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Discriminating Uranium Isotopes Using the Time-Emission Profiles of Long-Lived Delayed Neutrons

Journal Article · · Physical Review Applied
 [1];  [2];  [3];  [3];  [3];  [2]
  1. Univ. of Michigan, Ann Arbor, MI (United States); DOE/OSTI
  2. Univ. of Michigan, Ann Arbor, MI (United States)
  3. Pennsylvania State Univ., University Park, PA (United States)
In nuclear nonproliferation and safeguards, detecting and accurately characterizing special nuclear material remains one of the greatest challenges. Uranium enrichment determination is typically achieved by measuring the ratio of characteristic γ -ray emissions from 235U and 238U. Fission also produces β -delayed neutrons, which have been used in the past to determine uranium enrichment from the time dependence of the long-lived delayed-neutron emission rate. Such measurements typically use moderated 3He-tube detectors. We demonstrate an alternative measurement technique that employs a fast neutron active-interrogation probe and a scintillation detector to measure the enrichment of uranium using both the buildup and decay of β -delayed-neutron emission. Instead of 3He tubes, a capture-based heterogeneous composite detector consisting of scintillating Li glass and polyvinyl toluene is constructed and used, offering a prospect to scale delayed-neutron measurements to larger detector sizes. Since the technique relies on the existing tabulated nuclear data, no calibration standards are required. It is shown that the buildup of delayed-neutron emission can be used to distinguish between uranium samples and infer the uranium enrichment level, with accuracy that rivals the method that employs the time-dependent decay of delayed-neutron emission.
Research Organization:
Univ. of Michigan, Ann Arbor, MI (United States)
Sponsoring Organization:
US Department of Homeland Security (DHS); USDOE National Nuclear Security Administration (NNSA)
Grant/Contract Number:
NA0002534
OSTI ID:
1540692
Journal Information:
Physical Review Applied, Journal Name: Physical Review Applied Journal Issue: 2 Vol. 10; ISSN 2331-7019
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

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