Cold Dissolved Saltcake Waste Simulant Development, Preparation, and Analysis
- BATTELLE (PACIFIC NW LAB)
CH2M Hill Hanford Group, Inc. is identifying and developing supplemental process technologies to accelerate the Hanford tank waste cleanup mission. Bulk vitrification, containerized grout, and steam reforming are three technologies under consideration for treatment of the radioactive saltcake wastes in 68 single-shell tanks. To support development and testing of these technologies, Pacific Northwest National Laboratory (PNNL) was tasked with developing a cold dissolved saltcake simulant formulation to be representative of an actual saltcake waste stream, preparing a 25-L batch of the simulant, and analyzing the composition of the batch to assure conformance to formulation targets. Lacking a defined composition for dissolved actual saltcake waste, PNNL used available tank waste composition information and an equilibrium chemistry model (Environmental Simulation Program, ESP) to predict the concentrations of analytes in solution. Observations of insoluble solids in initial laboratory preparations for the model predicted formulation prompted minor modifications in the concentration of phosphate and silicon in the final simulant formulation. The analytical results for the 25-L simulant batch agree within the expected measurement accuracy (~10%) of the target concentrations and are highly consistent for replicate measurements, with a few minor exceptions. The instrumental analyses indicate that the batch of solution adequately reflects the as-formulated simulant composition. In parallel with the simulant development effort, a nominally 5-M (molar) sodium actual sodium waste solution was prepared at the Hanford site from a limited number of tank waste samples. Since this actual waste solution was also to be used for testing of the supplemental treatment technologies, the modeled simulant formulation was predicated on the composite of waste samples used to prepare it. Subsequently, the actual waste solution was filtered and pretreated to remove radioactive cesium at PNNL and then analyzed using the same instrumentation and procedures applied to the simulant samples. The overall agreement of measured simulant and actual waste solution compositions is better than 10% for the most concentrated species including sodium, nitrate, hydroxide, carbonate, and nitrite. While the magnitude of the relative difference in the simulant and actual waste composition is large (>20% difference) for a few analytes (aluminum, chromium, fluoride, potassium, and total organic carbon), the absolute differences in concentration are in general not appreciable. Our evaluation is that these differences in simulant and actual waste solutions should have a negligible impact on supplemental treatment process testing.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 15003618
- Report Number(s):
- PNNL-14194; 820201000
- Country of Publication:
- United States
- Language:
- English
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