MCC-1: A Standard Leach Test for Nuclear Waste Forms

A Materials Characterization Center (MCC) has been established by the U.S. Department of Energy at the Pacific Northwest Laboratory (PNL). Five proposed standard leach tests and typical results using the MCC-1 static test are presented. For the borosilicate glass studied (PNL 76-78), fivefold replicate experiments show that errors in elemental leach values are usually less than ±10%. Regular time-dependent leach curves are obtained, and no significant difference is observed between pure water and simulated silicate/bicarbonate groundwater results. Leaching in salt brine is quite different, especially as shown by elemental depth profiles in the solid; these profiles show significant magnesium penetration into the gel layer from the brine solution.