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ANS Student Conference 2025
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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.”
Dandong Feng, Pavel Hejzlar, Mujid S. Kazimi
Nuclear Technology | Volume 160 | Number 1 | October 2007 | Pages 16-44
Technical Paper | Annular Fuel | doi.org/10.13182/NT07-A3882
Articles are hosted by Taylor and Francis Online.
This paper presents steady-state thermal-hydraulic analyses of various lattices of externally and internally cooled annular pressurized water reactor (PWR) fuel to identify the geometry that allows the largest possible power density while maintaining or increasing the minimum departure from nucleate boiling ratio (MDNBR) margin in current PWRs. Differences from the typical solid rod fuel are identified, and tools for the analysis are established. These involve an in-house code developed for this purpose and an adaptation of the VIPRE-01 whole-core model using a built-in heated tube option. A 13 × 13 square array that maintains the same assembly dimensions as the current 17 × 17 fuel assembly and keeps the same fuel-to-moderator ratio was identified to achieve the best performance and the largest MDNBR margin. It is demonstrated that with a proportional increase of the core flow rate, the annular fuel allows for an up to 50% power uprate at the same MDNBR margin as in current solid PWR fuel, or for a smaller uprate with larger MDNBR margins. The same uprate was found to be possible if annular fuel is used with a hexagonal lattice, such as in VVER plants. Even at this large power rating, the peak fuel temperature is smaller by hundreds of degrees centigrade than for the solid fuel. Analyses have also shown that the annular fuel is stable against both a power excursion and density wave oscillations and has only small sensitivity to oxide layer growth and manufacturing tolerances. Gap conductance asymmetry (between the inner and outer gaps) was identified as the key issue that will limit the design because gap heat transfer resistance affects the MNDBR, unlike for the solid fuel. The annular fuel MNDBR was also found to be more sensitive to variations in core operating parameters than solid fuel, but this is more than compensated for by a significantly larger MDNBR margin during normal operation.