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A year in orbit: ISS deployment tests radiation detectors for future space missions
The predawn darkness on a cool Florida night was shattered by the ignition of nine Merlin engines on a SpaceX Falcon 9 rocket. The thrust of the engines shook the ground miles away. From a distance, the rocket appeared to slowly rise above the horizon. For the cargo onboard, the launch was anything but gentle, as the ignition of liquid oxygen generated more than 1.5 million pounds of force. After the rocket had been out of sight for several minutes, the booster dramatically returned to Earth with several sonic booms in a captivating show of engineering designed to make space travel less expensive and more sustainable.
Brian J. Ade, Daniel P. Schappel, Benjamin R. Betzler, Grant W. Helmreich, Alberto Talamo, Dylan D. Richardson, Michael P. Trammel, Brian P. Jolly, Austin T. Schumacher, Kurt A. Terrani
Nuclear Science and Engineering | Volume 196 | Number 12 | December 2022 | Pages 1517-1538
Technical Paper | doi.org/10.1080/00295639.2022.2049995
Articles are hosted by Taylor and Francis Online.
Detailed analysis of the particle distribution in Transformational Challenge Reactor fuel elements indicates that particle packing is not random; instead, it follows a relatively ordered structure near fuel element surfaces. Discrete particle neutronic simulations indicate that the core reactivity is not impacted when assuming homogenization of particles with the silicon carbide matrix. However, the neutronic power distribution resulting from the ordered packing structure indicates that the highest-power particles reside at the top and bottom of the fuel elements and nearest the YH1.85 moderator rods. The power distribution results were applied to thermomechanical simulations using mesh-based power distributions. Previous results indicated high stress at the bottom of the fuel element, where packing is most ordered. To reduce this stress concentration, additively manufactured protrusions were added to the bottom of a test fuel element to disrupt dense particle packing. These protrusions reduced the overall power peaking, but the thermomechanical simulations did not indicate a significant change in the fuel element’s maximum stress or failure probability.