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
Jul 2025
Jan 2025
Latest Journal Issues
Nuclear Science and Engineering
August 2025
Nuclear Technology
Fusion Science and Technology
Latest News
ANS joins others in seeking to discuss SNF/HLW impasse
The American Nuclear Society joined seven other organizations to send a letter to Energy Secretary Christopher Wright on July 8, asking to meet with him to discuss “the restoration of a highly functioning program to meet DOE’s legal responsibility to manage and dispose of the nation’s commercial and legacy defense spent nuclear fuel (SNF) and high-level radioactive waste (HLW).”
Seung Min Baek, Hee Cheon No, In Yong Park
Nuclear Technology | Volume 74 | Number 3 | September 1986 | Pages 260-266
Technical Paper | Fission Reactor | doi.org/10.13182/NT86-A33828
Articles are hosted by Taylor and Francis Online.
A nonequilibrium three-region model is developed for the accurate prediction of the pressure in the pressurizer under both transient and accident conditions. The mathematical model derived from the general conservation equations includes all of the important thermal-hydraulics processes occurring in the pressurizer: bulk flashing and condensation, wall condensation, and interfacial heat and mass transfer, etc. The Stanton number for the interfacial heat transfer coefficient is obtained by fitting the experimental results in terms of the surge rate. The bubble rising and rain-out models are developed to describe bulk flashing and condensation, respectively. To obtain the wall condensation rate, a one-dimensional heat conduction equation is solved by the pivoting method. The mathematical model is numerically solved by the back substitution and successive iteration method for fast convergence and stability. For verification, several numerical tests are done on a mild transient in the Shippingport nuclear power plant, an experimental test done at the Massachusetts Institute of Technology, and the Three Mile Island accident. It is proved that predicted results are in better agreement with experimental tests than those by previous models. Sensitivity analysis is done to see the effect of each model on the behavior of the pressurizer. Discrepancy between results predicted with the three- and the tworegion models becomes apparent in an outsurge after insurge transient. Although the interfacial heat transfer of the pressurizer can be neglected in the case of the high water level, it becomes one of the most dominant processes in the low level. The wall condensation rate becomes important with an increase in pressure due to an insurge transient.