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Title: The Behavior of Iodine in Stabilized Granular Activated Carbon and Silver Mordenite in Cementitious Waste Forms

Journal Article · · Journal of Environmental Radioactivity

Both granular activated carbon (GAC) and silver mordenite (AgM) are utilized for the removal of contaminants and radionuclides (e.g., radioiodine) from the off-gas streams in nuclear fuel reprocessing and high temperature immobilization of nuclear waste. Following their service lifetimes, the GAC and AgM contain an inventory of contaminants and/or radionuclides and require stabilization in a matrix for disposal. Cementitious waste forms can be used as the stabilization matrix for GAC and AgM, however, for successfully stabilization, the inclusion of GAC and AgM should not negatively impact the physical behavior of the cementitious waste form or the increase the release of the contaminants/radionuclides compared to the baseline case without stabilization. The present work focuses on evaluation of cement formulations, with and without slag, for the stabilization of iodine-loaded GAC or AgM. The results showed that both a slag-containing and slag-free formulation were able to stabilize GAC and AgM, up to 30 vol%, without deleterious impacts on the bulk physical properties of the resulting waste form. When monolithic samples of the GAC or AgM containing cement formulations were subjected to leach tests, it was observed that iodide leached from the SSW had limited sorption to either of the cement matrices but the iodine can interact with the SSW materials themselves. Specifically, iodine retention within monolithic samples containing the iodine-loaded GAC or AgM was improved for AgM containing waste forms while no improvement was observed for the GAC containing waste forms. The improvement for the AgM containing waste forms was likely due to an enrichment of Ag at the interface between the AgM particles and the cement matrix that can impede iodine migration out from the waste form. The results are significant in highlighting the potential for long-term retention of iodine in cementitious waste forms.

Research Organization:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Organization:
DOE Contract Number:
Report Number(s):
Journal Information:
Journal of Environmental Radioactivity, Vol. 244-245
Country of Publication:
United States

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