Incorporating delayed neutrons into the point-model equations routinely used for neutron coincidence counting in nuclear safeguards. (January 2017)

• Record Type: Journal Article
• Authors: Croft, S.; Favalli, A.
• Is Part Of: Annals of nuclear energy. Volume 99(2017:Jan.)
• Page Start: 36
• Page End: 39
• Publication Date: 2017-01
• Subjects: Delayed neutrons -- Neutron coincidence counting -- Point-model equations -- Neutron multiplicity counting; Nuclear energy -- Periodicals; Nuclear engineering -- Periodicals; 621.4805
• DOI: 10.1016/j.anucene.2016.08.012
• Languages: English
• ISSNs: 0306-4549

Abstract

Highlights: The Bӧhnel point model equations of neutron coincidence counting are extended to include delayed neutrons. Delayed neutrons may be treated as random for correlated neutron counting. Examples are given to show the impact over the range for safeguards applications. Abstract: 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.