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Review and Assessment of Developmental Issues Concerning the Metal Parts Treater Design for the Blue Grass Chemical Agent Destruction Pilot Plant Summary The United States is in the process of destroying its chemical weapons stockpile. In 1996, Congress mandated that the weapons at two sites, Blue Grass Army Depot in Kentucky and Pueblo Chemical Depot in Colorado, would not be destroyed by incineration and that the Department of Defense should demonstrate and select alternative methods. In 1999, Congress also passed Public Law 105-261, which required that the Under Secretary of Defense certify “in writing to Congress” that the alternative technology would “be as safe and cost effective for disposing of assembled chemical munitions as is incineration of such munitions….” The Assembled Chemical Weapons Alternatives (ACWA) program was established in response to these mandates. Because the selected alternatives at each site would be new applications of existing technologies, the Army designated the facilities used to implement the alternatives as pilot plants—the Blue Grass Chemical Agent Destruction Pilot Plant (BGCAPP) and the Pueblo Chemical Agent Destruction Pilot Plant (PCAPP). The Program Manager for Assembled Chemical Weapons Alternatives is overseeing the efforts of systems contractors to develop and test equipment to be used in the designs for constructing the two disposal pilot plants. Among the first-of-a-kind equipment under development for the BGCAPP are two metal parts treaters (MPTs), which would be used primarily for the treatment of washed-out metal munitions cases from which the agent has been drained. The MPTs could also be used to treat secondary waste generated during the destruction operations and waste materials generated during facility closure operations. During recent testing, results have shown the heat-up times of trays of munition casings to be longer than expected. Another issue that has developed involves problems in sealing the MPT as the temperature inside is increased. The Program Manager for Assembled Chemical Weapons Alternatives requested that the National Research Council (NRC) form a committee to review ongoing testing to investigate and determine causes for the longer-than-expected heat-up times and other issues concerning the MPT design. The full statement of task for the Committee to Review and Assess Developmental Issues Concerning the Metal Parts Treater Design for the Blue Grass Chemical Agent Destruction Pilot Plant is given in the Preface. Contracts to design, build, operate, and close both pilot plants were awarded to Bechtel International, teamed with Parsons Engineering. For PCAPP, Parsons is a subcontractor to Bechtel. For BGCAPP, Bechtel and Parsons formed a joint venture called the Bechtel Parsons Blue Grass Team (BPBGT) and are teamed as prime contractors. These contractors tailored the specific design of the respective facilities to the content of each site’s stockpile.1 THE METAL PARTS TREATER AND THE MUNITIONS TREATMENT UNIT Originally the MPT was planned for use at both BGCAPP and PCAPP to decontaminate metal parts. The current PCAPP design now calls for a munitions treatment unit (MTU) to decontaminate projectile and mortar casings. The MPT uses radiant and convection heating in an enclosed metal cylinder to raise metal parts to 1000ºF for a duration of 15 minutes in order to decontaminate these materials. Steam is used as a carrier or sweep gas to remove vapors and particulates released during heating. The intention is also to use the MPT to treat contaminated secondary waste before its off-site disposal. The two MPTs being developed for the BGCAPP are 1 The stockpile at the Blue Grass Army Depot includes two nerve agents and a blister agent in various types of munitions. The agents are nerve agent sarin (GB) (C4H10FO2P), nerve agent VX (C11H26NO2PS), and Levinstein mustard agent (H) (C4H8Cl2S). The nerve agents are in M55 rockets and 8-inch or 155-mm projectiles. The mustard agent H is in 155-mm projectiles. The stockpile at the Pueblo Chemical Depot consists of 105-mm boxed cartridges, palletized 155-mm projectiles, and 4.2-inch mortars, all of which are filled with one of two forms of mustard agent: distilled mustard agent (HD) or mustard agent HT.
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Review and Assessment of Developmental Issues Concerning the Metal Parts Treater Design for the Blue Grass Chemical Agent Destruction Pilot Plant designated as first-of-a-kind equipment because they are unique, are being designed for this particular application, and have never been used in an actual process. A small-scale test unit called the Technical Risk Reduction Program (TRRP) MPT was fabricated to demonstrate the operation of the MPT concept for the decontamination of metal parts and waste. In this report, the phrase “first-of-a-kind” or “full-scale MPT” is used to describe the full-scale equipment, and the term “TRRP MPT” is used to describe the three-quarter-scale version. The PCAPP design calls for an MTU to decontaminate the projectile and mortar casings. The MTU, an adaptation of a metal annealing oven, is a continuous-belt muffle-type oven with material-handling equipment at the feed and discharge ends. Modifications include new feed and exit sections and a muffle large enough in cross section (10 in. high by 30 in. wide) to accommodate 155-mm projectile bodies riding on the metal conveyor. The muffle section is also long enough to ensure that all parts of the munitions reach 1000°F for at least 15 minutes at the operating speed of the metal conveyor. The committee was not charged with evaluating the MTU in detail. What this report presents is a technical description and evaluation of the MPT (Chapters 2-4) plus an evaluation of the technical feasibility of replacing the MPT with an MTU and supplemental decontamination units and autoclaves such as those being designed and tested for PCAPP (Chapter 5). ASSESSMENT OF METAL PARTS TREATER TESTING ACTIVITIES The MPT concept has been subjected to testing in TRRPs, with most of the pertinent testing conducted under the Bechtel TRRP 05c test plan (BPBGT, 2007d). This testing has used the three-quarter-scale TRRP MPT. The testing objectives as given in the TRRP 05c test plan were as follows (BPBGT, 2007d): Demonstrate reliable mechanical performance of all parts and functions of the MPT design, including seals, doors, bearings, and projectile jamming. Demonstrate BGCAPP-specific design improvements such as: projectile orientation, steam-injection orientation, gas take-off orientation, and tray design to improve heatup. Calibrate the computational fluid dynamics (CFD) model of the test unit on VX 155-mm projectiles to serve as a basis for first-of-a-kind (FOAK) full-scale unit modeling. Inherent in this objective is the necessary demonstration that the MPT can heat all parts of materials fed to it to 1000°F for at least 15 minutes at a rate that meets expected feed rates during operation. Demonstrate treatment of simulated energetics batch hydrolyzer (EBH) rocket warhead debris. Demonstrate limited secondary-waste treatment options to gather data for further effort with the CFD model. Perform test runs and cycles of components to make observations of critical design parameters that apply to the FOAK unit under design—particularly those that affect the risk of scale-up to the full-scale unit. These include, but are not limited to projectile paint debris generation and accumulation, thermal expansion stresses and deformation points, interferences, Gaussian field measurements and localized heating effects, and wall temperature distribution. The TRRP MPT testing used an off-gas treatment system that included a catalytic oxidizer unit rather than a bulk oxidizer unit (more accurately called a flameless thermal oxidizer) and did not include the venturi scrubber. Thus, the flow of off-gas from the MPT enclosures was demonstrated, but not the off-gas treatment system configuration or equipment that will be provided for the full-scale MPT. The off-gas treatment system bulk oxidizer unit is also considered to be a first-of-a-kind system. TRRP MPT testing was performed using surrogates of all munitions metal parts and waste feed streams anticipated for the two BGCAPP full-scale MPTs. All feed streams were tested. However, the BPBGT terminated the waste stream testing before the completion of all planned tests because it was believed that sufficient data to design the full-scale MPT had been obtained. All feed streams were tested to the extent allowed by existing permits at the Parsons fabrication facility. The permitting limitation prevented testing of the energetics batch hydrolyzer waste with energetics remnants and halogenated materials. During testing, the TRRP MPT unit experienced recurring operating problems, such as mechanical failures and munitions bodies taking longer than expected to reach the necessary high temperatures as estimated by computer modeling. The committee grouped the MPT test results into three areas for review and evaluation: (1) mechanical issues and (2) secondary and closure waste treatment issues, which are assessed in this section, and (3) results of thermal testing, modeling, and predicted throughput of the MPT, which are assessed further below. Mechanical Issues New Door Closure Mechanism and Seals Difficulties with getting an acceptably tight closure on the air lock and main chamber doors for the TRRP MPT have resulted in a change in the design of the door closure mechanism and seals for the full-scale MPT. Instead of the J-type sliding closure mechanism used on the TRRP MPT, the door for the full-scale MPT will be moved against the closure face by using a two-direction cam design recommended by a commercial oven contractor. In addition, the seal material design has been altered to give the equivalent of two gaskets between the door and closure face.
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Review and Assessment of Developmental Issues Concerning the Metal Parts Treater Design for the Blue Grass Chemical Agent Destruction Pilot Plant Bearings for the Conveyor Rollers The Graphalloy® bearings for the conveyor rollers in the main chamber experienced galling and other wear failures attributed to oxidation/corrosion at the main chamber operating temperature. Three different bearing materials were evaluated: “improved” Graphalloy®, Stellite, and Deva (Deva-Mogul sintered metal). All materials experienced wear, and the BPBGT concluded that the “improved” Graphalloy® bearings were acceptable, although they exhibited some pitting. During full-scale MPT testing, the BPBGT intends to reconsider Stellite bearings that are interchangeable with the Graphalloy® bearings. The BPBGT has also developed maintenance protocols that shorten replacement times for bearings as much as possible. Heating Zones The full-scale MPT will use two heating zones in the main chamber. Each will be capable of about 450 kW of induction heating. The TRRP MPT used one 600-kW induction heater. The use of two-zone heating in the full-scale MPT main chamber should improve heating rates and control of heating. It is unclear whether maintenance on one MPT will be possible while the other is in operation. If not, the availability of the MPTs would be reduced, since both would have to be shut down if either required in-room maintenance. TRRP testing and CFD modeling showed that certain areas of some projectiles were heating more slowly than the rest of the projectiles. This slower heating required longer heatup times to achieve a uniform 1000°F for 15 minutes for all projectiles. After its review of the chamber design, the BPBGT concluded that the slow heating resulted from “shadowing” of parts of the projectiles during the radiant heating process. The shadowing is being addressed by redesign of the projectile trays, the superheated steam inlet header, and the off-gas outlet header. Secondary and Closure Waste Treatment Issues Waste to be treated in the MPT includes the washed munitions bodies from the munitions washout system, solid residues from the energetics batch hydrolyzer, and secondary and closure waste. Agent-contaminated waste will be treated by chemical decontamination. When chemical decontamination cannot be used, waste (e.g., agent-contaminated pallets) will be treated in the MPT before off-site disposal. Secondary waste that is not agent-contaminated is not expected to be processed through the MPT. In general, secondary waste can be shipped off-site safely if it meets one of two criteria: (1) if analysis shows levels less than the applicable waste control limits (WCLs)2 or (2) if the waste has been subjected to thermal treatment at 1000°F for 15 minutes. The second criterion, formerly called treatment to 5X, was a requirement for off-site shipment until June 2004 when the criteria on WCL were introduced. The BPBGT plans to heat all secondary waste to 1000°F for at least 15 minutes in the MPT. At that temperature, in the very low oxygen activity environment of the MPT, many secondary waste materials will pyrolyze, leading to the formation of chars and tars. By lowering the temperature to ~500° F for 1 to 2 hours, six nines (99.9999 percent) agent destruction and removal efficiency should be achievable, and char and tar formation should be greatly reduced. RESULTS OF THERMAL TESTING, MODELING, AND PREDICTED METAL PARTS TREATER THROUGHPUT TRRP testing of secondary waste treatment in the MPT was conducted at the Parsons fabrication facility in Kennewick, Washington, in May 2007. The test results were generally favorable. However, the range of waste types treated was narrow, and the total amount of waste treated was small. Thus, the committee recommends that the BPBGT perform more comprehensive testing during systemization, using waste representative of that encountered during closure as well as various types of secondary waste from operations and maintenance. Heat-up times for projectiles located in the trays passing through the TRRP MPT were measured and predicted to demonstrate that the metal parts at all locations in the tray could be heated to 1000°F for at least 15 minutes within a total time duration that supported the design production rate. The experimental data and the modeling focused on the temperature-time profiles for projectiles at specified locations in the tray. The key elements of this effort were as follows: Thermocouple measurements of the surface temperature were made on a limited number of projectiles at specific locations in the tray as they passed through the MPT and were heated. Predictions of the temperature distribution in the projectiles were made by using a CFD thermal modeling program that was compared with a previous model used in initial PCAPP MPT testing. However, all model results must be validated with experimental data, as discussed elsewhere in this report. Experimental Temperature Measurements Type K thermocouples encased in stainless steel sheaths were mounted to the top and bottom of three projectile cas- 2 WCLs and the analytical methods required to demonstrate that they have been achieved vary by state. In general, the WCL is defined as 20 parts per billion (ppb) for GB and VX and 200 ppb for HD, as determined by EPA’S toxicity characteristic leachate procedure (TCLP) applied to the residuals from the metal parts treater. The WCL may also, or additionally, be based on agent concentration in the air space above the containerized waste treatment residuals. Minimum required levels are typically 1 STEL (short-term exposure limit )—0.0001 mg/m3 for GB, 0.00001 mg/m3 for VX, and 0.003 mg/m3 for HD.
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Review and Assessment of Developmental Issues Concerning the Metal Parts Treater Design for the Blue Grass Chemical Agent Destruction Pilot Plant ings in order to allow the monitoring of temperature-time profiles in the prototype TRRP MPT. Selection of the locations on the casings was aided by use of the CFD thermal model to identify potential cool spots. Temperature Prediction by Computational Fluid Dynamics Thermal Modeling The BPBGT used a mathematical model for comparison with the TRRP experimental measurements and to predict the performance of the full-scale MPT for BGCAPP. The BPBGT model gives spatial and temporal temperature behavior of the parts being processed in the MPT. The purpose of the modeling was to show that the MPT design was adequate for treating munitions at 1000°F for 15 minutes while meeting operational and schedule requirements and that the design could guide the scale-up and the testing of the full-size unit. Comparison with the experimental measurements was used to validate and modify the model. The improved model appears to be fairly rigorous. The code is based on a nonlinear solver that (1) is accurate to second order in space and time; (2) globally and locally conserves mass, momentum, and energy; and (3) allows a choice of finite-element shape function. The model handles multimode heat transfer, including graybody radiation with view factor computation. COMPARISON OF THE METAL PARTS TREATER AND MUNITIONS TREATMENT UNIT FOR BGCAPP The committee reviewed the applicability of the MTU as an alternate method for decontaminating munitions bodies and secondary waste at BGCAPP. As noted above, the MTU is currently planned for installation at PCAPP for the thermal decontamination of 155-mm and 105-mm projectiles and 4.2-in. mortars that have been drained of mustard agent and passed through a high-pressure wash. Table S-1 compares various operating requirements and features of the MPT and the MTU and identifies changes that would be required for the MTU to be used at BGCAPP. The same table appears in Chapter 5, which gives additional supporting and clarifying information. GENERAL FINDINGS AND RECOMMENDATIONS Finding. The full-scale MPT as currently designed for BGCAPP can decontaminate projectile bodies and secondary and closure waste, and it will be able to achieve its target throughput rates provided that the BPBGT is able to resolve the following issues: Successful implementation of new designs for door closure and seals, for roller bearings on conveyors, and for the superheated steam header; Effective thermal treatment of secondary waste without excessive fouling of the duct work leading to the bulk oxidizer; Successful integration of the MPT with its flameless thermal oxidizer (i.e., the bulk oxidizer) and cyclone; and Complete destruction of energetic materials in the waste stream of the energetics batch hydrolyzer without adversely affecting the MPT. Finding. The current range of heat-up times of munitions in the MPT should not affect the overall schedule of BGCAPP operations. Heat-up times in the TRRP tests are close to target and appear to be capable of being improved by raising the wall temperature of the full-scale MPT. CFD modeling predicts correct trends in temperature-time profiles and locations of cold spots and should be useful in guiding the design and testing of the full-scale MPT. The processing rate of projectile bodies in the MPT is not on the critical path of the process throughput. The design calls for two MPTs. The second is intended to be used for secondary waste, but it could also be used for treating munitions bodies in an emergency. Finding. The MTU could be substituted for the MPT at BGCAPP; however, it would be necessary to do the following: Use supplemental decontamination units and autoclaves to treat secondary waste, Find another means of treating the detonators in the M417 rocket fuzes, Modify the MTU design to accommodate 8-in. projectiles, Modify the footprint of the building to accommodate the units, and Modify the existing permits. Finding. For BGCAPP, the TRRP testing did not address a method to thermally treat the fuzes and a limited number of igniters from contaminated propellant that are not decomposed in the energetics batch hydrolyzers. Recommendation 6-1. The BPBGT needs to develop a method to collect and pop the igniters and fuzes that will not adversely affect the operation of the MPT. Recommendation 6-2. To reduce the technical risks in treating secondary waste in the MPT, the BPBGT should continue to strive to send secondary waste off-site whenever possible and minimize the use of halogenated materials.
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Review and Assessment of Developmental Issues Concerning the Metal Parts Treater Design for the Blue Grass Chemical Agent Destruction Pilot Plant Recommendation 6-3. To reduce the load on the off-gas treatment system, the BPBGT should consider obtaining permits that allow the use of the Airborne Exposure Limit Guidelines to operate the MPT at lower temperatures for the thermal treatment of secondary waste whenever possible. Finding. TRRP testing demonstrated the validity of using an MPT for thermal decontamination. It also identified many changes and design improvements that will be necessary to achieve an acceptable throughput rate and control maintenance and operating costs. Further testing with varied secondary waste materials including halogenated waste is still required. These changes and improvements may require several iterations before satisfactory results are achieved. Recommendation 6-4. A test plan should be prepared for all design changes identified for the MPT but not verified in the TRRP tests. This test plan should be conducted at the fabrication facility and should include time for the repeated trials needed to arrive at acceptable performance for the overall full-scale MPT. A similar test plan should be prepared for testing the integrated full-scale off-gas treatment system for the MPT at BGCAPP. This test plan should include the testing of a full range of secondary, energetics batch hydrolyzer, and closure waste at the full-scale MPT design rates. TABLE S-1 Comparison of the Metal Parts Treater and the Munitions Treatment Unit Characteristic MPT at BGCAPP MTU at PCAPP Changes for MTU Use at BGCAPP Status of testing Prototype (~3/4 scale) demonstrated on surrogate munitions and waste streams. Two full-size MPTs will be built and tested at the manufacturer’s facility. Full-scale unit completed acceptance tests at the manufacturer’s facility with surrogate munitions. Full testing would be required, using the energetic dregs and agent or appropriate surrogate material. Only small design changes from the PCAPP MTU are required. Using the MTU would save extensive testing of the MPT with secondary waste. Treatment of secondary waste in the SDUa and autoclaves has already been performed at the other sites. Feed streams 4.2-inch mortars and base plates None 97,106 (HD) Applies only to PCAPP, no mortar rounds at BGCAPP. 105-mm projectiles None 383,418 (HD) Not applicable to BGCAPP. 155-mm projectiles 15,492 (H) 12,816 (VX) 299,534 (HD) A new permit will be needed to use the MTU at BGCAPP. 8-inch projectiles 3,977 (GB) None Muffle height must be increased for use at BGCAPP. The MTU currently has internal height of 9.75 in. and width of 30 in. M55 rockets; undissolved fragments, including undissolved squibs and fuzes from hydrolysis of rocket warhead and rocket motor segments in EBHsb 51,716 (GB) 17,757 (VX) Method for treating squibs and fuzes in the MPT is to be tested. None Squibs and fuzes must be thermally decomposed (must be popped). Some fragments are combustible and may require inert gas and special baskets if treated in the MTU or, alternatively, they may be treated in the SDU or autoclave if WCLc guidelines for offsite disposal are used. Secondary waste Thermal treatment in MPT using special carrying trays. Treatment in SDU or autoclaves. SDU and autoclave use based on approach used at ABCDF.d Use at BGCAPP may require special permitting and higher temperatures for GB- and VX-contaminated waste. Only limited testing on various waste types has been performed in the MPT. Closure waste Thermal treatment in MPT. Treatment in second SDU. See comments for secondary waste. Agents destroyed Mustard Yes Yes
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Review and Assessment of Developmental Issues Concerning the Metal Parts Treater Design for the Blue Grass Chemical Agent Destruction Pilot Plant Characteristic MPT at BGCAPP MTU at PCAPP Changes for MTU Use at BGCAPP GB and VX Yes None SDU and autoclave would be required with the MTU for GB- and VX-contaminated waste streams. This method of decontamination may require higher treatment temperatures to achieve acceptable treatment times to meet WCL guidelines for off-site disposal. Number of units 2 MPTs with one for projectile processing and one for waste streams and as a backup spare. 2 MTUs with only one ordinarily required to meet PCAPP processing rates. BGCAPP might require only 1 MTU because the number of projectiles is an order of magnitude less than at PCAPP; MTU availability expected to be higher than that of the MPT. MDBe footprint ~70 ft long × 40 ft wide × 20 ft high ~100 ft long × 30 ft wide × 20 ft high MTU would require changes in BGCAPP MDB layout to accommodate longer processing length and SDU and autoclave units and to provide for collection bins for receiving treated metal parts from MTU discharge chute. Total direct footprint for 2 MPTs plus 50 percent of MPT/washout support room plus MPT cooling room is 4,640 square feet. Total direct footprint for 2 MTUs is 5,100 square feet plus 216 square feet for collection bin enclosures. Post-treatment agent clearance In exit air lock before leaving level A area. In treated munition collection bin in Level D area. MTU use at BGCAPP would require permit change for use of current MTU discharge configuration. Atmosphere in unit Nitrogen in air locks and superheated steam in main chamber. Air flowing from both ends of muffle to off-gas duct exit from muffle system. Change in Kentucky permit would be required for use of MTU and SDU or autoclave. Off-gas treatment system Flame arrestor, cyclone, bulk oxidizer, venturi scrubber, and reheater. Flame arrestor, filter media, bulk oxidizer, venturi scrubber, and reheater. Same components, with different gas flow rates and sizes. Method of heating 2 induction coils at 450 kW each plus 75 kW resistance heating for steam superheater. Resistance heaters at 600 kW None Method of operation Batch Continuous Would have to change from a batch stream to a continuous stream. Char and tar buildup from secondary waste treatment Expected, but the design allows for addressing tar and char buildup. Secondary waste not processed in MTU. Secondary waste not processed in MTU. Method of control of atmosphere in main treatment unit Doors and seals on air locks attached to main chamber. Curtains on munitions cold feed end and cooling section exit of muffle. Curtains on munitions cold feed end and cooling section exit of muffle. Overall availability (percent of time the system will be operating) 83 percent estimated using spare MPT. 91 percent estimated for single MTU; no estimate given with spare MTU. Both estimates based on using both treatment units. Munitions throughput rates 4.2-inch mortars None for BGCAPP ~60/hr 105-mm projectiles None for BGCAPP ~60/hr 155-mm projectiles ~40/hr ~40/hr ~40/hr 8-inch projectiles ~15/hr None MTU should be capable of modification to achieve BGCAPP 8-inch projectile processing rates. aSDU, supplemental decontamination unit. bEBH, energetics batch hydrolyzer. cWCL, waste control limit. dABCDF, Aberdeen Chemical Agent Disposal Facility. eMDB, munitions demilitarization building. SOURCE: Adapted from BPBGT, 2007c.