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Title: A comparison of Monte Carlo fission models for safeguards neutron coincidence counters

Abstract

Monte Carlo simulation is a powerful tool used to model neutron coincidence detectors for international safeguards. The simulation has typically sampled properties such as the fission neutron multiplicity, energy, and direction, from independent probability density functions. However, multiplicity counters detect event-based neutron correlations and thus more accurate fission event modeling is needed. To respond to this need, the Fission Reaction Event Yield Algorithm (FREYA) and the Cascading Gamma-ray Multiplicity with Fission (CGMF) models were added in the newest version of MCNP, MCNP6.2. The models simulate individual fission events conserving momentum, energy, and angular momentum such that correlated particles are emitted. The effects of the new models on simulations of safeguards neutron coincidence counters were studied and compared to standard MCNP simulations. The MCNPX-PoliMi model was also included in the comparison. The properties of fission neutrons from safeguards relevant isotopes were compared to literature references. Then a hypothetical simplified detector was modeled to isolate the effects of specific differences between models. Experimental measurements from previous work were modeled and agreements were compared. Lastly, the probabilities of correlated events occurring in the experimental measurements were calculated with the different models. For example, the probability was calculated of detecting neutrons from both inducedmore » fission in uranium and spontaneous fission of Cf-252 in the same fission chain.« less

Authors:
ORCiD logo [1]; ORCiD logo [2];  [2]; ORCiD logo [2];  [2];  [3]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of Florida, Gainesville, FL (United States)
  2. Univ. of Florida, Gainesville, FL (United States)
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1458959
Report Number(s):
LA-UR-18-20887
Journal ID: ISSN 0168-9002
Grant/Contract Number:  
AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment
Additional Journal Information:
Journal Volume: 903; Journal Issue: C; Journal ID: ISSN 0168-9002
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; FREYA; CGMF; MCNP; Safeguards; Neutron coincidence and multiplicity counting

Citation Formats

Weinmann-Smith, Robert K., Swinhoe, Martyn Thomas, Trahan, Alexis Chanel, Andrews, Madison Theresa, Menlove, Howard Olsen, and Enqvist, Andreas. A comparison of Monte Carlo fission models for safeguards neutron coincidence counters. United States: N. p., 2018. Web. doi:10.1016/j.nima.2018.06.055.
Weinmann-Smith, Robert K., Swinhoe, Martyn Thomas, Trahan, Alexis Chanel, Andrews, Madison Theresa, Menlove, Howard Olsen, & Enqvist, Andreas. A comparison of Monte Carlo fission models for safeguards neutron coincidence counters. United States. doi:10.1016/j.nima.2018.06.055.
Weinmann-Smith, Robert K., Swinhoe, Martyn Thomas, Trahan, Alexis Chanel, Andrews, Madison Theresa, Menlove, Howard Olsen, and Enqvist, Andreas. Sat . "A comparison of Monte Carlo fission models for safeguards neutron coincidence counters". United States. doi:10.1016/j.nima.2018.06.055.
@article{osti_1458959,
title = {A comparison of Monte Carlo fission models for safeguards neutron coincidence counters},
author = {Weinmann-Smith, Robert K. and Swinhoe, Martyn Thomas and Trahan, Alexis Chanel and Andrews, Madison Theresa and Menlove, Howard Olsen and Enqvist, Andreas},
abstractNote = {Monte Carlo simulation is a powerful tool used to model neutron coincidence detectors for international safeguards. The simulation has typically sampled properties such as the fission neutron multiplicity, energy, and direction, from independent probability density functions. However, multiplicity counters detect event-based neutron correlations and thus more accurate fission event modeling is needed. To respond to this need, the Fission Reaction Event Yield Algorithm (FREYA) and the Cascading Gamma-ray Multiplicity with Fission (CGMF) models were added in the newest version of MCNP, MCNP6.2. The models simulate individual fission events conserving momentum, energy, and angular momentum such that correlated particles are emitted. The effects of the new models on simulations of safeguards neutron coincidence counters were studied and compared to standard MCNP simulations. The MCNPX-PoliMi model was also included in the comparison. The properties of fission neutrons from safeguards relevant isotopes were compared to literature references. Then a hypothetical simplified detector was modeled to isolate the effects of specific differences between models. Experimental measurements from previous work were modeled and agreements were compared. Lastly, the probabilities of correlated events occurring in the experimental measurements were calculated with the different models. For example, the probability was calculated of detecting neutrons from both induced fission in uranium and spontaneous fission of Cf-252 in the same fission chain.},
doi = {10.1016/j.nima.2018.06.055},
journal = {Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment},
number = C,
volume = 903,
place = {United States},
year = {Sat Jun 23 00:00:00 EDT 2018},
month = {Sat Jun 23 00:00:00 EDT 2018}
}

Journal Article:
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