Explosive Safety Compliance of a Weapon Assembly Operation

Abstract : SRI International evaluated the explosive operations of a weapons assembly operation to determine compliance with the U.S. Department of Defense (DOD) quantity/distance (Q/D) requirements for blast overpressure and fragment projection distance. Figure 1 shows a schematic of the weapon assembly and inhabited buildings. The closest distance between the two buildings (for later use with Q/D charts) is 550 ft. Our objective was to obtain a credible estimate of the hazardous overpressure range and fragment projection range should an accidental explosion (or "maximum credible event") occur in the weapon assembly building. The estimated hazardous ranges can then be compared with the 550-ft separation between the two buildings. The range estimates given here are based on computer simulation of mass detonation of an equivalent high explosive (HE) charge. The hydrocode calculations model the HE detonation, the formation and propagation of the resulting airblast, and the initial velocity imparted to fragments of known material and mass. A special algorithm (called UFO) was developed to trace the fragment trajectories and calculate the maximum projection distance possible for a given fragment mass and initial speed. The maximum amount of explosive and propellant in use in the weapon assembly operation at any given time was calculated from a combination of rocket motors, warheads, and complete weapons stored in several locations. The total equivalent HE for the entire weapon assembly operation is about 2450 lb. Thus, for the 6650 ft(2) weapon assembly building, the average explosive loading density is 0.37 lb/ft(2). This loading density is used in the blast overpressure and fragment projection distance calculations discussed in the following sections.