Session: 04-01 High-Level Waste Glass & Packaging

Paper Number: 110895

110895 - Advances in Fundamental Understanding of Hanford Glass Composition-Properties-Processing Relations 

About 212,000 cubic meters (~56 million gallons) of radioactive waste is currently stored in 177 underground tanks at the Hanford site in southeastern Washington state in the USA. The tank waste is highly heterogeneous, with some tanks consisting of large fractions of settled solid high-level waste (HLW) and others consisting of mostly caustic supernatant liquid or solid salt cake low activity waste (LAW). Vitrification operations are scheduled to begin at Hanford in 2023 on some LAW tanks using a modified direct-feed (DF) approach, consisting of tank-side pre-treatment with waste proceeding to the LAW Joule-heated ceramic-lined melters. The HLW processing flowsheet is currently being refined, with one option consisting of a similar DF process. Glass compositions are designed to maximize waste loading and glass production rate while maintaining predicted properties which allow adequate processing envelopes and conforming final glass product specifications. For HLW glass, several physical phenomena limit waste loading, the most important of which are: formation of spinel crystals which can cause processing difficulties and formation of nepheline crystals which can cause poor aqueous chemical durability of the cooled glass. For LAW glass, constraints are somewhat different, and can include: formation of a second phase salt layer (similar to “yellow phase”) containing alkali, sulfate, halides, and technetium; and corrosion of chromia-based melter refractory liner. Envisioned direct feed HLW approaches could potentially face constraints from both HLW and LAW components. In this presentation, we summarize work over the last decade in pursuit of fundamental understanding of compositional constraints for production of HLW glass at Hanford.

Presenting Author: John McCloy Washington State University

Presenting Author Biography: Dr. McCloy is Professor and current Director of the School of Mechanical & Materials Engineering and Lindholm Endowed Chair in Materials Engineering at Washington State University (WSU). His professional career includes stints in industry, national laboratory, and academia sectors: a professor at WSU since 2013, and previously a research scientist at Pacific Northwest National Laboratory, where he retains a joint appointment as Chief Scientist. At WSU, he leads the Nuclear, Optical, Magnetic, & Electronic (NOME) Materials Lab, where students and scientists research aspects of radioactive waste management, including development of glasses and other materials for nuclear waste immobilization.