The general backward theory of neutron fluctuations in subcritical systems with multiple emission sources

SummaryThe Feynman-alpha and Rossi-alpha formulae are derived analytically for subcritical systems driven by a multiple emission source,i.e. one that emits several neutrons on each source emission event. The prime example of such sources is a spallation source, which will be used in future accelerator driven subcritical systems (ADS) such as the energy amplifier. Such formulae for ADS have been derived recently but in simpler neutronic models. In this paper six groups of delayed neutron precursors are taken into account, and the full joint statistics of the prompt and all delayed groups is included. Thus the present results are generalisations of earlier ones. The involved problems that are encountered are solved with a combination of effective analytical techniques and symbolic algebra codes.

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