Performance of a buried radioactive high level waste (HLW) glass after 24 years

A radioactive high level waste glass was made in 1980 with Savannah River Site (SRS) Tank 15 waste. This glass was buried in a lysimeter in the SRS burial ground for 24 years. Lysimeter leachate data was available for the first 8 years. The glass was exhumed in 2004. The glass was predicted to be very durable and laboratory tests confirmed this. Scanning electron microscopy of the glass burial surface showed no significant glass alteration consistent with results of other laboratory and field tests. Radionuclide profiling for alpha, beta, and ¹³⁷Cs indicated that Pu was not enriched in the soil while ¹³⁷Cs and ⁹⁰Sr were enriched in the first few centimeters surrounding the glass. Lysimeter leachate data indicated that ⁹⁰Sr and ¹³⁷Cs leaching from the glass was diffusion controlled.