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This article describes the solution to a unique and challenging mixture experiment design problem involving (1) 19 and 21 components for two different parts of the design, (2) many single-component and multicomponent constraints, (3) augmentation of existing data, (4) a layered design developed in stages, and (5) a no-candidate-point optimal design approach. The problem involved studying the liquidus temperature of spinel crystals as a function of nuclear waste glass composition. A D-optimal approach was used to augment existing glasses with new nonradioactive and radioactive glasses chosen to cover the designated nonradioactive and radioactive experimental regions. The traditional approach to building D-optimal mixture experiment designs is to generate a set of candidate points from which design points are D-optimally selected. The large number of mixture components (19 or 21) and many constraints defining each layer of the waste glass experimental region made it impossible to generate and store the huge...

This report is the last in a series of currently scheduled reports that presents the results from the High Level Waste (HLW) glass formulation development and testing work performed at the Vitreous State Laboratory (VSL) of the Catholic University of America (CUA) and the development of IHLW property-composition models performed jointly by Pacific Northwest National Laboratory (PNNL) and VSL for the River Protection Project-Waste Treatment and Immobilization Plant (RPP-WTP). Specifically, this report presents results of glass testing at VSL and model development at PNNL for Product Consistency Test (PCT), one-percent crystal fraction temperature (T1%), electrical conductivity (EC), and viscosity of HLW glasses. The models presented in this report may be augmented and additional validation work performed during any future immobilized HLW (IHLW) model development work. Completion of the test objectives is addressed.

The Hanford Site in Washington State manages 177 underground storage tanks containing approximately 250,000 m3 of waste generated during past defense reprocessing and waste management operations. These tanks contain a mixture of sludge, saltcake and supernatant liquids. The insoluble sludge fraction of the waste consists of metal oxides and hydroxides and contains the bulk of many radionuclides such as the transuranic components and 90Sr. The saltcake, generated by extensive evaporation of aqueous solutions, consists primarily of dried sodium salts. The supernates consist of concentrated (5-15 M) aqueous solutions of sodium and potassium salts. The 177 storage tanks include 149 single-shell tanks (SSTs) and 28 double -hell tanks (DSTs). Ultimately the wastes need to be retrieved from the tanks for treatment and disposal. The SSTs contain minimal amounts of liquid wastes, and the Tank Operations Contractor is continuing a program of moving solid wastes from SSTs to interim storage in the DSTs. The Hanford DST system provides the staging location for waste feed delivery to the Department of Energy (DOE) Office of River Protection’s (ORP) Hanford Tank Waste Treatment and Immobilization Plant (WTP). The WTP is being designed and constructed to pretreat and then vitrify a large portion of the wastesmore » in Hanford’s 177 underground waste storage tanks.« less

The U.S. Department of Energy (DOE) Office of River Protection’s Waste Treatment Plant (WTP) will process and treat radioactive waste that is stored in tanks at the Hanford Site. The waste treatment process in the pretreatment facility will mix both Newtonian and non-Newtonian slurries in large process tanks. Process vessels mixing non-Newtonian slurries will use pulse jet mixers (PJMs), air sparging, and recirculation pumps. An anti-foam agent (AFA) will be added to the process streams to prevent surface foaming, but may also increase gas holdup and retention within the slurry. The work described in this report addresses gas retention and release in simulants with AFA through testing and analytical studies. Gas holdup and release tests were conducted in a 1/4-scale replica of the lag storage vessel operated in the Pacific Northwest National Laboratory (PNNL) Applied Process Engineering Laboratory using a kaolin/bentonite clay and AZ-101 HLW chemical simulant with non-Newtonian rheological properties representative of actual waste slurries. Additional tests were performed in a small-scale mixing vessel in the PNNL Physical Sciences Building using liquids and slurries representing major components of typical WTP waste streams. Analytical studies were directed at discovering how the effect of AFA might depend on gas composition and predicting the effect of AFA on gas retention and release in the full-scale plant, including the effects of mass transfer to the sparge air. The work at PNNL was part of a larger program that included tests conducted at Savannah River National Laboratory (SRNL) that is being reported separately. SRNL conducted gas holdup tests in a small-scale mixing vessel using the AZ-101 high-level waste (HLW) chemical simulant to investigate the effects of different AFAs, their components, and of adding noble metals. Full-scale, single-sparger mass transfer tests were also conducted at SRNL in water and AZ-101 HLW simulant to provide data for PNNL’s WTP gas retention and release modeling.

The capacity of the waste treatment plant (WTP) being built at the Hanford Site is not sufficient to process all of the tank waste accumulated from more than 40 years of nuclear materials production. Bulk vitrification can accelerate tank waste treatment by providing some supplemental low-activity waste (LAW) treatment capacity. Bulk vitrification combines LAW and glass-forming chemicals in a large metal container and melts the contents using electrical resistance heating. A castable refractory block (CRB) is used along with sand to insulate the container from the heat generated while melting the contents into a glass waste form. This report describes engineering-scale (ES) and full-scale (FS) tests that have been conducted. Several ES tests showed that a small fraction of soluble Tc moves in the CRB and results in a groundwater peak different than WTP glass. The total soluble Tc-99 fraction in the FS CRB is expected to be different than that determined in the ES tests, but until FS test results are available, the best-estimate soluble Tc-99 fraction from the ES tests has been used as a conservative estimate. The first FS test results are from cold simulant tests that have been spiked with Re. An estimated scale-up factor extrapolatesmore » the Tc-99 data collected at the ES to the FS bulk vitrification waste package. Test FS-38A tested the refractory design and did not have a Re spike. Samples were taken and analyzed to help determine Re CRB background concentrations using a Re-spiked, six-tank composite simulant mixed with soil and glass formers to produce the waste feed. Although this feed is not physically the same as the Demonstration Bulk Vitrification System feed , the chemical make-up is the same. Extensive sampling of the CRB was planned, but difficulties with the test prevented completion of a full box. An abbreviated plan is described that looks at duplicate samples taken from refractory archive sections, a lower wall sample, and two base samples to gain early information about Re and projected Tc-99 levels in the FS box.« less

This study evaluated the feasibility of transferring waste now stored in Tank SY-101 in the 200 West Area of the Hanford Site to a storage tank in 200 East Area through a 6.2-mile-long, 3-inch-diameter stainless steel pipeline. Using the Wasp slurry transport model, the critical velocity and expected pressure drop were calculated to determine 1) whether current SY-101 waste can be transferred through the existing cross-site transfer pipeline without additional dilution and, if it is not possible, how much dilution is needed.