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Isotopes & Radiation
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.”
Mark Massie, Benoit Forget
Nuclear Technology | Volume 182 | Number 2 | May 2013 | Pages 207-223
Regular Technical Paper | Special Issue on the Symposium on Radiation Effects in Ceramic Oxide and Novel LWR Fuels / Fission Reactors | doi.org/10.13182/NT13-A16431
Articles are hosted by Taylor and Francis Online.
This work presents a methodology for determining the optimal neutron energy spectrum for meeting user-specified transmutation objectives. A simulated annealing routine is used to find the optimal neutron energy distribution by iteratively modifying the flux spectrum, performing depletion calculations, and computing the value of the cost function.To demonstrate this methodology, we found optimal flux spectra for transmuting used nuclear fuel (UNF) to maximize proliferation resistance and to maximize repository capacity by minimizing decay heat. Multiple cost functions are evaluated for each of the two objectives. For maximizing proliferation resistance, we determined the optimal spectra for minimizing 239Pu mass, maximizing 238Pu mass, maximizing 240Pu mass, and minimizing the mass ratio of 239Pu to 238Pu and 240Pu. The results of this study show that while both fast and thermal neutrons are useful for reducing the amount of 239Pu, a thermal spectrum is best for rendering plutonium from UNF unusable as weapons material.Optimal spectra for maximizing repository capacity are found for minimizing the time-integrated decay heat generated by the transmuted UNF. This study shows that optimal transmutation of the full UNF vector can reduce the amount of decay heat released over 10 000 yr by [approximately]39% and that even more substantial reductions are possible with transuranic element-only transmutation, which can decrease decay energy by >81%. Furthermore, it is shown that a thermal spectrum is substantially more effective than a fast spectrum for reducing decay heat released by UNF over 10 000 yr, thus increasing the capacity of heat-limited waste repositories. Results such as these provide powerful insight into the complicated energy dependence of transmutation and illustrate this methodology's effectiveness as a scoping tool.