The U.S. Army has asked the National Research Council (NRC) to evaluate whether supercritical water oxidation (SCWO) is an effective and appropriate means of eliminating hazardous or toxic organic constituents in VX hydrolysate for ultimate disposition. The NRC was not asked to conduct an in-depth analysis of the entire integrated VX bulk agent destruction and disposal process for the Newport Chemical Agent Disposal Facility. As the facility design is being finalized (March 1999-April 2000), the NRC will probably be asked to assess all aspects of the facility design, including monitoring, containment, process control, and redundancy, as well as the quantitative risk assessment (QRA). This report outlines the elements of the proposed neutralization/SCWO technology, evaluates the results of ongoing SCWO tests, and makes recommendations concerning aspects of the technology that require further development. The scope of this evaluation did not include evaluations of other potential technologies or management options for the treatment of VX hydrolysate.

The Program Manager for Assembled Chemical Weapons Assessment (PMACWA) of the Department of Defense (DOD) requested the National Research Council (NRC) to assess the engineering design studies (EDSs) developed by Parsons/Honeywell and General Atomics for a chemical demilitarization facility to completely dispose of the assembled chemical weapons at the Pueblo Chemical Depot in Pueblo, Colorado. To accomplish the task, the NRC formed the Committee on Review and Evaluation of Alternative Technologies for Demilitarization of Assembled Chemical Weapons: Phase II (ACW II Committee). This report presents the results of the committee's scientific and technical assessment, which will assist the Office of the Secretary of Defense in selecting the technology package for destroying the chemical munitions at Pueblo. The committee evaluated the engineering design packages proposed by the technology providers and the associated experimental studies that were performed to validate unproven unit operations. A significant part of the testing program involved expanding the technology base for the hydrolysis of energetic materials associated with assembled weapons. This process was a concern expressed by the Committee on Review and Evaluation of Alternative Technologies for Demilitarization of Assembled Chemical Weapons (ACW I Committee) in its original report in 1999 (NRC, 1999). The present study took place as the experimental studies were in progress. In some cases, tests for some of the supporting unit operations were not completed in time for the committee to incorporate results into its evaluation. In those cases, the committee identified and discussed potential problem areas in these operations. Based on its expertise and its aggressive data-gathering activities, the committee was able to conduct a comprehensive review of the test data that had been completed for the overall system design. This report summarizes the study.

The U.S. Army is pilot testing chemical hydrolysis as a method for destroying the chemical agents stockpiled at Aberdeen, Maryland (HD mustard agent), and Newport, Indiana (VX nerve agent). The chemical agents at both locations, which are stored only in bulk ton containers, will be hydrolyzed (using aqueous sodium hydroxide for VX and water for HD) at slightly below the boiling temperature of the solution. The resulting hydrolysate at Aberdeen, which will contain thiodiglycol as the primary reaction product, will be treated by activated sludge biodegradation in sequencing batch reactors to oxidize organic constituents prior to discharge to an on-site federally owned wastewater treatment facility. The hydrolysate at Newport, which will contain a thiol amine and methyl phosphonic acid as the major reaction products, is not readily amenable to treatment by biodegradation. Therefore, organic constituents will be treated using supercritical water oxidation (SCWO). Integrated Design of Alternative Technologies for Bulk-Only Chemical Agent Disposal Facilities focuses on the overarching issues in the process designs integrating individual processing steps, including potential alternative configurations and process safety and reliability. This report reviews the acquisition design packages (ADPs) for the ABCDF and NECDF prepared by Stone and Webster Engineering Company for the U.S. Army.