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2026 Annual Conference
May 31–June 3, 2026
Denver, CO|Sheraton Denver
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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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Modernizing I&C for operations and maintenance, one phase at a time
The two reactors at Dominion Energy’s Surry plant are among the oldest in the U.S. nuclear fleet. Yet when the plant celebrated its 50th anniversary in 2023, staff could raise a toast to the future. Surry was one of the first plants to file a subsequent license renewal (SLR) application, and in May 2021, it became official: the plant was licensed to operate for a full 80 years, extending its reactors’ lifespans into 2052 and 2053.
C. S. Brown, I. A. Bolotnov
Nuclear Science and Engineering | Volume 184 | Number 3 | November 2016 | Pages 363-376
Technical Paper | doi.org/10.13182/NSE15-126
Articles are hosted by Taylor and Francis Online.
The spectral analysis of turbulent single- and two-phase direct numerical simulation (DNS) data in flat plane channel, circular pipe, and reactor subchannel geometries is performed using the recorded DNS velocity fluctuations as a function of time and applying the fast Fourier transform. This results in an energy spectrum of the liquid turbulence in a frequency domain. The complexity of multiphase flow results in a mixed velocity time history coming from either the liquid or the gas phase. A modified single-phase signal that mimics the presence of bubbles (“pseudo-void”) is developed to quantify the effect of the liquid signal intermittency as the bubble passes through a virtual probe.
Comparisons of single-phase, pseudo-void, and two-phase results quantify the changes to the expected −5/3 slope of the energy spectrum for single-phase flows due to turbulent interactions caused by the wakes behind a bubble. The two-phase energy spectra show a slope close to −3 and similar shape in the different geometries while single-phase energy spectra exhibit the expected −5/3 slope. Pseudo-void results indicate that the change to the energy spectrum in bubbly two-phase flows is due entirely from liquid turbulence interactions with the bubble wakes.
A comprehensive spectral analysis for different geometries and different Reynolds number flows at varying distances from the wall is an essential step in developing physically sound closure models for bubble-liquid interactions. The comparison between different geometries demonstrates the direct applicability of various models to reactor-relevant geometries.
