Highly reactive fission product cesium may volatilize at high temperatures. PbO–B 2 O 3 –ZnO glass with low melting temperature and excellent chemical durability can be used as a potential matrix for immobilizing Cs. In this work, five PbO–B 2 O 3 –ZnO glasses with different contents of Pb were synthesized via a melt-quenching process. These specimens were characterized with XRD , Raman, DTA and viscosity measurements . The results showed that the melting temperature decreases, viscosity decreases and structural polymerization increases with increasing lead content. Cs-doped 35PbO–60B 2 O 3 –5ZnO glasses were synthesized at low temperatures. XRD results revealed the amorphous nature of the glass solidified bodies. EDS and ICP-MS studies confirmed that Cs is retained in the glass. Clear vitrified waste products containing up to 13.6 wt% Cs were obtained. The chemical durability of the samples was evaluated via PCT-A and MCC-1 method. For the glass solidified body comprising a Cs/matrix ratio of 0.136, the leaching rate of Cs was 1.6 × 10 −1 g m −2 d −1 from the PCT test, which indicates that it has a good chemical stability. 35PbO–60B 2 O 3 –5ZnO glass was expected to be a suitable matrix for Cs immobilization.
In this paper, we present a productive low-temperature fabrication of Cs-hollandite ceramics by adding Bi 2 O 3 as a sintering aid to achieve high cesium retention. The effects of Bi 2 O 3 addition on the phase composition, crystal structure and aqueous stability of the stoichiometric Ba 0.9 Cs 0.3 Cr 2.1 Ti 5.9 O 16 ceramic waste form were investigated. It was found that adding Bi 2 O 3 can effectively reduce the sintering temperature and promote densification of Cs-containing hollandite products. The Cs-hollandite ceramic with 2 wt% Bi 2 O 3 sintered at 1000 °C showed a single phase with > 98 % cesium retention, which was ∼ 200 °C lower and ∼ 11 % retention rate higher than those of reported Cs-bearing hollandite. Moreover, the leached sample remained stable tetragonal structure, the LR Cs was in the order of 10 -3 g·m - 2 ·d -1 after 28 days and the leaching indexes > 8, exhibiting good aqueous stability. This route can be considered as a promising solution to prevent cesium loss for incorporating the cesium waste in ceramic hosts.
Geopolymers prepared from recycled fly ash have emerged as sustainable and effective solutions for the solidification of radioactive wastewater. In this study, fly ash-based geopolymers with varying 137 Cs concentrations are prepared, and their solidification effects as well as the compressive strength, porosity, microstructure, and leaching behavior after solidification are investigated. The results indicate the uniform incorporation of Cs into the prepared fly ash-based geopolymers. As the concentration of Cs in the geopolymers increases, the compressive strength decreases and porosity increases; however, the chemical structure remains almost unchanged. These observations are attributed to the electrostatic interaction between Cs + ions and the negatively charged [SiO 4 ] 4− and [AlO 4 ] 5− ions in the geopolymers. Moreover, the geopolymers exhibited lower leaching rates and cumulative leaching fractions in both deionized water and Beishan groundwater; the leaching rate and cumulative leaching fraction of 137 Cs in fly ash-based geopolymers were lower than the Chinese national standards. Further, the Cs solidification performances of the prepared geopolymers and traditional cement on real radioactive wastewater were compared. The fly ash-based geopolymers demonstrated a superior performance than traditional cement, making them a promising material for radioactive wastewater treatment. This study offers new insights into reducing radioactive waste and makes a substantial contribution to the knowledge of nuclear waste solidification processes employing fly ash-based geopolymers.
危险品化学品经营许可证（带存储）