A list of typical uses for carbon filter units in a chemical agent disposal facility using incineration for agent destruction is given in Table 2-1. The used carbon from most processes is not expected to be contaminated with agent. The only two places where used carbon is expected to become exposed to agent during normal operations are the unit filters for the agent collection system (ACS) and Banks 1 and 2 of the MDB HVAC filters. The semicontinuous monitoring (noted in Table 2-1) by a combination of near-real-time ACAMS and DAAMS after Banks 1, 2, 3, and 4 establishes that there is no exposure to agent beyond Bank 2.2 This conclusion does not preclude plant management from changing out filters from Banks 1 and 2 for other reasons, e.g., to measure conditions of the carbon.
As indicated in Table 2-1, changeout of the carbon in Banks 1 and 2 would take place if agent breakthrough above the short-term limit is detected between Banks 2 and 3 at the Tooele, Anniston, and Pine Bluff Chemical Agent Disposal Facilities (TOCDF, ANCDF, and PBCDF). At Umatilla Chemical Agent Disposal Facility (UMCDF), the policy is that changeout would occur if agent breakthrough above the short-term limit is detected between Banks 3 and 4. However, as has been and continues to be the case at the other sites, the committee does not expect that it would ever become necessary for MDB HVAC Bank 3 carbon at UMCDF to be changed out due to contamination. For this reason, for each site covered in this report the first two banks of MDB HVAC carbon will be considered to be exposed to agent and the last four banks will be considered to be unexposed carbon.
The PFS filters are not expected to be exposed to agent during normal operation of the liquid incinerator (LIC), the metal parts furnace (MPF), or the deactivation furnace system (DFS) and their respective PAS units. The PFS units at the more recently constructed ANCDF, PBCDF, and UMCDF were not required by the regulations applicable to these facilities that implement the Resource Conservation and Recovery Act (RCRA), but they were included in the design of these facilities as an extra precaution to relieve public concerns about the possibility of uncontrolled gaseous emissions. The report Carbon Filtration for Reducing Emissions from Chemical Agent Incineration examined various technical and risk-related aspects surrounding the use of PFSs at chemical agent disposal facilities (NRC, 1999). From the start of operations in 1996, TOCDF has operated without a PFS but was adding units downstream of the two LICs and the MPF as this report was being prepared. Sulfur-impregnated carbon is being installed in these units to capture mercury from the incineration of mercury-containing mustard agent. The PFS at ANCDF, PBCDF, and UMCDF will also use sulfur-impregnated carbon when these facilities are processing mustard agent-containing munitions and ton containers.
Table 2-2 estimates total quantities of used carbon expected to be generated during disposal operations and site closure for each of the incineration-based chemical agent disposal facilities currently operating and for the neutralization (hydrolysis)-based Newport