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Nominations open for CNTA awards
Citizens for Nuclear Technology Awareness is accepting nominations for its Fred C. Davison Distinguished Scientist Award and its Nuclear Service Award. Nominations for both awards must be submitted by August 1.
The awards will be presented this fall as part of the CNTA’s annual Edward Teller Lecture event.
W. F. Miller, Jr., Wm. H. Reed
Nuclear Science and Engineering | Volume 62 | Number 3 | March 1977 | Pages 391-411
Technical Paper | doi.org/10.13182/NSE62-391
Articles are hosted by Taylor and Francis Online.
Using projection operators, we rederive x-y geometry discrete ordinates-to-spherical harmonics (SN → PN-1.) fictitious sources defined in the literature as ray-effect mitigating devices. We define a new x-y geometry fictitious source with certain properties that are superior to earlier sources. A detailed description of the S2 → P1 source, including a discussion of vacuum and reflective boundary conditions, is provided. We then derive fictitious sources in r-z geometry that give spherical harmonics and spherical-harmonics-like solutions. Finally, a simple algorithm is presented that allows a significant reduction in the iteration time needed to obtain ray-effect-free solutions. This algorithm effectively reduces the size of the fictitious source in energy groups where ray-effect distortions are not expected. The new sources and the algorithm for reduction of computation time make this approach viable for solving the ray-effect problem.