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Division Spotlight
Robotics & Remote Systems
The Mission of the Robotics and Remote Systems Division is to promote the development and application of immersive simulation, robotics, and remote systems for hazardous environments for the purpose of reducing hazardous exposure to individuals, reducing environmental hazards and reducing the cost of performing work.
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.”
Thomas R. Boyle, Robert V. Tompson, Sudarshan K. Loyalka, Tushar K. Ghosh, Michael L. Reinig, Jr.
Nuclear Technology | Volume 183 | Number 2 | August 2013 | Pages 149-159
Technical Paper | Fission Reactors/Materials for Nuclear Systems | doi.org/10.13182/NT13-A18108
Articles are hosted by Taylor and Francis Online.
Very high temperature reactors (VHTRs) and high temperature gas-cooled reactors (HTGRs) can develop extreme temperatures in excess of 900°C that make them theoretically very efficient, potentially in the range of 45% to 50%. The high temperatures, however, can also lead to a corresponding increase in fission product transport out of the fuel, which is potentially a source term-related safety issue. The aim of this work was to develop a repeatable, accurate, and cost-effective process to measure the diffusion coefficients of fission products in graphitic VHTR materials, particularly those materials used in the fabrication of TRISO [tristructural isotropic] fuel pellets. Specifically, this work has focused on the diffusion of silver in graphite. We constructed graphite cells that could be filled with a silver diffusant in the form of silver flakes, silver powder, or a preloaded, silver-laden graphite powder. The cells were hermetically sealed and heated to temperatures comparable to those that will be found in VHTRs. After being kept at various amounts of time and temperature, these cells were imaged using microtomography and electron microscopy. Concentration profiles were measured by sectioning the heat-treated cells and analyzing them using neutron activation analysis. Estimated diffusion coefficients for silver in a commercial grade of graphite are reported, but the method is easily adapted to any grade of graphite material including nuclear grades and to a variety of other fission product species.