Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 1
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 the Army Chemical Stockpile Disposal Program January 29, 2001 Dr. Hank Dubin Director, Assessments and Evaluation Office of the Assistant Secretary of the Army for Acquisition, Logistics and Technology SAAL-ZC 2511 Jefferson Davis Highway, Suite 11300 Arlington, VA 22202 Re: Assessment of Supercritical Water Oxidation Technology Development for Treatment of VX Hydrolysate at the Newport Chemical Agent Disposal Facility Dear Dr. Dubin: Since 1994, the National Research Council (NRC) Committee on Review and Evaluation of the Army Chemical Stockpile Disposal Program (Stockpile Committee) has had a continuing interest in applications of supercritical water oxidation (SCWO) in the Army's Chemical Stockpile Disposal Program (CSDP). The committee is very concerned about problems that have arisen during engineering-scale tests (EST) of SCWO as a secondary treatment for the hydrolysate from the neutralization of bulk VX nerve agent. Because of these problems, data critical to confirming the design and predicting the efficiency of operations for the full-scale reactor may not be available in time to meet the current schedule for construction and operation of the Newport Chemical Agent Disposal Facility (NECDF). Situation NECDF must dispose of approximately 1,300 tons of VX nerve agent stored in 1,690 ton containers. The operation is scheduled to be completed by October 2004. Agent disposal must be completed by April 2007 to comply with the provisions of the Chemical Weapons Convention (CWC). According to the Army's plans, VX will be destroyed by alkaline hydrolysis, with secondary treatment of the hydrolysate by SCWO. The 65-percent design for NECDF has already been completed by Stone & Webster, Incorporated. Parsons Corporation, the NECDF systems contractor, is completing the plant design and initiating the fabrication of critical (long
OCR for page 2
lead time) SCWO reactor components, as currently designed by General Atomics, Inc. The projected cost of these components is $4 million. The projected cost of delaying fabrication until completion of the EST would be $8 million (Wojciechowski, 2000). The EST facility in Corpus Christi, Texas—designed, constructed, and presently operated by General Atomics—is a one-tenth-scale pilot version of the SCWO reactor planned for NECDF. The EST facility was initially scheduled to produce the data necessary to confirm the SCWO reactor system design and operational parameters by April 1999. However, difficulties have arisen, including problems in (1) fabrication (flange welds have failed), (2) design (two multilayered removable platinum liners have proved to be unworkable), (3) materials of construction (the platinum liner has developed a bulge and separated from its supporting structure, and platinum has migrated into a deposit of solids), and (4) operation (erosion has been found in the feed nozzle and the automatic control system, and the high-pressure oxygen supply system failed in one test). EST processing of surrogate hydrolysate solutions began in late October 1999, but results to date have not provided sufficient data to support scaleup. The Stockpile Committee has reviewed the use of SCWO for the disposal of hydrolysate in three previous reports (relevant excerpts are included in the attachment to this letter) (NRC, 1994, 1998, 2000a). To avoid the very problems that have arisen, the committee has consistently recommended that pilot-scale testing of SCWO be done to verify the equipment design and process performance for the destruction of VX hydrolysate. At this point, critical decisions concerning the NECDF plant in general (e.g., equipment and building layout) and the design of SCWO equipment in particular may not be supported by the results of the EST. Nevertheless, some of these decisions are already being implemented to maintain the schedule for disposal operations. However, no critical path schedule or decision matrix has been prepared in the event that a further evaluation of SCWO and/or consideration of other alternatives becomes necessary (Wojciechowski, 2000). Unresolved issues with the General Atomics SCWO process include: the ability to operate stably under steady-state conditions for long periods of time; incomplete demonstration of destruction and removal efficiency (DRE) over the range of operating variables; adequate capacity and availability; instability and corrosion of the reactor liner; erosion of the pressure let-down system; deposition of sodium sulfite, sulfate, phosphate, or carbonate salts, which may cause plugging, fouling, and obstructions under some conditions; and difficulties in fabricating the SCWO reactor. The purpose of the SCWO EST is to demonstrate a workable range of operating parameters (e.g., temperature, excess oxygen, hydrolysate flow and dilution, and pressure), the reliability of the equipment design, and the robustness of the materials of construction. All of these parameters must be sufficiently characterized to support scaleup of a SCWO reactor system and maintain the NECDF schedule for disposal of VX. Finally, the committee found no evidence that stakeholders have been informed of problems encountered in the development of SCWO technology for NECDF or the possibility that an alternative treatment technology may have to be found.
OCR for page 3
Observations and Findings The treatment of VX hydrolysate by SCWO at Newport will place severe demands on an immature technology, which would be used in an application significantly different from, and more complex than, any previous SCWO application (NRC, 1998, 2000a). Consequently, certain developmental and operational issues must be addressed, including: (1) identification and specification of reliable materials of construction for the reactor, the pressure let-down system, and other critical components; (2) evaluation and quantification of corrosion and erosion rates, corrosion mechanisms, and equipment operational lifetimes; (3) management of salts and solids within and downstream of the reactor, including in the pressure let-down system; (4) development of a basis for scaleup of the SCWO reactor and auxiliary equipment designs to maintain the established schedule for NECDF operations; and (5) operational issues, including demonstration of a robust pressure let-down system, continuous operation, and worker safety. In 1996, because of the severe requirements involved in the treatment of VX hydrolysate by SCWO and the slow progress in the development of SCWO technology, the Stockpile Committee recommended that an engineering-scale pilot plant test (at least one-tenth of full-scale) of the NECDF design be conducted (NRC, 1998). The committee also recommended that the final NECDF design include “lessons learned” from the EST (see attachment). However, progress by the Army and its contractors in addressing the critical issues listed above has been slow. The Stockpile Committee is concerned that if the current course of action continues, implementing SCWO and using it as part of the process to destroy the NECDF stockpile may not be possible within the CWC timeframe. Since the publication of Using Supercritical Water Oxidation to Treat Hydrolysate from VX Neutralization in 1998, little progress has been made on two critical problems: (1) identification of materials of construction with acceptable corrosion rates and mechanisms and (2) management of salts/solids (NRC, 1998). Delays in the EST have been caused by problems in reactor design, reactor fabrication, and system operation. The understanding of corrosion mechanisms in materials of construction appears to have been advanced minimally, if at all, since the committee pointed out its importance in Integrated Design of Alternative Technologies for Bulk-Only Chemical Agent Disposal Facilities (NRC, 2000a). In that report, the committee also raised concerns about possible difficulties (that have arisen) with fabrication of the liner and with scaleup (NRC, 2000a). No time frame or criteria have been established for deciding if development of SCWO technology for NECDF should be abandoned. The committee is not aware of any formal decision-making process for comparing progress in the development of SCWO technology with the development of alternative methods of hydrolysate disposal. The EST test plan, as presented to the Stockpile Committee, does not provide an adequate basis for scaleup or for predicting reactor lifetime (U.S. Army, 2000). In its present configuration, the EST will leave a number of essential questions unanswered: (1) the reactor lifetime, (2) the basis for scaleup, (3) the effects of operating conditions (e.g., temperature, excess oxygen, hydrolysate flow and dilution, sodium salt concentration, and pressure) on process effectiveness and equipment corrosion, and (4) the ability to fabricate reliable platinum liners for the full-scale SCWO reactor. Without confirming test results from an EST, equipment
OCR for page 4
specification for the NECDF SCWO system cannot proceed. And without a full-scale plant design, the present schedule for NECDF disposal operations appears to be in jeopardy. In view of these circumstances and the tight schedule for implementing a treatment technology at NECDF, alternative SCWO configurations, technologies other than SCWO, and temporary storage must be considered for the disposition of VX hydrolysate at Newport. The committee believes the Army could consider such alternatives as: (1) continued development of the SCWO reactor system, as presently configured, through an expanded EST program; (2) modifications to the SCWO reactor system design and/or operating conditions, including multiple smaller scale reactors or lined sacrificial reactors; (3) off-site shipment and disposal of hydrolysate; (4) on-site thermal oxidation of hydrolysate; (5) other on-site methods for disposing of hydrolysate that have been demonstrated or could be demonstrated without jeopardizing the NECDF schedule and budget; and (6) temporary storage pending the development of an alternative treatment process. Changes to the NECDF plant configuration would have potential risk management implications, which should be explained to stakeholders, possibly through implementation of the Army's change management process (NRC, 2000b). The public may react strongly to some of these alternatives and should be informed of the difficulties experienced in SCWO reactor design and fabrication for the EST (NRC, 1996). Recommendations Recommendation 1. The Army should determine the impact on the disposal schedule for the Newport Chemical Agent Disposal Facility caused by delays and difficulties encountered in the planned engineering-scale tests of supercritical water oxidation. Recommendation 2. The Army should develop a realistic critical path schedule and decision process for implementing a secondary treatment at Newport Chemical Agent Disposal Facility, including the following steps: The engineering-scale test (EST) should be considered as a design and operating proof of the supercritical water oxidation (SCWO) reactor system proposed for NECDF. The results to date should be reviewed to determine whether a SCWO reactor can be made that will operate reliably at full capacity to meet the treaty schedule. The scope of the current EST should be upgraded or expanded to provide a broader basis for design scaleup of the SCWO reactor system, including the selection of optimal operating conditions, the prediction of the effects of corrosion, the deposition of salts in the reactor, and the erosion of pressure let-down equipment. The Army should immediately undertake a comparative evaluation of alternatives for treating and/or disposing of the VX hydrolysate produced at NECDF. The critical path to complete NECDF disposal operations within the treaty requirements of the Chemical Weapons Convention should be identified.
OCR for page 5
Recommendation 3. The criteria for each step in the decision process should include (1) protection of the safety and health of workers and the public and (2) the impacts on schedule and budget for the complete disposal of VX agent stored at Newport. Recommendation 4. The Army should involve all appropriate stakeholders in its consideration of an appropriate technology for the secondary treatment of VX hydrolysate at Newport Chemical Agent Disposal Facility. Respectfully yours, Peter B. Lederman, Ph.D., chair Committee on Review and Evaluation of the Army Chemical Stockpile Disposal Program (Stockpile Committee) Attachment
OCR for page 6
REFERENCES NRC (National Research Council) . 1994 . Recommendations for the Disposal of Chemical Agents and Munitions . Committee on Review and Evaluation of the Army Chemical Stockpile Disposal Program, Board on Army Science and Technology . Washington, D.C. : National Academy Press . NRC . 1996 . Public Involvement and the Army Chemical Stockpile Disposal Program . Committee on Review and Evaluation of the Army Chemical Stockpile Disposal Program, Board on Army Science and Technology . Washington, D.C.: National Academy Press. NRC. 1998 . Using Supercritical Water Oxidation to Treat Hydrolysate from VX Neutralization . Committee on Review and Evaluation of the Army Chemical Stockpile Disposal Program, Board on Army Science and Technology . Washington, D.C. :National Academy Press . NRC. 2000a. Integrated Design of Alternative Technologies for Bulk-Only Chemical Agent Disposal Facilities. Committee on Review and Evaluation of the Army Chemical Stockpile Disposal Program, Board on Army Science and Technology . Washington, D.C.:National Academy Press. NRC . 2000b. A Review or the Army's Public Affairs Efforts in Support of the Chemical Stockpile Disposal Program. Committee on Review and Evaluation of the Army Chemical Stockpile Disposal Program, Board on Army Science and Technology . Washington, D.C. :National Academy Press . U.S. Army. 2000. Supercritical Water Oxidation Engineering Scale Test (EST) Test Plan R07V-03-1, October 2000 . Aberdeen Proving Ground, Md. :U.S. Army Program Manager for Chemical Demilitarization. Wojciechowski, P. 2000. Effect of EST on Full-Scale SCWO. Briefing by Paul Wojciechowski, PMCD contractor (Parsons), to the Committee on Review and Evaluation of the Army Chemical Stockpile Disposal Program, Woods Hole, Massachusetts, October 26, 2000 .
OCR for page 7
ATTACHMENT PRIOR STOCKPILE COMMITTEE REPORTS AND RECOMMENDATIONS RELATIVE TO SUPERCRITICAL WATER OXIDATION FOR THE NEWPORT CHEMICAL AGENT DISPOSAL FACILITY From Integrated Design of Alternative Technologies for Bulk-Only Chemical Agent Disposal Facilities (NRC, 2000a): Recommendation 3-1a. The Army should develop criteria and a schedule for resolving design and operational issues raised in the 1998 report, Using Supercritical Water Oxidation to Treat Hydrolysate from VX Neutralization, that have not yet been resolved for supercritical water operation at Newport. These issues include materials of construction, fabrication methods, system plugging, pressure let-down, and the duration of successful continuous pilot-scale operations. Recommendation 3-1b. The Army should pursue the testing of materials of construction for treating VX hydrolysate by supercritical water oxidation (SCWO) more aggressively to finalize materials selection, design, and fabrication methods for critical components, including the SCWO reactor, inlet, and pressure let-down system. This testing should clearly define mechanisms and rates of corrosion and erosion under the range of anticipated process conditions. An independent panel of experts in materials of construction should evaluate testing to date and identify further needs to ensure that the reliability of the SCWO system is adequate to meet the processing objectives. Additional points made by the committee in this report are summarized below: “Unusual materials of construction may create challenges for reactor fabrication.” As described below, fabrication of the liner for the EST has proven to be problematic. “MOC [Materials of Construction] testing and performance evaluation will have to be an intrinsic part of the EST program,” and an “independent panel of experts in materials of construction” should evaluate testing and identify further needs. Although preliminary claims from General Atomics about noble metal liners seemed promising, and they “may be viable materials,” the committee's concern that “no material has provided reliable operation over a sufficient period of time” has proved to be well founded. In addition, little progress has been made in understanding corrosion mechanisms and rates. The committee is unaware of any new data supporting preliminary measurements of corrosion rates from coupon testing described in the Integrated Design Report. Based on claims that General Atomics was able to fabricate 20-mil-thick precious metal liners, the Army has proceeded with noble metal liners in the EST experimental plan. It is not clear how the decision was made to adopt platinum rather than platinum with 20 percent iridium as the material for the liner. Because of a lack of fundamental understanding of the phases, flows, and reaction zones in the reactor, the committee recommended that the EST be configured to provide missing information on corrosion kinetics and mechanisms. The present EST
OCR for page 8
experimental design includes a demonstration of liner fabrication and reliability, but it does not include a study of corrosion kinetics and mechanisms. In addition, no testing specifically addresses reactor lifetime, which must be determined for full-scale design configuration, as well as for the development of maintenance, monitoring, and change-out requirements. From Using Supercritical Water Oxidation to Treat Hydrolysate from VX Neutralization (NRC, 1998): Recommendation 1. A pilot-scale SCWO process facility with the critical characteristics of the full-scale design should be constructed and operated to further define operating characteristics and demonstrate sustained continuous operation of the process. Objectives for the process development and demonstration should include: operation with either hydrolysate or a suitable surrogate to demonstrate reliable operation for periods similar to full-scale design operating cycles the development and validation of process monitoring and control strategies for salt management and the destruction of organic constituents the definition of stable operating regimes, including the temperature, pressure, and the use of the oxidant (liquid oxygen or compressed air) selected for full-scale operation the definition of a basis for process scale-up, operation, and maintenance of a full-scale system the development and demonstration of a reliable pressure let-down system. Because the understanding of the fundamental process mechanisms and operating characteristics is limited, the committee recommends that the pilot-scale system be within an order of magnitude of the total mass and heating throughput of a full-scale design unit. Based on testing and reactor scale-ups to date, a vertical cylindrical reactor configuration is recommended as the system that will probably require the least amount of additional development. Other reactor configurations may perform at required levels but would require significant additional development. Recommendation 2. Testing of materials of construction should be carried out as necessary to finalize the selection of materials for critical components, including the SCWO reactor and the pressure let-down system. Additional pilot-scale testing indicated in Recommendation 1 should include fabrication with the materials of construction selected from testing smaller samples and evaluation of corrosion and erosion rates for critical components. Recommendation 3. Flexibility and redundancy of critical components should be incorporated into the design of the full-scale system to allow for uncertainties about the basis for scale-up and operation. Trade-offs should be evaluated to establish an appropriate balance between two 100 percent capacity SCWO reactors or a greater number of smaller reactors. The analysis should consider performance uncertainties associated with process scale-up and complexity, as well as the reliability of operating several reactors in parallel.
OCR for page 9
Recommendation 4. The Army should make provisions for targeted research and development to resolve problems identified during pilot-scale testing and the full-scale implementation of SCWO technology. Recommendation 5. Requirements for process destruction efficiencies and final disposal standards for all effluent streams from SCWO treatment should be clearly defined to ensure that the final design meets regulatory standards. From Recommendations for the Disposal of Chemical Agents and Munitions (NRC, 1994): Recommendation 14B. Neutralization (agent hydrolysis) research should be accompanied by preliminary analyses of integrated systems capable of reducing agent all the way to materials acceptable for transport or disposal. Recommendation 16. Neutralization followed by transport for final treatment should be examined as an alternative at the Aberdeen and Newport sites. The examination should include location of acceptable receiver sites and transport routes, and a comparison of costs and schedules relative to onsite baseline treatment. If favorable results are indicated, the examination should be expanded as an option to eliminate the liquid incinerator at other sites. At those locations, onsite incineration of energetics and associated metal parts is still recommended. Additional pertinent remarks from the report include [P. 112] Research and development will be needed for each of these processes (wet air oxidation, supercritical water oxidation). Some important problems have been identified that require engineering solutions, for example: Materials of construction for wet air oxidation and supercritical water oxidation capable of handling the corrosion problems require further work. The salts formed by caustic addition are insoluble in the fluid phase in supercritical water oxidation; ”plugging” problems caused by these salts have been a concern. Operating requirements will have to be determined to ensure that the products meet environmental standards. [Pp. 118–119] In order to advance the status of a viable alternative technology, each potential alternative technology must progress through three levels of research and development: laboratory scale scientific proof of principle demonstration for each system component over the full range of agent chemical and physical composition and agent decomposition products expected under operational conditions component process integration into a bench scale simulation for the alternative technology system and successful demonstration with a full range of agent composition to provide basic data for further scale up engineering, construction, and successful test demonstration of an essentially full scale pilot plant.
Representative terms from entire chapter: