A high selectivity and sorption capacity for iodine and a feasible consolidation to a durable SiO2-based waste form makes silver-functionalized silica aerogel (Ag0-aerogel) an attractive choice for the removal and sequestration of iodine compounds from the off-gas of a nuclear fuel reprocessing plant. Hot uniaxial pressing of iodine-loaded Ag0-aerogel (20.2 mass% iodine) at 1200°C for 30 min under 29 MPa pressure provided a partially sintered product with residual open porosity of 16.9% that retained ~93% of sorbed iodine. Highly iodine-loaded Ag0-aerogel was successfully consolidated by hot isostatic pressing at 1200°C with a 30-min hold and under 207 MPa. The fully densified waste form had a bulk density of 3.3 g/cm3 and contained ~39 mass% iodine. The iodine was retained in the form of nano- and micro-particles of AgI that were uniformly distributed inside and along boundaries of fused silica grains.
Revised: January 24, 2017 |
Published: August 1, 2016
Citation
Matyas J., N.L. Canfield, S.E. Sannoh, and M.R. Zumhoff. 2016.Silica-based waste form for immobilization of iodine from reprocessing plant off-gas streams.Journal of Nuclear Materials 476.PNNL-SA-117831.doi:10.1016/j.jnucmat.2016.04.047