Understanding phase formation in glasses, crystalline compounds, and sorbent materials for applications in nuclear waste forms and WTP LAW off-gas systems
EMSL Project ID
60698
Abstract
The objective of this proposal is to understand the formation of different phases in glass waste forms, crystalline compounds, and sorbent materials using X-ray diffraction (XRD) analysis for development of durable waste forms and efficient sorbent materials. Glass wasteform simulants can be prepared by either preparing a glass using common glass-forming chemicals (oxides and carbonates) and directly melting to produce a glass or by preparing simulant waste (representative of the Hanford tank waste) and mixing with the glass forming chemicals (GFCs) currently planned to be used by the Hanford Waste Treatment and Immobilization Plant (WTP) then characterizing the materials during conversion to glass. Glass waste forms are composed of multiple constituents, and different crystalline phases can be formed within the glass matrix depending on the melting and cooling conditions. XRD analysis on the glass waste forms provides the structural information about crystalline phases within the glass matrix. For further characterization, pure crystalline compounds shown in the glass waste forms and other similar isostructural compounds can be synthesized for XRD analysis to understand the change in structures with different element incorporation, and the resulting data can be related to other properties such as chemical durability. Ex-situ XRD analysis of wasteforms during melting provides identification and quantification of the fraction of crystalline GFCs. This quantification provides an indication of the overall rate expected for a glass formulation planned for the WTP. Tailoring the makeup of the blend of the GFCs and tank waste simulant can guide WTP procedures and formulations. For the sorbent materials, XRD analysis provides information about phase transformation and chemisorption of sorbent materials during adsorption process. In the Hanford WTP Low-Activity Waste (LAW) Facility primary and secondary off-gas systems, capture of iodine (I) and mercury (Hg) is challenging, and different sorbent materials will be investigated. XRD analysis is critical to understand the adsorption mechanism by characterizing Hg and/or I containing phases in the sorbent materials after adsorption. All the testing samples are not radioactive.
Project Details
Start Date
2023-02-27
End Date
2023-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members