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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.”
Jochen Max Linke, Takeshi Hirai, Manfred Rödig, Lorenz Anton Singheiser
Fusion Science and Technology | Volume 46 | Number 1 | July 2004 | Pages 142-151
Technical Paper | Stellarators | doi.org/10.13182/FST04-A550
Articles are hosted by Taylor and Francis Online.
Beside quasi-stationary plasma operation, short transient thermal pulses with deposited energy densities on the order of several tens of MJ/m2 are a serious concern for next-step devices, in particular, for tokamak devices such as ITER. The most serious of these transient events are plasma disruptions. Here, a considerable fraction of the plasma energy is deposited on a localized surface area in the divertor strike zone region. The timescale of these events is typically on the order of 1 ms. In spite of the fact that a dense cloud of ablation vapor will form above the strike zone, only partial shielding of the divertor armor from incident plasma particles will occur. As a consequence, thermal shock-induced crack formation, vaporization, surface melting, melt layer ejection, and particle emission induced by brittle destruction processes will limit the lifetime of the components. In addition, dust particles (neutron-activated metals or tritium-enriched carbon) are a serious concern from a safety point of view.Other transient heat loads that occasionally occur in magnetic confinement experiments such as instabilities in the plasma positioning (vertical displacement events) also may cause irreversible damage to plasma-facing components (PFCs), particularly to metals such as beryllium and tungsten. Other serious damage to PFCs is due to intense fluxes of 14-MeV neutrons in D-T burning plasma devices. Integrated neutron fluence of several tens of displacements per atom in future thermonuclear fusion reactors will degrade essential physical properties of the components (e.g., thermal conductivity). Another serious concern is the embrittlement of the heat sink and the plasma-facing materials (PFMs).To investigate the performance of carbon-based and metallic PFMs under the aforementioned thermal loads, simulation experiments have been performed in highly specialized high-heat-flux test facilities. The neutron-induced degradation of materials and components was investigated on selected test samples that were irradiated in high-flux material test reactors.