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Conference Spotlight
Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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ANS joins others in seeking to discuss SNF/HLW impasse
The American Nuclear Society joined seven other organizations to send a letter to Energy Secretary Christopher Wright on July 8, asking to meet with him to discuss “the restoration of a highly functioning program to meet DOE’s legal responsibility to manage and dispose of the nation’s commercial and legacy defense spent nuclear fuel (SNF) and high-level radioactive waste (HLW).”
Edward W. Larsen, Michael Williams
Nuclear Science and Engineering | Volume 65 | Number 2 | February 1978 | Pages 290-302
Technical Paper | doi.org/10.13182/NSE78-A27158
Articles are hosted by Taylor and Francis Online.
We show that in a medium consisting of asymmetric cells, neutrons can “drift,” or diffuse, in a special preferred direction. The drift is caused by selective asymmetric changes in the cross sections in each cell. We describe several physical mechanisms that produce a drift, and we briefly discuss a possible application in a reflector design. (A reflector constructed of asymmetric cells, oriented so that the drift is always directed toward the reactor core, would be more efficient than a homogeneous driftless reflector.) Our theoretical treatment consists of an asymptotic analysis of the one-dimensional neutron transport equation. We show that a simple modification of the diffusion equation describes the neutron drift, and we provide numerical results for several problems. We also numerically compare the solution of an initial value problem for the transport equation in an asymmetric cellular medium to the corresponding diffusion theory problem. The results are in reasonably good agreement for both short and long times.