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Division Spotlight
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.
Matthew P. Simones, Sudarshan K. Loyalka
Nuclear Technology | Volume 189 | Number 1 | January 2015 | Pages 45-62
Technical Paper | Reactor Safety | doi.org/10.13182/NT14-14
Articles are hosted by Taylor and Francis Online.
In high-temperature gas-cooled reactors (HTGRs), an improved understanding of the production of carbonaceous dust (e.g., by abrasion, corrosion, radiation damage, and gas-to-particle conversion) and the subsequent transport of the dust and associated sorbed fission products is needed. Diffusion charging and/or self-charging of the suspended dust particles (aerosol) is likely to occur, which affects how the aerosol evolves in time and ultimately deposits on surfaces. At present, nuclear reactor safety codes, such as MELCOR, do not account for these effects and there is currently no consensus on their importance, partly due to a lack of experimental data as well as tools for computations. Further experimentation and modeling of these effects are therefore needed to resolve these issues. We report on an experimental investigation of the coagulation of charged aerosols pertinent to HTGRs by measuring the evolution of size and charge distributions over time and comparing the experimental results with computations using the direct simulation Monte Carlo method. Measurements have been completed for both silver and carbon ultrafine aerosols using a tandem differential mobility analyzer and an open-flow coagulation chamber with a residence time of nearly 400 s. Results for both aerosols indicate that coagulation occurs faster than predicted by the simulations, at times differing by an order of magnitude. While the paper is focused on specific aerosols, it is of wider significance in that it provides the first such comparisons between data and simulations on charged aerosol coagulation.