Incorporating delayed neutrons into the pointmodel equations routinely used for neutron coincidence counting in nuclear safeguards
Here, we extend the familiar Bӧhnel pointmodel 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 subcritical 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)tospontaneous fission promptneutron 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.
 Authors:

^{[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)
 Publication Date:
 Report Number(s):
 LAUR1622782
Journal ID: ISSN 03064549
 Grant/Contract Number:
 AC5206NA25396
 Type:
 Accepted Manuscript
 Journal Name:
 Annals of Nuclear Energy (Oxford)
 Additional Journal Information:
 Journal Name: Annals of Nuclear Energy (Oxford); Journal Volume: 99; Journal Issue: C; Journal ID: ISSN 03064549
 Publisher:
 Elsevier
 Research Org:
 Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
 Sponsoring Org:
 USDOE National Nuclear Security Administration (NNSA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL PROTECTION; Delayed neutrons; Neutron coincidence counting; Pointmodel equations; Neutron multiplicity counting
 OSTI Identifier:
 1394968
 Alternate Identifier(s):
 OSTI ID: 1358754
Croft, Stephen, and Favalli, Andrea. Incorporating delayed neutrons into the pointmodel equations routinely used for neutron coincidence counting in nuclear safeguards. United States: N. p.,
Web. doi:10.1016/j.anucene.2016.08.012.
Croft, Stephen, & Favalli, Andrea. Incorporating delayed neutrons into the pointmodel equations routinely used for neutron coincidence counting in nuclear safeguards. United States. doi:10.1016/j.anucene.2016.08.012.
Croft, Stephen, and Favalli, Andrea. 2016.
"Incorporating delayed neutrons into the pointmodel equations routinely used for neutron coincidence counting in nuclear safeguards". United States.
doi:10.1016/j.anucene.2016.08.012. https://www.osti.gov/servlets/purl/1394968.
@article{osti_1394968,
title = {Incorporating delayed neutrons into the pointmodel equations routinely used for neutron coincidence counting in nuclear safeguards},
author = {Croft, Stephen and Favalli, Andrea},
abstractNote = {Here, we extend the familiar Bӧhnel pointmodel 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 subcritical 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)tospontaneous fission promptneutron 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.},
doi = {10.1016/j.anucene.2016.08.012},
journal = {Annals of Nuclear Energy (Oxford)},
number = C,
volume = 99,
place = {United States},
year = {2016},
month = {9}
}