Testing Strategy
These hazardous waste forms were (1 ) an aqueous alkaline mixture of sodium nitrate and sodium nitrite; (2) a chlorinated hydrocarbon mixture; (3) a simulant liquid scintillation fluid; and (4) a mixture of ketones. Ten polymers with anticipated high resistance to one or more of these types of environments were proposed for testing. These potential seal and liner materials were butadiene-acrylonitrile copolymer rubber (NITRILE), cross-linked polyethylene (XLPE), epichlorohydrin rubber (EPI), ethylene-propylene rubber (EPDM), fluorocarbons polychlorotrifluoroethylene (PCTFE) and fluoroelastomer (FKM), polytetrafluoroethylene (PTFE), high-density polyethylene (HDPE), isobutylene-isoprene copolymer rubber (Butyl), polypropylene (PP), and styrene-butadiene rubber (SBR). The screening tests used relatively severe exposure conditions such as high gamma radiation levels [~ 4 kiloGray (kGy)] and high temperatures (60 degrees C) during a 14 day time period to quickly reduce the number of possible materials being tested further. The screening tools used were specific gravity changes in liners and changes in permeability rates [Vapor Transport Rates (VTR)] in seals. Those liner materials which exhibited specific gravity changes greater than 10% and those seals which had VTR greater than ~ 1 g/m2/hr were considered to have failed the screening tests. The polymers which passed the screening tests will be subjected to a comprehensive material testing program in the second phase of the program. During this 2nd phase of the program, gamma-radiation doses of ~ 1, 3, 6, and 36 kGy, exposure times of 7, 14, 28, and 180 days, exposure temperatures of 18, 50, 60 degrees C with the above waste forms will be used. The data obtained from this testing program is available to packaging designers for the development of mixed waste packagings.

The results of the first phase of this experimental program involved the screening of five candidate liner and six seal materials respectively to four simulant mixed wastes. The seal materials were tested using VTR measurements while materials suitable for liner applications were tested using specific gravity measurements. It was experimentally determined that while all seal materials passed exposure to the aqueous simulant mixed waste, EPDM and SBR had the lowest VTRs. In the chlorinated hydrocarbon simulant mixed waste, only FKM passed the screening tests. In both the simulant scintillation fluid mixed waste and the ketone mixture simulant mixed waste, none of the seal materials met the screening criteria. The results are shown here.

The results of the second phase of this experimental program are presently being analyzed. The data obtained from this testing program is also available to packaging designers for the development of mixed waste packagings. The implication of these testing results on the selection of appropriate materials as packaging components may be significant.