Vitrified waste corrosion

Waste corrosion. After canister failure, the waste form will begin to corrode in an environment of stagnant porewater. Vitrified waste dissolves at a very low rate and the corrosion rate is assumed to be constant with time (Grauer 1985). Arguments have been advanced for possible acceleration mechanisms (formation of crystalline secondary products which lower silica concentration and thus accelerate glass corrosion) but long-term (c. 5 year) experiments... 

Due to chemical buffering by the canister corrosion products and bentonite minerals (particularly pyrite and siderite), it is not expected that the oxidizing conditions, which may form at the surface of spent fuel, will have a significant influence on the rest of the EBS (Smith Curti 1995). In this case, the solubility limits derived for the vitrified waste case can be directly applied - a redox front may exist within the canister corrosion products or bentonite but this will not influence releases from the nearfield to the geosphere. Extensive precipitation may occur at this redox front which may initially be in the form of colloids. The small pore size (average c. 2-lOnm, Pusch 1980 McKinley 1988) of the compacted bentonite should ensure that any colloids formed are immobile in this... 

According to researchers, limitations of DC arc systems include the corrosive nature of the vitrified material, limitations on salt and water content, and uncertain performance in the destruction of organic wastes. The addition of flux materials may be required to allow the vitrified material to be poured and to allow the final waste form to meet performance goals. Volatile radionuclides and metals may accumulate in the off-gas treatment system. 

Corrosion and stability of vitrified material derived from municipal solid waste... 

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