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This system simuZates radioactive sodium saZt wastes stored in underground tanks at Sanford. Equitibrium water vapor pressure of the aqueous phase and solub€Zity of the saZts were measured. as a function of temperaturo and NaOH concentration.These data are used to predict deZiquescence of stored saZt.wastes and also to predict the chemicaZ / identity of soZid residues from evaporation of Ziquid wastes.

RHO-REST -1 P WER Effects of H anford High-Level ft W aste Com ponents on Sorption o f Cobalt, S tro ntium , N eptunium , Plutonium , and A m ericium on H anford Sedim ents

Large quantities of organic chemicals used in reprocessing spent nuclem&els at the Hanford Site have accumulated in udrground high-level radioactive waste tanks. The organic content of these tanks must be known so that the potential for hardous reactions between organic components and sodium nitrate/nim'te salts in the waste can be evaluated The solubilities of organic compound described in this reprt will help determine ifthey are present in the solidphases (salt cake and sludges) as well as the liquidphase (interstitial liquor/supernate) in the tanks. l2e solubilities offive significant sodium salts of carboxylic acids and aminocarboxylic acid [sodium oxalate, formate, citrate, nitrilotriacetate (NTA) and ethylendiaminetetraacetate (EDTA)] were measured in a simuhted supernate solution at 25 "c, 30 "c, 40 "c, and 50 "c. The organic compound were selected because they are expected to exist in relatively high concentrations in the tanks. The tank supernate simulant was a 4.0 usodium nitrate-0.9 7 usodium nitrite solution with sodium hyhoxide concentrations rangingfiom 0.00003Mto 2.0& Sodium oxalate solubilities were found to be relatively low and this compound could be expected to precipitate pom some tank supernate solutions. B e energy content of oxalate salts is, however, relatively small. Sodium formate, citrate, EDTA, andNTA solubilities are high and these salts are unlike& to precipitate under waste tank conditions. This conclusion is based on a comparison of measured total organic carbon (TOC) concentrations in actual tank supemates with the organic salt solubilities determined in this stue. Because these organic compoundr will onIy exist in aqueous supernate solutions, self-propagating reactions with nitrate or nitrite salts in the waste are unlike&. Also, haining the supernate Porn the waste tanks will lower the quantify of these organics le@ in the tanks. Solubilities of all the organic salts decrease with increasing sodium hyhoxide concentration due to the common ion efect of Nu+. In general, increasing temperatures raised the solubilities, although for sodium citrate and NTA the temperature efect was small.

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