MCNP-PoliMi analysis of neutron-source penetrability in uranium-oxide samples measured with an active well coincidence counter

S. D. Clarke, Marek Flaska, S. A. Pozzi, R. B. Oberer, L. G. Chiang

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations

Abstract

Active well coincidence counters (AWCCs) are widely used for nondestructive assay and nuclear-safeguards applications, mainly for special nuclear material. The measurement method is based on the detection of time-correlated neutrons from fission by 3He tubes embedded in a polyethylene moderator. The purported advantage of this method over traditional gamma-ray spectral analysis is the greater penetrability of neutrons in the measured sample. However, the degree of this advantage has not been yet fully quantified. In order to accurately characterize the AWCC response, the Monte Carlo simulations must take into account all detailes of an AWCC measurement. In this study, all these issues are addressed and a detailed simulation analysis of the measurement system is presented. The three-dimensional behavior of the neutron flux within the AWCC has been obtained through the analysis with the MCNPX-PoliMi code. Particular interest has been paid to the flux behavior within the analysis sample: a 4-kg can of U3 O8 powder. The distribution of fission reactions occurring in the sample is peaked near the bottom of the sample while it is fairly constant in the radial direction. The fission-position data were further analyzed in order to determine the origin of the captured neutrons. Approximately twice as many counted neutrons originate from the sample peripheries (both top and radial) than from the center. This means that the AWCC can see the interior of a bulk powder sample only half-as-well as the peripheries.

Original languageEnglish (US)
Title of host publicationIEEE Nuclear Science Symposuim and Medical Imaging Conference, NSS/MIC 2010
Pages995-999
Number of pages5
DOIs
StatePublished - Dec 1 2010
Event2010 IEEE Nuclear Science Symposium, Medical Imaging Conference, NSS/MIC 2010 and 17th International Workshop on Room-Temperature Semiconductor X-ray and Gamma-ray Detectors, RTSD 2010 - Knoxville, TN, United States
Duration: Oct 30 2010Nov 6 2010

Publication series

NameIEEE Nuclear Science Symposium Conference Record
ISSN (Print)1095-7863

Other

Other2010 IEEE Nuclear Science Symposium, Medical Imaging Conference, NSS/MIC 2010 and 17th International Workshop on Room-Temperature Semiconductor X-ray and Gamma-ray Detectors, RTSD 2010
CountryUnited States
CityKnoxville, TN
Period10/30/1011/6/10

All Science Journal Classification (ASJC) codes

  • Radiation
  • Nuclear and High Energy Physics
  • Radiology Nuclear Medicine and imaging

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    Clarke, S. D., Flaska, M., Pozzi, S. A., Oberer, R. B., & Chiang, L. G. (2010). MCNP-PoliMi analysis of neutron-source penetrability in uranium-oxide samples measured with an active well coincidence counter. In IEEE Nuclear Science Symposuim and Medical Imaging Conference, NSS/MIC 2010 (pp. 995-999). [5873913] (IEEE Nuclear Science Symposium Conference Record). https://doi.org/10.1109/NSSMIC.2010.5873913