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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.
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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!
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Latest News
Supreme Court rules against Texas in interim storage case
The Supreme Court voted 6–3 against Texas and a group of landowners today in a case involving the Nuclear Regulatory Commission’s licensing of a consolidated interim storage facility for spent nuclear fuel, reversing a decision by the 5th Circuit Court of Appeals to grant the state and landowners Fasken Land and Minerals (Fasken) standing to challenge the license.
Yunzhao Li, Hongchun Wu, Liangzhi Cao
Nuclear Science and Engineering | Volume 174 | Number 2 | June 2013 | Pages 163-171
Technical Paper | doi.org/10.13182/NSE11-111
Articles are hosted by Taylor and Francis Online.
The isotropic simplified spherical harmonics (SP3) method is employed to cast the neutron transport equation into a coupled set of two equations each of which shares identical mathematical form with the neutron diffusion equation. An exponential function expansion nodal (EFEN) method is presented for an arbitrary triangular grid and implemented to solve the coupled SP3 equations. The EFEN method couples adjacent nodes by defining partial currents on each interface and expanding the detailed flux distribution within each node into a sum of exponential functions to obtain a response matrix between the incoming and outgoing partial currents and a neutron balance condition for each node to obtain the nodal average flux. Numerical results demonstrate that both keff and power distributions agree well with other codes. We find comparable accuracy in most situations, and the new method appears to be faster than the other codes even in cases where EFEN requires a finer unstructured mesh.