Particle Release Experiment (PRex) Final Report

126 Pages·2015·6.98 MB·English

by  Mike Parker

PNNL-23997
Prepared for the U.S. Department of Energy
under Contract DE-AC05-76RL01830
Particle Release Experiment (PRex)

Final Report

ME Keillor BD Milbrath
LM Arrigo JP Rishel
RS Detwiler A Seifert
WJ Kernan CE Seifert
RR Kirkham JE Smart
M MacDougall D Emer1
V Chipman1

September 2014

1 National Security Technologies LLC

PNNL-23997

Particle Release Experiment (PRex)
Final Report

ME Keillor BD Milbrath
LM Arrigo JP Rishel
RS Detwiler A Seifert
WJ Kernan CE Seifert
RR Kirkham JE Smart
M MacDougall D Emer1
V Chipman1

September 2014

Prepared for
the U.S. Department of Energy
under Contract DE-AC05-76RL01830

Pacific Northwest National Laboratory
Richland, Washington 99352
1 National Security Technologies LLC
PNNL-23997
Abstract
An experiment to release radioactive particles representative of small-scale venting from an underground
nuclear test was conducted to gather data in support of treaty verification and monitoring activities. For
this experiment, a CO -driven “air cannon” was used to release 140La at ambient temperatures.
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Lanthanum-140 was chosen to represent the fission fragments because of its short half-life and prominent
gamma-ray emissions; the choice was also influenced by the successful production and use of 140La with
low levels of radioactive contaminants in a Defence Research and Development Canada Field Trial. The
source was created through activation of high-purity natural lanthanum oxide at the reactor of Washington
State University, Pullman, Washington. Multiple varieties of witness plates and air samplers were laid in
an irregular grid covering the area over which the plume was modeled to deposit. Aerial survey, a
NaI(Tl) mobile spectrometer, and handheld and backpack instruments ranging from polyvinyl toluene to
high-purity germanium were used to survey the plume. Additionally, three varieties of soil sampling
were investigated. The relative sensitivity and utility of sampling and survey methods are discussed in
the context of On-Site Inspection. The measurements and samples show a high degree of correlation and
form a valuable set of test data.

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Executive Summary
The Comprehensive Nuclear-Test-Ban Treaty is a nuclear non-proliferation treaty adopted by the
United Nations and open for signature and ratification or accession by States Parties, but not yet entered
into force. The CTBT makes provision for a verification regime that includes the conduct of an On-Site
Inspection. The sole purpose of an OSI is to determine whether a nuclear explosion has occurred in
violation of the Treaty and, if so, gather facts that might assist in identifying the violator. The Treaty
allows for an OSI to include many techniques, including the radionuclide techniques of gamma radiation
survey and spectrometry and environmental sampling and analysis (of solids, liquids, and gases). A good
understanding of the possible contamination distribution, along with the most valuable equipment and
search techniques for locating accessible radioactive contamination, would dramatically improve the
likelihood of conducting a successful OSI. In support of future OSIs, Pacific Northwest National
Laboratory conducted work to understand the realistic distribution of nuclides that might occur under
actual venting conditions from an underground nuclear test.
In May 2013, Pacific Northwest National Laboratory, in collaboration with National Security
Technologies LLC, performed an atmospheric release of ~40 µm particulate La O after neutron
2 3
activation in the Washington State University research reactor produced short-lived 140La within the
powder. The short-lived radioactive particulate material was successfully injected into the lowest levels
of the atmosphere to simulate the release from a weakly vented underground nuclear test. Following the
release, project personnel used a variety of radiation sampling and survey techniques to characterize the
downwind deposition of the material. The Remote Sensing Laboratory supported this effort by
performing a fixed wing aerial survey shortly after the release. The techniques applied to this test are
typical of those being planned for use in the event of an international On-Site Inspection under the
Comprehensive Nuclear-Test-Ban Treaty.
The contamination plume deposited on the ground for this experiment was narrow; in fact, it was
more narrow than the corresponding plume generated using the meteorological conditions and plume
modeling. This discrepancy is likely due to the short duration of the release (1-2 minutes), as compared to
the 10 minute averaging of the plume model generated in Hotspot (Homann 1994) .
The material released for this test was successfully detected through all applied techniques. The
project team found that vehicle-based ground survey provided a data set that was the most informative
and readily interpreted for location and definition of the extent of the plume deposited on the ground.
Germanium-based gamma spectroscopy in the field laboratory and in-situ gamma spectroscopy with
handheld HPGe detectors provided roughly comparable sensitivity, however for this exercise the field
team felt that, with the same manpower effort, a larger number of samples could be processed through the
field laboratory than could be measured with in-situ systems. Both the sampling and in-situ gamma
spectroscopy methods were limited in coverage of the plume due to the need to take discreet
measurements for each physical location. Despite this limitation, the techniques are valuable for isotope
identification and good sensitivity, in particular for samples that have been identified as high-interest
through other inspection techniques.
The use of inert microspheres detected through optical microscopy methods did not provide sufficient
results to define the deposition plume, though they did appear to track with the radiation plume.
Microspheres were successfully collected and identified on optical witness plates downwind from the
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release. In order to use this method with more viable results, it would be necessary to release a larger
quantity of microspheres. The use of colored or fluorescent microspheres would also aid in
discriminating the released microspheres from naturally occurring spherical particles.
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Acknowledgments
This work would not have been possible without the support of many people from several
organizations. The authors express their gratitude to the National Nuclear Security Administration,
Defense Nuclear Nonproliferation Research and Development, and the Comprehensive Inspection
Technologies working group, a multi-institutional and interdisciplinary group of scientists and
engineers. This work was performed by Pacific Northwest National Laboratory under award number DE-
AC52-06NA25946.

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Acronyms and Abbreviations
AGL Above ground level
ALARA As Low As Reasonably Achievable
ASL Above mean sea level
AMS Aerial Measuring System
ATM Atmospheric transport model(ing)
ATV All-terrain vehicle
CA Contaminated area
CFM Cubic Feet per Minute
CSS Comprehensive Sampling/Survey (Site)
CTBT(O) Comprehensive Nuclear Test-Ban-Treaty (Organization)
FL Field Laboratory
GIS Geographic Information System
GM Geiger-Mueller
GPS Global Positioning System
GZ Ground zero
HCA High Contamination Area
HDPE High Density Polyethylene
HPGe High purity germanium
ISOCS In Situ Object Counting Systems – Canberra Industries
MCNP Monte Carlo N-Particle Transport Code
MDA Minimum detectable activity
MEDA Meteorological data acquisition
NCNS National Center for Nuclear Security
NNSS Nevada National Security Site
NOAA National Oceanic and Atmospheric Administration
NSTec National Security Technologies LLC
NTS Nevada Test Site
NWS National Weather Service
OSI On-Site Inspection
PAPR Powered air-purifying respirators
PDT Pacific Daylight Time
PNNL Pacific Northwest National Laboratory
PPE Personal protective equipment
PRex Particle Release Experiment
PVC Polyvinyl chloride
PVT Polyvinyl toluene
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