Characterization of PAX-21 Insensitive Munition Detonation Residues

Insensitive high explosives are being used in military munitions to counteract unintended detonations during storage and transportation. These formulations contain compounds such as 2,4-dinitroanisole (DNAN) and 3-nitro-1,2,4-triazol-5-one (NTO), which are less sensitive to shock and heat than conventional explosives. We conducted a series of four tests on snow-covered ice utilizing 60-mm mortar cartridges filled with 358g of PAX-21, a mixture of RDX, DNAN, and ammonium perchlorate. Rounds were detonated high- and low-order using a fuze simulator to initiate detonation. Blow-in-place (BIP) operations were conducted on fuzed rounds using an external donor charge or a shaped-charge initiator. Results indicate that 0.001% of the original mass of RDX and DNAN were deposited during high-order detonations, but up to 28% of the perchlorate remained. For the donor block BIPs, 1% of the RDX and DNAN remained. Residues masses for these operations were significantly higher than for conventional munitions. Low-order detonations deposited 10-15% of their original explosive filler in friable chunks up to 5.2g in mass. Shaped-charge BIPs scattered 15% of the filler and produced chunks up to 15g. Ammonium perchlorate residue masses were extremely high because of the presence of large AP crystals, up to 400m in the recovered particles.