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Fusion Energy
This division promotes the development and timely introduction of fusion energy as a sustainable energy source with favorable economic, environmental, and safety attributes. The division cooperates with other organizations on common issues of multidisciplinary fusion science and technology, conducts professional meetings, and disseminates technical information in support of these goals. Members focus on the assessment and resolution of critical developmental issues for practical fusion energy applications.
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Utility Working Conference and Vendor Technology Expo (UWC 2024)
August 4–7, 2024
Marco Island, FL|JW Marriott Marco Island
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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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NRC engineers share their expertise at the University of Puerto Rico
Robert Roche-Rivera and Marcos Rolón-Acevedo are licensed professional engineers who work at the U.S. Nuclear Regulatory Commission. They are also alumni of the University of Puerto Rico–Mayagüez (UPRM) and have been sharing their knowledge and experience with students at their alma mater since last year, serving as adjunct professors in the university’s Department of Mechanical Engineering. During the 2023–2024 school year, they each taught two courses: Fundamentals of Nuclear Science and Engineering, and Nuclear Power Plant Engineering.
Jeffrey E. Seifried, Ehud Greenspan
Nuclear Science and Engineering | Volume 181 | Number 1 | September 2015 | Pages 82-95
Technical Paper | doi.org/10.13182/NSE14-104
Articles are hosted by Taylor and Francis Online.
An expression is derived for attributing the reactivity response due to perturbations to spectral, spatial, and isotopic effects. It is shown to be consistent at a global level with similar expressions derived in previous work but can provide more detailed information on the physics phenomena contributing to the reactivity response of the perturbation. Using this expression, the reactivity effect of local coolant density perturbations [local void coefficient of reactivity (VCR)] is studied for two reduced-moderation boiling water reactor (RBWR) core designs—the thorium-fueled RBWR (RBWR-Th) and the uranium-fueled RBWR (RBWR-AC)—as well as for a standard advanced boiling water reactor (ABWR). The RBWR core designs feature large axial variation in their neutron spectra.
The axial distribution of local VCR along the RBWR-Th seed and along the ABWR core were found to have the same general shape: negative throughout but most negative near the bottom and asymptotically approaching zero toward the top. However, the RBWR-Th VCR is roughly four times more negative. The RBWR-AC local VCR axial distribution varies greatly: it is very close to zero in the seed regions and has a significant positive component in the central blanket.
Three effects were identified as contributing to the VCR due to a local water density change in the lower part of the RBWR-Th seed: local spectrum hardening that tends to increase the local reproduction factor (ηr) of each of the fuel isotopes; a redistribution of the local neutron absorption between the fuel isotopes resulting in a shift of absorptions from higher to lower isotopic reproduction factors and, hence, to a reactivity loss; and an axial flux tilt across the core from axial zones of higher ηr to axial zones of lower ηr, which makes another negative contribution to the reactivity worth of the perturbation.