Radiochemistry Webinars Nuclear Forensics Series Source & Route Attribution. In Cooperation with our University Partners

Transcription

1 Radiochemistry Webinars Nuclear Forensics Series Source & Route Attribution In Cooperation with our University Partners

2 2 Meet the Presenter Dr. Jenifer Braley Dr. Braley joined the faculty at the Colorado School of Mines (CSM) in the fall of 2012 after two years at Pacific Northwest National Laboratory. During her undergraduate research, she studied the solid-state synthesis of f-block elements at Colorado State University with Professor (and now 2017 ACS President-Elect) Peter Dorhout. In 2006 she worked with In 2006 she joined the group of Professor Ken Nash at Washington State University. Here she examined the fundamental solution chemistry of the f-elements relevant to solid-liquid and liquid-liquid separations chemistry. While in graduate school, she was able complete an internship at Eichrom Technologies with Dr. Phil Horwitz and bolstered her understanding of extraction chromatographic (solid-liquid) separations. She has joined the faculty at Colorado School of Mines to educate students on the fundamental and applied concerns of nuclear chemistry and radiochemistry (including the nuclear fuel cycle, nuclear forensics, and radioisotope production). As a member of the Nuclear Engineering Program at Mines, she actively engages the U.S. Geological Survey 1 MW TRIGA Nuclear Reactor at the Denver Federal Center to accomplish research and educational goals. Phone: jbraley@mines.edu

3 Source & Route Attribution Professor Jenifer C. Braley Colorado School of Mines National Analytical Management Program (NAMP) U.S. Department of Energy Carlsbad Field Office TRAINING AND EDUCATION SUBCOMMITTEE

4 4 Learning Objectives Understand attribution Techniques for source and route assessment General aspects of nuclear forensic analysis Laboratory process for source assessment Laboratory process for route assessment Prioritization of forensic tools Analytical techniques

5 Forensic Analyses 5

6 6 Attribution Goals Allows law enforcement to understand illicit nuclear materials trafficking early Prevent development, deployment or exploding a nuclear weapon or radiological device Important to seriously assess cases that may not seem serious may lead to a bigger case Small material quantities or low enriched material Conclusions from technical nuclear forensic analysis are separate from attribution

7 7 Attribution Process Begins with nuclear forensic analysis Holistic assessment of situation where material was interdicted Container, packaging, transport vehicle Best to consider source and route attribution separately Source Attribution: Assesses origin and intended use. Based on investigation of nuclear material itself. Route Attribution: History of material once it was diverted. Based on investigation of affiliated non-nuclear material.

8 8 Source Attribution Questions Where did the materials originate? What are the materials (SNM, Weapons Grade, etc)? Were the materials diverted from a legitimate path? Where were the materials obtained? Where was legitimate custody lost? What is the potential for more illicit material from this source?

9 9 Route Attribution Questions Are the characteristics of the route unique? What was the route taken by the interdicted materials? Was this an isolated event, or one in a series of shipments? Who are the perpetrators? What is the potential end-use (e.g., nation-state weapons program, subnational terrorist group, organized crime, etc.)?

10 10 Forensic Analysis First steps Measure / interpret data accurately and in a timely manner Begins with detection of the incident and an onsite evaluation Safety and security must be given top priority Unique Challenge: handling potentially large quantities of radioactivity while preserving trace quantities of nonnuclear materials

11 11 Forensic Analysis Sample transport Need to get materials to a facility capable of handling radioactive materials and preserving forensic evidence Prescreening accomplished onsite will help narrow the type of analyses required and, ultimately, the appropriate laboratory facilities The value of a particular technique is related to its utility in answering the various attribution questions

12 12 Forensic Analysis A tiered approach Approach is structured to ensure that each successive level of study is based on previously acquired results. Routine NDA Allows the interrogation process to be halted as soon as sufficient data have been acquired to meet the requesting agency s (e.g., law enforcement or intelligence) needs Highly specific

13 13 Forensic Analysis Stage 1 Get samples into chain-of-custody and photo-document Non-destructive analysis (NDA) provides bulk chemical composition and radiological nature x-ray fluorescence and α-particle, γ-ray, and neutron spectroscopy Perhaps solid-phase microextraction, followed by gas chromatography-mass spectrometry (GC-MS) Stage 1 conclusions: semiquantitative, bulk-chemical composition, an estimate of the abundances of major radioactive species, a preliminary assay of organic compounds, and a detailed photographic representation.

14 14 Forensic Analysis Stage 2 - Microscopy Optical microscopy down to roughly 5 10 μm Search for and remove adhering particles, fibers, and hair (route information) Scanning electron microscope (SEM) with an energy dispersive x-ray detector (~100 nm) grain size and morphology Tamasi, A.L., Cash, L.J., Mullen, W.T. et al. J Radioanal Nucl Chem (2016).

15 15 Forensic Analysis Stage 2 Elemental Analysis Mass spectrometry techniques: glow-discharge quadrupole and multicollector inductively-coupled-plasma spark-source secondary-ion mass spectrometry thermal ionization (major actinide isotopes) Assess parent/daughter ratios for chronometric assessment Ratios for geolocation wiki/file:inductively_coupled_pl asma.jpg Stage 2 conclusions: complete physical description of the sample on spatial scales ranging from μm to cm, a representative assay of major and trace-element concentrations, U andpu isotopic compositions, and a preliminary age determination.

16 16 Forensic Analysis Stage 3 Separations! Key, low-abundant isotopes, including fission products and trace radionuclides (e.g., 3 H, 129 I, 226 Ra, 231 Pa) The full suite of actinide radionuclides (Ra Cm), plus several fission products (e.g., Zr, Cs, Sm) should be measured Accelerator Mass Spectrometry to measure ultratrace, low-specific-activity radionuclides ( 10 Be, 14 C, 26 Al, 36 Cl, and 129 I) Chemical, isotopic, and trace-element characterization of any extraneous (environmental) material Stage 3 conclusions: sufficient information should have been collected to perform a credible assessment of source attribution

17 17 Non-Nuclear Characterization (Route) Gathering clues to decipher the history of a sample from the time it passed from legitimate control until it was intercepted by a law-enforcement agency. The earth is heterogeneous with respect to the distribution of elements, isotopes, flora, and fauna Stable and radiogenic isotopes, in soil particles, hair, fibers, vegetation, and pollen basically anything Analyses use many of the same analytical tools described for source attribution, but are now applied to nonnuclear materials

18 18 Success Probability Depends to a large degree on the ability to associate characteristic signatures of a sample with specific geographic locations Access to comprehensive databases containing information on a variety of environmental parameters and commercial / manufacturing signatures

19 Packaging: bulk items, the exterior container and all nonnuclear materials contained therein, and particles and fibers adhering to the packaging materials 19 Broad Materials Categories Biologic: microscopic entities (pollen, spores), vegetation, and animal and human materials. Geologic: aerosol particles and deposits, soil, and rock fragments. Industrial: fluids and particles and include all possible indicators of various industrial processes and materials - lubricants, explosive residues, industrial plant effluents, detritus from commercial products /

20 20 Type of Laboratory Analytical Measurement Primary catagories: isotopes, major and trace-element compositions, organic species, DNA, and physical/structural characteristics tools categorized here include the traditional forensic techniques that have been developed and used extensively by lawenforcement-focused forensic labs 60 possible forensic tools!

21 21 Prioritization of tools The value of these forensic tools depends on considerations about which scenarios are considered most likely and most important. Four categories of prioritization essential, important, specialized, and not relevant Essential forensic tools are those that could be applied in numerous cases, would answer the largest number of relevant questions, and would provide timely answers. Specialized tools provide specific information but are unable to provide timely answers Important tools fall between these two categories and may be extremely valuable in answering questions for route attribution, but they should be used only after the initial set of essential forensic analyses has been completed.

22 22 Geolocation No single measurement is likely to provide geolocation information that is unique or even very specific Use each forensic geolocation measurement to successively narrow the possible areas of the world that are consistent with the measurement. Even if each indicator is individually consistent with a substantial part of the earth, the intersection between just several indicators can often define a very small regional area.

23 23 Real World Examples: Pb-Isotopes Contamination by environmental Pb at some point is unavoidable, and essentially any material can be sampled for its Pb isotopic composition. Forensic investigations have measured Pb in such matrices as newspaper, currency, shipping containers, ammunition, galvanized coatings from fences, and dust from pockets. Concentrations of Pb can be quite low, and special clean-room procedures to isolate and purify Pb may be required.

24 24 Real World Examples: Pb-Isotopes Compares the Pb-isotopic composition of three paper samples with the isotope composition of aerosols and gasoline. The paper samples were packaged together with suspect nuclear material The Pb-isotopic composition of the questioned paper samples clearly excludes the possibility that the paper was manufactured in the United States or Western Europe and is fully consistent with an origin in Southeast Asia. Comparison of Pb-isotope compositions ( 207 Pb/ 206 Pb and 208 Pb/ 206 Pb) for aerosol particles and gasoline from different geographic locations and for questioned paper samples collected together with nuclear material.

25 25 Real World Examples: O-Isotopes O isotopes can be used as a geolocation signature for uranium oxide ore and reactor fuel elements The O-isotopic composition of U ore reflects the local environment during ore formation, whereas O isotopes in uranium oxide fuel elements primarily carry information related to U refining and enrichment processes

26 26 Real World Examples: O-Isotopes Enrichment Signatures Uranium oxide reactor fuel is produced from low-enriched uranium (typically 2 4% 235U), which in turn is derived from U ore concentrate, known as yellowcake for its characteristic yellow appearance. Yellowcake is first converted to UF6 for U isotope enrichment, and then to UO2 for fuel fabrication [13]. The conversion to UO2 involves hydrolysis of the UF6, nearly always using water obtained from sources close to the conversion facility. In this process, the UO2 product assumes the O-isotope composition of the water. Thus, as U ore is converted to enriched UO2 reactor fuel, the original O-isotopic composition of the ore is changed step by step, until no memory of the starting composition remains. The 18O/16O ratio in the UO2 fuel will reflect that of the water or acid used in the hydrolysis reaction.

27 27 Conclusions The attribution process includes numerous aspects Nuclear forensics Source & Route Classical forensics Other intelligence Many analytical techniques are utilized to develop a complete forensic investigation/story Selection of a given technique must be weighted with the timeliness and number of questions it will address Nuclear forensics is a growing area with many opportunities for development and investigation

28 28 Acknowledgments & References Slides and information provided by Ms. Anna Baldwin Moody, K. J.; Grant, P. M.; Hutcheon, I. D.; Nuclear Forensic Analysis, CRC Press, Chapters 19 &20

29 Upcoming Webinars in the Nuclear Fuel Cycle Series Biodosimetry TENORM Strontium NAMP website