Abstract

Waste forms containing glassy and crystalline phosphate and silicate phases were produced to immobilize salt waste simulants from pyro processing and characterized by using Raman spectroscopy, Mössbauer spectroscopy, X-ray diffraction, scanning electron microscopy, heat capacity, and chemical durability measurements. In this work, a phosphosilicate waste form is presented to leverage the benefits of both borosilicate glasses and iron phosphate glasses. To improve waste loading, prior to immobilization, salt simulants were successfully dechlorinated using ammonium dihydrogen phosphate, mixed with a borosilicate frit (5–30 wt. %) and Fe2O3, and vitrified. Additions of 2.5–15 wt. % borosilicate glass (NBS3) improved normalized release rates for Cs relative to iron-phosphates without NBS3, resulting in chemical durability's similar to high-level waste borosilicate glass reference materials. The release rates of the alkalis (i.e., Li, Na, K, Cs) were the lowest with the addition of 5 wt. % NBS3. Although Sr was not specifically targeted in this study, evidence exists that it preferentially partitioned with Si to form an amorphous droplet phase within the iron phosphate glass matrix.

Department(s)

Materials Science and Engineering

Second Department

Chemistry

Publication Status

Open Access

Comments

Office of Nuclear Energy, Grant DE-AC05-76RL01830

Keywords and Phrases

electrochemical; glass; nuclear; phosphate; pyroprocessing; silicate; waste form

International Standard Serial Number (ISSN)

2837-1445

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 2025 American Chemical Society, All rights reserved.

Creative Commons Licensing

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Publication Date

27 Mar 2025

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