SEMINAR
To be held on Monday, November 23rd, 2020, 12:10-13:00
via zoom meeting - link
Portland Cement-based matrices for nuclear waste immobilization
Dr. Gabriela (Gabi) Bar-Nes
Head, Applied Chemistry Laboratory, Chemistry Department, NRCN
Abstract:
Cement based materials are widely used as binding matrices for radionuclides in low level waste management applications. These matrices are designed to retain the hazardous materials and assure no contamination is dispersed to the biosphere during their long-term disposal in the repository. Towards improvement of waste immobilization, the addition of pozzolanic additives such as slag, metakaolin and silica fume was studied as well as the durability of the above matrices under various degradation mechanisms.
This presentation will present an overview of research done, focusing on the effect of irradiation and carbonation on the leaching of Sr ions from Portland cement-based samples.
The retention properties were studied using leaching tests according to ANSI/ANS 16.1 standard and supplemented by post-leaching characterization including local chemical analysis (LA-ICPMS) crystallographic analysis (XRD), and EPMA imaging. The experimental results were further modeled using a simple analytical leaching diffusion-kinetic model that accounts for both strontium diffusion and strontium carbonate precipitation. The results show that carbonation was the main factor determining the retention of Sr ions, whereas irradiation did not have a significant effect. Moreover, carbonation has a positive effect on the retention of Sr ions in the matrix with the formation of carbonated zone.
About the speaker:
Dr Gabriela Bar-Nes obtained her PhD in Civil and Environmental Engineering at the Technion and since 1996 she has been a researcher and a scientific leader in the waste management field in the NRCN. Her main research topics involve the development of cementitious and geopolymeric immobilization matrices for radioactive waste streams. These studies involve the architecture and chemical characterization of the various binding matrices, their ability to retain contaminants within their structure and the various degradation mechanisms affecting their integrity. An additional field of interest is the development of sustainable building materials based on industrial waste.
