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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.”
Ronald J. DiMelfi, John M. Kramer
Nuclear Technology | Volume 62 | Number 1 | July 1983 | Pages 51-61
Technical Paper | Nuclear Fuel | doi.org/10.13182/NT83-A33231
Articles are hosted by Taylor and Francis Online.
Characteristics of solid fuel fragmentation and energetic spallation during hypothetical accident transients are calculated. Fission gas, having migrated to the grain boundaries as intergranular bubbles, is assumed to provide the potential energy sufficient to fracture the fuel and induce fuel particle motion radially. Fuel cladding is assumed to maintain a radial constraint on the fuel until the cladding fails by melting. It is shown that the vapor pressure of elemental cesium contained in the fuel cladding gap can impose a compressive stress on the fuel sufficient to maintain a large quantity of intergranular fission gas trapped within equilibrium bubbles. On cladding melting and relaxation of constraint the extent of fuel fracture initiated at the overpressured bubbles is calculated. It is shown that expanding fission gas in the fractured grain boundaries is sufficient to eject fuel particles at substantial velocities. The results of calculations are consistent with experimental observations. The calculated compressive constraint of 3 to 5 MPa is in agreement with cladding failure stresses near the melting point and with those tensile stress levels necessary to cause observed cladding swelling. In further concurrence with the experiment, it was found that higher burnup fuel (≈9.9 at.% burnup) containing more fission gas was more likely to undergo energetic spallation, with larger quantities of fuel moving at greater speeds, than fuel irradiated to intermediate levels (4.7 at.% burnup). In the high burnup case, fuel particles of 0.5 to 1.0 mm in size were ejected radially at speeds >0.5 m/s. In the intermediate burnup case, smaller particles ≈ 0.2 mm in size move somewhat slower at speeds ≤0.4 m/s. A low burnup fuel (2.3 at.%) was calculated not to fragment and spall at all. Since the calculated vapor pressure of elemental cesium was used to account for the compressive constraint, the analysis requires the presence of cesium to predict spallation.