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Division Spotlight
Thermal Hydraulics
The division provides a forum for focused technical dialogue on thermal hydraulic technology in the nuclear industry. Specifically, this will include heat transfer and fluid mechanics involved in the utilization of nuclear energy. It is intended to attract the highest quality of theoretical and experimental work to ANS, including research on basic phenomena and application to nuclear system design.
Meeting Spotlight
Utility Working Conference and Vendor Technology Expo (UWC 2024)
August 4–7, 2024
Marco Island, FL|JW Marriott Marco Island
Standards Program
The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
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Nuclear Science and Engineering
August 2024
Nuclear Technology
Fusion Science and Technology
Latest News
Vogtle-3 shuts down for valve issue
One of the new Vogtle units in Georgia was shut down unexpectedly on Monday last week for a valve issue that has been investigated and repaired. According to multiple local news outlets, Georgia Power reported on July 17 that unit 3 was back in service.
Southern Company spokesperson Jacob Hawkins confirmed that Vogtle-3 went off line at 9:25 p.m. on July 8 “due to lowering water levels in the steam generators caused by a valve issue on one of the three main feedwater pumps.”
Gert Jan Auwerda, Jan-Leen Kloosterman, Danny Lathouwers, Tim H. J. J. Van Der Hagen
Nuclear Technology | Volume 183 | Number 3 | September 2013 | Pages 272-286
Technical Paper | Fission Reactors and Heat Transfer | doi.org/10.13182/NT13-A19417
Articles are hosted by Taylor and Francis Online.
In pebble bed-type nuclear reactors, the fuel pebbles form a randomly stacked bed with a nonuniform packing density. To investigate flow and heat transfer through these beds and to develop realistic models, we need a good understanding of the nature of randomly stacked beds and validated computational methods that can generate realistic beds. To this end, the average packing fraction (PF) and the radial and axial PF profiles were accurately measured of a bed containing 5400 acrylic pebbles with a diameter of 12.7 mm. In a second experiment, we determined the pebble locations of a bed containing 8900 glass pebbles with diameters of 1.66 to 2.00 mm using three-dimensional X-ray tomography, from which various microscopic stacking properties were evaluated for both the bulk of the bed away from the wall and in the near wall region. Results were compared with the properties of a bed that was generated by using a computational method based on the removal of overlaps to validate that method.Results for the computed bed are in good agreement with the experiments and with the literature, giving confidence that the method is capable of generating beds with realistic packing structures, although the experimental results for the microscopic stacking properties in the near-wall region are of insufficient quality for a meaningful comparison. Analysis of the various results shows different stacking properties near the wall than in the bulk of the bed, indicating the stacking is anisotropic near a boundary forming semiordered layers parallel to the wall with hexagonal-like stacking properties, which implies flow and heat transfer might also be isotropic near the wall and could need different models near the wall than in the bulk to be accurately described. Finally, the probability distribution of PFs of small clusters of around 45 pebbles showed that the local PF inside a packed bed can vary strongly, both in the bulk and near the wall, which might significantly affect flow rates and could result in hot spots.