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 Nonproliferation Policy
The mission of the Nuclear Nonproliferation Policy Division (NNPD) is to promote the peaceful use of nuclear technology while simultaneously preventing the diversion and misuse of nuclear material and technology through appropriate safeguards and security, and promotion of nuclear nonproliferation policies. To achieve this mission, the objectives of the NNPD are to: Promote policy that discourages the proliferation of nuclear technology and material to inappropriate entities. Provide information to ANS members, the technical community at large, opinion leaders, and decision makers to improve their understanding of nuclear nonproliferation issues. Become a recognized technical resource on nuclear nonproliferation, safeguards, and security issues. Serve as the integration and coordination body for nuclear nonproliferation activities for the ANS. Work cooperatively with other ANS divisions to achieve these objective nonproliferation policies.
Meeting Spotlight
Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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
Jun 2025
Jan 2025
Latest Journal Issues
Nuclear Science and Engineering
August 2025
Nuclear Technology
July 2025
Fusion Science and Technology
Latest News
NRC cuts fees by 50 percent for advanced reactor applicants
The Nuclear Regulatory Commission has announced it has amended regulations for the licensing, inspection, special projects, and annual fees it will charge applicants and licensees for fiscal year 2025.
Miriam A. Kreher, Samuel Shaner, Benoit Forget, Kord Smith
Nuclear Science and Engineering | Volume 197 | Number 2 | February 2023 | Pages 279-290
Technical Paper | doi.org/10.1080/00295639.2022.2067739
Articles are hosted by Taylor and Francis Online.
The Frequency Transform method is used for the first time to efficiently model a multiple-second transient problem with Monte Carlo (MC). This is achieved by coupling MC with a time-dependent coarse mesh finite difference (TD-CMFD) diffusion solver. TD-CMFD presents a large advantage over commonly used point kinetics equations since it preserves spatial resolution during the transient and provides equivalence with the high-order method through nonlinear diffusion coefficients. As TD-CMFD computes time-dependent and spatially dependent neutronics information, it also computes frequencies that describe the rate of change of neutron and delayed precursor concentrations. These frequencies are used in MC shape function calculations as an approximation for the time derivatives. As the simulation proceeds, MC calculations update the multigroup cross sections, currents, and diffusion coefficients that are needed in TD-CMFD, and in turn, TD-CMFD updates the frequencies. Our results show the success of the Frequency Transform method in prescribed transient problems on the C5G7 geometry and on a fuel pin geometry. The Frequency Transform method showed significant improvement compared to the Adiabatic approximation, which does not use any frequency information in the MC calculation. The improvements in spatial resolution are shown to be a direct result of frequencies. Additionally, a study of how TD-CMFD’s nonlinear diffusion coefficients behave in time provides a first-of-its-kind study of how equivalence factors are impacted by transients.
