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Conference Spotlight
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.
E.J. McGrath and Robert W. Albrecht
Nuclear Science and Engineering | Volume 29 | Number 1 | July 1967 | Pages 67-86
Technical Paper | doi.org/10.13182/NSE67-A17811
Articles are hosted by Taylor and Francis Online.
Formal development of the theory for harmonic analysis of neutron multiplying systems is carried out completely in the frequency domain. From basic probability theory, and an assumed reactor model, the problem is expressed as the Fokker-Planck equation in terms of the characteristic function, thus enabling the moments required for a statistical analysis to be obtained. Second-moment calculations include investigation into the bias in estimates of the power spectral density arising from the existence of finite record lengths. It is seen that for even very long records large biases can result, particularly at the lower frequencies. Variance analysis for estimates of the power spectral density investigates all moments up to and including the fourth for neutrons, delayed neutron precursors, and Fourier coefficients. The results show that for the most part, the variances can be described by a single parameter in which the extraneous neutron source plays a particularly important role. For reactors with large sources, the Fourier coefficients are shown to be Gaussian. For systems with small sources, variance in estimates of the power spectral density can become very large, and even the classical smoothed estimate is not consistent.