High-Level Waste (HLW) is a waste associated with the dissolution of spent nuclear fuel for the recovery of weapons-grade material. It is the priority problem for the U. , on MST, which were added (individually) from stock solutions of Sr and 238 U(VI) with spectroscopic and transmission electron microscopic techniques. The local structural speciation of sorbed U varied with loading and but not for Sr. Sorbed Sr exhibited specific adsorption as partially-hydrated species whereas sorbed U exhibited specific adsorption as monomeric and dimeric U(VI)-carbonate complexes. Sorption proved site specific. These differences in site specificity and sorption mechanism may account for the difficulties associated with predicting Sr and U loading and removal kinetics using MST.

High-level nuclear waste produced from fuel reprocessing operations at the Savannah River Site (SRS) requires pretreatment to remove Pu. This paper provides a summary of data acquired to measure the performance of MST to remove strontium and actinides from simulated waste solutions. These tests evaluated the influence of ionic strength, temperature, solution composition and the oxidation state of plutonium.

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Pretreatment processes at the Savannah River Site will separate 90 Sr, alpha-emitting and radionuclides (i.e., actinides) and 137Cs prior to disposal of the high-level nuclear waste.Separation of 90 Sr and alpha-emitting radionuclides occurs by ion exchange/adsorption using an inorganic material, monosodium titanate (MST). Previously reported testing with simulants indicates that the MST exhibits high selectivity for strontium and actinides in high ionic strength and strongly alkaline salt solutions. This paper provides a summary of data acquired to measure the performance of MST to remove strontium and actinides from actual waste solutions. These tests evaluated the effects of ionic strength, mixing, elevated alpha activities, and multiple contacts of the waste with MST. Tests also provided confirmation that MST performs well at much larger laboratory scales (300 2 -700 times larger) and exhibits little affinity for desorption of strontium and plutonium during washing.3

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