Evaluating Residence Time for SuperLig(R) 644 Columns with Simulated LAW Envelope C (AN-107) Solution

摘要

A series of batch contact and column tests were conducted with new and aged Envelope C (AN-107) simulant using SuperLig{reg_sign} 644 resin. In addition to the batch contact tests, four column loading and elution tests were performed with aged Envelope C (AN-107) simulant to evaluate the effects of volumetric flow rate on cesium sorption. A single-column (2.7 cm i.d.) containing {approx} 100 mL of SuperLig 644{reg_sign} resin was used. The column test results show more than 100 BVs of simulated AN-107 feed can be processed at nominal flow rate of 3 BV/h before reaching 50% cesium breakthrough at the column outlet. The results from the column tests also revealed that iron was loaded onto the SuperLig{reg_sign} 644 resin. Since only small quantity of iron ({approx} 26 ppm) is present in AN-107 simulant, the presence of iron had obviously no impact on the cesium loading on SuperLig{reg_sign} 644 resin. Further monitoring of iron loading in the full-height pilot testing is recommended to understand the long-term impact of residual iron on resin stability. The first series of batch contact tests were aimed to determine the distribution coefficients (K{sub d} ) for cesium at various concentration levels (10.4, 74, and 131 mg/L). The lower concentration (10.4 mg/L) was likely to be encountered based on Best Basis Inventory data for Envelope C (AN-107) supernates. The high cesium concentrations ({approx}74 and 131 mg/L) were selected with the purpose of promoting particle diffusion control. The results showed that the cesium Kd values generally decreased with increasing initial concentration levels. A second series of batch contact tests were performed with fresh AN-107 simulant to determine the impact of AN-107 post-Sr/TRU filtration precipitation solids formation on the cesium ion exchange. The cesium K{sub d}s for the fresh simulant were comparable to those of the aged AN-107 in the same concentration ranges. The test results, therefore, did not reveal an impact of post-filtration solids formation on the cesium sorption. The final series of the batch contact tests were conducted to evaluate the extent of cosorption of uranium on the resin. The results from the present tests revealed that the uranium is sorbed onto the SuperLig{reg_sign} 644 resin. The {sup 238}U K{sub d} for AN-107 simulant containing 3.7 mg/L of {sup 238}U at cesium concentration levels of 10.4 and 68 mg/L were 540 and 708 mL/g, respectively. The cause of the increase in {sup 238}U K{sub d} at higher cesium concentration is unknown. Further monitoring of uranium sorption on SuperLig{reg_sign} 644 resin during AW-101 processing is recommended.