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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.
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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
Take steps on SNF and HLW disposal
Matt Bowen
With a new administration and Congress, it is time once again to ponder what will happen—if anything—on U.S. spent nuclear fuel and high-level waste management policy over the next few years. One element of the forthcoming discussion seems clear: The executive and legislative branches are eager to talk about recycling commercial SNF. Whatever the merits of doing so, it does not obviate the need for one or more facilities for disposal of remaining long-lived radionuclides. For that reason, making progress on U.S. disposal capabilities remains urgent, lest the associated radionuclide inventories simply be left for future generations to deal with.
In March, Rick Perry, who was secretary of energy during President Trump’s first administration, observed that during his tenure at the Department of Energy it became clear to him that any plan to move SNF “required some practical consent of the receiving state and local community.”1
Rodolfo M. Ferrer, Joel D. Rhodes III
Nuclear Science and Engineering | Volume 182 | Number 2 | February 2016 | Pages 151-165
Technical Paper | doi.org/10.13182/NSE15-6
Articles are hosted by Taylor and Francis Online.
A linear source (LS) approximation scheme is presented for the two-dimensional method of characteristics (MOC). The LS approximation relies on the computation of track-based spatial moments over source regions to obtain the LS expansion coefficients. The proposed LS scheme improves the solution accuracy relative to the constant or flat source (FS) approximation. The LS scheme is capable of treating arbitrarily shaped source regions under isotopic or anisotropic scattering assumptions. The LS scheme is also compatible with standard coarse-mesh finite difference acceleration. Numerical tests presented for the C5G7 mixed oxide benchmark show that for comparable accuracy with respect to the reference solution, the LS approximation can reduce the run time by a factor of 4 and the memory requirements by a factor of 10 relative to the FS scheme. This is because the LS scheme permits the use of a much coarser grid than the FS scheme. Numerical tests presented for simple cold critical core configurations with anisotropic scattering confirm the advantage of using the LS scheme.
