Unexploded ordnance (UXO) contamination is present on at least 8 percent of U.S. Department of Defense (DoD) sites. Accurate characterization of these sites is required to make decisions about land reuse. Current UXO technology is costly, slow, labor intensive, and subject to human error. This project demonstrated a new technology, potentially more time and cost efficient, to detect and locate UXO without probing soil.

The UXO detector system, which includes two sensors, was mounted on a radio-remote controlled all-terrain vehicle operated at distances of up to 1 mile. The two sensors operate in tandem: an induction metal detector quickly detects suspicious targets that may be UXO, and the secondary thermal neutron activation (TNA) sensor confirms the detection. The induction metal detector, detects any surface or buried objects with metallic components. The TNA sensor, responds specifically to explosives and can therefore confirm whether a suspicious object is UXO or a harmless piece of metal.

Schiebel metal detector array

This project was executed in two parts, a test and a demonstration phase. The test phase, conducted at Socorro, New Mexico, operated the metal detector and TNA sensor separately. At Socorro, clutter and several different types of UXO targets were buried to verify the TNA's ability to distinguish between actual UXO and metallic clutter. The detection phase demonstration at Yuma Proving Ground (YPG) operated both devices as an integrated system over a total scanned area of 2,860 square meters. Overall, the UXO detector system showed that a scan and search method was more efficient than a stop and go method when locating UXO targets. This site had been used as a test range for decades, so the quantity of metallic debris and thus the number of false alarms for the metal detector, were high. Out of 91 targets buried, the complete system (TNA in conjunction with the metal detector) detected and identified 32 UXO targets successfully (35%) with a TNA false alarm rate of 22%. The TNA sensor detected all 105 mm and 2.5 lb. targets down to a depth of 12in. However, the present TNA sensor appears to have a performance limitation of 30 mm targets. More in-depth studies of the equipment are necessary to fully understand the capabilities of this integrated system.

This UXO detection technique can potentially cover more than seven times the area per day of current techniques. At a typical site of approximately 1,000 acres, a reduction in cleanup time from 18 to 3 months could result. By verifying the presence of explosives, the number of false alarm interrogations is reduced. Additionally, the ability to remotely control the system improves crew safety.

The results of this demonstration show that the UXO detector system is a potentially promising technology. However, further development is needed to improve equipment design, sensitivity, and accuracy. (Project Completed - 1998)