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Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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Hash Hashemian: Visionary leadership
As Dr. Hashem M. “Hash” Hashemian prepares to step into his term as President of the American Nuclear Society, he is clear that he wants to make the most of this unique moment.
A groundswell in public approval of nuclear is finding a home in growing governmental support that is backed by a tailwind of technological innovation. “Now is a good time to be in nuclear,” Hashemian said, as he explained the criticality of this moment and what he hoped to accomplish as president.
P. Goldschmidt
Nuclear Science and Engineering | Volume 49 | Number 3 | November 1972 | Pages 263-273
Technical Paper | doi.org/10.13182/NSE72-A22541
Articles are hosted by Taylor and Francis Online.
Pontryagin’s Maximum Principle and Robbins’ Criterion allow us to find, in the general case of intermediate reactors, the distribution of fuel enrichment that minimizes the critical mass of a reactor of given power and subject to constraints on the maximum power density and on the enrichment. The two group diffusion model is used in slab geometry. The optimal sequence of control (enrichment) zones is made up of a central constant power density zone, a zone of maximum enrichment, a zone of variable enrichment (where the control is singular) and finally an external zone of minimum enrichment (or a reflector). In the particular case of fast reactors the optimal solution does not include the singular control zone.