Effect of zeolite type, temperature, and pH on Stage III glass alteration behavior for two nuclear waste glasses

• Published in: Journal of nuclear materials 2022-08, Vol.567, p.153717, Article 153717
• Main Authors: Parruzot, Benjamin, Crum, Jarrod V., Reiser, Joelle T., Neeway, James J., Kerisit, Sebastien N., Daniel, Richard C., Bonnett, Jeffrey F., Reyes, Richard A., Seymour, Lorraine M., Burns, Carolyn A., Ryan, Joseph V., Smith, Gary L., Asmussen, R. Matthew
• Format: Article
• Language: English
• Subjects: Glass durability; Long-term behavior; Low-activity waste glass; MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; Zeolite
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2022.153717

·Zeolite addition caused sustained Stage III behavior for glasses down to 40 °C.·Activation energy for the Stage III rates range from 60 to 68 kJ·mol–1.·Secondary phases evolution with altered glass was characterized by XRD, SEM-EDS.·Precipitating zeolites were analcime, zeolite P1 & P2, same or different from seeds.·Avrami equation indicated zeolite growth occurred unimpeded in 3-dimensions. Long-term laboratory-scale static alteration tests (up to 1500 d) were conducted on two low-activity waste glasses (LAWA44 and IDF18-A161) at S/V = 2000 m–1. Tests were seeded with either analcime, clinoptilolite, zeolite P1, or zeolite P2 to induce Stage III glass alteration behavior. The effect of several parameters on glass Stage III behavior was studied with consideration of several variables, including temperature (22 °C–90 °C) and pH (floating or initially set using KOH at values from 9.5 to 11.5). Temporal solution data and solids characterization at the end of the experiments are reported. Solution data demonstrated the occurrence of a sustained rate acceleration at temperatures down to 40 °C and the activation energy for these Stage III rates was determined for both glasses. Three major secondary phases were identified at the end of the experiments for both glasses: zeolite P1, zeolite P2, and/or analcime (along with minor phases: zeolites, clays, carbonates). The identity of the crystalline phases at the end of the experiment often differed from the zeolite seed phase. In addition, the use of the Avrami equation showed unimpeded zeolite growth (3-dimensional) in certain conditions, suggesting that in certain conditions the glass dissolution rate is controlled by zeolite formation kinetics whereas in other conditions the glass corrosion process impeded zeolite formation kinetics. The morphological evolution of the samples revealed the growth of the zeolites which completely fill the intergranular space in the powder bed. These results are discussed with regards to previous seeded and unseeded Stage III dissolution rate experiments performed on low- and high-activity nuclear waste glasses.