtained for a reactor which has a minimum critical mass. Maximum sensitivity to an absorber-parameter-perturbation is obtained for a reactor which has a minimum amount of total absorptions. Both the fission and absorption sensitivity reach a maximum when the critical mass is minimum. For a reflected core and uniform fuel distribution, the sensitivity to a fissionable absorber can be increased 22% over the bare core sensitivity. By introducing an internal and external reflector, the sensitivity to a fissionable absorber can be increased 30% over the externally reflected core and 56% over the bare core. For nonuniform fuel distribution, an expression is derived relating the effect of a perturbation in fission and absorption to reactivity. The problem of finding a fuel distribution ψ(r) to maximize this expression is analytically formulated. A parameter study was made for the same reactors as for the uniform fuel distribution cases. This was done by shifting more fuel towards the center or towards the edge of the core. No gain in fissionable absorber sensitivity was observed for either the bare or the externally reflected cores. However, the internally and externally reflected core showed a 10% increase in fissionable absorber sensitivity when more fuel was shifted towards the center.