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Paul McConnell, (505) 844-8361
The purpose of hazardous and radioactive materials, i.e., mixed waste, packaging is to enable this waste type to be transported without posing a threat to the health or property of the general public. To achieve this goal, regulations have been written establishing general design requirement for such packagings. Based on these regulatory requirements, a Mixed Waste Chemical Compatibility Testing Program is intended to assure regulatory bodies that the issue of packaging compatibility towards hazardous and radioactive materials has been addressed. Such a testing program has been developed in the Transportation Systems Department at Sandia National Laboratories.
  • Specific Gravity
  • Dimensional
  • Shore Harness
  • Stress Cracking
  • Permeability
  • Thermal Cycling
  • Tensile Properties
  • The Testing Program
    The chemical compatibility testing program is a two phase program. During the first phase, known chemically resistant polymers were screened for chemical compatibility with four simulant mixed waste types described below. The effects of mixed waste forms were simulated by first exposing polymers to radiation followed by exposure to the hazardous chemicals. The strategy of the testing program is shown below:

    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.

    For specific gravity testing of liner materials the data shown below indicate all materials with the exception of polypropylene passed the screening criteria, PCTFE, HDPE, and XLPE were found to offer the greatest resistance to the combination of radiation and chemicals.

    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.

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