ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
Explore the many uses for nuclear science and its impact on energy, the environment, healthcare, food, and more.
Explore membership for yourself or for your organization.
Conference Spotlight
Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
Standards Program
The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
Latest Magazine Issues
Jul 2025
Jan 2025
Latest Journal Issues
Nuclear Science and Engineering
August 2025
Nuclear Technology
Fusion Science and Technology
July 2025
Latest News
Spent fuel transfer project completed at INL
Work crews at Idaho National Laboratory have transferred 40 spent nuclear fuel canisters into long-term storage vaults, the Department of Energy’s Office of Environmental Management has reported.
Y. S. Rana, S. B. Degweker
Nuclear Science and Engineering | Volume 169 | Number 1 | September 2011 | Pages 98-109
Technical Note | doi.org/10.13182/NSE11-A12499
Articles are hosted by Taylor and Francis Online.
Through our earlier papers, we have shown that reactor noise in accelerator-driven systems (ADS) is different from that in critical or radioactive source-driven subcritical systems due to periodically pulsed source and its non-Poisson character. We have developed a theory of reactor noise for ADS, taking into account the non-Poisson character of the source. Various noise descriptors, such as Rossi-alpha, Feynman-alpha (or variance to mean), power spectral density, and cross power spectral density, have been derived for a periodically pulsed source, including correlation between different pulses and finite pulses of different shapes. For mathematical simplicity, the theory was restricted to the case of prompt neutrons only. Recently, we extended the theory to the delayed neutron case and derived Feynman-alpha and Rossi-alpha formulae by considering the source to be a periodically pulsed non-Poisson source, without correlations between different pulses. The present paper extends the treatment to account for the possibility of correlations between pulses. Feynman-alpha and Rossi-alpha formulas are derived by considering the source to be a periodic sequence of delta function non-Poisson pulses, with exponential correlations.