REAL WASTE TESTING OF SPHERICAL RESORCINOL-FORMALDEHYDE ION EXCHANGE RESIN

This report presents data on batch contact and column testing tasks for spherical resorcinol-formaldehyde (sRF) resin. The testing used a non-radioactive simulant of SRS Tank 2F dissolved salt, as well as an actual radioactive waste sample of similar composition, which are both notably high in sodium (6 M). The resin was Microbeads batch 5E-370/641 which had been made on the hundred gallon scale. Equilibrium batch contact work focused on cesium at a temperature of 25 C due to the lack of such data to better benchmark existing isotherm models. Two campaigns were performed with small-scale ion exchange columns, first with Tank 2F simulant, then with actual dissolved salt in the Shielded Cells. An extrapolation of the batch contact results with radioactive waste over-predicted the cesium loaded onto the IX sRF resin bed by approximately 11%. This difference is not unexpected considering uncertainties from measurement and extrapolation and because the ion exchange that occurs when waste flows through a resin bed probably cannot reach the same level of equilibrium as when waste and resin are joined in a long term batch contact. Resin was also characterized to better understand basic chemistry issues such as holdup of trace transition metals present in the waste feed streams. The column tests involved using two beds of sRF resin in series, with the first bed referred to as the Lead column and the second bed as the Lag column. The test matrix included two complete IX cycles for both the simulant and actual waste phases. A cycle involves cesium adsorption, until the resin in the Lead column reaches saturation, and then regenerating the sRF resin, which includes eluting the cesium. Both the simulated and the actual wastes were treated with two cycles of operation, and the resin beds that were used in the Lead and Lag columns of simulant test phase were regenerated and reused in the actual waste test phase. This task is the first to demonstrate the treatment of SRS waste with sRF resin and the tests clearly demonstrated cesium decontamination for actual waste. The results of the column tests were similar for both the simulated and the actual waste and demonstrated Cs removal with sRF from both wastes. For a flowrate of 1.4 bed volumes (BV)/hour at 25 C those results with sRF resin were: (1) Simulant and actual waste results are equivalent; (2) Cs breakthrough began between 200 and 250 BV; (3) Cs breakthrough reached 100% at around 400 BV; (4) Cs breakthrough curve from 5% to 100% is approximately linear; (5) Cs elution with 0.5 M HNO3 starts at 2 BV and ends at 6BV; (6) Most, if not all, of Cs adsorbed during treatment is released during elution; (7) At 100% breakthrough of Cs the resin bed adsorbs approximately 85% of full capacity before detection in the effluent; the remaining 15% is adsorbed at saturation; (8) Approximately 90% of resin bed changes (color and volume) are complete by 6 BV; and (9) During elution the resin shrinks to about 80% of its fully working (sodium form) BV