Neutron-Based Inspection Technologies for Industry and Homeland Security

Ezra EliasVisiting Prof. KMUTT

This presentation is based on long term collaboration with Dr. T. Gozani at SAIC, Ancore and OSIS. Part of thedata were presented by Dr. Gozani in 2010 at the local ANS section of Northern California.

Why Neutron-Based Inspection Systems

Border Crossings

11M-15M containers/yr enter the USA, 8M trucks/yr cross USA borders 8 containers/min are processed in the West Coast

Air Cargo The problem: Illicit materials including, SNM, explosives, narcotics, contraband, chemical agents and dutiable goods could be smuggled in these and other conveyances

X-Ray Provides Shape InformationIncreased Penetration at Higher Energies

450 keV X-Ray System

2-3 MeV X-Ray System

Gamma Ray (60Co) System

9 MeV X-Ray System

Sometimes Shape is All We Need…Imaging techniques (Am. Sci. & Eng. Inc.)

Imaging techniques - Rapiscan

X-ray InspectionReveals Pistol

Neutron InspectionDetects Explosive

Neutron InspectionDetects Drugs

Many of the threats don’t have defined shapes

X-Ray Role in Medicine and Biology

1895Discovery of X

raysWilhelm C. Röntgen

1897First treatment of a hairy tissue with X rays started

the medical interest in using X-rays to remove hair

Leopold Freund

Brief History of n-Based Bulk NII Technologies,

Year MaterialKey ElementalFeatures & rel.

density

Usable Nuclear

Reactions

AvailableSignatures

1985CONTRABANDExplosives

relatively high O

relatively high N

relatively low C

relatively low H

(n,n’γ)

(nth,γ) /(n,n’γ)

(n,n’γ)

(nth,γ)

6.130 MeV

10.80 / 5.11, 2.31, 1.64 MeV

4.43 MeV

2.223 MeV

1990

Drugs (Cocaine / Heroin)

relatively high C

relatively high H

relatively low O

low-medium Cl (for HCl-drugs)

(n,n’γ)

(nth,γ)

(n,n’γ)

(nth,γ) & (n,n’γ)

as above

as above

s above

6.110 MeV & other strong lines for Cl

1980Minerals, Cement

Ca, Si, Fe, Al, Mg (nth,γ)

Specific capture γ-rays, e.g., 6.420 MeV for Ca 4.934 MeV for Si 7.630-46 MeV for Fe, etc.

1975 CoalC (high w/o)

H, S, Si, Al, Fe, Ca, K, Na, Ti

(nth,γ), (n,n’γ)

(nth,γ)

Specific capture (or inelastic) γ- rays, e.g., 4.945 MeV (n,γ) and 4.43 MeV (n,n’γ) for C, 2.223 MeV for H, 5.420 MeV for S, etc.

1965-Nuclear (NMM or NII)

232Th, 233U, 235U, 239Pu, 240Pu

(nth,f), (nf,f), (γ,f); 2nd: (nth,γ) (n,n’γ)

np, nd(t), γp, γd(t); also high multiplicity coincidence; very high Z & density

Non Intrusive Inspection technology time line Early period: late Sixties to late Eighties

Technology development focused naturally on the perceived threat or priority issue at the time

1970 1980

Bulk Coal/Mineral Analyzers

1985 1990

NDA of SNM Safeguards (n & γfiss /del n or coincidence signal)

GovernmentAEC/ ERDA /

NRC

1975

Specialty Equipment

Explosive Detection (TNA®/FNA™)

Rapid Sulfurmeter

Ashmeter

IndustryEPRI

LINAC

Government

Technology time line: 90th to early 2000 Maturing technologies, limited prototype deployments

Aviation security, border security & counter drug, anti vehicle mine and UXO detection

Technology Time Line: Early 2000 to PresentResurgence of the nuclear threat; A combined systems concept implemented:

active (and passive) inspection combined with x ray radiography

Threat Detection: Explosive/Contraband & Nuc. Material (TNA®/FNA™/PFNA™/(γ&n,f)

Historical PerspectiveIn historical perspective one of the greatest commercialization

success of neutron-based non-intrusive inspection technologies is

the coal and cement nuclear analyzer

Other success stories of neutron based inspections, though on

much more limited scale, are in the nuclear industry: •The thermal neutron Differential Die Away (DDA) waste scanner •Nuclear fuel and pellet scanner (based on delayed gamma rays) •Other SNM safeguards related systems

Success from a national point of view - High level professional nuclear engineering capability wasmaintained at a time of lower nuclear energy activity

Thermal Neutrons Capture and Fast Neutrons Inelastic Scattering

Isotopic Source – 252Cf

PGNAA-Coal and Iron-Ore On Line Analysis

(n,γ)&(n,n’γ) (e.g.252Cf, (d,T))

C(n,n’γ)

S

Coal

Combined Germanium and NaI Based Continuous On-Line Nuclear Analysis of

Coal: CONAC

NaI Based Sulfurmeter and Ashmeter: Off-Line, On-Line & In-Line Analysis of Coal

Ashmeter- dual γ energy gauge

Sulfurmeter-(n,γ) utilization

Nuclear Coal & Cement Analyzer: Time Line

1973 - 76 Concept development/feasibility demonstrations by SAIC/Ancore

1980 - 83 pilot plant operational: NaI & Ge based systems (TVA & Detroit Edison)

1985 1st commercial system sold1991 30 systems operational1998 30 to 40 units sold per year2002 Low cost version introduced2006 300 units sold; 4 vendors active in the market2010 >500 units are operational around the world

Explosive Signature - TNA Component of VEDS (Vehicular Explosive Detection System)

Thermal Neutrons Capture and Fast Neutrons Inelastic Scattering

Accelerator

Pulsed Neutron Generator Time Sequence

10 μs to 0.5 msBuildup of thermal n 90 μs

Thermal n “die-away”

“Activation” Domain

Repeated Pulse

New VEDS: Two-Parameter (t,E) Acquisition

2 parameters (time and energy) acquisition and analysis

Fundamentals of Active Interrogation with Neutrons

Main Components of System:source (w/tailoring/shielding),

inspected object w/conveyor,

detectors (w/shielding),

DAS (w/decision module)

1. Source neutrons generated during the pulse. Some are partially moderated in the source spectrum tailoring system. These and the uncollided source neutrons can either interact in the cargo materials as fast neutrons, or thermalize and be absorbed in the cargo, leak out, or,

2. interact with the threat elements and generate characteristic gamma rays 3. Some of the gamma rays escape absorption in the threat or cargo and are detected

by system detectors 4. Other gamma rays escape detection by the system detectors

Nuclear Reactions in Neutron Interrogation

Total Cross Sections of “Organic” Elements

These cross sections determine neutron penetrability. They may also provide some elemental signatures (e.g., resonance structure, backscattered energies)

O

C

H

Neutron Inelastic Scattering Cross Sections. Reactions Provide Unique γ Signatures

(n,n’γ) Elemental vs. Material Signatures(as measured by PFNA)

VEDS Time Dependent Spectra- During the 14MeV neutron pulse in various cargos

Acquisition starts ~50μs after neutron pulse and ends 1 ms after neutron pulse. This region provides most of the elemental signatures. In the example here they are: H, Fe, N

VEDS Time Dependent Spectra- During the 14MeV neutron pulse in various cargos

Very clean oxygen signature is obtained in this time region

VEDS Time Dependent Spectra- During the 14MeV neutron pulse in various cargos

Fast neutrons interactions: (n,n’γ), during the neutron pulse provide the carbon signature

Associated Particle Imaging (API) Technique

Nuclear Coal & Cement Analyzer: Methods and Applications

TNA - Thermal Neutron Analysis

PGNAA - Prompt Gamma Neutron Activation Analysis

PFNA - Pulsed Fast Neutron Analysis

PFTNA - Pulsed Fast/Thermal Neutron Analysis

PFNTS - Pulsed Fast Neutron Transmission

Spectroscopy

API – Associated Particle Imaging

Summary of Neutron-Based Techniques # Technique Advantages Disadvantages

1

Thermal Neutron Analysis (TNA)

Well understood, relatively low cost, readily, available, applicable to package size objects. Good sensitivity to N and Cl. Can use radioisotop neutron source.

Inapplicable to large container, poor imaging for large objects.

2

Generated Thermal Neutron Analysis (GTNA)

Lower background from source and lower energy neutrons because of the time delay; accelerator available.

As above, plus: intensity during the pulse much higher than in #1, resulting increased pile-up, leading to possibly lower sensitivity compared to #1.

3Fast Neutron Analysis (FNA)

Good penetration; multiple elemental signature; lowest cost among fast neutron interrogation concepts; accelerator available (14 MeV ENG). Applicable to empty or lightly loaded vehicles and tanker trucks.

Elemental sensitivity lower than PFNA, great difficulty in applying to large containers because of very poor image, large source induced background in detectors; accelerator needs improvement in reliability.

4

Pulsed Fast Neutron Analysis (PFNA)

Applicable to all size containers, good elemental sensitivities, low interference effects, low false alarm probability. Expandable, accelerator available.

More complex, requires more room, more expensive relative to above; reduced sensitivity for large dense hydrogenous contents. Requires nsec pulsed 6 MV d-accelerator.

5

Neutron Resonance Absorption (NRA)

Highest elemental cross-section among nuclear resonance based techniques, multiple organic element determination (H, C, N, O); accelerator available.

Two dimensional projection (like x-rays); complex and unproven, requires intense nsec pulsed accelerator for “white” neutron spectrum.

6

Gamma Resonance Absorption (GRA)

No neutrons used (considered by some as important). Good transmission through hydrogenous medium.

Single elemental determination (N), 2-D projection; requires accelerator with extremely high current and appropriate 13C target to handle it. Not applicable for large containers.

9 High Energy X-ray

High transmission through hydrogenous medium. High resolution 2-D images. A few systems already installed.

Not material/elemental specific. Only 2-D imaging. Human decision based on shapes.

Business Perspective

Commercial entity, like coal fired power plant or cement producer, is

motivated by bottom line.

Recession, costs of competing fuels, regulatory environment, cost

of acquisition and owning of equipment and return on investment

played very important role in the above time line and overcoming

the supposed “aversion” to the use neutrons

Acquisition and deployment of inspection technologies by government bodies are governed by very different rules.

Summary and ConclusionsNeutron-based inspection systems for explosives and drugs detection are mature

and operational in the coal and mineral processing industries. Further applications

in the chemical and mining industries could be identified

Some of nuclear material detection techniques have reached a level of field tests.

They are highly complementary to the active detection of bulk explosives, drugs

and other contraband.

Strong background in “nuclear engineering” is necessary to design and/or evaluate

the technology for the local needs.

Thank You