Performance evaluation of 24 ion exchange materials for removing cesium and strontium from actual and simulated N-Reactor storage basin water

Abstract

This report describes the evaluation of 24 organic and inorganic ion exchange materials for removing cesium and strontium from actual and simulated waters from the 100 Area 105 N-Reactor fuel storage basin. The data described in this report can be applied for developing and evaluating ion exchange pretreatment process flowsheets. Cesium and strontium batch distribution ratios (h's), decontamination factors (DF), and material loadings (mmol 8') are compared as a function of ion exchange material and initial cesium concentration.The actual and simulated N-Basin waters contain relatively low levels of aluminum, barium, calcium, potassium, and magnesium (ranging from 8.33E-04 to 6.40E-05 m, with slightly higher levels of boron (6.63E-03 M) and sodium (1.62E-03 M). The I3%s level is 1.74E-06 Ci L-' which corresponds to approximately 4.87E-10 M Cs. The initial Na/Cs ratio was 3.33E+06. The concentration of total strontium is 4.45E-06 M. while the %r radioactive component was measured to be 6.13E-06 Ci L-'.Simulant tests were conducted by contacting 0.067 g or each ion exchange material with approximately 100 mL of either the actual or simulated N-Basin water. The simulants contained variable initial cesium concentrations ranging from 1.00E-04 to 2.57E-10 M Cs while all other components were held constant.For all materials, the average cesium & was independent of cesium concentration below approximately 1 .OK06 M. Above this level, the average cesium I(d values decreased significantly. Cesium I(d values exceeding 1 .OE+07 mL g-' were measured in the simulated N-Basin water. However, when measured in the actual N-Basin water the values were several orders of magnitude lower, with a maximum of 1.24E+05 mL g-' observed. Several materials, including a potassium cobalt hexacyanoferrate (KCoHex), inorganic zeolites, crystalline silicotitanates, biotite micas, pharmacosiderites, and phlogopites exhibited substantial affinity for cesium. The nonspecific cation exchange materials did not show an appreciable affinity for cesium in the basin water.Because of the high levels of nonradioactive strontium and calcium, the strontium I& results were much lower (e.g., between 1 .OE+03 and 1 .OE+05 mL g-') than those for the cesium. The strontium I(d and loading were inversely correlated to the cesium concentration (increasing with decreasing concentration from 1.OE-04 to 1 .Os09 M Cs). The data suggest that either the two ions compete for similar ion exchange sites or the higher cesium loading perturbs the strontium sites such that the strontium exchange process is hindered.... SummaryThis report describes evaluations of the radionuclide uptake capability of several newly produced ion exchange materials under actual waste solution conditions and compares the results obtained with these materials to those obtained with other commercial and experimental exchangers. The ion exchange materials are being evaluated for their performance in treating water from the 105 N-Reactor basin at Hanford. Actual and simulated basin water was us...

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