A Comprehensive Study of the Solubility, Thermochemistry, Ion Exchange, and Precipitation Kinetics of NO3 Cancrinite and NO3 Sodalite

Colon, Carlos F. Joyce ; Navrotsky, Alexandra ; Krumhansl, James L. ; Nyman, May

Sandia National Laboratories

关键词: Evaporators;    Solubility;    12 Management Of Radioactive Wastes, And Non-Radioactive Wastes From Nuclear Facilities;    Sodium;    Liquid Wastes;   

DOI  :  10.2172/834993
RP-ID  :  EMSP-81959-2003
RP-ID  :  FG07-01ER63298
RP-ID  :  834993

美国|英语

来源: UNT Digital Library

【 摘 要 】

NO3 cancrinite and NO3 sodalite haves been found as a common sodium alumino-silicate forming in strongly caustic alkaline aqueous solutions associated with radioactive High Level Waste (HLW) stored in many underground tanks and also in nuclear waste treatment facilities such as the Savannah River Site (SRS). The precipitation of alumino-silicate phases from caustic nuclear wastes has proven to be problematic in a number of processes in waste treatment facilities including radionuclide separations (cementation of columns by aluminosilicate phases), tank emptying (aluminosilicate tank heels), and condensation of wastes in evaporators (aluminosilicate precipitates in the evaporators, providing nucleation sites for growth of critical masses of radioactive actinide salts). Therefore, in order to prevent their formation an assessment of the relative stability, formation kinetics, and the ion-exchange characteristics of these two phases in HLW solutions needs to be investigated. The goals of this project are to: (1) Develop a robust equilibrium thermodynamic framework to accurately describe and predict the formation of NO3 cancrinite and NO3 sodalite. (2) Provide a comprehensive characterization of the solid precipitation rates and mechanisms using novel spectroscopic (e.g., NMR) and thermochemical techniques in conditions encountered in HLW waste solutions. (3) Characterize the precipitation kinetics of the aluminosilicates and study the effects of temperature and fluid composition. (4) Investigate the ion exchange capacity of these zeolitic phases with respect to radionuclides and RCRA metal species.