Influence of long-term aqueous leaching of irradiated graphite on surface properties and behavior of radionuclides. (2020)

• Record Type: Journal Article
• Authors: Shiryaev, Andrey A.; Volkova, Anna G.; Dvoryak, Stanislav; Nickolsky, Maximillian S.; Zakharova, Elena V.
• Is Part Of: MRS advances. Volume 5:Number 3/4(2020)
• Page Start: 177
• Page End: 184
• Publication Date: 2020
• Subjects: waste management; Electrical engineering -- Congresses; Physics -- Congresses; Materials -- Research -- Congresses; Materials science -- Congresses; 620.11
• DOI: 10.1557/adv.2020.37
• Languages: English
• ISSNs: 2059-8521

Abstract

Abstract: Samples of real irradiated (i-)graphite from bushings of RBMK reactor after several types of decontamination treatments were put in contact with aqueous solutions modelling underground water of Nizhnekansky massif (Russia) equilibrated with bentonite for periods up to 1.5 years. Leach rates of radionuclides and evolution of graphite surface morphology and oxidation state were monitored using nuclear spectroscopy, SEM and XPS. After the experiment, less than one third of surface carbons remains unoxidised. Extensive precipitation of secondary phases (alumosilicates, carbonates) was observed on some samples and is possibly correlated with surface oxidation extent. The leach rates of dose-forming 14 C and 36 Cl are comparable with the leach rates of radionuclides in glassy waste forms. According to the current study i-graphite could be regarded as a waste form, which is suitable for near-surface disposal.