Status Report on the Passive Neutron Enrichment Meter (PNEM) for UF6 Cylinder Assay

Miller, Katherine; Swinhoe, Martyn T; Menlove, H.O.; Marlow, Johnna B

doi:10.2172/1039683

Cited by 4 publications

(26 citation statements)

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“…This is followed by a study of detector response and analysis of the simulations. Experimental confirmation of these computational results via measurements of UF 6 cylinders at an enrichment facility were performed, and are discussed. Finally, a review of some passive imaging work and a summary of the project are presented.…”

Section: Introductionmentioning

confidence: 82%

“…Passive neutron assay techniques can be based on simple counting of the thermalized neutron flux originating from the UF 6 cylinders [5], or may also consider the time dispersion of neutron counts for a multiplicity analysis [6]. Very few neutrons are generated directly from 235 U in UF 6 ; instead, most neutrons are generated from 238 U spontaneous fission or 234 U and 238 U alpha-decay processes.…”

Section: Introductionmentioning

confidence: 99%

“…Very few neutrons are generated directly from 235 U in UF 6 ; instead, most neutrons are generated from 238 U spontaneous fission or 234 U and 238 U alpha-decay processes. Thermal neutron methods are also sensitive to geometrical perturbations of the UF 6 within the cylinder, giving rise to potentially significant systematic measurement uncertainties [3]. Given the short path length of low-energy gammas and neutrons through UF 6 , these methods may also be insensitive to material in the center of the cylinder (see Figure 1.1).…”

Section: Introductionmentioning

confidence: 99%

“…Thermal neutron methods are also sensitive to geometrical perturbations of the UF 6 within the cylinder, giving rise to potentially significant systematic measurement uncertainties [3]. Given the short path length of low-energy gammas and neutrons through UF 6 , these methods may also be insensitive to material in the center of the cylinder (see Figure 1.1). In the context of international safeguards, for which coordinated state-level diversion is a theoretical possibility, it is undesirable to rely upon either gamma-ray or thermal neutron measurement techniques that are effectively measurements of the outer material skin, blind to the central contents.…”

Section: Introductionmentioning

confidence: 99%

“…However, application of the active technique in unattended measurements is difficult and requires special detection geometry [1]. Current active approaches are designed with the neutron detector in contact with the UF 6 cylinder to allow better detection efficiency. These approaches, however, may not be supported in unattended measurements where a minimum stand-off distance is required for safe movement of the UF 6 cylinders.…”

Section: Introductionmentioning

confidence: 99%

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Using fast neutron signatures for improved UF6 cylinder enrichment measurements.

Kiff¹,

Brubaker²,

Marleau³

2013

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The authors have investigated the use of fast neutrons-primarily the fast neutron energy spectrum-as a signature for uranium hexafluoride (UF 6 ) nuclear accountancy measurements. Detailed modeling of UF 6 storage cylinders and a proposed neutron detection system indicates that the measured neutron energy spectrum is indeed a function of uranium enrichment. Field measurements at the Department of Energy's Paducah Gaseous Diffusion Plant with a detection system similar to the modeled system provided an opportunity to collect signatures from several storage cylinders containing UF 6 with a range of enrichments. Subsequent analysis lends credibility to the modeling results, indicating that enrichment over the range measured (0.72% to 4.95% uranium-235) can be extracted from the measured neutron energy spectrum. These results were scaled to estimate the tradeoff in measurement system size and counting time to achieve a relative enrichment measurement uncertainty of 5%. 3 ACKNOWLEDGMENTSThe authors would like to thank several individuals for their contributions to this project. Robert Cooper provided modeling support for the simulated emissions of 30B cylinders, and played an important role in experiments and analysis of the detector response. Laura Kogler provided important analysis support, and generated important comparisons of the Neutron Scatter Camera to other mature technologies. Isaac Shokair was very helpful in understanding implementation of the Principal Component Analysis technique. Michael Streicher provided important simulation and experimental support, which was useful in understanding the detector response to 30B emissions and the characterization of hardware in the laboratory.Jim Brennan and Dan Throckmorton provided support during the assembly of the detector system fielded at the Paducah Gaseous Diffusion Plant (PGDP). Stanley Mrowka provided software for the data acquisition system and assisted in the data collection at PGDP. Randy DeVault (DOE/Oak Ridge Field Office) and Richard Mayer (DOE/Lexington Field Office) were instrumental in identifying and facilitating the measurement opportunity at PGDP. Brent Montgomery, John Price, and Tullus Crawford of the United States Enrichment Corporation (USEC) provided support for the PGDP measurements.

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Section: Introductionmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%