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.
Operations & Power
Members focus on the dissemination of knowledge and information in the area of power reactors with particular application to the production of electric power and process heat. The division sponsors meetings on the coverage of applied nuclear science and engineering as related to power plants, non-power reactors, and other nuclear facilities. It encourages and assists with the dissemination of knowledge pertinent to the safe and efficient operation of nuclear facilities through professional staff development, information exchange, and supporting the generation of viable solutions to current issues.
2024 ANS Annual Conference
June 9–12, 2024
Las Vegas, NV|The Mirage
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
Latest Journal Issues
Nuclear Science and Engineering
Fusion Science and Technology
The Sodium Reactor Experiment
In February 1957, construction was completed on the Sodium Reactor Experiment (SRE), a sodium-cooled, graphite-moderated reactor with an output of 20 MWt. The design of theSRE had begun three years earlier in 1954, and construction started in April 1955. On April 25, 1957, the reactor reached criticality, and the SRE operated until February 1964.
Simon A. Clément, Philippe M. Bardet
Nuclear Technology | Volume 199 | Number 2 | August 2017 | Pages 151-173
Technical Paper | doi.org/10.1080/00295450.2017.1327254
Articles are hosted by Taylor and Francis Online.
Because of the complexity of the flow within light water reactor (LWR) cores, numerous small-scale phenomena locally influence heat transfer and critical heat flux (CHF). They include development of viscous and thermal boundary layers, interchannel mixing, spacer grid mixing, rod vibrations, or confinement effects such as the proximity of the walls or the influence of the gap between adjacent fuel bundles. LWR prototypical conditions are particularly harsh environments and limit measurements to quantities such as pointwise pressure drop and temperature, the latter resulting in global heat transfer and CHF correlations. The local phenomena mentioned above are embedded in these correlations, leading to inherent empiricism (and therefore conservatism). Validated computational fluid dynamics (CFD) codes and models can predict these phenomena, thus providing modelization tools of greater accuracy. However, major requirements for validation campaigns include the matching of validation and application domains and the deployment of mature and high-resolution diagnostics. For the latter, many are available for single-phase flows due to their predominance in several research fields. Furthermore, in the lower part of LWR cores, flow is single phase, and only this regime is considered in this paper. To circumvent the challenges of deploying diagnostics in LWR conditions, surrogate fluids are commonly used, enabling the measurement of velocity, temperature, pressure, or wall shear stress. A large number of single-phase tests with resolution adequate to validate CFD models have been conducted with air, steam, and water at moderate temperature and pressure. However, to date, with these fluids, the application domain defined by the Reynolds and Prandtl numbers has not been reached.
Four surrogate gases are proposed to match application and validation domains while allowing the deployment of a broad range of diagnostics: pressurized sulfur hexafluoride, xenon, cryogenic nitrogen, and highly pressurized air. By controlling their operating temperature and pressure, they allow matching prototypical Reynolds and Prandtl numbers while preserving the length scale, velocity scale, and timescale. This is achieved by reproducing the kinematic viscosity and thermal diffusivity of several nuclear reactor coolants. Furthermore, for single-phase conjugate heat transfer, a complete scaling analysis is performed for one pressurized water reactor fuel rod within a bundle under normal operating conditions. Electrically heated rods made of magnesium oxide and Zircaloy, combined with the proposed surrogate fluids, provide a close matching of conjugate heat transfer. Additionally, the use of these surrogates offers a significant decrease of the heating and pumping powers. Single-phase heat transfer separate-effect tests can then be performed for the first time in a laboratory setup with one, or several, full-size fuel bundles at prototypical conditions, while allowing the deployment of a large range of diagnostics. Finally, existing test facilities for hydraulics and thermal hydraulics of prototypical fuel bundles can be utilized with minor retrofits, further facilitating test implementation.