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Nuclear Criticality Safety
NCSD provides communication among nuclear criticality safety professionals through the development of standards, the evolution of training methods and materials, the presentation of technical data and procedures, and the creation of specialty publications. In these ways, the division furthers the exchange of technical information on nuclear criticality safety with the ultimate goal of promoting the safe handling of fissionable materials outside reactors.
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Atlanta, GA|Atlanta Marriott Marquis
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WIPP’s SSCVS: A breath of fresh air
This spring, the Department of Energy’s Office of Environmental Management announced that it had achieved a major milestone by completing commissioning of the Safety Significant Confinement Ventilation System (SSCVS) facility—a new, state-of-the-art, large-scale ventilation system at the Waste Isolation Pilot Plant, the DOE’s geologic repository for defense-related transuranic (TRU) waste in New Mexico.
K. Wisshak, F. Käppeler, R. L. Macklin, G. Reffo, F. Fabbri
Nuclear Science and Engineering | Volume 87 | Number 1 | May 1984 | Pages 48-58
Technical Paper | doi.org/10.13182/NSE84-A17445
Articles are hosted by Taylor and Francis Online.
The neutron capture widths of the s-wave resonances at 13.9 and 33.8 keV in 64Ni have been determined using a setup with extremely low neutron sensitivity completely different from all previous experiments on this isotope. This feature is important because these resonances exhibit a very large scattering-to-capture ratio. A pulsed 3-MV Van de Graaff accelerator and a kinematically collimated neutron beam, produced via the 7Li(p, n) reaction, was used in the experiments. Capture gamma rays were observed by three Moxon-Rae detectors with a graphite, a bismuth-graphite, and a bismuth converter, respectively. The samples were positioned at a neutron flight path of only 6 to 8 cm. Thus, events due to capture of resonance-scattered neutrons in the detectors or in surrounding materials are completely discriminated by their additional time of flight. The short flight path and the high neutron flux at the sample position allowed for a signal-to-background ratio of approximately unity even for the broad resonance at 33.8 kev. The data obtained with the individual detectors were corrected for the efficiency of the different converter materials. For that purpose, detailed theoretical calculations of the capture gamma-ray spectra of the measured isotope and of gold, which was used as a standard, were performed. The final radiative widths are Γγ(13.9 kev) = 1.01 ± 0.07 eV and Γγ(33.8 kev) = 1.16 ± 0.08 Ev, considerably smaller than the rough estimates obtained in previous work.