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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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The fire that powers the universe: Harnessing inertial fusion energy
It was a laser shot for the ages. By achieving fusion ignition on December 5, 2022, Lawrence Livermore National Laboratory proved that recreating the “fire” that fuels the sun and the stars inside a laboratory on Earth was indeed scientifically possible.
F. J. Homan, T. B. Lindemer, E. L. Long, Jr., T. N. Tiegs, R. L. Beatty
Nuclear Technology | Volume 35 | Number 2 | September 1977 | Pages 428-441
Performance and Performance Modeling | Coated Particle Fuel / Fuel | doi.org/10.13182/NT35-428
Articles are hosted by Taylor and Francis Online.
Two fuel failure mechanisms were identified for coated particle fuels that are directly related to fuel kernel stoichiometry. These mechanisms are thermal migration of the kernel through the coating layers and chemical interaction between rare-earth fission products and the silicon carbide (SiC) layer (the primary barrier to diffusion of metal fission products out of the particle) leading to failure of the SiC layer. Thermal migration appears to be most severe for oxide fuels, while chemical interaction is most severe with carbide systems. Thermodynamic calculations indicated that oxide-carbide fuel kernels may permit a stoichiometry that reduces both problems to manageable levels for currently planned high-temperature gas-cooled reactors. Such stoichiometry adjustment is possible over the complete spectrum from UO2 to UO2 for the present recycle fuel, a weak acid resin (WAR)-derived fissile kernel. Thermodynamic calculations indicate that WAR kernels containing <15% UC2 (>85% UO2) will develop excessive CO overpressures within the particle during irradiation. In 100% UO2 particles, thermal migration and oxidation of the SiC layer were observed after irradiation. The calculations also indicate that WAR kernels containing >70% UC2 (<30% UC2) contain insufficient oxygen to oxidize the rare-earth fission products formed in fuel operated to the maximum burnup levels of 75% fissions per initial metal atom (75% FIMA). Instead, the rare earths are present in part or completely as dicarbides. As such, they were observed to segregate from the kernel and collect at the SiC interface on the cold side of the particle, react with the SiC, and eventually fail this coating. Five WAR kernel stoichiometries were irradiated. These are either UO2 kernels, UO2 plus 15, 50, or 75% UC2, or 100% UC2. Results of these tests are consistent with thermodynamic calculations. Additional tests are in progress to establish the optimum stoichiometry; preliminary indications suggest an optimum value of ∼35% conversion with a permissible range of ±20%.