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
Radiation Protection & Shielding
The Radiation Protection and Shielding Division is developing and promoting radiation protection and shielding aspects of nuclear science and technology — including interaction of nuclear radiation with materials and biological systems, instruments and techniques for the measurement of nuclear radiation fields, and radiation shield design and evaluation.
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
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.
B. R. Merk, D. G. Cacuci
Nuclear Science and Engineering | Volume 151 | Number 2 | October 2005 | Pages 194-211
Technical Paper | doi.org/10.13182/NSE05-A2540
Articles are hosted by Taylor and Francis Online.
Closed-form expressions for three-timescale approximations are developed for the one-group time-dependent P1 and P3 equations for a homogeneous multiplying medium in planar geometry with two effective groups of delayed neutrons. The development of these three-scale approximations does not rely on imposing separation of space and time. The differences between the three-scale approximations for the P1, P3, and diffusion equations, respectively, are analyzed in detail. In particular, the results obtained using the three-scale approximations for the P1 and P3 equations underscore their efficiency and accuracy, particularly for the shortest timescales and in the presence of large reactivity insertions.
