Fast Neutron and Gamma-Ray Interrogation of Air Cargo Containers

CRP Report: Fast Neutron and Gamma-Ray Interrogation of Air Cargo Containers

Brian Sowerby CSIRO Minerals, Lucas Heights, NSW, Australia IAEA, Johannesburg, South Africa, 16-20 November 2009 Outline

Scope of IAEA Project Air Cargo Scanning - Industry Requirements CSIRO Air Cargo Scanner and Commercial Development Description and history How does it work? Images Evaluation Enhancements Neutron generators and detectors Scope of Project under Coordinated Research Project

Under the terms of the Research Agreement between the IAEA and CSIRO, the specific activities include:

Evaluation of Fast Neutron and Gamma-ray Radiography (FNGR) for the detection of contraband in consolidated air cargo Enhancement of FNGR technology as it relates to the examination of air cargo with a view to improved contraband detection and to reduce the incidence of false positives and false negatives The assessment of neutron generator and detector systems for FNGR Requirements for Air Cargo Screening System

Two distinct application areas, namely 1) Customs inspection of incoming cargo for contraband such as illicit drugs, illegal imports, weapons, nuclear materials 2) Explosives detection in outgoing cargo.

Both application areas require: Scanning of air-cargo containers (ULDs) without unpacking Provide imaging & composition information to enable operator to find contraband Real-time inspection (<1-2 minutes per container) High throughput (>30 ULDs per hour) Readily integrated with existing airport systems Good radiation safety Reasonable capital and operating costs Air Cargo Compared to Sea Cargo and Luggage

• Luggage Smaller dimensions than air cargo Readily penetrated by ‘conventional’ X-rays Not very cluttered Short analysis time

Air Cargo Thickness up to 8’ Often cluttered Time < few minutes

Sea Cargo Containers Larger dimensions (20’ or 40’ long; 8’ wide) Less cluttered than air cargo Not as time constrained Australian Customs Container Examination Facilities for Sea Containers

• Customs container examination facilities (CEF) have been highly successful since the first CEF opened in November 2002. • Illicit drugs with a street value of more than $1.5 billion have been seized and over $84 million in revenue evasion prevented. • Total seizures for the period 1 November 2002 to 31 March 2007 include: 162 kg of heroin 4002 kg of ecstasy (MDMA) 395 kg of crystal methylamphetamine (ice) 315 kg cocaine 1270 kg of ephedrine and pseudoephedrine 3200 litres of precursor chemicals, which can be used in the production of amphetamine type stimulants over 128 million cigarette sticks more than 202 tonnes of tobacco; and over 11,000 bottles of alcohol. Fast Neutron and Gamma Radiography

14 MeV and transmitted γ- or X-rays neutrons and γ-rays

Collect images (radiographs) using fast neutrons and high-energy gamma-rays Neutron attenuation: In/I on = exp (-µ14 ρ x) Gamma attenuation: Ig/I og = exp (-µg ρ x) Form ratio of mass attenuation coefficients:

R = µ14 /µg = ln (I n/I on ) / ln(I g/I og ) From the radiographic images and the calculated R values, form a 2D composite image showing average density and composition 60 R-Values : 14 MeV Neutrons & Co γ-Rays

1.8

1.6

1.4

1.2

1 Dual high-energy X-ray R-values R-Value 0.8 (6/3 MeV)

0.6

0.4

0.2

d n s e n e T n r r n e r l e m s t i t e a i n e o a o u e l o N t o o i t n n e I r i l a r f h t p g a e p T a u r a a L i n G c e o e c h h n T a P S W t t m r C H o y o C E l l u C G o A P Penetration: Material Thicknesses for 0.1% Transmission of Neutrons and High Energy X rays

Incoming air cargo at

Brisbane International 500 Airport 450 14 MeV Neutrons 3 MeV Brem X-rays 50% in ULDs, 50% on 400 6 MeV Brem X-rays pallets 350

) A scanner capable of 2 300 penetrating through 100 2 250 g/cm would be able to image 200 MPUA(g/cm 99.6% of cargo 150 A scanner capable of 100 2 penetrating through 50 g/cm 50 would be able to image 87% 0 Polythene Carbon Aluminium Iron Lead of cargo CSIRO/Australian Customs Collaboration

CSIRO Minerals first approached by Customs in December 2001

CSIRO initiated a feasibility study : Stage 1 (Completed September 2002)

Full scale demonstration of FNGR at CSIRO using consolidated ULDs with contraband: Stage 2 (Completed June 2003)

Federal Government allocated A$8.4 million to Australian Customs to construct and evaluate a commercial-scale CSIRO Air Cargo Scanner at Brisbane Airport: Stage 3 (Mar 2004 – February 2007)

Reference scanner commissioned at CSIRO for trials, R&D (2005 – ongoing)

Commercialisation phase CSIRO Air Cargo Scanner at Brisbane International Airport

Detector Tower

Direction of cargo travel

Radiation sources Image Display System

Image Processing System Data preconditioning, registration, and geometry distortion corrections Correct scattering, cross-talk, background Smoothing and sharpening Determine composite R value and map it to hue, and map gamma attenuation to lightness Background subtraction Image manipulating tools Brightness, contrast, zoom (mouse) Full colour, black/white, organic/inorganic Histogram equalization, density contours Material type indicator Highlight window With independent image manipulation tools Background removal ULD info / User Library Evaluation of Trial at Brisbane Airport

CSIRO Air Cargo Scanner trialled by Australian Customs on incoming air cargo at Brisbane International Airport: June 2006- March 2007

Demonstration of FNGR for material discrimination and ability to make hidden organic materials more obvious.

Consolidated cargo was scanned in less than two minutes once the cargo is at the scanner, thus allowing high volumes of cargo to be screened rapidly.

Comparative tests against two commercial X-ray scanners in Brisbane on a range of cargo showed that, with improved spatial resolution (5 mm detectors or smaller) and multi-view capability, the CSIRO Air Cargo Scanner has the potential to significantly outperform the current best commercial X-ray air cargo scanners. Reference Scanner at Lucas Heights

Reference Scanner to provide a platform for trials (e.g. improvised explosive devices), enhancements, new applications, etc. Simulate Brisbane scanner but with : 8 • Weaker sources (neutrons ~10 n/s, 2.4 GBq Co60) • Reduced source-detector distance • Same detector sizes but reduced height of detector arrays (~1.9 m) and tunnel • Accommodate ULDs up to 1.7 m high and 2.5 m wide • Typical scan time ~few hours Enhancement R&D using Reference Scanner

Reference Scanner upgraded in 2006/7 to assess and compare super-resolution and small detector methods for improving spatial resolution The use of small (5 mm) gamma detector elements provides better spatial resolution than super-resolution methods using two offset columns of the 10 mm gamma detectors For the larger neutron detector elements, super-resolution provided an adequate improvement in resolution Tests conducted for Australian Government on detection of concealed contraband (real and simulated) showed that higher resolution images are a significant aid in understanding complex, high-clutter cargos Resolution Enhancements

10205 mmmmmm pixelspixelspixels Reference Scanner: ULD Loaded with Mixed Cargo

From left-to-right, the cargo contains assorted computer equipment, heavy steel industrial items, mixed boxes of food stuffs (including bottled drinks, frozen meat and fish, boxed apples) and boxes containing office files and papers. Demonstration of Background Stripping

Background stripping tool used to identify material Commercial Scanner: CSIRO-Nuctech Collaboration

January 2008 – Commence joint work April 2008 – Official signing of CSIRO/Nuctech joint venture in Canberra May 2008 – Finished main mechanical design, start scanner manufacturing Aug-Sept 2008 – Short delay in mechanical manufacturing due to the shutdown for Beijing Olympics Oct-Nov 2008 – Installation in Nuctech’s production base at Miyun, Beijing Dec 2008-Apr 2009 Commissioning, integration and optimisation (hardware & software) May 2009 onwards – Continuing R&D; start trials for various customers Nov-Dec 2009 – first sales First Commercial Scanner – Nuctech AC6015XN

Neutron detectors

Neutron generator

X-ray detectors

X-ray LINAC source Features of Commercial Air Cargo Scanner

X-Ray System 60 Dual energy (3 & 6 MeV) X-ray source used in place of Co Dual energy X-ray analysis can be used on thick organic cargo through which 14 MeV neutrons cannot penetrate 5 mm X-ray detectors (compared to 10 mm in Brisbane) Neutron System Upgraded Thermo A-711neutron generator to Thermo D-711 system (digital control, cooling system) New neutron shielding, collimator and source housing designs – smaller footprint, easier to deploy New neutron detector assembly to match Nuctech X-ray scanner with vertical and horizontal sections – same detector size Offset neutron detector columns to implement super resolution Beam Hardening Correction Binocular Stereoscopic Imaging Improved Imaging Software and Human-Machine Interface Binocular Stereoscopic Imaging

Binocular stereoscopic imaging to separate images into multiple layers to aid operators Comparison of X-Ray and Combined Neutron/X-Ray Scans Comparison of R-Values

1.8 Polythene (9) Ethanol (8) 1.6 Water (7)

1.4 Wood (6)

1.2 Graphite (5)

1 Glass (4) Theoretical R Value 0.8 Aluminium (3) 0.6 Iron (2) 0.4 Lead (1) 0.2 0.5 1 1.5 2 Measured R Values

Scan of a selection of material samples and common Standard deviation = 0.0154, objects arranged on shelves, etc in the AC6015XN Correlation coefficient = 0.9997 scanner Combined Neutron and X-Ray Scan of ULD Loaded with Mixed Cargo in the AC6015XN Scanner

The cargo contains computer monitors (CRT and LCD), a porcelain vase, glass bottles and a sack of industrial chemicals (left), air conditioners and gas bottles (middle), and vegetables (right). Combined Neutron and X-Ray Scans obtained with the AC6015XN Scanner

Scan of diesel generator, gas bottles, large truck wheel, pumps, and other machines

Scan of a small car on a steel platform Room for Improvement: 14 MeV Neutron Generator

Require • High neutron output (~10 10 n/s continuous) • Small volume target (~<25mm) • High availability (>95%) • High reliability • Lifetimes of neutron tube >2000 hours • Reasonable purchase and running costs Neutron Detector Arrays

Plastic scintillator + photodiode readout CSIRO developed low-noise preamplifiers, shaping amplifiers and digital counting and readout New neutron detector boards design and arrangement in Nuctech scanner (four boards offset and L-shape arms) Summary

Requirements for air cargo screening include speed, ability to detect contraband, imaging, low false alarm rate, radiation safety, ease of maintenance, acceptable cost Fast-neutron/X-ray or gamma-ray radiography adds composition information to conventional X-ray images and meets most of these requirements for screening air cargo Technique can also be applied to sea containers

Benefits • Effective and rapid inspection of air cargo • Find more contraband • Deter trafficking of contraband CSIRO Minerals Brian Sowerby

Phone: +61 2 9528 6634 Email: [email protected]

Thank you