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
Nuclear Criticality Safety
NCSD provides communication among nuclear criticality safety professionals through the development of standards, the evolution of training methods and materials, the presentation of technical data and procedures, and the creation of specialty publications. In these ways, the division furthers the exchange of technical information on nuclear criticality safety with the ultimate goal of promoting the safe handling of fissionable materials outside reactors.
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.
N. Authier, J. P. Both, J. C. Nimal
Nuclear Science and Engineering | Volume 137 | Number 2 | February 2001 | Pages 146-155
Technical Paper | doi.org/10.13182/NSE01-A2181
Articles are hosted by Taylor and Francis Online.
New biasing sampling schemes for the "once-more-collided-flux-at-a-point" method for gamma calculations are studied. This technique, designed by Kalos, Steinberg, Kalli, and Cashwell, for neutron point flux estimation cannot be directly applied to photon transport problems. Because of the different interaction processes, it is shown that even if the mean and second moment remain bounded, very large variations of the scoring weights occur for specific collision deviations, which leads again to jumps of mean and variance. Two biasing methods are proposed for the resampled postcollision direction and the next deterministic collision to treat the anisotropic behavior of the coherent scattering that is the main cause of instability. The method is tested on an MCNP4A benchmark. This new treatment of the point flux estimation has been integrated in the TRIPOLI-4 Monte Carlo code. Note that no bias results are achieved with CPU costs, which reserves this method for reference calculations.