Hanford River Protection Project Waste Research Articles

Characterization of SuperLig® 639 Rhenium and Technetium Resin with Batch Contact and Column Tests

Two new (2013) lots of SuperLig® 639 ion exchange resin (IBC Advanced Technologies, American Forks, UT) were tested for the first time above typical sodium concentrations (7.8 M sodium, along with typical 5 M concentration) in highly alkaline solutions. Batch contact and ion exchange column tests characterized rhenium (perrhenate) adsorption as a surrogate for pertechnetate. The work supports technetium removal options for Supplemental Low Activity Waste processing at the Hanford River Protection Project Waste Treatment Plant (WTP). The current work found that the resin performs well in the 7.8 M sodium simulant despite complete floating of the beads. A notable difference in performance between the two new resin lots was found. Resin loading overall versus temperature, potassium concentration, and rhenium/nitrate ratios is consistent with previous data and expectations despite the high sodium concentration and floating of the resin beads.

Characterization of Spherical Resorcinol-Formaldehyde Resin Cesium Adsorption with Batch Contact Tests

Batch contact tests provided data that will be useful in cesium isotherm modeling of spherical resorcinol-formaldehyde ion exchange resin. This resin is the baseline for cesium removal from alkaline high sodium nuclear waste at the Hanford River Protection Project Waste Treatment Plant and is being considered for other applications. Batch contact work at 25°C found that increasing potassium concentration in alkaline solution simulating waste unexpectedly improves cesium adsorption when cesium concentration exceeds about 0.001 M. At lower cesium levels potassium competes with cesium for adsorption on the resin as expected. Additional batch work found that dimethylamine cation competes strongly with sodium adsorption with no significant reduction in cesium adsorption.

Column Performance Testing of SuperLig® 639 Resin with Simulated Hanford Waste Supernates: Identification of the Primary Sorbing Species and Detailed Characterization of Their Desorption Profiles

:Several benchscale column tests (resin bed volume ≤75 mL) have been conducted with SuperLig® 639 resin and simulated U.S. Department of Energy tank waste supernates. Rhenium (surrogate for technetium in actual waste samples) breakthrough profiles were determined for three simulant compositions, which are representative of the basic waste categories requiring treatment in the Hanford River Protection Project Waste Treatment Plant. Considerable loading performance variability was observed between the three waste types, although the resin is effective at rhenium removal from each solution. Careful and frequent analysis during elution studies conducted at the conclusion of the column loading tests confirmed that sodium nitrate and sodium perrhenate ion pairs are primary sorbing species on SuperLig® 639 resin. Furthermore, it was discovered that potassium nitrate and potassium perrhenate salts are significant competitors for sorption sites on the resin. Successive desorption profiles were identified for all four salt species during elution tests. Integration of the desorption profiles revealed that the resin is selective for removal of the potassium salts over the sodium salts.

Regulatory Off-Gas Analysis from the Evaporation of Hanford Simulated Waste Spiked with Organic Compounds

After strontium/transuranics removal by precipitation followed by cesium/technetium removal by ion exchange, the remaining low-activity waste in the Hanford River Protection Project Waste Treatment Plant is to be concentrated by evaporation before being mixed with glass formers and vitrified. To provide a technical basis to permit the waste treatment facility, a relatively organic-rich Hanford Tank 241-AN-107 waste simulant was spiked with 14 target volatile, semi-volatile, and pesticide compounds and evaporated under vacuum in a bench-scale natural circulation evaporator fitted with an industrial stack off-gas sampler at the Savannah River National Laboratory. An evaporator material balance for the target organics was calculated by combining liquid stream mass and analytical data with off-gas emissions estimates obtained using U.S. Environmental Protection Agency (EPA) SW-846 Methods. Volatile and light semi-volatile organic compounds (<220 °C BP, >1 mm Hg vapor pressure) in the waste simulant were found to largely exit through the condenser vent, while heavier semi-volatiles and pesticides generally remain in the evaporator concentrate. An OLI Environmental Simulation Program (licensed by OLI Systems, Inc.) evaporator model successfully predicted operating conditions and the experimental distribution of the fed target organics exiting in the concentrate, condensate, and off-gas streams, with the exception of a few semi-volatile and pesticide compounds. Comparison with Henry's Law predictions suggests the OLI Environmental Simulation Program model is constrained by available literature data.