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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.”
C. Sari
Nuclear Technology | Volume 35 | Number 1 | August 1977 | Pages 145-153
Technical Paper | Fuel | doi.org/10.13182/NT77-A31857
Articles are hosted by Taylor and Francis Online.
Temperature gradients similar to those existing in high-rated MX-type fuel [UC, (U,Pu)C and (U, Pu)C0.9 N0.1] have been obtained by heating cylindrical pellets with an alternating electrical current flowing in the axial direction. The power used and the heat impedance existing between the surface of the pellets and the cladding material is sufficient to produce average temperature gradients on the order of 150 kK/m in temperature regions between 1273 and 2273 K. Preliminary experiments show that under these temperature conditions, important restructuring of the MX-type fuel occurs after a comparatively short time (<40 h). Generally, four structural zones, characterized by a temperature and a temperature gradient, have been observed in cross sections of the heated specimens. In the direction of increasing pellet radius (decreasing temperature), one finds a zone with large rounded pores and large equiaxed grains, a zone where pores and grains are elongated in the direction of the temperature gradient, and next to this, a zone with intergranular pores and equiaxed grains, and, finally, an unrestructured zone at the edge of the pellet. Lenticular pores are not responsible for the fuel restructuring. They appear at temperatures around 1773 K, and their apparent migration rate is lower than that observed in uranium-plutonium oxides. The fuel heated in a thermal gradient also shows a general tendency to sinter at temperatures as low as 1523 K and a tendency to crack. The free volume created by the formation of cracks is independent of the initial density of the fuel. Plutonium enrichment at the open and healed cracks and at the surface of the pellets has been observed.