Effective Immobilization of Iodine with Ag⁰-Aerogel—Different Matrices and Processing Conditions

One of the primary challenges for reprocessing of spent nuclear fuel, vitrification of nuclear waste, and development of advanced and innovative reactors and their nuclear fuel cycles is to immobilize iodine into durable and economically viable waste forms. These waste forms must meet criteria of high iodine loading, high chemical durability, and low processing costs. There has been significant progress made over the years with silver-functionalized silica aerogel (Ag⁰-aerogel) as a means for efficient removal and sequestration of iodine from various off-gas streams. The number of lab- and bench-scale consolidation tests with hot isostatic pressing and spark plasma sintering were demonstrated. Also included were other potential pathways such as incorporation of Ag⁰-aerogel into cement or low-temperature melting matrices. The presentation will focus on summarizing different strategies that have been developed to sequester iodine, discuss results from durability tests and conclude with a summary of highlights and a prognosis for future research.