EFFECTS OF SIMULANT MIXED WASTE ON EPDM AND BUTYL RUBBER

We have developed a Chemical Compatibility Testing Program for the evaluation of plastic packagingcomponentswhichmaybeusedintransportingmixedwasteforms. Inthisprogram, we have screened 10 plastic materials in four liquid mixed waste simulants. 'These plastics were butadiene-acrylonitrile copolymer (Nitrile) rubber, cross-linked polyethylene, epichlorohydrin rubber, ethylene-propylene (EPDM) rubber, fluorocarbons (Viton® and Kel-FN), polytetrafluoroethylene (Teflon®), high-density polyethylene, isobutylene-isoprene copolymer (Butyl) rubber, polypropylene, and styrene-butadiene (SBR) rubber. 'The selected simulant mixed wastes 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. The screening testing protocol involved exposing the respective materials to -3 kGy of ganuna radiation followed by 14-day exposures to the waste simulants at 6o·c. The rubber materials or elastomers were tested using vrR measurements while the liner materials were 2 tested using specific gravity as a metric. For tAese tests, screening criteria of -1 glbr/m for VTR and specific gravity change of 10% were used. Those materials that failed to meet these criteria werejudged to have failed the screening tests and were excluded from the next phase of this experimental program. We have completed the comprehensive testing phase of liner materials in a simulant Hanford Tank waste consisting of an aqueous alkaline mixture of sodium nitrate and sodium nitrite. From the data analyses performed, we have identified the chlorofluorocarbon Kel-P\"' as having the greatest chemical durability after having been exposed to gamma radiation followed by exposure to the aqueous alkaline simulant mixed waste. The most striking observation from this study was the extremely poor perfonnance of Teflon under these conditions. We have also completed the comprehensive testing of two elastomers, EPDM and Butyl rubber, in simulant Hanford Tank waste. In the evaluation of these two elastomeric materials, we have concluded that while both materials exhibit remarkable resistance to these environmental conditions, EPDM bas a greater resistance to this corrosive mixed waste.