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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.”
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In order to analyze the hydrogen distribution during a hypothetical station blackout accident in the Korean next-generation Advanced Power Reactor 1400 (APR1400) containment, the three-dimensional computational fluid dynamics code GASFLOW was used. The source of the hydrogen and steam for the GASFLOW analysis was obtained from a MAAP calculation. The discharged water, steam, and hydrogen from the pressurizer are released into the water of the in-containment refueling water storage tank (IRWST). Most of the discharged steam is condensed in the IRWST water because of its subcooling, and dry hydrogen is released into the free volume of the IRWST; finally, it goes out to the annular compartment above the IRWST through the vent holes. From the GASFLOW analysis, it was found that the gas mixture in the IRWST becomes quickly nonflammable by oxygen starvation but the hydrogen is accumulated in the annular compartment because of the narrow ventilation gap between the operating deck and containment wall when the igniters installed in the IRWST are not operated. When the igniters installed in the APR1400 were turned on, a short period of burning occurred in the IRWST, and then the flame was extinguished by the oxygen starvation in the IRWST. The unburned hydrogen was released into the annular compartment and went up to the dome because no igniters are installed around the annular compartment in the base design of the APR1400. From this result, it could be concluded that the control of the hydrogen concentration is difficult for the base design. In this study design modifications are proposed and evaluated with GASFLOW in view of the hydrogen mitigation strategy.