ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
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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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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.
Richard Sporrer, John M. Christenson
Nuclear Technology | Volume 25 | Number 3 | March 1975 | Pages 440-449
Technical Paper | Reactor | doi.org/10.13182/NT75-A24382
Articles are hosted by Taylor and Francis Online.
Fission-product decay heat rates in shutdown 239Pu-fueled fast reactors are determined by direct calculation using a modified version of the CINDER code with a fission-product library of 344 nuclides. Systematic variations in fluence, flux level, irradiation time, and the initial 238U/239pu ratio are made for the ranges of current interest, and their effects on the decay heat rate for the first ten years after reactor shutdown are investigated. Variations in irradiation history and the 238U/239Pu ratio over the ranges considered cause the total decay heat rate to vary by <18% during the first day after shutdown.
