Dr. Steve Agnew, Principal Scientist at Columbia Energy, presented a research paper entitled, “Solubility Predictions for Sodium Nitrate from Water Activity for Hanford Tank Concentrates” at 2015 Waste Management Conference (, which is held annually in Phoenix, Arizona.

High-level waste tank space at Hanford Site is at a premium and evaporation campaigns regularly recover vital space by concentrating dilute waste. Prior to each evaporator campaign, assays of a boil down of a sample of tank liquid provide a planning basis for the evaporator campaign.

Although there are many well-established techniques for calculating electrolyte solubilities, or making solubility predictions, the complexity of Hanford electrolyte mixtures has proven challenging for such predictions.

About Columbia Energy – Solubility Predictions for Hanford Waste Tanks

Columbia Energy and Environmental Services (CEES), a woman-owned Tri-Cities engineering company has developed a novel approach for solubility predictions that promises to minimize the effort associated to sampling the waste before each evaporation campaign. The research is led by Dr. Agnew and consists an Excel spreadsheet model that conducts solubility predictions consistent with those obtained by concentrating the radioactive waste samples.

Accurate solubility predictions of water activity for these concentrates provides an alternative method for calculating solubilities and this work along with previous work has validated a relatively simple spreadsheet model for predicting the water activity of even these complex electrolyte mixtures.

Dr. Agnew’s research on solubility predictions for sodium nitrate (NaNO3) as well as other electrolytes ofHanford Tank concentrates has the potential to save Hanford considerable amounts of money and time. More accurate predictions for solubility mean fewer resources are needed for sampling and assay.

“The bottom line is Hanford has collected a lot of data on boiling down of tank waste before each evaporator campaign,” said Dr. Agnew, “one of the goals of the solubility model is to create a waste processing tool that will minimize that testing.”

“When you gain confidence with the tool and avoid additional sampling, that means you save those precious resources for other efforts,” said Dr. Agnew.

For more information and for all media related requests please contact Columbia Energy and Environmental Services.