recycling. The Department of Defense (DoD) has instituted a policy for the identification of munitions and munitions scrap that are free of explosive safety hazards (DoD, 2008). The defined process includes specific training, storage, handling, inspection, and certification requirements for all materials potentially presenting an explosive hazard (MPPEH)—that is, any material that has come into contact with an energetic material—before their release from DoD control. The policy applies to any scrap metal recovered from the separated M55 rocket motors.
If the M28 propellant is treated while inside the steel motor case the, remaining metal parts will be contaminated with lead and lead dust. Separation of the propellant, igniter, and other energetic components of the rocket motor from the case, fins, and electronics would simplify the recovery of the scrap metal from these components. However, the recovered metal may still have to be thermally or chemically treated to ensure that energetic residues are destroyed before the materials can be released to a recycler.
Finding 3-2. It is feasible to recycle the metal components of the separated rocket motors.
Finding 3-3. Depending on the destruction technology used, metal components may be contaminated with lead and lead dust.
Recommendation 3-1. The Blue Grass Chemical Agent-Destruction Pilot Plant program staff should inform the recipient of materials for recycling of the potential for the presence of lead or lead dust on recovered materials.
A wide variety of technologies have been proposed for the demilitarization and disposal of conventional solid rocket motors. The technologies can be divided into thermal and chemical. Thermal technologies for separated rocket motor demilitarization and disposal include open detonation, buried detonation, contained detonation, open burn, open static firing, contained combustion, contained static firing, confined combustion, and incineration. Chemical technologies include base hydrolysis, supercritical water oxidation, and the use of humic acid. The chemical technologies typically require pretreatment in which the propellant is broken into a manageable form (e.g., a solution, powder, or slurry). That process increases the handling of energetic materials and the attendant risks. Thermal treatment usually requires less handling, but precautions must be taken to prevent unplanned detonation or propulsive ejection of the rocket motors. Technologies discussed here are summarized in Table 3-1. The committee envisions that the separated rocket motors would be removed from the shipping and firing tubes before disposal of the separated rocket motors, partly because the shipping and firing tubes contain polychlorinated biphenyls; this is discussed in more depth in Chapter 5. Among the criteria that will need to be considered in selecting a disposal technology for use with the separated rocket motors is the TNT equivalence of the roughly 20 lb of M28 propellant in each motor.