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Conference Spotlight
Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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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Watch as solid hydrogen is extruded to feed German stellarator
In May, the Wendelstein 7-X stellarator in Greifswald, Germany, concluded an experimental campaign by sustaining a plasma with a high triple product for 43 seconds. The machine far surpassed its own previous performance with a value that the Max Planck Institute for Plasma Physics (IPP) says “exceeds previous tokamak records for long plasma durations”—in part because of a fuel pellet injection system developed by researchers at Oak Ridge National Laboratory.
Watch ORNL’s video of that fuel pellet injection system—in use since September 2024—as it extrudes a column of frozen hydrogen and then cuts individual 3.2-millimeter-long pellets. The process, which takes just half a millisecond, was captured in slow motion by ORNL engineer Steve Meitner.
Francisco I. Valentín, Narbeh Artoun, Ryan Anderson, Masahiro Kawaji, Donald M. McEligot
Nuclear Technology | Volume 196 | Number 3 | December 2016 | Pages 661-673
Technical Paper | doi.org/10.13182/NT16-46
Articles are hosted by Taylor and Francis Online.
Very high temperature reactors (VHTRs) with helium-cooled prismatic cores are one type of Generation IV gas-cooled reactors proposed for implementation in next-generation nuclear power plants. To contribute to the VHTR development, a high-temperature/high-pressure test facility has been constructed and used to investigate the convection heat transfer of gaseous coolants. This test facility consisted of a single flow channel with a diameter of 16.8 mm in a graphite column with a length of 2.7 m (9 ft) equipped with four 2.3-kW heaters. Convection heat transfer experiments were conducted with air, nitrogen, and helium for inlet Reynolds number (Re) values ranging from 500 to 70000. Extensive three-dimensional numerical modeling was also performed using a commercial finite element package, COMSOL Multiphysics. The numerical results agreed with the convection heat transfer data, with maximum error percentages under 15%. Based on this agreement, important information was extracted from the numerical model regarding the axial and radial velocity and temperature profiles as well as the axial variations in gas properties. This work examines deteriorated turbulent heat transfer and flow laminarization for a wide range of Re, including laminar, transition, and turbulent flows.