The i-SANEX solvent formulation consisting of n ominally 0.2 M TODGA/5% 1octanol/dodecane was g-irradiated under realistic conditions in the INL radiolysis test loop, in contact with both extraction and stripping aqueous phases. The extraction aqueous phase was 4.5 2 M HNO 3 , and the stripping aqueous phase was 0.018 M SO 3-Ph-BTP/0.35 M HNO 3. When irradiated in contact with only the 4.5 M HNO 3 phase, the TODGA solvent maintained excellent extraction performance for americium, cerium, europium and neodymium to a maximum absorbed dose of nearly 0.9 MGy. The results for preliminary static, batch irradiations were consistent with test loop findings. When the aqueous phase was changed to that containing the aqueous soluble BTP, the irradiated aqueous phase showed a dramatic color change, but this does not appear to have had adverse effect on solvent extraction performance. The distribution ratios for both the lanthanides and actinides were invariant with a bsorbed dose, and the separation factors were essentially unchanged to a maximum absorbed dose of 174 kGy. The results of ICP-MS analysis of the aqueous and organic phases showed that ruthenium and strontium were not extracted in the presence of the irradiated BTP-aqueous phase. Molybdenum was extracted under both conditions. Further, the build-up of corrosion products of stainless steel in the presence of the BTP was not dramatically greater than in the nitric acid-only system. Phase separation times were not adversely affected by irradiation for either system. The results presented here indicate that the performance of the TODGA/SO 3-Ph-BTP, i-SANEX process under test loop radiolysis is much better than expected based on a literature report using singlephase batch irradiation experiments, and better than might be predicted base on DGA radiolysis studies alone.

Conversion of Idaho National Engineering and Environmental Laboratory radioactive sodium-bearing waste into a single solid waste form by evaporation was demonstrated in both flask-scale and pilot-scale agitated thin film evaporator tests. A sodium-bearing waste simulant was adjusted to represent an evaporator feed in which the acid from the distillate is concentrated, neutralized, and recycled back through the evaporator. The advantage to this flowsheet is that a single remote-handled transuranic waste form is produced in the evaporator bottoms without the generation of any low-level mixed secondary waste. However, use of a recycle flowsheet in sodium-bearing waste evaporation results in a 50% increase in remote-handled transuranic volume in comparison to a non-recycle flowsheet. iv SUMMARYConversion of surrogate Idaho National Engineering and Environmental Laboratory (INEEL) sodium-bearing waste (SBW) into a single solid waste form by evaporation was demonstrated in flask-scale and pilot-scale agitated thin film evaporator (ATFE) tests. The advantage to this flowsheet is that a single remote-handled transuranic (RH-TRU) waste form is produced without the generation of a secondary waste stream from the condensation of evaporator overheads (i.e., distillate).Producing a single waste form in this manner requires that acid in the evaporator overheads be concentrated, neutralized, and recycled. This report presents results from the flask-scale and pilot-scale ATFE tests that were run to evaluate an "SBW with overhead recycle evaporation flowsheet." Three different surrogate waste feeds were tested at the flask-scale including simulated waste feed compositions that would result from neutralizing the overheads with sodium, aluminum, or magnesium and blending this recycle stream with simulated SBW. The flask-scale tests were completed to identify appropriate mass reduction ratios for each of the three recycle flowsheets. Solid evaporator bottoms product characteristics, such as pourability, solidification capability, and product toughness (e.g. hardness, non-friable/monolithic), were evaluated for acceptability. This included an evaluation of the effects of overhead recycle on bottoms product characteristics. The SBW with aluminum and magnesium recycle flowsheets yielded bottom waste form products with acceptable characteristics. However, the SBW with sodium recycle flowsheet feed formed crystals in the evaporation flask and had to be concentrated more than the others to produce a solid bottoms waste form upon cooling. Based on the results of the flask-scale tests, only the aluminum and magnesium recycle feeds were tested in the pilot-scale ATFE.ATFE pilot-scale tests yielded bottoms product with desirable characteristics for both of the simulated waste feeds tested. However, neutralizing with magnesium oxide would be the preferred choice for producing a single waste form with overhead recycle. The original concept of direct evaporation was based on the ability of aluminum nitrate to chemically bond with nine m...

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