Savannah River site experiment

As was mentioned before, Arey et al. [19] conducted batch equilibration experiments to evaluate the ability of hydroxyapatite to remove uranium from contaminated sediments at the Savannah River Site of DOE and showed that removal of U was due to secondary phosphate minerals that had solubility even lower than autunite (Ca(U02)2(P04)2- IOH2O). The authors suggest formation of Al/Fe secondary phosphate. A similar conclusion was reached by Fuller et al. [20], who showed that uranyl ions can be removed by using hydroxyapatite. 

The most important consideration in tank design is minimization of corrosion. Originally two storage philosophies were believed to be equally safe in this respect (1) neutralized waste in mild steel tanks and (2) acid waste in stainless steel tanks. Almost three decades of experience have proved that only the latter satisfies all safety requirements. No leakage from stainless steel tanks has become known, whereas 20 out of 183 mild steel tanks at the Hanford and Savannah River sites developed leaks [L2]. It is now generally accepted that a minimum conosion rate can be maintained with suitable types of stainless steel and nitric acid concentrations in the range of 2 to 4 Af. If the HNO3 concentration falls below 1 M stress corrosion due to chloride ions may be promoted. 

Real waste batch tests conducted at the Savannah River Site provided the concentrations of major components (sodium, potassium, cesium, hydroxide, and nitrate) of the waste. From these results, simulants were prepared using either nitrite or chloride. These initial concentrations were entered into a data file, and the program SXFIT predicted the cesium distribution ratio based on all the species and formation constants presented above. Table 10 presents the comparison between the measured distribution ratios and those that were predicted. The O/A volume ratios were all 113. All experiments were carried out at 25°C. 

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