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November 8–12, 2025
Washington, DC|Washington Hilton
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Nuclear News 40 Under 40—2025
Last year, we proudly launched the inaugural Nuclear News 40 Under 40 list to shine a spotlight on the exceptional young professionals driving the nuclear sector forward as the nuclear community faces a dramatic generational shift. We weren’t sure how a second list would go over, but once again, our members resoundingly answered the call, confirming what we already knew: The nuclear community is bursting with vision, talent, and extraordinary dedication.
Emerson Paul Chivington, William E. Kastenberg
Nuclear Science and Engineering | Volume 83 | Number 3 | March 1983 | Pages 350-365
Technical Paper | doi.org/10.13182/NSE83-A17568
Articles are hosted by Taylor and Francis Online.
A technique is developed for the treatment of space-time neutron kinetics, which can include the effects of material motion. The new method is applied to sample problems where azimuthal fuel motion is postulated to occur. The technique developed employs the finite element method, Gear's variable predictor corrector scheme, and a Lagrangian mesh that moves with the reactor materials. We treat a cylindrical reactor in (r,θ) geometry. Because finite elements are used to describe both the fluxes and the boundaries of the mesh elements, the resulting deformed elements could be arbitrarily shaped. Second-order polynomials (elements) were found to be better than linear polynomials in treating the geometry because of the curved boundaries used in the problem. Azimuthal motion was found to increase reactivity, and large motion resulted in large increases in reactor power for the cases studied. However, the cases studied showed that azimuthal motion was less important than both inward and outward radial motion. Point kinetics (based on first-order perturbation theory) did not accurately predict the power excursion in cases where substantial azimuthal displacement occurred.