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At least 19 records

An introduction to the significance of sample size in particle analyses for nuclear forensics and radiological investigations

Particulate isotopic analysis in nuclear forensics has developed rapidly during the past two decades due to technical advances in determining the isotopic composition of individual particles. This paper introduces basic statistical concepts that can be applied by analysts to understand the importance of statistical adequacy when interpretating particle data. While these basic statistical methods provide a useful point-of-entry to particle data analysis, more sophisticated statistical and modeling approaches are needed to extract maximal information from such datasets in the future.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

Analytical method for nitroaromatic explosives in radiologically contaminated soil for ISO/IEC 17025 accreditation

Here, unique hazards are presented in the analysis of radiologically contaminated samples. Strenuous safety and security precautions must be in place to protect the analyst, laboratory, and instrumentation used to perform analyses. A validated method has been optimized for the analysis of select nitroaromatic explosives and degradative products using gas chromatography/mass spectrometry via sonication extraction of radiologically contaminated soils, for samples requiring ISO/IEC 17025 laboratory conformance. Target analytes included 2-nitrotoluene, 4-nitrotoluene, 2,6-dinitrotoluene, and 2,4,6-trinitrotoluene, as well as the degradative product 4-amino-2,6-dinitrotoluene. Analytes were extracted from soil in methylene chloride by sonication. Administrative and engineering controls, as well as instrument automation and quality control measures, were utilized to minimize potential human exposure to radiation at all times and at all stages of analysis, from receiving through disposition. Though thermal instability increased uncertainties of these selected compounds, a mean lower quantitative limit of 2.37 µg/mL and mean accuracy of 2.3% relative error and 3.1% relative standard deviation were achieved. Quadratic regression was found to be optimal for calibration of all analytes, with compounds of lower hydrophobicity displaying greater parabolic curve. Blind proficiency testing (PT) of spiked soil samples demonstrated a mean relative error of 9.8%. Matrix spiked analyses of PT samples demonstrated that 99% recovery of target analytes was achieved. To the knowledge of the authors, this represents the first safe, accurate, and reproducible quantitative method for nitroaromatic explosives in soil for specific use on radiologically contaminated samples within the constraints of a nuclear analytical lab.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

RADIOLOGICAL SEALED SOURCE LIBRARY: A NUCLEAR FORENSICS TOOL

If a terrorist were to obtain and possibly detonate a device that contained radiological material, radiological forensic analysis of the material and source capsule could provide law enforcement with valuable clues about the origin of the radiological material; this information could then provide further leads on where the material and sealed source was obtained, and the loss of control point. This information could potentially be utilized for attribution and prosecution. Analyses of nuclear forensic signatures for radiological materials are generally understood to include isotopic ratios, trace element concentrations, the time since irradiation or purification, and morphology. Radiological forensic signatures for sealed sources provide additional information that leverages information on the physical design and chemical composition of the source capsule and containers, physical markings indicative of an owner or manufacturer. Argonne National Laboratory (Argonne), in collaboration with Idaho National Laboratory (INL), has been working since 2003 to understand signatures that could be used to identify specific source manufacturers. These signatures include the materials from which the capsule is constructed, dimensions, weld details, elemental composition, and isotopic abundances of the radioactive material. These signatures have been compiled in a library known as the Argonne/INL Radiological Sealed Source Library. Data collected for the library has included open-source information from vendor catalogs and web pages; discussions with source manufacturers and touring of production facilities (both protected through non-disclosure agreements); technical publications; and government registries such as the U.S. Nuclear Regulatory Commission’s Sealed Source and Device Registry.

National Nuclear Forensics Library↗

Traditional Forensic Examinations on Bulk Special Nuclear Material

The Federal Bureau of Investigation (FBI) Laboratory at Quantico, Virginia is responsible for the forensic examination of radiological evidence and evidence contaminated with radioactive materials. Due to these unique hazards and the necessary specialized safety protocols, the FBI has developed a network of Partner Laboratories (PLs) across the United States of America to support conventional forensic examinations of radiological evidence and evidence contaminated with radioactive materials. In support of this, the FBI Laboratory has established the Hazardous Evidence Analysis Team (HEAT), a group of qualified forensic examiners, scientists, technicians, and photographers who can deploy to laboratories outside of the FBI Laboratory at Quantico, VA to perform conventional forensics on evidence containing/contaminated with hazardous materials. One of the FBI’s PLs, the United States Department of Energy’s Los Alamos National Laboratory (LANL), in Los Alamos, New Mexico, has unique facilities, personnel, and procedures to secure, safely handle, and process significant quantities of special nuclear material (SNM). While LANL’s procedures for working with SNM are well established, working with SNM under evidentiary controls is not. Close cooperation between LANL and FBI HEAT is required due to FBI policies on evidence handling, as well as the challenges associated with the exploitation and preservation of conventional forensics (fingerprints, trace evidence, and photography) on SNM evidence.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗

New Radiological Material Detection Technologies for Nuclear Forensics: Remote Optical Imaging and Graphene-Based Sensors

We developed new detector technologies to identify the presence of radioactive materials for nuclear forensics applications. First, we investigated an optical radiation detection technique based on imaging nitrogen fluorescence excited by ionizing radiation. We demonstrated optical detection in air under indoor and outdoor conditions for alpha particles and gamma radiation at distances up to 75 meters. We also contributed to the development of next generation systems and concepts that could enable remote detection at distances greater than 1 km, and originated a concept that could enable daytime operation of the technique. A second area of research was the development of room-temperature graphene-based sensors for radiation detection and measurement. In this project, we observed tunable optical and charged particle detection, and developed improved devices. With further development, the advancements described in this report could enable new capabilities for nuclear forensics applications.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Structuring Cooperative Nuclear RIsk Reduction Initiatives with China.

The Stanford Center for International Security and Cooperation engaged several Chinese nuclear organizations in cooperative research that focused on responses to radiological and nuclear terrorism. The objective was to identify joint research initiatives to reduce the global dangers of such threats and to pursue initial technical collaborations in several high priority areas. Initiatives were identified in three primary research areas: 1) detection and interdiction of smuggled nuclear materials; 2) nuclear forensics; and 3) radiological (“dirty bomb”) threats and countermeasures. Initial work emphasized the application of systems and risk analysis tools, which proved effective in structuring the collaborations. The extensive engagements between national security nuclear experts in China and the U.S. during the research strengthened professional relationships between these important communities.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗

Overview of Accelerator Applications for Security and Defense

Particle accelerators play a key role in a broad set of defense and security applications including war-fighter and asset protection, cargo inspection, nonproliferation, materials characterization and stockpile stewardship. Accelerators can replace the high activity radioactive sources that pose a security threat for developing a radiological dispersal device and be used to produce isotopes for medical, industrial, and re-search purposes. Lastly, we present an overview of current and emerging accelerator technologies relevant to addressing the needs of defense and security.

43 PARTICLE ACCELERATORS↗

Age determination of a 75 Se gamma radiography source for nuclear forensics

Here, two methods were used to evaluate the age of 75 Se sealed source material. Both methods utilized gamma spectroscopy to determine the quantity of parent 75 Se present, but they differed in the technique used to determine the quantity of daughter 75 As. In one method, 75 As was quantified using inductively coupled plasma-mass spectrometry (ICP-MS) after using chromatographic techniques to separate the parent and daughter isotopes. In the other method, total As was measured using optical emission spectroscopy (OES), which did not require separation prior to measurement. The OES method was faster and gave slightly lower uncertainties, but required more daughter material to be present because of higher concentration requirements, making it unsuitable for young material. Both methods are hampered by the monoisotopic nature of As, but still gave reasonable model ages that were in agreement with each other.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

Evaluation of the Radioactive Material Released in the Harborview Research and Training Building and Some Implications for Emergency Response

On 2 May 2019, during the 137 Cs source recovery operation, a source capsule in a research irradiator containing approximately 77.1 TBq was breached. Based on a geometric reconstruction analysis of the damage to the capsule, approximately 46.3 GBq (0.04%) was impacted by the chop saw (grinder) inside a mobile hot cell on the loading dock at the University of Washington Harborview Research and Training (HRT) Building. A very small fraction of the material impacted, less than 1%, was released from the mobile hot cell and then to the rest of the HRT Building. The objectives of this project were to assess the accidental release of 137 CsCl and its implications related to emergency response methods and the ramifications of 137 CsCl transport. The phenomenology of this event was also compared with past alkali halide dispersal events. The vast number of measurements and samples collected by the remediation contractors, the Department of Energy’s Nuclear Emergency Support Team, and the small number of retrospective samples collected by the authors informed the analysis. The techniques included (1) autoradiography and electron microscopy of samples collected from the HRT Building and the irradiator, (2) 3D visualization of deposition on surfaces and within the ventilation system, and (3) a study of the damage to the source capsule to evaluate the Cs particle size and particle composition due to the grinding accident. Subsequently, the cesium contaminant transport through the numerous pathways in the building was reconstructed to assess the deposition on surfaces as a function of particle size. Furthermore, the implications for emergency response are relevant to data quality and management. A Data Quality Objective guides data collection methods so that they have appropriate accuracy and precision for the intended application. Recommendations were made with respect to the sample collection protocols and archiving of samples.

46 - INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AN↗

Uncertainty in the use of MAMA software to measure particle morphological parameters from SEM images

The MAMA software package developed at LANL is designed to make morphological measurements on a wide variety of digital images of objects. At LANL, we have focused on using MAMA to measure scanning electron microscope (SEM) images of particles, as this is a critical part of our forensic analysis of interdicted radiologic materials. In order to successfully use MAMA to make such measurements, we must understand the level of uncertainty involved in the process, so that we can rigorously support our quantitative conclusions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

National technical nuclear forensics: U.S. approach to capability sustainment

In the event of a nuclear detonation in the United States (U.S.), the interdiction of a nuclear device, or the seizure of nuclear materials, there will be tremendous pressure to attribute the source of the material, establish responsibility, and ensure the prevention of another incident. Along with intelligence and law enforcement investigations, nuclear forensics is one of the three pillars supporting attribution. The field of nuclear forensics includes the collection, analysis, and evaluation of radiological or nuclear materials, devices, and debris after an event or interdiction. The nuclear forensics scientific workforce is situated primarily in national and defense laboratories, but in recent decades has experienced a decline in numbers. The Domestic Nuclear Detection Office has implemented an expertise development program in order to off-set these declines and sustain a workforce of educated and trained scientists skilled in areas needed for nuclear forensics. Since its inception in 2008, the National Nuclear Forensics Expertise Development Program (NNFEDP) addresses this challenge holistically, through support to undergraduate and graduate students, university faculty and programs, as well as post-doctoral researchers at national laboratories in fields which are directly relevant to nuclear forensics. In that time, the program has placed 44 Ph.D.'s directly into national laboratories and U.S. federal agencies, maintaining the technical expertise required to execute the Nation's nuclear forensics mission. In 2017, the NNFEDP will institute the new Nuclear Forensics Research Award that will foster collaborations between university students and faculty with national laboratory researchers to further support and reinforce the advancement of nuclear forensic science through joint efforts. This opportunity will increase participation in this exciting and critically important national security mission space and contribute to the sustained development of the nuclear forensics workforce. (authors)

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗

Advances in Autoradiography Systems for Nuclear Forensic Analysis

Nuclear forensic analysis techniques work to determine the contents of radiological samples with nondestructive and destructive analysis methods. Autoradiography is a nondestructive analysis method that creates an image of the distribution of radioactivity within the sample. These images allow the location of the radiological content within a sample to be ascertained, which can be used for further analysis. Autoradiography has been used since the discovery of radiation and has been continuously developed to better suit the needs of the medical, nuclear security, nuclear safeguards, and nuclear forensic communities. Recent developments in autoradiography have led to a higher spatial resolution down to a level of tens of microns, real-time capabilities that minimize the risk of overexposure, and the ability to discriminate particles. All of these developments in autoradiography would assist the nuclear forensics community in understanding the placement of radiological content within a sample and in understanding the locations of beta-particle interactions versus those for alpha-particle interactions. This article aims to discuss the history of autoradiography as well as multiple different autoradiographic technologies while focusing on imaging plates, the BeaQuant system, and the ionizing-radiation Quantum Imaging Detector system. This article reviews three autoradiographic techniques and detectors, discusses how they relate to nuclear forensics, and addresses the drawbacks and benefits of each detector.

Autoradiography↗

U/Pu Analysis with Gamma-Ray Spectroscopy

This report presents an overview of the nuclear materials for the international workshop on nuclear, material forensics methodologies.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

Sensitivity and Uncertainty Analysis of Plutonium and Cesium Isotopes in Modeling of BR3 Reactor Spent Fuel

Nuclear forensics has a broad task to characterize recovered nuclear or radiological material and interpret the results of investigation. One approach to isotopic characterization of nuclear material obtained from a reactor is to chemically separate and perform isotopic measurements on the sample and verify the results with modeling of the sample history, for example, operation of a nuclear reactor. The major actinide plutonium and fission product cesium are commonly measured signatures of the fuel history in a reactor core. This study investigates the uncertainty of the plutonium and cesium isotope ratios of a fuel rod discharged from a research pressurized water reactor when the location of the sample is not known a priori. A sensitivity analysis showed overpredicted values for the 240 Pu/ 239 Pu ratio toward the axial center of the rod and revealed a lower probability of the rod of interest (ROI) being on the periphery of the assembly. The uncertainty analysis found the relative errors due to only the rod position and boron concentration to be 17% to 36% and 7% to 15% for the 240 Pu/ 239 Pu and 137 Cs/ 135 Cs ratios, respectively. Lastly, this study provides a method for uncertainty quantification of isotope concentrations due to the location of the ROI. Similar analyses can be performed to verify future chemical and isotopic analyses.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

National technical nuclear forensics: history and U.S. research priorities

In the event of a nuclear detonation in the United States, the interdiction of a nuclear device, or the seizure of nuclear materials, there will be tremendous pressure to attribute the source, establish responsibility, and ensure the prevention of a subsequent incident. The U.S. response to any attack will have to be backed up by demonstrable proof. Nuclear forensics contributes to this demonstrable proof by helping to identify the type of weapon and nuclear material used and where it came from. Nuclear forensics is the collection, analysis, and evaluation of pre-detonation (intact) and post-detonation (exploded) radiological or nuclear materials, devices, and debris, as well as the immediate effects created by a nuclear detonation. Along with intelligence and law enforcement investigations, nuclear forensics stands as one of the three pillars supporting attribution. To ensure the nation's readiness to execute the mission, the National Technical Nuclear Forensics (NTNF) Interagency, which include the Departments of Homeland Security, Defense, Energy, Justice, and State and the Office of the Director of National Intelligence, is consistently focused on improving its analytical capabilities by continually assessing and enhancing the accuracy, precision, and timeliness of NTNF relevant conclusions, while ensuring the quality of those conclusions. This focus drives the Inter-agency's Research and Development priorities, which are divided into four key technical mission areas (TMA). The TMAs span the spectrum of the NTNF enterprise, from pre- to post- detonation, and guide agency funding decisions. (authors)

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗