Prior to the selection of a disposal method for unexploded ordnance (UXO), a determination must be made of the filler material. Trained UXO experts currently perform this determination using external markings and visual examination. However, the UXO often has weathered or corroded and the markings and external visual cues are deteriorated or absent. A means of quickly and correctly determining the fill of UXO is needed to allow rapid disposition of inert rounds and proper handling of explosive or chemical-filled UXO. The Naval Explosive Ordnance Technology Division (NAVEODTECHDIV) has been investigating the use of the Pulsed Elemental Analysis with Neutrons (PELAN) with support from the Office of Naval Research and Environmental Security Technology Certification Program. These efforts have demonstrated the utility of using PELAN to gather data from explosive-, chemical-, and inert-filled UXO, but have highlighted the need for more advanced signal processing to increase the probability of detection and reduce the false alarm rate.

The objective of this project was to investigate the use of more effective and reliable algorithms for analyzing the data collected from the PELAN system and classifying UXO items as to their filler material.

Technical Approach

PELAN is a man-portable system for the detection of explosives and chemical warfare agents. It is based on the principle that explosives and other contraband contain various chemical elements such as hydrogen, carbon, nitrogen, and oxygen in quantities that differentiate them from innocuous substances. Separate gamma-ray spectra from fast neutron, thermal neutron and activation reactions are accumulated and analyzed to determine elemental content.


Results are available in the Final Report and its distribution is authorized to U.S. Government agencies only (Critical Technology) (14 April 2004). Other requests for this document shall be referred to: Commander, Naval EOD Technology Division, 2008 Stump Neck Rd, Indian Head, MD 20640.


During cleanup operations, it is necessary to identify the filler material in UXO to select the appropriate disposal methods. The application of algorithms developed in this project enable the PELAN to provide more robust UXO filler identification capability (i.e., lower false alarm rates and higher probability of detection). This extends its utility to general UXO operations where the target types are not known a priori. Further, understanding how the inclusion of different input parameters and changes in environmental conditions affect the operation of the system enables the reliability of the PELAN to be increased.