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Solid Progress for Turning Nuclear Waste into Glass

January 2015
Solid Progress for Turning Nuclear Waste into Glass
Conceptual scaled drawing of WTP high-level waste glass melter.
Image courtesy of Bechtel National, Inc.

The Hanford Tank Waste Treatment and Immobilization Plant (WTP) is the cornerstone of the U.S. Department of Energy's plan to remediate over 50 million gallons of radioactive waste stored in aging underground tanks at the Hanford site in southeast Washington. At this plant, the waste will be separated into two different streams based on how "active" the waste is; low-activity or high-level. Each stream will be sent in batches to separate facilities within the plant, where it will be mixed with additives and melted, or "vitrified," into glass for safe storage and disposal.

Dong-Sang Kim, a researcher in PNNL's Nuclear Sciences division, worked along-side WTP project staff to recently complete a mathematical algorithm, called the high-level waste (HLW) glass formulation algorithm, to achieve the optimal waste and additive mixture for each HLW batch to be vitrified. The exact mixture of waste and additives – including silica sand, boric acid, sodium carbonate, and lithium carbonate – is designed to simultaneously meet 14 different property constraints and 7 optimization parameters for effective plant operations. Once processed, the resulting glass will be ready for long-term storage in a deep geologic repository.

The algorithm was delivered to Bechtel National, Inc., the contractor in charge of commissioning the WTP, and was accepted by the DOE glass scientist. With the completion of this algorithm, DOE and BNI are positioned to formulate the HLW glass once plant construction is complete.

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