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Nuclear Criticality Safety
NCSD provides communication among nuclear criticality safety professionals through the development of standards, the evolution of training methods and materials, the presentation of technical data and procedures, and the creation of specialty publications. In these ways, the division furthers the exchange of technical information on nuclear criticality safety with the ultimate goal of promoting the safe handling of fissionable materials outside reactors.
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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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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.
Cen Wei, Bao-Wen Yang, Bin Han, Aiguo Liu
Nuclear Technology | Volume 205 | Number 1 | January-February 2019 | Pages 328-337
Technical Paper | doi.org/10.1080/00295450.2018.1510266
Articles are hosted by Taylor and Francis Online.
Mixing vanes attached to a space grid play an important role in heat transfer enhancement, thus increasing critical heat flux. Subchannel analysis and computational fluid dynamics (CFD) are usually applied to simulate the coolant flow behavior in a fuel assembly. In subchannel analysis, the mixing effect, mainly turbulent mixing, produced by mixing vane grids (MVGs) is represented by a coefficient β without considering flow direction and mixing vane arrangement. However, in CFD computation, the mixing effect can be simulated more closely. The objective of this paper is to evaluate the mixing coefficient β used in subchannel analysis by a CFD code. Then, the effects of the three MVGs are compared qualitatively and quantitatively.
Through the analysis, an effective mixing coefficient adopted in the subchannal codes should be related to the vane arrangement. Improvements for β are needed to better reflect the true mixing function from the spacer grid relevant to its mixing vane arrangement. Besides the lateral velocity distribution, secondary flow intensity, temperature distribution, and thermal nonuniformity are different for different vane arrangement patterns.