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Analysis of Engineering Design Studies for Demilitarization of Assembled Chemical Weapons at Blue Grass Army Depot 6 General Findings In this chapter, the committee presents its general findings on the three alternative technology packages that have been proposed for Blue Grass. The general findings should be considered with the caveat that various ACWA EDS tests were not completed in time for the committee to review the final results and that some process steps remain to be demonstrated on a pilot scale. Also, following its statement of task, the committee limited its evaluations to separate assessments of the total solutions proposed by AEA, Eco Logic, and General Atomics for destroying the assembled chemical weapons at Blue Grass Army Depot. That is, the committee has neither compared the proposed alternatives with one another or compared them with the Army’s baseline incineration system. General Finding 1. The reverse assembly of munitions, followed by water or caustic hydrolysis of nerve or mustard agents and associated energetic materials, is a mature, safe, and effective method for initial treatment of the chemical weapons stored at Blue Grass Army Depot. It is ready for immediate implementation for the neutralization of energetics and agents. However, the resulting hazardous streams must be treated further before they are released to the environment. This finding is based on the test results presented earlier in this report for the EDS hydrolysis of energetic materials and on the effectiveness of the modified baseline reverse assembly and agent hydrolysis processes discussed in this and previous NRC reports (NRC, 1999, 2001a). Because hydrolysis destroys agents and active energetics, the resulting hydrolysates pose a lesser hazard than the assembled chemical weapons.1 This finding is independent of any subsequent secondary treatment steps that will be necessary to render the hydrolysates environmentally acceptable. That is, agent and energetics could be hydrolyzed even before the secondary treatment process is selected. However, further treatment is necessary to reduce hazardous waste concentrations to a level sufficiently low to allow for final disposal. Additional treatments will also be required for dunnage and the metals parts generated in the reverse assembly process. General Finding (Blue Grass) 2. Several of the unit operations of the technology packages have process streams that are not unique to the chemical weapons stockpile. These streams, which include dunnage, brines from water recovery, and hydrolysates, could potentially be treated at existing off-site treatment, storage, and disposal facilities. Off-site treatment of these wastes would simplify the overall technology and facilitate process integration by eliminating the need for 1 All tests of agent destruction were performed with field-grade chemical agents produced at approximately the same time as the agents loaded into the chemical weapons. Thus, any complications arising from stabilizers, other additives, or degradation products were accounted for during testing.
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Analysis of Engineering Design Studies for Demilitarization of Assembled Chemical Weapons at Blue Grass Army Depot further development of individual process steps in the secondary treatment processes and their integration into a whole system. It might also simplify design requirements to meet safety concerns. All of the process streams that could be treated off-site have compositions similar to waste streams routinely treated by commercial industrial waste treatment facilities. Thus, they could be transported by standard commercial conveyance to commercial facilities that are appropriately permitted to receive the waste. General Finding (Blue Grass) 3. Based on the results of the PMACWA-sponsored test program on the hydrolysis of energetic materials, the committee believes that hydrolysis can be used safely, effectively, and on the scale necessary for the destruction of the energetic materials contained in assembled chemical weapons at Blue Grass, provided that lead-containing propellants are not processed with tetrytol until the possibility of lead picrate formation can be eliminated. The test plan that was executed at HAAP demonstrated that the hydrolysis process for the energetic materials of interest successfully destroyed more than 99.7 percent of the energetics treated. Over 9,500 pounds of energetic materials were destroyed while encountering only the types of problems normally expected during the implementation of a new facility and process. The suite of tests performed at Los Alamos National Laboratory (LANL) and at HAAP covered a range of reaction temperatures and caustic concentrations. Under all these conditions, the destruction of energetics was carried out safely and effectively. Effective destruction of energetic materials during the test program is interpreted by the committee to mean that the products resulting from destruction no longer pose an explosion or detonation hazard. The committee notes, however, that the hydrolysate produced and the gaseous decomposition products are not benign. Gases such as ammonia and oxides of nitrogen are evolved, and cyanide or other toxic substances may be present in the hydrolysate. However, a variety of conventional methods for treating the offgases are available. The fate of lead during energetics hydrolysis in the presence of picrate is not understood. Until more information becomes available on the speciation of lead and the solubility of lead picrate under the conditions of hydrolysis, the possibility of solid lead picrate formation cannot be dismissed. As a precautionary measure, lead-based propellants should be processed separately from tetryl and tetrytol, eliminating the possibility of lead picrate formation. General Finding (Blue Grass) 4. Based on the results of EDS testing and the engineering design package, the committee believes that the AEA SILVER II™ total solution technology package could eventually destroy the assembled chemical weapons stored at the Blue Grass Army Depot. However, the immaturity of a significant number of processes in this electrochemical destruction technology could threaten PMACWA’s achievement of its objectives for weapons destruction. Considerable additional development and demonstration must be completed before this technology can proceed to a full-scale facility. There is also concern that the ever-increasing complexity and frequent configuration changes that have occurred in the AEA technology package to date are indicative of the immaturity of the process. The approach employed by AEA has been to solve problems as they arise by incorporating additional steps that are modifications of previously demonstrated technologies. The technology provider infers the success of these new steps based on previous demonstrations in other applications but has not generated the data to show that the modifications will result in a safe, effective, and reliable integrated system for assembled chemical weapons destruction. The AEA SILVER II™ technology process does accomplish the following: It destroys chemical agent to a 99.9999 percent DRE and energetic materials to a 99.999 DRE by mediated electrochemical oxidation, provided that the following safeguards are observed: hydrocyclones are used on all slurry feed streams, high-shear vortex mixers are used, piping design minimizes dead legs, and all system equipment and piping use trace heating to prevent precipitation of energetic intermediates, and a second set of electrochemical cells is used to polish the anolyte to the required destruction level. It produces acceptable slurry compositions for processing burster energetics and rocket propellants. It safely treats process offgases using a combina-
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Analysis of Engineering Design Studies for Demilitarization of Assembled Chemical Weapons at Blue Grass Army Depot tion of thermal treatment, catalytic oxidation, activated carbon filters, and treatment of the munitions demilitarization building (MDB) HVAC system ventilation air through activated carbon filter media prior to release. However, the committee notes that the effectiveness of some process steps has not been demonstrated: Removal of energetics from rockets using the new tube-cutting technology in a modified baseline RDM, and achievement of agent-free energetics for processing by SILVER II™ electrochemical cells in a Category C area. Integrated operation of the primary and polishing anolyte circuits with a common catholyte circuit. Effective control of the flow of slurry mixture to a large number of parallel flow paths. (Currently, flow control has been demonstrated on only three parallel paths, whereas the full-scale application would have up to 432 parallel flow paths in the catholyte feed circuit.) Reliable operation of the electrochemical cell membrane, particularly for agent-containing slurries. (Currently, cell pressures and chemistry must be carefully controlled, and it is unclear if the membranes will work well in prolonged exposure to organophosphate-containing slurries.) Demonstration of a method to control the movement of fluorine and assure that all elements of the system exposed to fluorine-containing liquids and vapor streams can operate without excessive corrosion and maintenance. Decontamination of metal parts and fuzes to a 5X condition in the metal parts treater (MPT). Decontamination of dunnage and DPE suits to a 5X condition in the proposed, but as yet untested, enclosed-augur version of the dunnage treatment systems (DTS) and successful management of dioxins and furans in the offgas from this process. General Finding (Blue Grass) 5. Stable operation of the ELI-Eco Logic/Foster Wheeler SCWO system at the design conditions has not yet been demonstrated. The SCWO system for treatment of hydrolysates in EDS II testing exhibited frequent spiking in hydrocarbon and carbon monoxide concentrations in the offgas. This issue must be resolved before implementing the Eco Logic process at Blue Grass. If it is resolved, the committee believes that the Eco Logic package could provide an effective and safe means for destroying the assembled chemical weapons. However, the following design features still require validation: Design of the overhead conveyor system for the caustic bath should be tested to demonstrate satisfactory reliability. Removal of aluminum from the feed to the SCWO reactor. At this time, Eco Logic has not proposed an aluminum removal technology. Smoke abatement from the thermal reduction batch processor (TRBP) smoking rooms and the measurement and management of carbon monoxide and other products of incomplete combustion generated in these rooms. (These processes were not adequately addressed in the EDP.) The Eco Logic technology does accomplish the following: It disassembles munitions by a modified baseline reverse-assembly technology. It destroys chemical agent to a 99.9999 percent destruction and removal efficiency (DRE) and energetic materials to a 99.999 DRE. It effectively treats solid and gaseous residues in a gas-phase chemical reduction (GPCR™) system and decontaminates solids to a 5X condition. It destroys by SCWO the hydrolysates and slurries that result from upstream processing. It adequately treats the low volumes of offgases produced in the process, including those from the SCWO reactors, through catalytic oxidation and activated carbon adsorption systems. The committee also points out the following: Eco Logic’s munitions reverse-assembly process starts with the baseline system technology, but modifications have been made. The rocket dismantling machine (RDM) operation is complex and differs in several aspects from the baseline operation. Further development of this process is needed. A testing program, described in Chapter 4, showed that the M28 propellant grinding could be done safely. However, additional testing with a larger, modified grinder is required to demonstrate any design modifications and to determine grinder and motor sizes for the full-scale plant.
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Analysis of Engineering Design Studies for Demilitarization of Assembled Chemical Weapons at Blue Grass Army Depot The Demo II tests generally confirmed the performance and efficacy of the GPCR™ process for the treatment of the waste streams from the process. However, problems with the agent detection method hampered a full evaluation of the process, and some concerns were raised about the selection of materials of construction for the processing agent. EDS testing has provided additional design data, but the results have not yet been used in operating systems. General Finding (Blue Grass) 6. Based on the results of the EDS testing and the EDP, the committee believes that the General Atomics technology package is an effective and safe method for the destruction of assembled chemical weapons at the Blue Grass Army Depot. The GATS SCWO system appears to have reached a level of maturity where construction and testing of a full-scale reactor to treat agent hydrolysate is the next logical step. Tests of the SCWO system have shown that the SCWO reactor requires frequent scheduled maintenance; however, the level of maintenance estimated by General Atomics for the Blue Grass application is manageable by well-trained operators and maintenance personnel. The committee still is concerned about possible problems associated with the extent of scale-up that will be needed for the SCWO reactor. Another concern is the proposed operation of the full-scale ERH and PRH in a continuous rather than batch mode and the maintenance difficulties that would result. The General Atomics technology does accomplish the following: It disassembles munitions by a modified baseline disassembly that removes the agent from the projectile bodies by cryofracture. It destroys chemical agents to a 99.9999 percent DRE by hydrolysis. It destroys fuzes by processing first in the ERH and then in the HDC. It destroys energetic materials by hydrolysis. It provides effective 5X-level decontamination for munition bodies using an electrically heated HDC. It destroys by SCWO the hydrolysates and slurries that result from this processing. It adequately treats the offgases produced in the process, including those from the SCWO reactors, through a CATOX unit and activated carbon adsorption systems. It is expected that weapons processing at Blue Grass will require no SCWO liner changes for the SCWO reactors treating energetics hydrolysates and dunnage slurried in energetics hydrolysates. For each of the two operating reactors used to treat agent hydrolysates, the technology provider has scheduled six liner changes that are estimated to be necessary for treatment of GB hydrolysate (i.e., 12 liner changes total for the GB campaign) over the 16-month operating life of the plant. During periods of steady operation with GB hydrolysate, based on six liner changes per reactor, each liner will be replaced after 110 hours of operation. It appears likely that liner change-out procedures in the full-scale system will encounter more problems than were encountered in the smaller test reactors used to date. Although no evidence was found of material hanging up in the ERH during the batch testing conducted to date, this is, in the committee’s opinion, a distinct possibility during the longer operating runs of a full-scale system in a continuous mode. The energetics rotary hydrolyser (ERH) is 50 feet long and the projectiles rotary hydrolyser (PRH) is 40 feet long in the Blue Grass design. Should some form of blockage or other problem occur inside cylinders of this length, maintenance would be extremely difficult, especially considering that energetics and/or agent might be present. The tests demonstrated that the ERH and PRH appear to work well in a batch mode. Replacing the continuous-flow hydrolyzers proposed for Blue Grass with larger versions of the batch hydrolyzers used during the Demo I and EDS testing would appear to eliminate this risk and simplify system operation. General Finding (Blue Grass) 7. As the ACW I Committee observed, the unit operations in any of the three technology packages have never been operated as total integrated processes (NRC, 1999). As a consequence, a prolonged period of systemization will be necessary to resolve integration issues for the selected technology as they arise, even for apparently straightforward unit operations.
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