Passive NMIS Measurements to Estimate the Shape of Plutonium Assemblies

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Description

A new technique to estimate the shape attribute of plutonium assemblies using the Nuclear Materials Identification System (NMIS) is described. The proposed method possesses a number of advantages. It is passive no external radiation source is required to estimate the shape of plutonium assemblies. Instead, inherent gamma and neutron emissions from spontaneous fission of {sup 240}Pu and subsequent induced fission of {sup 239}Pu are detected to estimate the shape attribute. The technique is also stationary: shape is estimated without scanning the assembly by moving the detectors relative to the assembly. The proposed method measures third order correlations between triplets of ... continued below

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12 p.

Creation Information

Mattingly, J.K.; Chiang, L.G.; March-Leuba, J.A.; Mihalczo, J.T.; Mullens, J.A.; Perez, R.B. et al. July 22, 1999.

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  • Oak Ridge Y-12 Plant
    Publisher Info: Oak Ridge Y-12 Plant, TN (United States)
    Place of Publication: Tennessee

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Description

A new technique to estimate the shape attribute of plutonium assemblies using the Nuclear Materials Identification System (NMIS) is described. The proposed method possesses a number of advantages. It is passive no external radiation source is required to estimate the shape of plutonium assemblies. Instead, inherent gamma and neutron emissions from spontaneous fission of {sup 240}Pu and subsequent induced fission of {sup 239}Pu are detected to estimate the shape attribute. The technique is also stationary: shape is estimated without scanning the assembly by moving the detectors relative to the assembly. The proposed method measures third order correlations between triplets of gamma/neutron-sensitive detectors. The real coincidence of a pair of gammas is used as a ''trigger'' to approximately identify the time of a spontaneous or induced fission event. The spatial location of this fission event is inferred from the real coincidence of a subsequent neutron with the initial pair of correlated gammas by using the neutron's time-of-flight (approximately the delay between the gamma pair and the neutron) and the fission neutron spectra of {sup 240}Pu and {sup 239}Pu. The spatial distribution of fission sites and hence the approximate shape of the plutonium assembly is thereby inferred by measuring the distribution of a large number of these correlated triplets. Proof-of-principle measurements were performed using {sup 252}Cf as a surrogate for {sup 240}Pu to demonstrate that the technique is feasible. For the simple shapes approximated with {sup 252}Cf sources, the measurements showed that the proposed method is capable of correctly identifying the shape and accurately estimating its size to within a few percent of actual.

Physical Description

12 p.

Notes

INIS; OSTI as DE00012636

Medium: P; Size: 12 pages

Source

  • Other Information: PBD: 22 Jul 1999

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  • Report No.: Y/LB-16,012
  • Grant Number: AC05-84OR21400
  • DOI: 10.2172/12636 | External Link
  • Office of Scientific & Technical Information Report Number: 12636
  • Archival Resource Key: ark:/67531/metadc628286

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

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Creation Date

  • July 22, 1999

Added to The UNT Digital Library

  • June 16, 2015, 7:43 a.m.

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  • April 6, 2017, 8:06 p.m.

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Mattingly, J.K.; Chiang, L.G.; March-Leuba, J.A.; Mihalczo, J.T.; Mullens, J.A.; Perez, R.B. et al. Passive NMIS Measurements to Estimate the Shape of Plutonium Assemblies, report, July 22, 1999; Tennessee. (digital.library.unt.edu/ark:/67531/metadc628286/: accessed October 18, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.