IAEA-CN-184/325
The Use of Lasers in IAEA Safeguards
A. Monteitha, J. Whichelloa, S. Poiriera.
Department of Safeguards,
International Atomic Energy Agency,
Vienna
[email protected]
On the 16th May 1960 Theodore Maiman produced the first functioning laser based on a synthetic ruby
crystal and, at the time, it was famously described as a “solution looking for a problem”. However, the
intervening half century has seen intense research, innovation and development in the field of laser
instrumentation and the laser now forms a vital part of modern life. Lasers are used in a wide variety of
fields for an enormous range of applications from cutting and welding to eye surgery. With the advent of
these new techniques and hardware the IAEA is slowly introducing appropriate laser systems to improve
the efficiency and effectiveness of safeguards. This paper will outline the current use of lasers in IAEA
safeguards, for example, the deployment of the 3D Laser Range Finder instrument which allows the
inspector to scan a location to mm accuracy for use when undertaking Design Information Verification
visits. The paper will also seek to outline foreseen uses of laser systems in the short to medium term, such
as the use of Laser Induced Breakdown Spectroscopy for „in-field‟ analytical measurements and the laser
surface authentication of IAEA seals.
1. Introduction
For comprehensive safeguards agreements between the Agency and a state (or regional inspectorate) the
primary technical objective is “the timely detection of diversion of significant quantities of nuclear material
from peaceful nuclear activities to the manufacture of nuclear weapons or of other nuclear explosive
devices or for purposes unknown, and deterrence of such diversion by the risk of early detection”
(INFCIRC/153, para. 28). This technical objective is the basis for detailed and specific inspection goals for
each facility inspected under comprehensive safeguards agreements (CSA).
Under INFCIRC/153 the Agency also agrees to “take full account of technological developments in the
field of safeguards” (INFCIRC/153, para. 6) and that the “Agency's verification shall include, inter alia,
independent measurements and observations” (INFCIRC/153, para. 7). These two principles underpin the
introduction and use of various physical verification techniques for safeguards.
When undertaking safeguards the Agency uses a wide variety of verification tools and physical techniques.
These include the use of non-destructive assay (NDA) tools, the installation of unattended remote
monitoring instruments, the use of destructive analysis and environmental samples and the installation of
appropriate containment and surveillance measures.
In seeking to further enhance the efficiency and effectiveness of verification the Agency continually
undertakes a programme of development to identify appropriate technologies that may benefit the
inspection effort. The Division of Technical Support (SGTS) has successfully employed the use of lasers in
a number of diverse areas such as, design information verification and cylinder identification. We are
currently investigating the use of lasers in containment verification and material analysis. Further
information on these efforts is given in the following sections.
2. Design Information Verification (DIV)
1
Under INFCIRC/153 States are required to provide design information on existing and new facilities
including “…the form, location and flow of nuclear material and to the general layout of important items of
equipment which use, produce or process nuclear material” (INFCIRC/153, para. 43(b)). This information
allows the Agency, inter alia, to “identify features of facilities and nuclear material relevant to the
application of safeguards to nuclear material in sufficient detail to facilitate verification” (INFCIRC/153,
para. 46(a)).
The process of undertaking a DIV begins with examination of the declared design documents, this is
followed by collection of information on the „as-built‟ facility and finally a comparison of the „as-built‟
facility with the declared information is undertaken. It should be noted that DIV activities take place over a
number of years due to construction and commissioning constraints and random re-verification may be
carried out at future intervals.
The complexity of many nuclear facilities and the associated large burden on resources in undertaking a
DIV called for a solution that would simplify verification activities and maintain continuity-of-knowledge
(CoK) of the verified design. This was achieved with the development of the 3D-Laser Range Finder
(3DLR) in association with the European Union Joint Research Centre (Ispra).
The 3DLR comprises of a laser range scanner mounted on a movable tripod, with associated electronics and
software, as can be seen in figure 1 below. The laser operates at 780 nm with a continuous power output of
32 mW and is classified as laser safety class 3R.The system is capable of rapidly creating a 3D reference
model of a facility by scanning the environment from a number of viewpoints and integrating the resultant
data into a 3D virtual model. The system is accurate to 5mm up to 50m distance and has in-built data
authentication and encryption features.
Tripod mount
Pan/Tilt Laser
Scanning Head
Battery power
Computer
Figure 1: The 3D Laser Range Finder
Re-verification of the facility can be undertaken by re-scanning from the same viewpoints and overlaying
the resultant data. The 3DLR software automatically highlights any changes in the target against the
original reference scan, as shown below in Figure 2. This allows the inspector to rapidly identify any
undeclared modifications that may have been made since the previous verification.
(a) Reference Scan
(b) Verification Scan
(c) Differences highlighted
Figure 2: Differences between the (a) reference and (b) verification scan are automatically highlighted (c),
courtesy EC-JRC, Ispra
The 3DLR has been used on a number of occasions to improve the efficiency and effectiveness of DIV
activities. In the cases where commercially/safeguards sensitive facilities are scanned the resultant data are
held, on-site, under joint IAEA and State/operator seals.
Work has been ongoing to extend the range of the 3DLR and to integrate other datasets such as geo-location
information. This will provide the ability to map outdoor locations within a facility and create a virtual
model that could perhaps be used for familiarization pre-inspection or as a future training tool.
A further enhancement is the possible integration of a Compton gamma radiation imaging system with the
3DLR to provide a gamma „map‟ of the facility allowing the inspector to detect hidden/undeclared
pipework containing nuclear material. Further information on this topic can be found in chapter 4 of the
Idaho National Laboratory‟s “Report of the Workshop on Nuclear Facility Design Information Examination
and Verification for Safeguards” [2].
3. Cylinder Identification
Similar laser scanning technology may also be applied to the area of cylinder identification. This is of
particular benefit where radiation, or other safety, concerns make the tagging of cylinders impractical, such
as within a uranium enrichment plant. A solution to the need to track UF6 cylinders in an enrichment plant
has been developed in cooperation with the European Union Joint Research Centre (Ispra) and is currently
undergoing field testing. The Laser Item Identification System (L2IS) uses a class 3B laser mounted on a
rotation stage and allows the operator to „map‟ a range of cylinders (30B, 48Y, 48Z) rapidly and with a very
high degree of accuracy150μm.
As with the 3DLR the first stage of the process is to obtain a reference spectrum by scanning each cylinder
of interest with a portable laser scanner. This reference spectrum can be considered a unique fingerprint of
the cylinder and results from the intrinsic surface micro-roughness of a cylinder that cannot be reproduced
without considerable effort of the part of a proliferator. With the reference database in place it is simply a
matter of using a fixed instrument to screen the cylinders at strategic points within a process and match
them to the known database, (see figure 3 for a schematic of a typical setup). This provides unambiguous
tracking of individual cylinders throughout the process, independent of tags or operator labels.
IAEA Standard video
surveillance cameras
(SDIS camera)
L2IS position
Figure 3: Schematic of a typical setup of the L2IS, courtesy M. Lang-IAEA
Any tampering with a cylinder‟s surface will automatically be detected by the system and flagged to
inspectors, see figure 4 for an example. The system‟s decision algorithms are capable of distinguishing and
filtering out small marks, scratches and dents in order to reduce false alarm probability to a minimum
(a) Example of a „matching‟ scan
(b) A non-matching scan showing major deviation
Figure 4: Example of a matching scan (a) and a non-matching scan(b), courtesy EC-JRC, Ispra
The verification is further strengthened by the use of standard surveillance methods at the screening stage to
ensure that measurements are unimpeded and hence strengthening the verification.
3. Containment Verification
One of the mainstay technologies utilized by the inspector is the IAEA metallic seal (CAPS), with in excess
of 20,000 deployed yearly. However, the process of preparing, deploying and finally verifying the seal is a
manually labour intensive process. There is a need for technologies to improve the efficiency and
effectiveness of this process. Recent research has shown that almost all paper documents, plastic cards and
product packaging contain a unique physical identity code formed from microscopic imperfections in the
surface. This covert „fingerprint‟ is intrinsic and virtually impossible to modify controllably. It can be
rapidly read using a low-cost portable laser scanner. This new proprietary technique, known as laser surface
authentication (LSA), uses the optical phenomenon of laser speckle to examine the fine structure of
materials.
The Agency has been working with the UK Support Programme and Ingenia Technology to develop a
system that will be capable of uniquely identifying each CAPS seal without extensive manual intervention.
A prototype LSA Laboratory Robot Reader was developed and the technique and the system are currently
under evaluation by the Seals Unit of the Department of Safeguards. The prototype can be seen in figure 5.
During the extensive evaluation period the technique will be deployed in parallel with current manual
verification methods.
Figure 5: The LSA Laboratory Robot Reader developed for automatic verification of CAPS seals
4. Material Analysis
In meeting the need for in-field identification of unknown material the inspector is well served with the
choice of a large range of gamma and neutron detection devices tailored to specific measurement
circumstances, these instruments focus mainly on the measurement of U and Pu content. However, there
are other materials that could indicate clandestine activity that are of interest to the inspector, such as
precursor chemicals and other material of interest (e.g. tributyl phosphate, fluorine resistant lubricants etc.).
The IAEA is lacking in the appropriate equipment for the in-field identification of such materials. However,
laser-based spectroscopy is a well proven technique, which is in use in an extensive range of industrial and
scientific applications. With the advent of relatively low-cost and miniaturized laser sources, across the
spectrum range, it is has now become possible to equip the inspector with instruments based on a number of
laser spectroscopy techniques. Several of the proposed technologies and techniques are discussed below in
further detail.
4.1 Laser Induced Breakdown Spectroscopy
Over the last number of years the Department of Safeguards has been developing a prototype, portable
instrument, based on Laser Induced Breakdown Spectroscopy (LIBS), in cooperation with the Canadian
Support Programme. It is intended that this instrument will be used for the analysis of unknown materials
in-the-field. LIBS is a well characterized analytical technique which was first developed in the early 1960s.
It operates by focusing a short-pulsed laser on to the target material, which leads to ablation at the surface
of the material. This creates a high temperature plasma which, upon cooling (within microseconds), emits
the characteristic atomic emission lines of the elements contained within the target material. By matching
the spectroscopic output to a library of known substances, using advanced chemometrics, an identification
of the target material may be undertaken. The advantages of the technique are that it can be applied on
solid, liquid or gaseous materials; it requires no sample preparation; only a small target mass is required; the
measurement takes place in ambient air and at atmospheric pressure; and, it provides remote and real time
analysis.
During early tests, the prototype instrument demonstrated a capability to not only identify yellowcake
material but also to successfully discriminate between samples from nine different yellowcake sources,
without any false positive or false negative results. Development work is continuing on the instrument and
inspectors are providing feedback on the ergonomic factors of the prototype to allow us to improve the user
experience.
Safety shroud
Laser trigger
Figure 6: The laser head of the prototype LIBS instrument
During the last few years the Agency has also became increasingly aware of the extensive body of
work that has been undertaken on the use of LIBS for industrial detection, measurement and
monitoring applications which could have direct relevance to safeguards. Following the
recommendations of an Experts and Users Advisory Meeting on Laser Induced Breakdown
Spectroscopy for Safeguards Applications [3], held in Vienna in July 2008 the Agency is interested
in three other areas for the deployment of LIBS technology, these are:

the development of a LIBS-based prototype field-deployable hot cell screening system;

the development a LIBS-based environmental swipe sample system for the screening of
environmental swipe samples;

the development of a proof of concept LIBS-based system tailored for monitoring
pyroprocess flow, with the potential to expand the system to monitor other nuclear
processes.
Preliminary work is currently underway at the Fraunhofer-Institut für Lasertechnik under the
support of the German Support Programme to understand the feasibility of the production of an
environmental swipe sample system. The Agency is currently looking at raising proposals for the
remaining developments through it Member State Support programme.
4.2 Raman Scattering
Raman spectroscopy is named after the Indian physicist, Chandrasekhara Venkata Raman, who first
described "a new radiation" (later known as the Raman effect) in 1928, for which he won the Nobel prize
for physics in 1930. It is closely related to infrared (IR) spectroscopy, in that it records the vibrating,
stretching, and bending movements of molecules. This allows the user to characterize an unknown liquid,
solid or gas by illuminating the sample with a low-power laser and matching the response to a 'library' of
pre collected spectra.
The technique works by impinging low power laser light on a target material, much this light passes
through the sample unchanged or some may be absorbed, depending upon the wavelength of the light and
the nature of the target material. A small fraction of the light is elastically scattered (know as Rayleigh
scattering) and an even smaller fraction of this incident light may be scattered inelastically (known as
Raman scattering). Raman spectroscopy probes the vibrational modes of the target molecules and it is these
vibrational modes that can be regarded as a „fingerprint‟ that uniquely identifies the substance. The
technique is non-destructive in nature and has the ability to obtain spectra through transparent media such
as glass bottles or bags, maintaining the integrity of the sample and also protecting the user and instrument
from contamination.
The last few years has seen a large number of hand-held Raman instruments becoming commercially
available to meet the demand of the „first-responder‟ market. Many of these instruments conform to the
needs of the safeguards inspector in that they are hand-held and lightweight (less than 1 kg), they are battery
powered and fully ruggedized. Following a full market survey and demonstrations of various instruments
the Agency has released a tender for the purchase of a commercial Raman scattering instrument for further
evaluation during 2011.
4.2 Standoff surveillance
In September 2009, the Agency convened a workshop comprising experts and users to evaluate laser based
stand-off detection as a viable NDA-surveillance tool in support of emerging and future IAEA safeguards
implementation needs [4]. The main objectives of the workshop were to identify specific applicable
safeguards needs, to define and assess the state-of-the-art in differential absorption LIDAR1 (DIAL) and
other similar techniques, and to understand the benefits and limitations of these techniques when applied to
specific safeguards scenarios. There are a number of known advantages that NDA-surveillance and
sensing can provide in support of IAEA safeguards implementation:

The technique offers the ability to probe locations that are difficult to access for point
analysis, such as the detection and identification of plumes from a stack;

The technique offers the ability to probe a large area, or volume, rapidly in near real-time;

It provides the Agency with the ability to measure concentrations and distributions in-situ
before any degradation or reaction of the target species (e.g. the rapid hydrolysis of UF6
into hydrogen fluoride upon release into the atmosphere).
The workshop discussed a number of techniques that may provide a solution to the need for NDAsurveillance including, Differential Absorption LIDAR, Radar Resonance Enhanced Multiphoton
Ionization (REMPI), Tunable Diode Laser Spectroscopy (TDLS), Differential Optical Absorption
Spectroscopy (DOAS) and Fourier Transform Infrared Spectroscopy (FTIR).
The workshop concluded that the development of a system suitable for safeguards applications
should be considered as medium-to long-term goal (5-10 years) and that further meetings between
IAEA technical staff, end-users and experts are essential for determining the relevance of these
techniques to safeguards and the path forward for refining requirements for the research and
development community. Following on from these conclusions it is intended to hold a further
experts and users workshop in 2011.
1
LIDAR is an abbreviation for light detection and ranging and is analogous to RADAR.
5. Conclusions
The Department of Safeguards interest in lasers continues to grown and encompasses a broad range of areas
including DIV, item identification and tracking, containment verification and material analysis. Driven by
technological advances in the laser industry it is expected that the use of laser-based instrumentation will
increase over the coming years and this will provide a direct benefit to the effectiveness and efficiency of
safeguards implementation.
[1] http://www.iaea.org/Publications/Documents/Infcircs/Others/infcirc153.pdf
[2] http://www.inl.gov/technicalpublications/Documents/4363858.pdf
[3] Department of Safeguards Technical Report (STR) number 362 (restricted distribution), April 2009.
[4] Department of Safeguards Technical Report (STR) number 367 (restricted distribution), July 2010.