Incorporating delayed neutrons into the point-model equations routinely used for neutron coincidence counting in nuclear safeguards

Croft, Stephen; Favalli, Andrea

doi:10.1016/j.anucene.2016.08.012

Title: Incorporating delayed neutrons into the point-model equations routinely used for neutron coincidence counting in nuclear safeguards

Journal Article · Wed Sep 21 00:00:00 EDT 2016 · Annals of Nuclear Energy (Oxford)

DOI:https://doi.org/10.1016/j.anucene.2016.08.012· OSTI ID:1394968

Croft, Stephen ^[1];

^[2]

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Safeguards & Security Technology, Nuclear Security and Isotope Technology Division
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Here, we extend the familiar Bӧhnel point-model equations, which are routinely used to interpret neutron coincidence counting rates, by including the contribution of delayed neutrons. After developing the necessary equations we use them to show, by providing some numerical results, what the quantitative impact of neglecting delayed neutrons is across the full range of practical nuclear safeguards applications. The influence of delayed neutrons is predicted to be small for the types of deeply sub-critical assay problems which concern the nuclear safeguards community, smaller than uncertainties arising from other factors. This is most clearly demonstrated by considering the change in the effective (α,n)-to-spontaneous fission prompt-neutron ratio that the inclusion of delayed neutrons gives rise to. That the influence of delayed neutrons is small is fortunate, and our results justify the long standing practice of simply neglecting them in the analysis of field measurements.

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Research Organization:: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

Sponsoring Organization:: USDOE National Nuclear Security Administration (NNSA)

Grant/Contract Number:: AC52-06NA25396

OSTI ID:: 1394968

Alternate ID(s):: OSTI ID: 1358754

Report Number(s):: LA-UR-16-22782

Journal Information:: Annals of Nuclear Energy (Oxford), Vol. 99, Issue C; ISSN 0306-4549

Publisher:: ElsevierCopyright Statement

Country of Publication:: United States

Language:: English

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Cited by: 3 works

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References (12)

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Feynman variance-to-mean in the context of passive neutron coincidence counting Croft, S.; Favalli, A.; Hauck, D. K. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 686 https://doi.org/10.1016/j.nima.2012.05.042	journal	September 2012
On the equivalence of the RTI and SVM approaches to time correlated analysis Croft, S.; Favalli, A.; Henzlova, D. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 773 https://doi.org/10.1016/j.nima.2014.11.064	journal	February 2015
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Title: Incorporating delayed neutrons into the point-model equations routinely used for neutron coincidence counting in nuclear safeguards

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