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.
Division Spotlight
Education, Training & Workforce Development
The Education, Training & Workforce Development Division provides communication among the academic, industrial, and governmental communities through the exchange of views and information on matters related to education, training and workforce development in nuclear and radiological science, engineering, and technology. Industry leaders, education and training professionals, and interested students work together through Society-sponsored meetings and publications, to enrich their professional development, to educate the general public, and to advance nuclear and radiological science and engineering.
Meeting Spotlight
International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering (M&C 2025)
April 27–30, 2025
Denver, CO|The Westin Denver Downtown
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
Apr 2025
Jan 2025
Latest Journal Issues
Nuclear Science and Engineering
June 2025
Nuclear Technology
Fusion Science and Technology
May 2025
Latest News
Argonne’s METL gears up to test more sodium fast reactor components
Argonne National Laboratory has successfully swapped out an aging cold trap in the sodium test loop called METL (Mechanisms Engineering Test Loop), the Department of Energy announced April 23. The upgrade is the first of its kind in the United States in more than 30 years, according to the DOE, and will help test components and operations for the sodium-cooled fast reactors being developed now.
D. D. B. van Bragt, Rizwan-uddin, T. H. J. J. van der Hagen
Nuclear Science and Engineering | Volume 131 | Number 1 | January 1999 | Pages 23-44
Technical Paper | doi.org/10.13182/NSE99-A2016
Articles are hosted by Taylor and Francis Online.
A dynamic model of natural circulation boiling water reactors (BWRs) is analyzed using a bifurcation code and numerical simulations. The two fundamental bifurcation types relevant to BWRs, the supercritical and the subcritical Hopf bifurcations, are first studied in natural circulation systems without nuclear feedback. The effect of nodalization approximation in the riser on stability and bifurcation characteristics of the system is determined. The strong effect of the nuclear-thermohydraulic interaction on the nonlinear characteristics of a natural circulation BWR is then explored in a parametric study. Supercritical bifurcations become dominant in the (high-power) Type-II region for small values of the subcooling number and a strong nuclear-thermohydraulic coupling. A cascade of period-doubling pitchfork bifurcations (deep in the unstable region) is also predicted by the model under these conditions. Subcritical bifurcations in the Type-II instability region were found for larger values of the subcooling number. Both Hopf-bifurcation modes were also encountered in the Type-I instability region (low power or high power/high subcooling). Finally, the nonlinear reactor model was validated successfully compared with nonlinear power oscillations measured in a natural circulation BWR.