Iodine solubility in a low-activity waste borosilicate glass at 1000°C

The purpose of this study was to determine the solubility of iodine in a low-activity waste borosilicate glass when heated inside an evacuated and sealed fused quartz ampoule. The iodine was added to glass frit as KI in quantities of 99.4–24,005ppm iodine (by mass). Each mixture was added to an ampoule, heated at 1000°C for 2h, and then air quenched. In samples with ⩾11,999ppm iodine, low viscosity salt phases were observed on the surface of the melts that solidified into a white coating upon cooling. These salts were identified by X-ray diffraction as mixtures of KI, NaI, and Na2SO4. Iodine concentrations in glass specimens were analyzed with inductively-coupled plasma mass spectrometry, and the overall iodine solubility was determined to be 10,000ppm. Several crystalline inclusions of iodine sodalite, Na8(AlSiO4)6I2, were observed in the 24,005ppm specimen.