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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
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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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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
Sean O’Brien, John Mattingly, Dmitriy Anistratov
Nuclear Science and Engineering | Volume 185 | Number 3 | March 2017 | Pages 406-425
Technical Paper | doi.org/10.1080/00295639.2016.1272988
Articles are hosted by Taylor and Francis Online.
It is frequently important to estimate the uncertainty and sensitivity of measured and computed detector responses in subcritical experiments and simulations. These uncertainties arise from the physical construction of the experiment, uncertainties in the transport parameters, and counting uncertainties. Perturbation theory enables sensitivity analysis (SA) and uncertainty quantification on integral quantities like detector responses. The aim of our work is to apply SA to the statistics of subcritical neutron multiplicity counting distributions. Current SA methods have only been applied to mean detector responses and the keff eigenvalue. For multiplicity counting experiments, knowledge of the higher-order counting moments and their uncertainties are essential for a complete SA. We apply perturbation theory to compute the sensitivity of neutron multiplicity counting moments to arbitrarily high order. Each moment is determined by solving an adjoint transport equation with a source term that is a function of the adjoint solutions for lower-order moments. This enables moments of arbitrarily high order to be sequentially determined, and it shows that each moment is sensitive to the uncertainties of all lower-order moments. To close our SA of the moments, we derive forward transport equations that are functions of the forward flux and lower-order moment adjoint fluxes. We verify our calculations for the first three moments by comparison with multiplicity counting measurements of a subcritical plutonium metal sphere. For the first three moments, the most influential parameters are ranked, and the validity of first-order perturbation theory is demonstrated by examining the series truncation error. This enables a detailed SA of subcritical multiplicity counting measurements of fissionable material based on transport theory.