Pulsed neutron identification

A pulsed neutron beam can penetrate the casing of munitions and identify the filler contents, be it explosive, chemical agent, incendiary, or smoke. This is a one-sided device, unlike an x-ray, and requires a minimum of disturbance to the item. In fact, the item does not need to be dug to the point of being visible. It is absolutely necessary for any ordnance remediation work, and it should be part of any health and safety plan. 

A portable isotopic neutron spectroscopy (PINS) detector can be used to help eliminate an anomaly or munitions as being dangerous. The PINS detector is only effective for six inches, thus the object does not have to be completely excavated. A larger truck-mounted version called pulsed fast neutron analysis (PFNA) can penetrate to five feet, but it is extremely dangerous to drive a heavy vehicle over a munitions site. Still larger permanently mounted versions are available for customs work, which can look through an 8-ft wide steel shipping container or semitrailer. 

In some cases, these devices are able to positively identify the chemical constituents inside a steel shell. They can locate plastic land mines by the same technique, for that matter. They save valuable time in eliminating the careful handhng of expended ordnance. Neutron beams can identify chemical, explosive, smoke, and incendiary munitions, each of which may require special handling. 

One example suffices An MARB was established to review shell finds from the Spring Valley site. The board, composed of very experienced EOD people, PINS nuclear physicists, and historians, misinterpreted data. The PINS system revealed silicon in a number of shells. The MARB incorrectly concluded that they were sand-filled training rounds. Actually, they contained Kieselgur, a silicon substance used to keep the poison gas down at ground level after detonation. 

a PINS unit small enough to be lowered into a borehole located alongside of the anomaly is available. This is the only device remotely capable of determining whether or not an anomaly is a viable explosive or chemical ordnance item, what the chemical or explosive is, and possibly whether or not it is fused. But, as we have seen, it has uncertainty. Also, boreholes are too labor intensive on a range impact area with hundreds of anomalies. 

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G. Vourvopoulos, P.C. Womble and J. Paschal, PELAN a pulsed neutron portable probe for UXO and landmine identification, Proc. SPIE, 4142 (2000) 142-149. 

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