NATIONAL and homeland SECURITY S&T

The threat of an explosive terrorist attack on infrastructures and 

interests within the United 

States – such as military 

bases, government buildings 

and national monuments – is 

ever present. In the last five 

years, rudimentary and easily 

constructed devices such as 

roadside bombs and vehicleborne improvised explosive 

devices have become a common tactic used by insurgents 

in countries like Iraq 

and Afghanistan.

For security professionals, dealing with explosive 

devices hidden in cars and 

trucks is a particularly difficult tactic to confront because 

large vehicles like cargo 

trucks and moving vans act as 

their own delivery mechanism 

and can move large amounts 

of explosive material without drawing suspicion. The 

1995 bombing of the Alfred 

P. Murrah Federal Building 

in Oklahoma City provided a 

vivid example. 

In collaboration with the United States Air Force Electronics Systems Center, scientists 

at Idaho National Laboratory 

have developed and deployed 

a portal-style vehicle-borne 

detection unit known as the 

Idaho Explosives Detection 

System (IEDS). In 2006, 

IEDS was installed at Ohio’s 

Wright-Patterson Air Force 

Base for random anti-terrorism field testing.

How it Works

The award-winning IEDS is 

designed to nonintrusively interrogate cargo trucks before 

they get near high-profile targets like federal buildings or 

foreign embassies. The detection system functions similar 

to an automated car wash. 

As cargo vehicles approach 

a facility, they are directed to 

drive into an open-air inspection zone. Once the driver 

exits the vehicle and proceeds 

beyond a 30-foot safety area, 

two 25-foot metal racks – one 

on each side of the vehicle 

– enclose like brushes in a 

car wash. 

The system’s effectiveness 

relies on a technique called 

pulsed thermal neutron activation. In this setup, two neutron generators saturate the 

vehicle with pulsed neutrons. 

This interrogation causes the 

molecular makeup of materials 

inside the vehicle to excite and 

emit gamma rays. Following 

each neutron pulse, a series 

of 32 sodium-iodide detectors 

measures signature gamma 

rays from the material present. 

Idaho Explosives Detection System

P-5466-37

Continued next page

The Idaho Explosives 

Detection System 

interrogates a mail 

delivery vehicle before it 

enters Wright-Patterson 

Air Force Base.
NATIONAL and homeland SECURITY S&T

Continued from previous page

Andrew Edwards

INL Program Manager

208-526-8358

Andrew.Edwards@inl.gov

Edward Reber, Ph.D.

Technical Lead

208-526-1410

Edward.Reber@inl.gov

The entire interrogation 

process takes less than 300 

seconds. At the end of the 

interrogation, IEDS will alert 

the operator whether explosives were detected. The 

inspection process scans the 

entire truck at once and is up 

to three times faster than a 

manual inspection while leaving no residual impact on the 

truck or cargo items. Accurate 

identification of explosives 

relies on patented mathematical algorithms written by INL 

researchers. Large amounts 

of raw data from the detectors are fed into the control 

computer. The algorithms 

interpret the data and feed it 

into a custom graphical user 

interface, which displays a 

simple-to-understand pass 

or fail icon. This simplistic 

design was built intentionally 

for a technician or soldier to 

operate with minimal training.

In addition, IEDS doesn’t 

require continuous human 

interface, so operators can 

control the unit remotely from 

a secure location using 

Ethernet transmission. 

IEDS was designed to 

detect the presence of nitrogen-based explosives with 

a minimum accuracy rate 

of 95 percent, and a false 

positive rate of less than 5 

percent. Nitrogen is a common component found in over 

98 percent of explosives. The 

INL team also designed the 

system to monitor the health 

of its individual components, 

so an operator could quickly 

pinpoint potential problems 

and make adjustments.

Custom Applications

Through the combination of 

rapid neutron interrogation 

and the use of high probability 

statistical inference, the IEDS 

has the ability to yield precise 

determination of the presence 

of explosives, while minimizing the indication of false positives. The current system has 

been developed for all-weather 

environments, allowing it to 

function accurately in desert 

Key Capabilities 

• Detects explosives:

– A fraction of the size 

of those used in 

Oklahoma City

– Concealed in any 

location on a vehicle

– Within 300 seconds 

(five minutes)

– such as ANFO, HMX, 

PETN, RDX, TNT, etc.

• Detects radiological 

material

• Proven technology

• Operationally safe

• Non-destructive, 

non-intrusive, 

non-contact

System Components

• Neutron generators

• Large array of sodium 

iodide (NaI) detectors

• Laptop computer

07-50651

A U.S. Department of Energy

National Laboratory

For more information

07-GA50070-02

and sub-zero environments. 

IEDS can be configured to 

detect a range of contraband 

items, or built for custom 

installation applications.

The Idaho Explosives Detection 

System can be configured for 

custom applications such as 

interrogating semitrucks for 

contraband items.