ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
Explore the many uses for nuclear science and its impact on energy, the environment, healthcare, food, and more.
Explore membership for yourself or for your organization.
Conference Spotlight
Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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!
Latest Magazine Issues
Aug 2025
Jan 2025
Latest Journal Issues
Nuclear Science and Engineering
September 2025
Nuclear Technology
August 2025
Fusion Science and Technology
Latest News
Ho Nieh nominated to the NRC
Nieh
President Trump recently nominated Ho Nieh for the role of commissioner in the Nuclear Regulatory Commission through the remainder of a term that will expire June 30, 2029.
Nieh has been the vice president of regulatory affairs at Southern Nuclear since 2021, though he is currently working as a loaned executive at the Institute of Nuclear Power Operations, where he has been for more than a year.
Nieh’s experience: Nieh started his career at the Knolls Atomic Power Laboratory, where he worked primarily as a nuclear plant engineer and contributed as a civilian instructor in the U.S. Navy’s Nuclear Power Program.
From there, he joined the NRC in 1997 as a project engineer. In more than 19 years of service at the organization, he served in a variety of key leadership roles, including division director of Reactor Projects, division director of Inspection and Regional Support, and director of the Office of Nuclear Reactor Regulation.
W. C. Rivard, J. R. Travis
Nuclear Science and Engineering | Volume 74 | Number 1 | April 1980 | Pages 40-48
Technical Paper | doi.org/10.13182/NSE80-A18945
Articles are hosted by Taylor and Francis Online.
A new model is described for nonequilibrium vapor production (flashing) in critical two-phase flow. The model is based on a description of turbulence enhanced thermal diffusivity in the liquid and a Weber number criterion for bubble size. In a quiescent environment, the model reduces to the well-known conduction controlled rate. Results of calculations are compared with flow rate and pressure data from blowdown experiments with various nozzle geometries. The nozzle throat diameters range from 1.8 to 51.0 cm and nozzle inlet conditions vary from water subcooled 30°C to saturated water at 98% vapor volume fraction. The calculations are made with the two-fluid code K-FIX and show very good agreement throughout the entire blowdown.
