Primary Colloids at Hydrothermally Modifed Aluminophosphate Glass with Imitators of Radionuclides

• Published in: Radiochemistry (New York, N.Y.) Vol. 62; no. 3; pp. 411 - 423
• Main Authors: Yudintsev, S. V., Mal’kovskii, V. I., Aleksandrova, E. V.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.03.2020; Springer Nature B.V
• Subjects: Aluminum phosphate; Bentonite; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Colloids; Crystallization; Fluid filters; Glass; Nuclear Chemistry; Phosphates; Pore size; Porosity; Radioisotopes; Repositories; crystallization; migration; vitreous matrix; colloids; radioactive wastes
• ISSN: 1066-3622; 1608-3288
• DOI: 10.1134/S1066362220030157

In Russia, highly active wastes (HAWs) from nuclear power engineering are incorporated in Na–Al–P glass (matrix) for final deposition in a geological repository at a depth of about 500 m. The reliability of such a repository is largely determined by the stability of the HAW matrix in underground water and by its ability to firmly retain radionuclides during the whole time of their being hazardous. Electron microscopy was used to examine the composition and structure of colloid particles formed in the interaction of water with a glass and products of its crystallization at 95°C. To isolate particles, solutions were passed after an experiment through filters with pore size decreasing from 450 to 25 nm. The colloids were represented by Na and Al or Sr, Ln, and U phosphates, with their particle size exceeding 200 nm. The migration of colloids from a repository can be restricted by a barrier based on densified bentonite because particles can be mechanically retained due to the low permeability of rocks.