Nuclear Forensic Reference Materials (RM) for 

Attribution of Urban Nuclear Terrorism

Kenneth G.W. Inn & Jacqueline Mann (NIST-RBPD)

Jeffrey Leggitt & JoAnne Buscaglia (FBI)

Simon Jerome (NPL)

John Molloy (NIST/ACD)

Normal Probability Plot William Pramenko (VIP)

-5 -2 1 4 7 10

(X 10000) Col_1

0.1

1

5

20

50

80

95

99

99.9 cumulative percent
Understanding DoJ, DoD, DHS, DOE needs requires close

relationships

Nuclear Forensics require high-level expertise, undisputed 

signatures & extremely high fidelity measurement 

capabilities

CBRNE countermeasures must withstand legal scrutiny, and 

requires strong metrology backbone

Requirements for CRMs exceedingly high 

2

BLUF
WHAT IS CNT?

Intent Planning

Acquire 

Weapon/ 

SNM

Transport Target Event

NonproliferationCounterproliferation

• Respond to illicit trafficking

• Detection of illicit programs

• Cooperative Threat Reduction

Nuclear Materials

• Fuel cycles

• Limit fissile material

production

• Reactor conversion

Securing SNM

• Reliable inventories

• Physical Security

• Blending down HEU

Render Safe and 

Elimination

• Advanced mobile 

 diagnostics

• Defeat capability

Find SNM in Transit

• Identify transit routes

• Monitor choke points

• Monitor smuggling gaps

• Nuclear detection programs

• International engagement

Wide Area Search

• Create exclusion areas

• Technology to enablers

• Surveillance & recovery

Attribution

• Identify from materials

and design

• Infer design post-shot

Immediate Response Capability

• Incident Response

• Assessing dispersal of 

radioactive material

• First responder requirements

Consequence 

Management

• Decontamination

• Psychological 

response

Intelligence

3
 Physical –Chemical –Radiological and Isotopic Characterization 

Increasing Uncertainty

What is it?

How was it constructed?

When?

Where, Who, Why?

• (NF) - Nuclear forensics is the use of physical and chemical properties to help determine the 

age, origin, and history of nuclear materials and the design of nuclear devices. Identifying 

these “nuclear signatures” can help investigators track nuclear materials back to their origin

• (A) Attribution is the integration of all information, including nuclear forensic data, law 

enforcement and intelligence data, to suggest or exclude the origin of nuclear materials and 

devices, routes of transit, and responsible groups or individuals

Definitions

Nuclear Forensics (NF) and Attribution (A)

4
Signatures are created and 

erased throughout the life 

cycle of nuclear materials

Some of these signatures are 

maintained in Interdicted & 

Post Detonation Materials5
Goals

• Identify those responsible for nuclear theft or nuclear terrorism

• Deter the theft of nuclear materials or acts of nuclear terrorism

• Enhance protection, control, and accounting for nuclear materials and weapons

• Prevent additional thefts or terrorist acts by plugging leaks and tracking down 

other missing materials or devices

Applications

• Intercepted nuclear materials or devices

• Debris from a nuclear explosion

• Debris from a radiological dispersal device

Nuclear Forensic Goals & Applications

Fetter, S. (2007) U.S.-Russia Dialogue on Strategic Cooperation

& Joint Crisis Management

6

Some of these signatures are 

maintained in 

Interdicted & Post Detonation Materials
What Information does 

Nuclear Forensics Provide?

7
Parameter Signature Analytical Technique

Appearance Material type (e.g. powder,

pellet)

Optical Microscopy

Dimensions (Pellet) Reactor Type Database

U, Pu, Content

Chemical Concentration,

nuclear fuel type, weapon 

type, and device type

Titration, Hybrid K-Edge Dosimetry, 

Isotope Dilution Mass Spectrometry

Isotopic Composition

Enrichment--intended 

use/reactor type, nuclear fuel 

type, weapon type, and device 

type

Gamma Spectrometry, TIMS, ICP-MS, 

SIMS

Impurities

Production Process, 

geolocation, device type, and 

weapon type

ICP-MS

Age Production Date Alpha Spectrometry, TIMS, ICP-MS

Surface Roughness Production Plant Profilometry

Microstructure Production Process SEM, TEM

Nuclear Forensics – Weapons Fuel Processing

8
Parameter Signature Analytical Technique

Fission Fuel Pu, U Ratio Radiochemistry, actinide 

mass spectrometry

Reactor Power

and Irradiation 

time

Fission Product Isotopic 

Ratios

Radiochemistry, 

beta/gamma counting

Fuel 

Sophistication

Enriched U and Pu Isotopic

Ratios

Radiochemistry, actinide 

mass spectrometry

Initiator 210PoBe

Chemical analysis, 

Radiochemistry, alphacounting

Boosting 6Li Mass Spectrometry

Fission neutron 

energy

Fission Yield Curve

Radiochemistry, 

alpha/beta/gamma 

counting

Nuclear Forensics – Weapon Design

9
Evidence Legal Standards

Daubert v. Merrell Dow Pharmaceuticals (1993)

- Has the technique been validated?

- Were the conditions controlling the technique’s operation

maintained?

- Were the results peer reviewed?

- Does, and at what frequency, the method lead to any erroneous

results? (false positives and/or negatives)

- Has the technique been generally accepted in the scientific

community?

US Federal Rules of Evidence 702

- evidence is based upon sufficient facts or data,

- evidence is the product of reliable principles and methods, and

- the principles and methods have been applied reliably to the facts

of the case
What is missing? Urgent CRMs to support State-of-the-Art 

Measurement Capabilities and Metrology Infrastructure

Non-Existent

Not Good Enough for High Fidelity Attribution 

in Short Supply 

Exceedingly Rare

Long Development Time

Very Expensive

Problem? Required CRMs are needed NOW

5 years to develop one CRM 

Few have the capability to develop state-of-the-art CRMs

CRM production require specialized non-existent facilities

Process is labor intensive and costly

How to Close the Gap?

Enlist increased numbers of capable metrologists

Focus their attention on this mission (affect their priority list)

Establish specialized facilities 

11
Nuclear Forensic Reference Materials (RM) for 

Attribution of Urban Nuclear Terrorism

Participants: Kenneth G.W. Inn (NIST-RBPD), Jacqueline Mann (NIST-RBPD), 

Jeffrey Leggitt (FBI), JoAnne Buscaglia (FBI), Simone Jerome (NPL), 

John Molloy (NIST-ACD), William Pramenko (VIP)

Forensic science problem: No fresh fission product urban RM to test nuclear 

forensics capabilities for attribution

Objective(s): 

— Micro-homogeneity Evaluation of UVC material using micro-XRF

— Microwave digestion/fusion dissolution

— Elemental/actinide concentration by ID-HR-ICP-MS

— Stable isotopic “fingerprint” by HR-ICP-MS

— Documentation/Publications

— Elemental/isotopic mass certification of UVC
End of project outcomes: Characterization of HEU doped UVC to test the 

U.S. nuclear attribution capabilities

— Documentation/Publications

— UVC RM certified for Elemental/isotopic mass

Anticipated impact on forensic science: RM for high fidelity attribution 

capabilities of an urban nuclear terrorist event

— Method development/validation/testing/preparedness

— High fidelity attribution/legal defensibility (Daubert v. Merrell Dow)

Nuclear Forensic Reference Materials (RM) for 

Attribution of Urban Nuclear Terrorism
Nuclear Forensics Challenge

Figure 1. Approved layout for the lab retrofit.

Figure 1.

Figure 2. Exterior Hard wall clean lab 

space for new mass spectrometer

Figure 2.

Figure 3.

Figure 3. Interior clean lab space 

with continuous flooring

Goal: Lab space with controlled humidity and 

temperature for optimal operation of new 

ELEMENT2 mass spectrometer.

Lab

Retrofit
Goal: Establish NIST atom-counting 

capability for required highprecision/accuracy assay/isotopic 

trace and major radio-element 

nuclear forensics certified 

reference materials

Nuclear Forensics Challenge

Mass 

Spectrometer 

Purchase

Element2 HR-ICP-MS highresolution (single-collector) 

sector field inductively-coupled 

plasma mass spectrometer
Nuclear Forensics Challenge

UVC Characterization/Certification Plan

UVC Composition

UVC Dissolution

Element ppm Element ppm Element ppm

Si 186000 As 14 Cl 37

Al 7900 B 3 Sr 130

Fe 230000 C 470 Cr 850

Ca 220000 Co 37 Zn 47

Mg 4800 Cu 220 F 260

S 3700 Mo 190 Zr 15

Na 700 Nb 55 (N 2)

K 1900 Ni 450 U 100

Ti 550 Sn 36 W 10

P 200 Ta 25 Th 10

Mn 1200 V 150 (O Balance)

 Assess UVC micro-homogeneity with micro-XRF

 Develop dissolution protocols 

 Determine elemental/actinide massic 

concentrations 

 Determine Stable Isotopic “Signature”

 Document/Certify UVC elemental/isotopic 

massic concentrations

Work 

Done

Procedure: 4 samples (2 of 0.100 g and 2 of 0.200 g):

Step 1 – Digest Al with H3PO4 + HCl 

Step 2 – Digest Si with HBF4 + HNO3

Microwave held at 200 bar, 300°C

Results: Success with 0.100g samples

 particles observed with 0.200g samples

Future: Will attempt with pure HF and then 

 H3BO3replacing HBF4
• Understanding DoJ [FBI], DoD [COCOMs, JRO], DHS 

[DNDO/NTNFC], DOE [NNSA] needs requires close

relationships

• Nuclear Forensics require high-level expertise, undisputed 

signatures & extremely high fidelity measurement 

capabilities

• CBRNE countermeasures must withstand legal scrutiny, and 

requires strong metrology backbone

• Uncertainty Requirements for CRMs exceedingly high 

17

Conclusions

Concentration [ppm] Uncertainty [k = 2, %]

High [500-1000] 1 - 5

Medium [100-500] 1 - 5

Low [1-100] 5 - 30
Thank You
Future Plans

Micro-homogeneity of UVC material using micro-XRF

Microwave digestion/fusion dissolution

Elemental/actinide concentration by ID-HR-ICP-MS

Stable isotopic “fingerprint” by HR-ICP-MS

Documentation/Publications

Elemental/isotopic mass certification of UVC