5
General Findings and Recommendations
In this chapter, the committee provides general findings on the two technology packages that have undergone EDS testing. The committee also reassesses the findings and recommendations in the two ACW I Committee reports. The general findings below must be considered with acknowledgment of the fact that some ACWA EDS testing was not completed in time for the committee to obtain final test results and that some process steps remain to be demonstrated on a pilot scale.
The energetics hydrolysis test program is progressing at a pace satisfactory to meet the engineering requirements for construction of a disposal facility at Pueblo Chemical Depot. Issues concerning hydrolysis of neat tetryl, optimum granulation sizes, more complete characterization of hydrolysis products from aromatic nitro compounds, and optimum process control strategies for full-scale operations are yet to be investigated.
ENGINEERING DESIGN STUDIES
General Finding (Pueblo) 1. Based on the results of the demonstration tests, the engineering design package, and available data, the committee believes that the Parsons/ Honeywell WHEAT technology package can provide an effective and safe means of destruction for the assembled chemical weapons stored at the Pueblo Chemical Depot. However, some of the process steps remain to be demonstrated.
The Parsons/Honeywell technology process provides effective means to:
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disassemble munitions by a modified baseline disassembly process that removes the agent from the projectile bodies by washout
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destroy chemical agent HD to a 99.9999 percent DRE by hydrolysis
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destroy fuzes with the energetics rotary deactivator
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destroy energetic materials to a 99.999 percent DRE by hydrolysis in 15 weight percent hot caustic solution, provided that the following safeguards are observed:
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different energetic materials are not processed together
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precautions are taken to ensure that all emulsified TNT is completely destroyed
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control the very large volumes of off-gases emitted from the biotreatment plant through a CATOX unit
However, the committee notes that the effectiveness of some process steps, including removal of energetics from munitions, has not been tested during the EDS. Treatment of metal parts, dunnage, and DPE suit material remains to be demonstrated. No tests are currently planned to demonstrate the efficacy of the burster washout and energetic materials size-reduction steps. The projectile washout system is currently being tested. Other remaining munition disassembly operations are very similar to those used in the baseline system and have therefore been proven. The energetics rotary deactivator concept appears workable but has not been demonstrated at the pilot scale. Energetics hydrolysis is relatively immature, but current testing at Holston AAP has the capability to resolve many, but not all, of these issues (see Chapter 2).
The testing of the continuous steam treater for dunnage and the projectile washout system will not be complete until October 2001. Dioxins and furans are present in the off-gas from the CATOX units on the bioreactors but are below levels of regulatory concern. The batch metal parts treater for small metal parts is being tested, and preliminary data are encouraging. The carousel fixture for the rotary metal parts treater for large metal parts has not been demonstrated. The use of catalytic oxidizers for various streams is currently being tested, but sufficient test data have not been provided to the committee. Because the honeycomb structure of the CATOX unit is susceptible to plugging, proper design must be employed to prevent particulates from entering the catalyst structure.
General Finding (Pueblo) 2. Based on the results of the demonstration tests, the engineering design package, and available data, the committee believes that many aspects of the General Atomics technology package can be effective and safe for the destruction of assembled chemical weapons at the Pueblo Chemical Depot. However, to achieve prolonged operability of the supercritical water oxidation (SCWO) system as designed will require extensive maintenance. In addition, the SCWO processing of dunnage slurried in energetics hydrolysate, which constitutes the vast majority of the feedstock to be processed, remains unproven. The viability of the General Atomics technology package will depend on acceptable operability of the SCWO systems.
The General Atomics technology process provides effective means to:
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disassemble munitions by a modified baseline disassembly that removes the agent from the projectile bodies by cryofracture.
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destroy chemical agent HD to a 99.9999 percent DRE by hydrolysis
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destroy fuzes with the energetics rotary hydrolyzer
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destroy energetic materials to a 99.999 percent DRE by hydrolysis in 15 weight percent hot caustic solution, provided that the following safeguards are observed:
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different energetic materials are not processed together
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precautions are taken to ensure that all emulsified TNT is completely destroyed
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provide effective 5X-level decontamination for munition bodies through the use of an electrically heated discharge conveyor
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readily control the very low volumes of off-gases produced through activated carbon adsorption systems
For dunnage, the materials are shredded and reduced in size to 1.0 mm. The slurry is then fed into the SCWO reactors to destroy all the dunnage.
However, the committee has serious concerns about the SCWO system that is used to process the hydrolysates and the slurried dunnage. At the time this report was prepared, not all of the long-term processing tests had been completed. On the basis of results to date, the committee has concerns about the ability of the SCWO reactor to operate continuously for adequate lengths of time. An additional concern is the ability of the size-reduction system to remove 100 percent of the tramp metal that comes with the dunnage. If the tramp metal is not removed from the dunnage, the committee believes it will clog the injectors of the SCWO system and further reduce the system’s online availability.
The SCWO tests that have been performed to date, especially those involving chlorinated organic compounds such as HD hydrolysate, have consistently encountered severe corrosion of the reactor material or plugging of the reactor with salts. General Atomics proposes to solve the problem of plugging by periodically (every 22 hours of operation) reducing the pressure of the reactor to slightly below the critical point of water and flushing with clean water for 2 hours to remove the accumulated salts. The technology provider proposes to deal with the corrosion problem by inserting into the SCWO reactor a sacrificial titanium liner and shutting down at approximately every 140 hours of operation to open the reactor and replace or reverse the liner.1 In the committee’s opinion, the flushing step does not pose an unreasonable operating requirement; however, it considers the need for a liner replacement at six-day intervals to be excessively disruptive and not in keeping with sound principles of effective operation. In the full-scale system, liner replacement will require the following steps:
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Cooling down and depressurizing the reactor,
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Unbolting and removing an approximately 16-inch-diameter, several-inch-thick pressure head from the top of the reactor,
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Withdrawing the 12.5-inch-diameter, 19-foot-long titanium liner from the tubular SCWO reactor,
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Reinserting the same liner reversed end to end or a new liner,
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Setting the pressure gasket back into place and reattaching the gasket coolant lines,
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Resetting and bolting the pressure head onto the reactor,
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Pressure testing the SCWO reactor to assure proper head seating and sealing, and
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Restarting the heat-up of the system and restarting the waste feed.
This appears to the committee to be a very time-consuming procedure. The experience of a number of committee members has been that large pieces of high-pressure equipment are very difficult and time consuming to seal. Tests have only been conducted with reactors 2 to 4 inches in diameter. The time required for this procedure at the far larger size of the full-scale SCWO unit is highly uncertain.
General Atomics proposes to build duplicate SCWO reactors so that one is operating while the second is being serviced; however, the committee has reservations about whether this level of redundancy is adequate to maintain the proposed operating schedule.
General Finding (Pueblo) 3. As the ACW I Committee observed, the unit operations in both the General Atomics GATS and the Parsons/Honeywell WHEAT technology packages have never been operated as total integrated
processes. As a consequence, a prolonged period of systemization will be necessary for both to resolve integration issues as they arise, even for apparently straightforward unit operations.
This finding continues to be valid following development of and testing for the EDS design packages for the General Atomics and Parsons/Honeywell technologies. Also, in both cases, some of the routine unit operations have not yet been designed or tested. Thus, although they appear straightforward, these unit operations could require some redesign during systemization.
General Finding (Pueblo) 4. Several of the unit operations in both the General Atomics and Parsons/Honeywell processes are intended to treat process streams that are not unique to the chemical weapons stockpile and that could potentially be treated at existing off-site facilities. These streams include agent-free energetics, dunnage, brines from water recovery, and hydrolysates. Off-site treatment would simplify the overall processes and facilitate process integration by eliminating the need for further development of these unit operations. It might also simplify design requirements to meet safety concerns.
All of the process streams that could potentially be treated off-site have compositions similar to waste streams routinely treated by commercial industrial waste treatment facilities and do not exhibit any unique toxicity. Thus, they could be transported by standard commercial conveyance to commercial facilities that are appropriately permitted to receive the waste.
UPDATE ON GENERAL FINDINGS AND RECOMMENDATIONS OF THE ACW I COMMITTEE
The committee reviewed all of the general findings and recommendations from the ACW I Committee reports for continued applicability and disposition (NRC, 2000). The ACW II Committee’s assessment of the status of these prior findings and recommendations is summarized below.
General Findings from the 1999 Initial ACW I Committee Report
General Finding 1. The chemistries of all four of the primary technologies (hydrolysis, SILVER II, plasma arc, and SET), as proposed, can decompose the chemical agents with destruction efficiencies of 99.9999 percent. However, each technology package raises other technical issues that must be resolved. One of the crucial issues is the identity and disposition of by-products [from the chemical agents].
The Demonstration I testing and EDS tests have shown that hydrolysis has achieved 99.9999 percent destruction and removal efficiency of agents.
General Finding 2. The technology base for the hydrolysis of energetic materials is not as mature as it is for chemical agents. Chemical methods of destroying energetics have only been considered recently. Therefore, there has been relatively little experience with the alkaline decomposition of ACWA-specific energetic materials (compared to experience with chemical agents). The following significant issues should be resolved to reduce uncertainties about the effectiveness and safety of using hydrolysis operations for destroying energetic materials:
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the particle size reduction of energetics that must be achieved for proper operation
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the solubility of energetics in specific alkaline solutions
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process design of the unit operation and the identification of processing parameters (such as the degree of agitation and reactor residence time) necessary for complete hydrolysis
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the characterization of actual products and by-products of hydrolysis as a function of the extent of reaction
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the selection of chemical sensors and process control strategies to ensure that the unit operation following hydrolysis can accept the products of hydrolysis
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development of a preventative maintenance program that minimizes the possibility of incidents during the cleanup of accumulated precipitates
The PMACWA has undertaken an extensive technology program in support of this finding. The successful completion of the EDS test program on energetics hydrolysis will provide the data called for in this finding.
General Finding 3. The conditions under which aromatic nitro compounds, such as trinitrotoluene (TNT) or picric acid, will emulsify in the aqueous phase and not be completely hydrolyzed are not well understood. Therefore, this type of material could be present in the output stream from an energetic hydrolysis step.
Precautions must be taken to ensure that all emulsified TNT is destroyed in the reactors.
General Finding 4. The products of hydrolysis of some energetic materials have not been characterized well enough to support simultaneous hydrolysis of different kinds of energetic materials in the same batch reactor.
To be conservative, different energetic materials should not be processed together, particularly if they contain lead compounds, until these concerns can be addressed with experimental data.
General Finding 5. The primary chemical decomposition process in all of the technology packages [is hydrolysis, which] produces environmentally unacceptable reaction products. Therefore, all of the packages are complicated processes that include subsequent treatment step(s) to modify these products.
Secondary treatments are required for both technology packages to produce environmentally acceptable products.
General Finding 6. The waste streams of all of the ACWA technology packages could contain very small amounts of hazardous substances (besides any residual chemical agent). These substances were not fully characterized at the time of this report; therefore, all waste streams must be characterized to ensure that human health and the environment are protected. If more than one phase (gas, liquid, or solid) is present in a waste stream, each phase should be characterized separately.
The Demonstration I tests and the EDS studies have substantially characterized the process streams and waste streams. Characterization should continue throughout the development and systemization process.
General Finding 7. None of the proposed technology packages complies completely with the hold-test-release concept for all gaseous effluents (both process and ventilation effluents).
This finding is still valid. However, as discussed elsewhere in this report and in earlier reports, hold-test-release is not necessary.
General Finding 8. Hold-test-release of gaseous effluents may not ensure against a release of agent or other hazardous material to the atmosphere. No evidence shows that hold-test-release provides a higher level of safety than current continuous monitoring methods for gaseous streams with low levels of contamination. Furthermore, none of the technologies provides for hold-test-release of effluents from ventilation systems that handle large volumes of gases from contaminated process areas.
This finding remains valid.
General Finding 9. Solid salts will be hazardous waste, either because they are derived from hazardous waste (see Chapter 2) or because they leach heavy metals above the levels allowed by the Resource Conservation and Recovery Act Toxicity Characteristic Leaching Procedure. Stabilization—mixing waste with a reagent or reagents to reduce the leachability of heavy metals—will probably be required before the salts can be sent to a landfill. The potentially high chloride and nitrate content of these salts will make the waste difficult to stabilize, and treatability studies will be necessary to determine a proper stabilization formula.
The concentrations of RCRA-regulated heavy metals in the evaporator brine have been found to be very low or nondetectable. This stream, and possibly the salts produced from it, will not be considered hazardous by characteristic.
General Finding 10. Testing, verification, and integration beyond the 1999 demonstration phase will be necessary because the scale-up of a process can present many unexpected challenges, and the ACWA demonstrations were limited in nature.
The issues of integration and scale-up still must be resolved.
General Finding 11. Although a comprehensive quantitative risk assessment (QRA), health risk assessment (HRA), and ecological risk assessment (similar to assessments performed for the baseline process) cannot be completed at this stage of process development, these assessments will have to be performed and refined as process development continues.
This finding is still valid.
General Finding 12. The “optimum” system for a particular chemical weapons storage depot might include a combination of unit operations from the technology packages considered in this report.
This finding is still valid. However, the PMACWA is committed to selecting one of the two technology packages discussed in this report. The ACW II Committee has only been asked to evaluate existing technology packages.
General Finding 13. Some of the ACWA technology providers propose that some effluent streams be used commercially. New or modified regulations may have to be developed to determine if these effluent streams can be recovered or reused.
This finding is not applicable to the processes evaluated in this report.
General Finding 14. An extraordinary commitment of resources will be necessary to complete the destruction of the assembled chemical weapons stockpile in time to meet the current [CWC] deadline using any of the ACWA technology packages. This would demand a concerted national effort. It is unlikely that any of the technology packages could meet this deadline.
This finding is still valid.
General Finding 15. The Dialogue process for identifying an alternative technology is likely to reduce the level of public opposition to that technology. The committee believes that the Dialogue has been and continues to be a positive force for public acceptance of alternatives to incineration. Although the Dialogue process requires a significant commitment of time and resources, it has been a critical component of the ACWA program to date.
The Dialogue process for public involvement has been instrumental in accelerating the development of nonincineration processes. Some form of public involvement
should be continued throughout the construction phase and operation of the Pueblo facility.
General Finding 16. Although the committee did not have access to scientific data on the attributes of a technology that would be most acceptable to the public, input from members of the active publics and previous research indicates that technologies with the following characteristics are likely to stimulate less public opposition:
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minimal emissions, particularly gaseous
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continuous monitoring of effluents to verify that the process is operating as designed (process assurance measurement)
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provisions for representatives of the local community to observe and participate in the process assurance measurement
This finding remains true. The two processes under consideration have followed these guidelines.
General Recommendations from the 1999 Initial ACW I Committee Report
General Recommendation 1. If a decision is made to move forward with any of the ACWA technology packages, substantial additional testing, verification, and especially integration should be performed prior to full-scale implementation (see General Finding 10).
EDS has provided additional testing. However, not all unit operations have been tested, and system integration has not yet been demonstrated.
General Recommendation 2. The sampling and analysis programs at each phase of development should be carefully reviewed to ensure that the characterization of trace components is as comprehensive as possible to avoid surprises in the implementation of the selected technology (see General Finding 6).
Extensive sampling and analysis have been performed during both Demonstration I and the EDS testing. Characterization of all streams should continue during development and systemization of the processes.
General Recommendation 3. If a decision is made to move forward with any of these technology packages, health and safety evaluations should progress from qualitative assessments to more quantitative assessments as the process design matures. Quantitative (QRA), health (HRA), and ecological risk assessments should be conducted as soon as it is practical. Early initiation of these assessments will allow findings to be implemented with minimal cost and schedule impact (see General Finding 11).
Both technology providers have been performing preliminary hazards analyses.
General Recommendation 4. Any of these technology packages, or any component of these technology packages, should be selected on a site-specific basis (see General Finding 12).
PMACWA is in the process of selecting the technology best suited to destroy the stockpile at Pueblo Chemical Depot.
General Recommendation 5. Whatever unit operation immediately follows the hydrolysis of energetic materials should be designed to accept emulsified aromatic nitro compounds, such as TNT or picric acid, as contaminants in the aqueous feed stream (see General Finding 3).
Precautions must be taken to ensure that all emulsified aromatic nitro compounds are destroyed in the reactors.
General Recommendation 6. Simultaneous processing of different types of energetic materials should not be performed until there is substantial evidence that the intermediates formed from the hydrolysis of aromatic nitro compounds will not combine with M28 propellant additives or ordnance fuze components to form extremely sensitive explosives, such as lead picrate (see General Finding 4).
This remains a concern. Different energetic materials should not be processed together.
General Findings from the 2000 Supplemental ACW I Committee Report
General (Demo I) Finding 1. Based on the committee’s assessment of the maturity of the various unit operations, none of the three technology packages is ready for integrated pilot programming, although certain unit operations are sufficiently mature to bypass pilot testing (e.g., hydrolysis of agent).
This finding has been updated by the findings in this report.
General (Demo I) Finding 2. The demonstration tests were not operated long enough to demonstrate reliability and long-term operation.
This finding is valid.
General (Demo I) Finding 3. The committee reiterates that none of the unit operations have yet been integrated into a complete system. The lack of integration remains a major concern as a significant obstacle to full-scale implementation.
This finding is still valid.
