137Cs and 90Sr, both byproducts of the fission process, make up the majority of high-level waste from nuclear power plants. 63Ni is a byproduct of the erosion-corrosion process of the reactor components in nuclear energy plants. The concentrations of these ions in solution determine the Waste Class (A, B, or C) and thus selective removal of these ions over large excesses of other ions is necessary to reduce waste and cut costs. Herein we report the use of the Inorganic Ion Specific Media (ISM) K2xMgxSn3-xS6 (x=0.5-0.9) (KMS-2) for the ion exchange of Cs+, Sr2+, and Ni2+ in several different conditions. We will also report the stability of this new material in the general conditions found at nuclear power plants (pH ∼6-8) and DOE sites (pH>10). Measurements at low concentrations were conducted with inductively coupled plasma mass spectrometry and Kd values are reported for each of the ions in a variety of conditions.