Development of New Waste Forms to Immobilize Iodine-129 Released from a Spent Fuel Reprocessing Plant
I-129 is a very long-lived radionuclide that is released to an off-gas stream when spent fuels are dissolved at a reprocessing plant. An iodine filter can capture I-129 in the form of AgI. However, because AgI is unstable under the reducing conditions of a geological repository and I-129 has a very long half-life, I-129 can migrate to the biosphere. These characteristics make I-129 a key radionuclide for the safety assessment of a geological disposal of radioactive wastes generated from a reprocessing plant (TRU wastes). To improve disposal safety, several new waste forms have been developed to confine I-129 for a very long period in order to reduce the leaching of I-129 from radioactive wastes. These new waste forms have technical objectives of solidifying more than 95% of I-129 into the waste form and achieving a leaching rate of less than 10-5/y. Several iodine immobilization techniques have been examined. This paper presents experimental results concerning the treatment process, leaching behavior, modeling, and related elements of these immobilization techniques.
Pietro VINCENZINI, Hua-Tay LIN and Kevin FOX
H. Tanabe et al., "Development of New Waste Forms to Immobilize Iodine-129 Released from a Spent Fuel Reprocessing Plant", Advances in Science and Technology, Vol. 73, pp. 158-170, 2010