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
Reactor Physics
The division's objectives are to promote the advancement of knowledge and understanding of the fundamental physical phenomena characterizing nuclear reactors and other nuclear systems. The division encourages research and disseminates information through meetings and publications. Areas of technical interest include nuclear data, particle interactions and transport, reactor and nuclear systems analysis, methods, design, validation and operating experience and standards. The Wigner Award heads the awards program.
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!
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Apr 2025
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Nuclear Science and Engineering
May 2025
Nuclear Technology
Fusion Science and Technology
Latest News
TerraPower begins U.K. regulatory approval process
Seattle-based TerraPower signaled its interest this week in building its Natrium small modular reactor in the United Kingdom, the company announced.
TerraPower sent a letter to the U.K.’s Department for Energy Security and Net Zero, formally establishing its intention to enter the U.K. generic design assessment (GDA) process. This is TerraPower’s first step in deployment of its Natrium technology—a 345-MW sodium fast reactor coupled with a molten salt energy storage unit—on the international stage.
W. O. Harms, A. P. Litman
Nuclear Technology | Volume 5 | Number 3 | September 1968 | Pages 156-172
Technical Paper and Note | doi.org/10.13182/NT68-A28045
Articles are hosted by Taylor and Francis Online.
The alkali metals lithium, potassium, and cesium are of principal interest as heat transfer and working fluids in high-performance space-nuclear reactors employing single- and multiloop Rankine cycle conversion. The compatibility of these alkali metals with structural alloys has been investigated for more than a decade in both laboratory- and engineering-scale tests. It is demonstrated that reliable engineering systems involving potassium and cesium can be constructed and operated at 2000°F with first-generation niobium-base alloys like Nb-1% Zr and at 2200°F with advanced niobium-base alloys. Niobium-base alloys can be used at higher temperatures in lithium systems. Tantalum-base alloys appear to be satisfactory for potassium or cesium to at least 2200°F and probably a few hundred degrees higher with lithium. Very advanced systems designed for temperatures of 2500°F and higher probably will require a new group of alloys; tungsten-base alloys appear to be strong candidates for these applications.
