While conventional explosives (i.e., hexogen, trinitrotoluene) produce minimal post-detonation residues (<10 mg/round), some new insensitive high explosives have been found to produce higher loading rates that may be environmentally significant. Command detonation allows a munition to be assessed for energetic residues early in the acquisition process, before the item is certified for live fire from a weapon. However, the ability for this technology to accurately represent residue loading as it occurs during training has not yet been validated. Application of this technology during life cycle environment assessment would help address potential future range sustainment issues and environmental issues. 

The objectives of this project were to: 

• determine live-fire residue loading rates for two insensitive munitions as they are produced during military training; 
• statistically compare loading rates between these actual live-fire tests and previous command-detonation tests of the same munitions using two different fuze simulators (SERDP Project ER-2219); and 
• transfer validation study results to armaments and ammunition stakeholders.

Command detonation enables a munition to be fired remotely in a static position at a testing location where residues can be collected and then analyzed. The key uncertainties in this practice are whether the required replacement of the munition’s fuze with a fuze simulator and the static upright positioning accurately represent residue production as it occurs during live fire. Previous command-detonation tests of the study munitions (60 mm and 81 mm IMX-104 mortar) used fuze simulators developed by Engineer Research and Development Center-Cold Regions Research and Engineering Laboratory and the Armaments Center, each initiated in nose-up orientation with military blasting caps. Snow was used as a sampling medium as it provides visual evidence for the spatial extent of deposited soot and residue, and this medium provides extremely sensitive method detection limits (typically less than 1 mg/cartridge).

Loading rates of IMX-104 compounds were successfully determined from live fire of 60 mm (n = 11 cartridges) and 81 mm (n = 14 cartridges) mortar munitions that were initiated upon impact with snow, and then sampled and analyzed in the same manner as previous command-detonation tests. Command detonation was found to have successfully reproduced total compound loading from live fire of the 60 mm munition (p = 0.76) but significantly underestimated live-fire loading from the 81 mm munition (p < 0.01). While command detonation underestimated loading of some residues, its utility was supported by the correct order-of-magnitude prediction of individual compound loading rates across both tested munitions. The cost of implementing this technology to new, in-development munitions was estimated as minor relative to costs associated with potential future remediation efforts, range restrictions, and acquisition modifications.

Implementation of this technology would introduce an additional performance test in the development of new munitions. Minimization in effort and cost can be derived through tailoring test logistics (i.e., test area and sampling medium) to data quality objectives (e.g., detection limits and targeted vulnerable receptors), while also examining opportunities to leverage existing test methods. Application of the results of this research will ultimately bolster operational capabilities and warfighter preparedness by increasing the availability of testing and training ranges. (Project Completion - 2023)

Beal, S.A., M.F. Bigl, C.A. Ramsey, W.M. Kadoya, A. Gelvin, and K.L. Broberg. 2023. Representation of Live-Fire Energetic Residues from Insensitive Mortar Munitions using Command-Detonation Testing. Propellants, Explosives, Pyrotechnics, 48(12):e202300161. doi.org/10.1002/prep.202300161.