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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.”
Shih-Hai Li, Hui-Ting Yang, Chun-Ping Jen
Nuclear Technology | Volume 148 | Number 3 | December 2004 | Pages 358-368
Technical Paper | Radioactive Waste Management and Disposal | doi.org/10.13182/NT04-A3573
Articles are hosted by Taylor and Francis Online.
Performance assessments of high-level radioactive waste disposal have emphasized the role of colloids in the migration of radionuclides in the geosphere. The transport of colloids often brings them in contact with fracture surfaces or porous rock matrix. Colloids that attach to these surfaces are treated as being immobile and are called filtered colloids. The filtered colloids could be released into the fracture again; that is, the attachment of colloids may be reversible. Also, the colloids in the fracture could diffuse into the porous matrix rock. A methodology is proposed to evaluate a predictive model to assess transport within the fractured rock as well as various phenomenological coefficients employed in the different mechanisms, such as filtration, remobilization, and matrix diffusion of colloids. The governing equations of colloids considering mechanisms of the colloidal transport in the fractured media, including filtration, remobilization, and matrix diffusion, have been modeled and solved analytically in previous studies. In the present study, transport equations of colloids and radionuclides that consider the combination of the aforementioned transport mechanisms have also been solved numerically and investigated. The total concentration of mobile radionuclides in the fracture becomes lower because the concentration of mobile colloids in the fracture decreases when the filtration coefficient for colloids increases. Additionally, the concentration of mobile radionuclides was increased at any given time step due to the higher sorption partition coefficient of radionuclides associated with colloids. The results also show that the concentration of radionuclides in the fracture zone decreases when the remobilization coefficient of colloids or the percentages of the matrix diffusion flux of colloids increase.