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THE NATIONAL ACADEMIES Advisers to the Nation on Science, Engineering, and Medicine National Academy of Sciences National Academy of Engineering Institute of Medicine National Research Council Board on Army Science and Technology Committee on Review and Evaluation of Alternative Technologies for Demilitarization of Assembled Chemical Weapons: Phase 2 February 1, 2002 Mr. Michael Parker Program Manager Assembled Chemical Weapons Assessment ATTN: AMSSB-PM-ACWA Aberdeen Proving Ground, MD 21010-5424 Re: Update on the engineering design studies evaluated in the NRC report Analysis of Engineering Design Studies for Demilitarization of Assembled Chemical Weapons at Pueblo Chemical Depot (August 2001) Dear Mr. Parker: In August 2001, the National Research Council (NRC) issued the report of the Committee on Review and Evaluation of Alternative Technologies for the Demilitarization of Assembled Chemical Weapons: Phase 2 (ACW II), Analysis of Engineering Design Studies for Demilitarization of Assembled Chemical Weapons at Pueblo Chemical Depot (NRC, 2001). However, several relevant tests had not been completed at the time (several months earlier) the report was being prepared for peer review, so the committee’s evaluation could not take into consideration information on some of the unit operations involved in the technologies under consideration for Pueblo. Since that time, the results of those tests have become available. Through this letter, the committee updates the findings of the August 2001 NRC report to support the Defense Acquisition Board in completing its technology selection process and in reaching its Record of Decision, based on available information. The Army has been developing alternative technologies to incineration for the destruction of the assembled chemical weapons at Blue Grass Army Depot in Richmond, Kentucky, and at Pueblo Chemical Depot in Pueblo, Colorado. Two technologies are under consideration for Pueblo by the Assembled Chemical Weapons Assessment (ACWA) program: Parsons/Honeywell Water Hydrolysis of Explosives and Agent Technology (WHEAT). This process uses water or caustic to hydrolyze and destroy the agent and energetic materials, followed by biotreatment of the resulting hydrolysates. Metal parts are treated to a 5X decontamination level in a metal parts treater, and dunnage is similarly decontaminated by treatment in a continuous steam treater (CST).
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General Atomics Total Solution (GATS). This process also uses hydrolysis with water or caustic to destroy the agents and the energetics. The resulting hydrolysates are treated by supercritical water oxidation (SCWO). All dunnage is slurried and also passed through a SCWO reactor. Metal parts are treated to a 5X decontamination level by an electrically heated discharge conveyor. The evaluation presented in the August 2001 report was requested by the Program Manager for Assembled Chemical Weapons Assessment (PMACWA), who sponsored the engineering design studies and associated tests for these two technologies. In presenting this update, the ACW II Committee first reiterates its observation that hydrolysis with water or caustic does destroy 99.9999 percent of the chemical agent and, in combination with secondary treatment steps, 99.999 percent of the energetic materials. The committee’s concerns with regard to the two technology options being considered for Pueblo relate only to steps after and ancillary to the hydrolysis step. Energetic Hydrolysis Studies Since the publication of the committee’s August 2001 report, EDS testing sponsored by PMACWA on hydrolysis of energetics has been completed (Bonnett and Elmasri, 2001). The purpose of the testing was to define process parameters, demonstrate safe processing for the scale-up of the hydrolysis process, and produce hydrolysates for future use in the ACWA program. The testing also addressed concerns raised by the NRC regarding processing, as well as issues encountered during previous energetics hydrolysis testing at other facilities (NRC, 2001). Effective destruction of energetic materials was achieved in both the bench-scale tests at Los Alamos National Laboratory and the larger-scale tests at Holston Army Ammunition Plant. Analyses of the end-of-run hydrolysate samples from the Holston tests indicated that they do not present an explosion hazard. Bench-scale tests at Los Alamos did not detect any energetic material in either the hydrolysate or the solid residue at the end of the reaction (Bonnett and Elmasri, 2001). For example, no picrates were found in the final products of the hydrolysis reaction by either differential scanning calorimetry or high-performance liquid chromatography (HPLC). However, the detection limit of the HPLC results was not stated. Some questions remain concerning the material balance for lead in the large-scale tests of propellant processing conducted at Holston. Specifically, only a little over 20 percent of the lead initially present is reported to be in solution in the hydrolysate from a run of mixed M28 propellant and Composition B4. No lead was found in the end-of-run hydrolysate samples for any of the M1 propellant runs. The Army suspects that the remaining lead is present as either lead hydroxide or lead picrate in the solids that remain in the reactor or that are suspended in the hydrolysate. Although there is no M28 propellant (and therefore no lead stearate) in any of the munitions at Pueblo, M1 propellant, which is present at Pueblo, contains 1 percent lead carbonate. The difficulty of accounting for all the lead, combined with the observed generation of energetic intermediates during the course of the run, raises the possibility that lead picrate, a
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sensitive nitroaromatic explosive, might precipitate under some conditions. This possibility can be eliminated by processing lead-containing propellant separately from nitroaromatic compounds (TNT and tetryl) that might form picrates. The energetics hydrolysis tests also demonstrated that rigorous optimization of process parameters for effective energetics hydrolysis was not necessary. That is, the selected conditions of operation during tests at Holston Army Ammunition Plant were found to be sufficiently effective for full-scale implementation (Bonnett and Elmasri, 2001). The EDS testing program for energetics hydrolysis also identified two sources of minor concern germane to the processing of mustard agent munitions stored at Pueblo Chemical Depot: (1) the handling and destruction of rayon bags containing M1 propellant charge and (2) the handling of cotton threads that are used to bundle M8 sheet propellant (Bonnett and Elmasri, 2001). Since neither the rayon bags nor the cotton threads are broken down during the hydrolysis, they (especially the cotton threads) could become caught in the internal moving parts of the equipment used for hydrolysis and could cause the equipment to jam. The committee expects that these problems can be easily resolved, for example, by filtering out the fibers in the reactor or before they reach the reactor. Finding (Pueblo Ltr) 1. Completed EDS test reports indicate that hydrolysis can safely destroy the energetic materials found in the assembled chemical weapons at Pueblo Chemical Depot. General Atomics GATS Process Supercritical Water Oxidation The only report on the processing of mustard agent (HD) hydrolysate by SCWO available to the committee when the NRC’s August 2001 report was prepared was a draft report (General Atomics, 2001a). Table 1 lists the new information that has become available and has been considered by the committee in preparing this letter report. The three tests listed in Table 1 pertain to the destruction of the weapons at Pueblo.1 The HD hydrolysate and tetrytol hydrolysate slurry (TD) runs are pertinent since they cover the agent hydrolysate, energetics hydrolysate, and dunnage that are found at the Pueblo facility. Although the MD (M28 rocket propellant and burster hydrolysates slurried with shredded and micronized dunnage) run is not directly relevant because the materials tested are not actually found at Pueblo, the elemental mixture (if not the specific compounds) that was used is similar to that of materials at Pueblo.2 As discussed below, the results may be 1 Other tests have also been conducted with hydrolysates of nerve agents GB and VX. 2 The chemistry within a SCWO reactor is probably very close to that of combustion, in which fuel is rapidly transformed into small molecules, atoms and transient species. The elemental composition of the feedstocks in the MD test is similar to that expected for some of the SCWO feedstocks at Pueblo. Thus, MD test results, which contain M28 hydrolysate, are still meaningful for the SCWO reactor being designed.
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TABLE 1 Schedule of Recent Tests and Reports on SCWO Pertinent to Pueblo Test Test Dates 2001 Draft Report Date Revised Report Date HD 1/3 to 1/29 2/2001 10/2001 TD 3/17 to 4/14 8/2001 11/2001 MD 5/22 to 6/29 9/2001 12/2001 NOTE: HD, HD hydrolysate (General Atomics, 2001b); TD, tetrytol hydrolysate slurried with shredded and micronized dunnage (pallets, DPE suits, gloves, etc.) (General Atomics, 2001c); and MD, M28 rocket propellant and burster hydrolysates slurried with shredded and micronized dunnage that has had the hydrolyzed aluminum removed by filtration. These tests included the results of aluminum filtration tests. The M28 propellant is not present at Pueblo, but the test demonstrated a modified chemistry for controlling solids transport through the reactor without the use of an additive that degrades the titanium reactor material (General Atomics, 2001b). useful for further estimating liner life when treating HD hydrolysate by SCWO. In addition, General Atomics provided a detailed schedule for SCWO liner replacement3 to the committee (Hong, 2001). Based on this new information, the committee reassessed the SCWO system’s performance and operability. The most significant observation from the new tests relates to treatment of energetics hydrolysate and micronized dunnage. Ultrasonic testing after the TD and MD tests showed excellent liner life after extended-duration tests with these materials, with no visible or measurable degradation of the liner (that is, any degradation seen was less than 3 mils in thickness). It appears that no liner change-outs would be necessary for the treatment of all-TD slurry during the disposal operations at Pueblo. Only SCWO reactor systems that would treat HD hydrolysate at Pueblo appear to require liner change-outs, and, as discussed below, there are signs that here, too, they may prove unnecessary. These results indicate that far fewer SCWO reactor liner change-outs would be required at Pueblo than had been thought previously by the committee. The testing with HD hydrolysate established a maximum corrosion rate for a titanium (grade 2) liner of 0.5 mils/hr. The area of maximum corrosion was observed to be up to 5 diameters from the inlet and appeared to be circumferentially uniform. No evidence of pitting was observed. The liner thickness for the test was 120 mils, and the liner was allowed to corrode through about 66 mils of corrosion before replacement. For the full-scale design to be used at Pueblo, the titanium wear liner is 0.5-inch (500 mils) thick. At a corrosion rate of 0.5 mils/hr, after 500 hrs the liner would be half its original thickness. The total disposal campaign for HD hydrolysate is scheduled to take somewhat less than 8,000 hours during 2 years of operation. When the reactor is operated continuously, liner change-out every 2 to 3 weeks will be required. While this is a high level of maintenance, it is, in the committee’s opinion, manageable for the duration of the disposal campaign at Pueblo. During the MD tests, satisfactory salt transport with essentially no liner degradation was obtained using a new proprietary additive. According to General Atomics, these results have raised the possibility that liner life may be extended (Hong, 2001). This new formulation avoids the use of the additive found to be responsible for the 3 The liner is a replaceable sacrificial component in the SCWO reactor to protect the reactor vessel from the corrosive environment; it is not intended to be a pressure-containing element.
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majority of the titanium corrosion. This formulation may also be applicable to mustard agent (HD) hydrolysate. These results are encouraging, and if validated for HD hydrolysate they would significantly improve the operability of a disposal facility employing SCWO at Pueblo. Finding (Pueblo Ltr) 2. The GATS SCWO system for Pueblo would require liner change-outs only when treating mustard agent (HD) hydrolysate. Based on test data and the current design, about 15 liner change-outs would be required during the somewhat less than 8,000 hours of operation occurring during a 2-year period of disposal operations for HD hydrolysate at Pueblo. This is a substantial number of SCWO reactor liner change-outs, but it is lower than the committee previously expected. It should be possible to restrict liner change-outs to no more than one every 2 or 3 weeks of operation when processing HD hydrolysate. In the committee’s opinion, this level of maintenance, while high, does not place an unmanageable burden on the operations and maintenance staff. These results resolve the committee’s earlier concerns pertaining to high maintenance requirements for the SCWO reactors as discussed in previous findings and recommendations (NRC, 2001). However, as discussed in the August 2001 report, there is still some concern about possible problems when the existing SCWO reactor is scaled up to an 18-inch diameter and 18-foot length (NRC, 2001). This will increase problems with sealing and interchanging the interior assemblies during liner change-outs. However, there does not appear to be a reasonable way of addressing this scale-up issue until a full-scale unit is built. Cryofracture General Atomics developed cryofracture technology for the Army from 1982 through 1993. In October 2001, General Atomics provided the committee with an extensive set of reports on tests it had performed for the Army on the cryofracture of a total of 3,695 agent-simulant-filled projectiles, rockets, and mines (General Atomics, 1993). The committee reassessed its findings regarding cryofracture based on these reports. Cryofracture successfully breached the agent cavity of all munitions. Cryofracture also successfully breached the energetics cavities, but these results are not relevant to the Pueblo design, where energetics are removed prior to cryofracture. Finding (Pueblo Ltr) 3. Although cryofracture was not demonstrated during the ACWA program, based on previous cryofracture tests carried out by General Atomics from 1982 through 1993 the committee now believes the technology has been sufficiently demonstrated for use at Pueblo. Parsons WHEAT Process Studies and test reports on two unit operations of the Parsons/Honeywell WHEAT technology package were still under way when the August 2001 report (NRC, 2001) was
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published. These have since been completed, and the results (Parsons, 2001a, 2001b) are discussed in the following paragraphs. Projectile Washout System The overall test objective for the projectile washout system (PWS) was to generate the data required to develop a full-scale pilot facility design, along with cost and schedule data for processing mustard agent projectiles. The 4.2-inch mortars present the largest challenge to complete washout because they contain an internal baffle. During this test, 85 HD-filled mortars were processed. The testing included the hydrolysis of HD for comparison with the results of hydrolysis of HD from ton containers at the Aberdeen, Maryland, bulk site facility. The PWS test is representative of an almost fully functional assembled chemical weapons demilitarization processing line except for the biotreatment of the hydrolysate (Parsons, 2001a). Testing with HD is now complete. Further tests that include mustard agent (HT)-filled mortars have been initiated, because very little testing has been done with HT agent. The test results with HD are discussed in the following paragraphs. The PWS test had four specific objectives (Parsons, 2001a): Design, fabricate, and install a viable, cost-effective, test-scale washout system that simulates a full-scale pilot system. Obtain data on the nature of the agent and sludge in the 4.2-inch mortars. Prove the effectiveness of the washout concept. Simulate full-scale system operation and establish design and operating data for the full-scale pilot system. Committee comments on the testing results as they pertain to the above objectives are as follows: Objective 1. The committee did not consider cost or schedule, but it notes that a projectile washout system was successfully designed and fabricated by Parsons/Honeywell during the EDS phase of the ACWA program. Objective 2. Samples of liquid agent and agent heels were taken for further characterization, but no results have been reported to the committee. This characterization was not necessary for the committee to evaluate the effectiveness of the washout operation. Objective 3. The washout parameters developed in testing were effective, and parameter studies were not considered necessary. Eighty-five HD 4.2-inch mortars were cut open and examined. After washout, the agent cavity was visually clean and the metal surfaces were bright; no corrosion was evident. Most rounds were washed in a 60-second cycle, and all pressures used were equally effective. Emulsions did not occur and a soak was not required. The heel material dissolved almost completely. The settling tank concept was effective in separating agent from the washout water.
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Objective 4. Eighty-five mortar rounds were successfully processed, the last 25 of which were in a production mode. The ability to consistently produce munition bodies with essentially no organic material except paint may have a major beneficial impact on the size of the downstream metal parts treatment train. Finding (Pueblo Ltr) 4. The testing of the Parsons’ projectile washout system indicates that a full-scale system can be satisfactorily designed, built, and operated. The tested system operated well during the tests, successfully removing all visible mustard agent residue from 85 4.2-inch mortars. Continuous Steam Treater Testing of the continuous steam treater (CST) and its effluent gas treatment system using dunnage and demilitarization protective ensemble (DPE) suit material has now been completed at the Chemical Agent Munitions Disposal System in Utah. Review of the preliminary draft of the test report (Parsons, 2001b) indicates successful treatment of the solids. The test report also identified additional design and development needs, which are currently being addressed for both the solid materials handling system and the gaseous treatment system. Solid materials handling issues include the following: Prevent segregation of the carbon carrier medium and wood dunnage in the solids feed to the CST to minimize fluctuations in performance and the challenges that these fluctuations pose for gaseous effluent treatment. Select materials of construction for the auger and air preheater that give satisfactory corrosion resistance. The test report indicates that auger corrosion appears related to the chlorine contained in shredded DPE. Improve the design to prevent solids from accumulating outside the auger trough at the feed end and in the bottom of the main chamber, which in turn would keep the chamber wall from overheating. Improve design of dust controls, especially those related to carbon dust generated by the carbon carrier. Gaseous effluent treatment issues still to be addressed include the following: Improve CATOX temperature controls to prevent damage to the catalyst from too-high temperatures, as occurred in earlier testing. Improve solids separation upstream of the CATOX unit to prevent fouling and plugging of catalyst by fine particulates. Change the design and operating conditions of the CST and CATOX units to reduce the formation of dioxins and furans when processing DPE material. With respect to the formation of dioxins and furans, the committee notes that Parsons has stated the following:
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. . . several further modifications have been proposed to help lower/eliminate dioxin formation within the CST system. These modifications are major in scale and budget/schedule constraints preempted their implementation in the test system, however the risk associated with the problem of dioxin/furan formation may warrant their implementation/testing before completing the detailed design of the full-scale pilot facility (FSPF), which will require characterization of the treated gaseous effluent. (Parsons, 2001b) Finding (Pueblo Ltr) 5. Tests of the CST and the proposed improvements provide reasonable assurance that the CST can accomplish acceptable treatment of dunnage, provided that acceptable treatment of the gaseous effluent can be achieved. Respectfully yours, Robert A. Beaudet, Ph.D., Chair Committee on Review and Evaluation of Alternative Technologies for Demilitarization of Assembled Chemical Weapons: Phase 2
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References Bonnett, P., and B. Elmasri. 2001. Base Hydrolysis Process for the Destruction of Energetic Materials, October. Aberdeen Proving Ground, Md.: Program Manager for Assembled Chemical Weapons Assessment. General Atomics. 1993. Design, Development Test Results: Munitions Cryofracture Test Summary, Testing Support of the Cryofracture/Incineration Demonstration Plant (CIDP) Test Program, DACA87-90-C00013, December 22. San Diego, Calif.: General Atomics, Inc. General Atomics. 2001a. Assembled Chemical Weapons Assessment (ACWA), Engineering Design Studies, Draft Test Report, February 10. San Diego, Calif.: General Atomics, Inc. General Atomics. 2001b. Engineering Design Studies, Supercritical Water Oxidation of M28 Hydrolysate/Cyclotol Hydrolysate/Dunnage Slurry, DAAM01-98-D-0003, GA-C23825, September . San Diego, Calif.: General Atomics, Inc. General Atomics. 2001c. Engineering Design Studies, Supercritical Water Oxidation of Tetrytol Hydrolysate/Dunnage Slurry, DAAM01-98-D-0003, GA-C23787, August. San Diego, Calif.: General Atomics, Inc.. Hong, Glenn. 2001. GATS Blue Grass Draft Final Submittal Design Briefing to the Independent Evaluators. Arthur D. Little, Boston, Mass., November 19. NRC (National Research Council). 2001. Analysis of Engineering Design Studies for Demilitarization of Assembled Chemical Weapons at Pueblo Chemical Depot. Committee on Review and Evaluation of Alternative Technologies for the Demilitarization of Assembled Chemical Weapons: Phase 2. Washington, D.C.: National Academy Press. Parsons, 2001a. Assembled Chemical Weapons Assessment (ACWA) Engineering Design Study: Projectile Washer System Testing, Draft Report, November. Pasadena, Calif.: Parsons Infrastructure and Technology Group. Parsons. 2001b. Draft ACWA EDS WHEAT – EDS Test Report, CST, November 2. Pasadena, Calif.: Parsons Infrastructure and Technology Group.
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