Fate of Uranium during Sodium Aluminosilicate Formation under Waste Tank Conditions

Wilmarth, B

Savannah River Site (S.C.)

关键词: Removal;    Aluminium Silicates;    Uranium;    Radioactive Waste Storage;    Forecasting;   

DOI  :  10.2172/890191
RP-ID  :  WSRC-TR-2005-00412
RP-ID  :  DE-AC09-96SR18500
RP-ID  :  890191

美国|英语

来源: UNT Digital Library

【 摘 要 】

Experiments have been conducted to examine the fate of uranium during the formation of sodium aluminosilicate (NAS) when wastes containing high aluminate concentrations are mixed with wastes of high silicate concentration. Testing was conducted at varying degrees of uranium saturation. Testing examined typical tank conditions, e.g., stagnant, slightly elevated temperature (50 C). The results showed that under sub-saturated conditions uranium is not removed from solution to any large extent in both simulant testing and actual tank waste testing. There are data supporting a small removal due to sorption of uranium on sites in the NAS. Above the solubility limit the data are clear that a reduction in uranium concentration occurs with the formation of aluminosilicate. This uranium precipitation is fairly rapid and ceases when uranium reaches its solubility limit. At the solubility limit, it appears that uranium is not affected, but further testing might be warranted. Lastly, analysis of the uranium speciation in a Tank 49H set of samples showed the uranium to be soluble. Analysis of the solution composition and subsequent use of the Hobb's uranium solubility model indicated a uranium solubility limit of 32 mg/L. The measured value of uranium in the Tank 49H matched the model prediction.