Low-Order, Underwater Detonation

Abstract : War activities, dumping, accidents, ordnance development, and military training have left significant quantities of unexploded ordnance (UXO) in coastal waters in the United States and abroad. UXO that is unsafe to move is countercharged or blown-in-place (BIP). The concern over underwater BIP is that it can cause acute environmental damage at a considerable distance from the detonation (Knowles, 1999). Damage to marine biota has to be balanced against the need for public safety. Low-order detonation techniques have matured as a means to render safe surface UXO. Low-order detonation is characterized by the partial energetic reaction of high explosive filler in ordnance. There is very little data on generating low-order detonations with UXO underwater. The use of low-order detonation has potential to mitigate the acute blast effects by over 90 percent of that associated with conventional BIP procedures. Tests on TNT-filled 155 mm projectiles and tritonal-filled Mk 82 bombs at the Aberdeen Test Center Briar Point Test Pond with a low-order tool were conducted in June and July 2001. The results showed that low-order detonation procedures were very effective in reducing the blast effects while causing a complete disruption of the ordnance. Pressure histories were equated to equivalent yields in pounds of TNT. The objective of this demonstration was to develop a procedure and validate a low-order technique as an alternative to countercharging submerged UXO. The demonstration investigated the effectiveness and reliability of the (German) HL-21 shaped charge as a low-order detonation tool against unfuzed 155 mm High Explosive (HE) projectiles and MK 82 bombs. (Other test programs demonstrated that presence of fuzing does not affect low-order results). Effectiveness was measured by a reduction in the net explosive yield. The equivalent pounds of TNT needed to generate measured pressure and impulse determined the net explosive yield of a low-order detonation.