Development, Fabrication and Study of Fullerene-Containing Carbon Material (FCC) for Immobilization of Iodine: Progress reports 1-1 and 1-2

Immobilization of highly radioactive and long-lived isotope of 129I, which is a fission product in spent nuclear fuel, requires development of new durable host-materials. Such materials should be characterized with the following principal features: High loading capacity to iodine incorporation Chemical durability and radiation resistance in order to prevent iodine release over long time (higher than 105 years) storage under conditions of underground repository of radioactive wastes Possibility to use iodine-doped material as a target for iodine transmutation. Iodine is a very volatile chemical element, and even its chemically strong compounds such as AgI and CuI are not stable under ultraviolet irradiation or oxidizing conditions. Therefore, development of host materials for iodine immobilization is based on unusual approach – the search and testing of new compounds which were not studied before in respect of iodine sorption and strong fixation. In the framework of first year (“KRI-KIRSI”-HRC Agreement 280203) we have studied optimal synthesis conditions and principal features of FCC. The preliminary results have been obtained from precise XRD analyses of iodine-doped and pure FCC samples before and after gamma-irradiation. It was found that iodine doping and irradiation caused principal changes in phase composition of FCC such as substituting of crystalline fullerene C60 (formed by benzene-like carbon rings) for crystalline chaoite phase (formed by carbyne carbon chains). It was decided to continue these experiments during second (current) year (“KRI-KIRSI”-HRC Agreement 280203-1) in comparison with study of activated carbon. In our experiments we decided to use samples of activated carbon SKT-3S that is widely used in Russian nuclear industry for different purposes including sorption of 129I