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Homeland security I: Radiation detection applications and nuclear safeguards

Session chair: Kouzes , Richard T. (Pacific Northwest National Laboraotry (PNNL), Richland, USA); Lintereur , Azaree (Penn State University, State College, USA)
Shortcut: N-18
Date: Wednesday, 20 October, 2021, 11:45 AM - 1:45 PM
Room: NSS - 2
Session type: NSS Session

This session includes presentations on radiation detection for homeland security including nuclear safeguards methods and other applications


Click on an contribution to preview the abstract content.

11:45 AM N-18-01

Self-induced X-ray Fluorescence measurements for Pu accountancy in Spent Nuclear Fuel using hard X-ray reflective optics (#1173)

J. Ruz Armendariz1, M. - A. Descalle1, J. B. Alameda1, T. A. Decker1, J. Klingman1, J. Lown1, M. J. Pivovaroff1, J. Robinson1, R. Soufli1, K. T. Schmitt2, K. K. Ziock2

1 Lawrence Livermore National Laboratory, PLS/Physicsc, Livermore, California, United States of America
2 Oak Ridge National Laboratory, Physics, Oak Ridge, Tennessee, United States of America


Self-induced X-ray fluorescence (XRF) is a direct non-destructive assay technique that can be used to estimate the Pu content in spent nuclear fuel (SNF).  However, measurements of U and Pu characteristic X-rays emitted by SNF remain challenging: K-shell lines are weak compared to intense gamma-ray emission lines from fission products, and to the down-scattered background in the 94 to 115 keV energy range. Some techniques such as pinhole collimation and Compton suppression have been applied to limit overall photon rates incident on detectors and to reduce the Compton background. An alternative approach relies on X-ray grazing incidence optics designed to preferentially reflect U and Pu fluorescence lines away from the direct beam. Previous experimental campaigns led to the first demonstrations of single and double reflections of U Ka lines with X-ray reflective optics.  Recent measurements were conducted at the Irradiated Fuel Examination Laboratory at Oak Ridge National Laboratory (ORNL) on MOX and UO2 spent nuclear fuel pins, some of which were only recently discharged from a reactor (~ 7 months old). Quantitative estimates of Pu/U peaks ratios were obtained for direct (without optic) and reflected beam configurations. Systematics and practical challenges of the technique are addressed.

Keywords: Grazing incidence optics, K-shell emission, Safeguards, Spent nuclear fuel, X-rays
12:00 PM N-18-02

Ab Initio Background and Anomaly Learning for Static Gamma-ray Detectors (#1204)

M. S. Bandstra1, N. Abgrall1, R. J. Cooper1, D. Hellfeld1, T. H. Y. Joshi1, B. J. Quiter1, M. Salathe1

1 Lawrence Berkeley National Laboratory, Nuclear Science Division, Berkeley, California, United States of America


Static gamma-ray detector systems that are deployed outdoors to monitor for threat sources will experience time-varying natural backgrounds and encounters with man-made nuisance sources. In order to be sensitive to illicit sources, such a system must be able to distinguish those sources from variations due to, e.g., weather and human activity. In addition to fluctuations due to non-threats, each detector will have its own detector response and energy resolution function, so providing a large network of detectors with pre-determined background and source templates can be a complex task. Instead, we propose that static detectors learn the background and nuisance sources ab initio, by using simple algorithms to bootstrap and inform more complex algorithms. Specifically, gross count rate filters are used to distinguish static from rainfall-related backgrounds due to increased radon progeny, and more complex spectral algorithms are used as additional checks on spectral anomalies. The outputs from these processes seed more complex algorithms for anomaly detection, clustering, and identification.

AcknowledgmentThis work was performed under the auspices of the U.S. Department of Energy by Lawrence Berkeley National Laboratory (LBNL) under Contract DE-AC02-05CH11231. The project was funded by the U.S. Department of Energy, National Nuclear Security Administration, Office of Defense Nuclear Nonproliferation Research and Development.
Keywords: radiation detection, background radiation, source identification, radon
12:15 PM N-18-03

Metal Loaded Organic Glass Scintillator for High Resolution Fast Neutron/X-Ray Radiography (#414)

V. V. Nagarkar1, C. Sosa1, S. Miller1, E. V. vanLoef1, U. Shirwadkar1, B. Singh1, M. McClish1, L. Nguyen2, P. L. Feng2

1 Radiation Monitoring Devices, Inc., Watertown, Massachusetts, United States of America
2 Sandia National Laboratories, Livermore, California, United States of America


Detectors enabling high-resolution X-ray and neutron radiography in time efficient manner are of critical importance to homeland security agencies for rapid identification of threats and generating the information needed to plan a response. Portable X-ray systems are commercially available, however neutron imaging detectors with similar spatial resolution to X-rays do not exist. Ideally, a system providing combined X-ray/neutron capability is desired.

Here we report on the development of a detector that relies on recent advancements in metal loaded organic glass scintillators (OGS) that offers high efficiency for fast neutron detection and enhanced absorption of high energy X-rays. To date we have produced up to 3.6 mm thick OGS specimens for imaging, which were integrated into sCMOS camera to form the detector. This detector has demonstrated spatial resolution of over 3 line-pairs per millimeter (>3 lp/mm or ~160 µm) for X-rays. GEANT4 Modeling estimates similar resolution response with fast neutrons. To our knowledge, these are the first ever imaging data obtained using OGS. The 3.6 mm thick metal loaded OGS has ~20% efficiency for 2.45 MeV DD neutrons and ~5% efficiency for 14.1 MeV DT neutrons.

This paper will present details of the scintillator, detector performance under MeV neutrons and high energy X-ray exposures, design approaches that enable balancing the efficiency-resolution tradeoffs, and ways to enhance MeV X-ray imaging using OGS.


This work has been supported by DOE contract # DE-SC0020942

and DE-SC0021545

Keywords: organic glass scintillator, tin-loaded, multi-mode radiography, homeland security instrumentation
12:30 PM N-18-04

SANDD: A directional antineutrino detector with segmented 6Li-doped pulse-shape-sensitive plastic scintillator (#577)

F. Sutanto1, N. Bowden1, T. Classen1, S. Dazeley1, M. Duvall3, M. Ford1, I. Jovanovic2, V. Li1, A. Mabe1, M. Mendenhall1, E. Reedy1, C. Roca1, T. Wu2, N. Zaitseva1, X. Zhang1

1 Lawrence Livermore National Laboratory, Physical and Life Sciences, Livermore, California, United States of America
2 University of Michigan, Department of Nuclear Engineering and Radiological Sciences, Ann Arbor, Michigan, United States of America
3 University of Hawaii at Manoa, Department of Physics and Astronomy, Honolulu, Hawaii, United States of America


We present a characterization of a small (9-liter) and mobile 0.1% 6Li-doped pulse-shape-sensitive plastic scintillator antineutrino detector called SANDD (Segmented AntiNeutrino Directional Detector), constructed for the purpose of near-field reactor monitoring with sensitivity to antineutrino direction. 
SANDD comprises three different types of module. A detailed Monte Carlo simulation code was developed to match and validate the performance of each of the three modules. The combined model was then used to produce a prediction of the performance of the entire detector. Analysis cuts were established to isolate antineutrino inverse beta decay events while rejecting large fraction of backgrounds. The antineutrino detection efficiency and SANDD directional performance were predicted. The impact of cosmic neutron background on the SANDD directional performance was investigated.

AcknowledgmentThis work was supported by the U.S. Department of Energy National Nuclear Security Administration and Lawrence Livermore National Laboratory [Contract No. DE-AC52-07NA27344, LDRD tracking number 20-SI-003 and 17-ERD-016, release number LLNL-ABS-822262. The work of I.J. was partially supported by the Consortium for Monitoring, Technology, and Verification under U.S. Department of Energy National Nuclear Security Administration award number DE-NE000863. 
Keywords: Li-doped pulse-shape-sensitive plastic, nuclear nonproliferation, directional antineutrino detector, neutron and gamma detector, segmented detector
12:45 PM N-18-05

Developing Delayed Gamma-ray Spectroscopy for Reprocessing Plant Nuclear Safeguards: Fissile Nuclide Content Analysis (#757)

D. C. Rodriguez1, K. Abbas2, M. Koizumi1, H. - J. Lee1, S. Nonneman2, B. Pedersen2, F. Rossi1, T. Takahashi1

1 Japan Atomic Energy Agency, Integrated Support Center for Nuclear Nonproliferation and Nuclear Security, Tokai-mura, Japan
2 Joint Research Centre, Nuclear Security Unit, Ispra, Italy


The Japan Atomic Energy Agency’s Integrated Support Center for Nuclear Nonproliferation and Nuclear Security (JAEA/ISCN) and European Commission Joint Research Centre (EC/JRC) are collaborating to develop technology for nuclear safeguards verification. Delayed gamma-ray spectroscopy (DGS) is being developed to supplement the verification of nuclear material in reprocessing plants by analyzing the fissile nuclide content in spent nuclear fuel solution samples. DGS is an active-interrogation technique that uses an external neutron source to induce fission in the sample followed by a measurement of gamma rays emitted by the decay of the generated fission products. Experiments were performed with the PUNITA instrument at the EC/JRC in Ispra, Italy to obtain spectra from both U and Pu samples. These were used to evaluate the gamma-ray peak dependence on both the interrogation pattern as well as the enrichment. Analysis of these spectra has resulted in clear distinction between the U-235 and Pu-239 fissile nuclide spectra for composition analysis as well as a linear correlation to the U-235 mass. Experiments with the JAEA/ISCN’s Delayed Gamma-ray Californium Test instrument in the EC/JRC PERLA facility show spectral results similar to PUNITA, even as a more compact instrument. These results are compared to the JAEA/ISCN Delayed Gamma-ray Spectroscopy Monte Carlo (DGSMC) and other simulation codes for validation and final evaluation of an inverse Monte Carlo analysis method. This work will describe the goals of the DGS project along with the experimental results in light of the efforts to develop the DGSMC for analysis of current and future applications.

AcknowledgmentThis work is supported by the Japan Ministry of Education, Culture, Sports, Science, and Technology subsidy for promoting nuclear security related activities. This work was performed under agreement between the JAEA and EURATOM in the field of nuclear material safeguards research and development.
Keywords: Fission, gamma rays, Monte Carlo methods, neutron interrogation, nuclear safeguards
1:00 PM N-18-06

Special Nuclear Material Detection Using Trans-Stilbene and Artificial Neural Network (#952)

A. J. Jinia1, T. E. Maurer1, S. D. Clarke1, H. - S. Kim2, D. D. Wentzloff2, S. A. Pozzi1, 3

1 University of Michigan, Department of Nuclear Engineering and Radiological Sciences, Ann Arbor, Michigan, United States of America
2 University of Michigan, Department of Electrical Engineering and Computer Science, Ann Arbor, United States of America
3 University of Michigan, Department of Physics, Ann Arbor, United States of America


Active interrogation (AI) is a promising approach to detect shielded special nuclear materials (SNMs). During AI, SNM targets are bombarded with ionizing radiation resulting in nuclear fission reactions that produces prompt fission neutrons up to 10 MeV in energy (Watt energy spectrum). At the University of Michigan, we are developing a photon-based AI system that uses bremsstrahlung radiation from an electron linear accelerator (linac) as an ionizing source and trans-stilbene organic scintillating detectors for prompt neutron detection. The stilbene scintillator is sensitive to fast neutrons and photons and has excellent pulse shape discrimination (PSD) capabilities. The traditional charge integration (CI) method used for PSD relies on a particle discrimination line to separate neutrons from photons. During AI, the intense bremsstrahlung radiation from the linac creates significant piled-up pulses in the stilbene scintillator posing a great challenge to the traditional CI method; this is due to the additional presence of a pile-up cloud and overlapping neutron, photon and pile-up clouds in the PSD analysis. Accurately identifying single neutron pulses is crucial. To correctly identify single neutron pulses and mitigate the effect of piled-up pulses during photon-based AI, an artificial neural network (ANN) system is used. We present the first results from the bombardment of bremsstrahlung radiation on a depleted uranium (DU) target, clearly indicating the presence of prompt fission neutrons produced as a result of photon-fission reactions in the DU target. The neutron spectroscopy information obtained from the ANN provides further evidence on the detection of prompt fission neutrons.


This work has been supported by the U.S. Department of Homeland Security, Countering Weapons of Mass Destruction Office, Academic Research Initiative under Grant No. 2016-DN-077-ARI106.

Keywords: artificial neural network, stilbene, linac, high photon flux, prompt photo-fission neutrons
1:15 PM N-18-07

Multi-Reactor Scientific Reach and Application Measurements with ROADSTR, a Mobile Antineutrino Detector (#1083)

C. Roca1, T. Akindele1, N. S. Bowden1, L. Carman1, T. Classen1, S. Dazeley1, V. Li1, M. Ford1, M. Mendenhall1, F. Sutanto1, N. Zaitseva1, X. Zhang1

1 Lawrence Livermore National Laboratory, Physical and Life Sciences, Livermore, California, United States of America


The Reactor Operations Antineutrino Detection Surface Testbed Rover (ROADSTR) project aims to develop technologies for readily mobile antineutrino detectors that will allow measurements at multiple reactors. Besides the clear advantages for nuclear safeguard and verification applications, an easily redeployable detector provides a unique chance to constrain flux and spectrum predictions for different nuclear fuels while minimizing the detector-related systematic uncertainties. Such measurements could prove crucial to understand the different anomalies observed in the short baseline reactor antineutrino field. In this talk, the variety of efforts underway within the project will be discussed, including the development of 6Li-doped plastic scintillators with Pulse Shape Discrimination capabilities, the mobile detector implementation, and the study of correlated background reduction strategies.

AcknowledgmentThis work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, release number LLNL-ABS-822238.
Keywords: multi-site measurement, surface level detector, pulse shape discrimination plastic scintillator, readily mobile system, reactor antineutrino spectrum
1:30 PM N-18-08

NRTA technique for elemental identification using an isotopic neutron source (#1151)

F. Naqvi1, P. Levine1, E. A. Klein1, A. Danagoulian1

1 Massachusetts Institute of Technology, Department of Nuclear Science & Engineering, Cambridge, Massachusetts, United States of America


Neutron resonance transmission analysis technique (NRTA) uses the resonance phenomenon to identify the isotopic composition of unknown materials. Several mid-Z to high-Z elements have discrete energy levels 1 eV- 100 eV above the neutron separation energy. In this energy range, the transmission spectra of epithermal neutrons for these elements exhibit unique resonant signatures due to which NRTA has found its applications
in the field of archaeology, warhead verification and spent fuel analysis. Presence and quantification of special nuclear materials such as U-235, U-238, Pu-239 and Pu-240 with NRTA is being explored, however its application is currently limited due to the availability of calibrated, strong neutron sources only at large experimental facilities. To eliminate this limitation, we have studied the feasibility of doing NRTA with a mobile, small-scale setup using an isotopic neutron source. Time-of-flight is measured between two detectors to provide the energy of the transmitted epithermal neutrons. Proposed experimental geometry, measurement times and acceptable source count rates investigated using Monte Carlo based GEANT4 code and experimental data will be presented. Preliminary results on resolution and background levels in the transmitted energy spectrum will be discussed to demonstrate confidence for future applications.

Keywords: neutron resonance, warhead verification, elemental composition

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