The Effects of Crystallization and Residual Glass on the Chemical Durability of Iron Phosphate Waste Forms Containing 40 wt% of a High MoO3 Collins-CLT Waste

Abstract

The effects of cooling rate on the chemical durability of iron phosphate waste forms containing up to 40 wt% of a high MoO3 Collins-CLT waste simulant were determined at 90 °C using the product consistency test (PCT). The waste form, designated 40wt%-5, meets appropriate Department of Energy (DOE) standards when rapidly quenched from the melt (as-cast) and after slow cooling following the CCC (canister centerline cooling)-protocol, although the quenched glass is more durable. The analysis of samples from the vapor hydration test (VHT) and the aqueous corrosion test (differential recession test) reveals that rare earth orthophosphate (monazite) and Zr-pyrophosphate crystals that form on cooling are more durable than the residual glass in the 40wt%-5 waste form. The residual glass in the CCC-treated samples has a greater average phosphate chain length and a lower Fe/P ratio, and those contribute to its faster corrosion kinetics.

Department(s)

Nuclear Engineering and Radiation Science

Second Department

Materials Science and Engineering

Comments

This work was supported by the US Department of Energy contract number DE-SC0011906.

Keywords and Phrases

Chemical Durability; Collins-CLT Waste; Iron Phosphate Glass; Nuclear Waste; Waste Form

International Standard Serial Number (ISSN)

0022-3115

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2018 Elsevier B.V., All rights reserved.

Publication Date

01 Mar 2018

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