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Division Spotlight
Radiation Protection & Shielding
The Radiation Protection and Shielding Division is developing and promoting radiation protection and shielding aspects of nuclear science and technology — including interaction of nuclear radiation with materials and biological systems, instruments and techniques for the measurement of nuclear radiation fields, and radiation shield design and evaluation.
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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Latest News
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.
Rahman S. Almusafir, Ahmed A. Jasim, Muthanna H. Al-Dahhan
Nuclear Science and Engineering | Volume 197 | Number 6 | June 2023 | Pages 1001-1037
Critical Review | doi.org/10.1080/00295639.2022.2146993
Articles are hosted by Taylor and Francis Online.
Knowledge and proper safety analyses of the gas coolant and heat transport mechanism in the dynamic core of packed pebble bed nuclear reactors pose challenges to the reliable design and efficient operation of these reactors. Therefore, this paper carefully reviews most of the gas coolant mixing and heat transport studies performed for the fluid flow and heat transfer processes in packed pebble bed reactors (PBRs). It begins with a brief introduction and description of nuclear PBRs. The second section summarizes the physical characteristics of packed bed reactors in terms of the bed structure (porosity) and its radial and axial distributions. The next section examines in detail the characteristics of fluid flow in terms of flow regime identification and pressure drop measurements and correlations. The fourth section considers the investigations and quantifications of the gas dispersion and mixing phenomena of packed bed reactors. The next section deals with the current state of the heat transfer characteristics, measurements, and predictions including both empirical correlations and semiempirical model-based studies. Tables summarize the reported experimental studies along with their operating condition ranges. Comprehensive comparisons with the empirical correlations and available models are presented with significant findings. The content and findings of the present work could provide a thorough understanding and useful information and advance knowledge of the pressure drop, gas coolant mixing, and convective heat transport phenomena in packed pebble bed nuclear reactors.