Methods of treating radioactive materials are disclosed. In one aspect, a method may include mixing a radioactive isotope diluted in a filler material with a radioactive material treatment composition to form a resulting material. The radioactive material treatment composition may include mostly salt, and from 0.5 to 15 wt % sorbent. The method may further include mixing the resulting material with one or more inorganic binding agents. Other methods of treating radioactive materials are also disclosed, as well as compositions for treating radioactive materials.