Nuclear forensics
international technical
working group

The Nuclear Forensics International Technical Working Group (ITWG) is open to all states interested in nuclear forensics. The objective of the ITWG is to advance the scientific discipline of nuclear forensics and to provide a common approach and effective technical solutions to competent national or international authorities that request assistance. Since its inception in 1995 the ITWG has been focused on nuclear forensic best practice through the development of techniques and methods for forensic analysis of nuclear, other radioactive, and radiologically contaminated materials.

Nuclear forensics is an essential component of national and international nuclear security response plans to events involving radioactive materials diverted outside of radioactive control. The ability to collect and preserve radiological and associated evidence as material is interdicted and conduct nuclear forensics analysis provides insights to the history and origin of nuclear material, the point of diversion, and the identity of the perpetrators.

Nuclear forensics is both a technical capability as well as an investigatory process. For this reason the ITWG is a working group of experts including scientists, law enforcement officers, first responders, and nuclear regulators assigned by competent national authorities, affiliated contractors, and international organizations.

Outreach is a primary goal of the ITWG. The working group disseminates recent progress in nuclear forensic analysis and interpretation with the broader community of technical and security professionals who can benefit from these advancements. Affiliated international partner organizations include the International Atomic Energy Agency (IAEA), EURATOM, INTERPOL, EUROPOL, and the United Nations Interregional Crime and Justice Research Institute (UNICRI).

As a technical working group, the priorities for the ITWG include identifying requirements for nuclear forensic applications, evaluating present nuclear forensic capabilities, and recommending cooperative measures that ensure all states can respond to acts involving illicit trafficking and unauthorized possession of nuclear or other radioactive materials. An objective of the working group is to encourage technical peer-review of the nuclear forensic discipline. These goals are met through annual meetings, exercises, and informal and formal publications.

ITWG participating states and organizations recognize that radiological crimes deserve thorough investigation and, when warranted, criminal prosecution. The ITWG encourages all states to possess the basic capability to categorize nuclear or other radioactive materials to assess their threat. As an international group, the ITWG shares its expertise through its membership to advance the science of nuclear forensics as well as its application to nuclear security objectives.

GUIDELINES

The first 13 approved guidelines for ITWG are online!

INFL Guideline for alpha spectrometry

Alpha Spectrometry is used for isotopic composition measurement of radioactive elements that decay by the emission of an alpha particle. These include many of the actinide elements (thorium, uranium, neptunium, plutonium, americium and curium) and some of the heavy elements (e.g. polonium and radium). The concentration of an isotope can be determined by using an isotope dilution technique (i.e. spiking the sample with a known quantity of a known isotopic composition). Separation and purification of the element of interest is required prior to analysis. The chemical processes are well developed and the equipment components for analysis are fairly inexpensive.

High-resolution gamma spectrometry - general overview

Gamma spectrometry is a non-destructive technique used to identify and quantify gamma-emitting radionuclides present in a given sample. Gamma spectrometry takes advantage of the characteristic gamma-ray energies emitted by each radionuclide and the proportionality between the intensity of the emitted radiation and the activity of the radionuclide in the sample being measured. A gamma spectrum displays the number of detected gamma photons as a function of energy.

INFL Guideline on age dating

Age dating (production date measurement or radiochronometry) of a radioactive/nuclear material in nuclear forensics refers to the time when the material was last chemically or physically purified or modified. The principle is based on the measurement of the radioactive progenies (decay products) relative to the parent nuclides, which serves as a chronometer for age dating. After the measurement of a progeny-to-parent ratio, the time of their last separation can be calculated based on the radioactive decay equations.

Importance of uncertainty in nuclear porensics measurements

Uncertainty of measurement is the doubt that exists about the result of any measurement. An uncertainty is a quantitative estimate of the doubt associated with a measurement result. Although a measurement process attempts to determine the value of a chemical attribute or physical property, the actual measurement value is only an estimate of the true value. Measurement uncertainty characterizes the range of values within which the true value is asserted to lie, with a specified level of confidence.

Guidelines for evidence collection in a radiological or nuclear contaminated crime scene

Effective response to the wide range of possible radiological incidents requires the development and implementation of a national response plan. This plan should describe the roles and responsibilities of the relevant national agencies involved in response to radiological incidents. Having such a plan in place in advance of an incident, as well as regularly exercising the plan, will facilitate an effect overall response to an actual incident.

INFL Guideline on powder X-Ray diffraction (XRD)

X-Ray Diffraction (XRD) is an analytical technique used to identify crystalline compounds. It is a bulk technique, though the volume of material sampled is relatively small (approximately 0.01 cm³). Specimens are typically examined in the form of powders or solid pieces. XRD analysis produces diffraction patterns which can be compared to large open databases of crystal diffraction patterns to give precise information about the crystal structure of the material examined.

INFL Guideline on characteristic parameters of UO2 fuel pellets

Low enriched uranium dioxide (UO2) in form of ceramic pellets is typically used in commercial nuclear power reactors as fuel. In order to find out the intended use of UO2 pellets, and subsequently to narrow down the possible production facility, UO2 pellets contain a few characteristic parameters (i.e. signatures) that can be helpful in the origin determination. Such signatures include e.g. dimensions, 235U enrichment and impurities.

In-field applications of high-resolution gamma spectrometry for analysis of special nuclear material

This document describes the use of gamma spectrometry in field conditions as a non-destructive tool for the characterization of nuclear material. In-field use of gamma spectrometry for nuclear security and nuclear forensics purposes provides a means to assess the threat posed by interdicted radioactive/nuclear (RN) material. This information can then be used to determine how the material can best be transported to a safe storage location or to a nuclear forensic laboratory for detailed analysis.

INFL Guideline on secondary ion mass spectrometry (SIMS)

Secondary Ion Mass Spectrometry (SIMS) is used for elemental and isotopic analysis of solid samples. SIMS is a destructive technique, although the amount of sample consumed during analysis is usually quite small. The greatest strength of SIMS is the ability to analyze very small areas (as small as 50 nm using the NanoSIMS, for example) and to generate high-spatial resolution maps of the distribution of elements and isotopes in the sample. SIMS may also be applied for the analysis of individual micrometer sized particles.

ITWG Guideline on elemental assay - PU titration

In this guide, plutonium (Pu) assay through titration refers to a methodology determining the Pu content in material where Pu is the major constituent. Pu assay through titration is a well-tested and well-understood method developed over the last 50 to 60 years as part of nuclear safeguards verification in di erent nations. Other Pu assay techniques commonly used across the nuclear industry include coulometric titration, spectrophotometry of Pu (III) or Pu (VI) and ignition gravimetry. These methods are described in separate ITWG guideline documents.

Laboratory applications of high-resolution gamma spectrometry for the analysis of special nuclear material

Laboratory applications of gamma spectrometry for nuclear security and nuclear forensics purposes provide a means to accurately determine the isotopic composition of gamma-emitting nuclides in a sample and to quantify the amount of each radioisotope present. In the analysis of special nuclear material, such as uranium and plutonium, gamma spectrometry may also be used to determine the total nuclear material content, the age of the material, the presence of reprocessed uranium, and the presence of fission products.

INFL Guideline on thermal ionisation mass spectrometry (TIMS)

Thermal Ionisation Mass Spectrometry (TIMS) is used for isotopic composition measurement of elements having relatively low ionisation potentials (e.g. Sr, Pb, actinides and rare earth elements). Also the concentration of an element can be determined by TIMS using the isotope dilution technique by adding to the sample a known amount of a “spike”. TIMS is a single element analysis technique, thus it is recommended to separate all other elements from the sample before the measurement as they may cause mass interferences or affect the ionisation behaviour of the element of interest.

ITWG Guideline on elemental assay - U titration

In this guide, the assay of uranium through titration refers to a methodology determining the U content in material where U is the major constituent. U assay through titration is a well-tested and well-understood method developed over the last 50 to 60 years as part of nuclear safeguards verification in di erent nations. Other U assay techniques commonly used across the nuclear industry include ignition gravimetry and X-ray fluorescence.

USEFUL LINKS

IAEA – International Atomic Energy Agency

Interpol

GICNT – The Global Initiative To Combat Nuclear Terrorism

EU-US Nuclear Forensics International Technical Working Group (ITWG) Joint Statement

MEMBERSHIP

The ITWG is open to all states interested in nuclear forensics. The ITWG stakeholders have encouraged the group to increase its international membership to states directly affected by the illicit trafficking and proliferation of nuclear and radiological materials.

1. Countries and organizations can apply to the Executive Committee for ITWG membership. Criteria for membership include an interest or capability in technical nuclear forensics.

2. Individuals may be approved for attendance at ITWG meetings if they are affiliated with a competent national or international authority recognized by the ITWG.

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