ISSN 0862-5468 (Print), ISSN 1804-5847 (online) 

Ceramics-Silikáty 37, (3) 137 - 143 (1993)


VITRIFICATION OF SIMULATED INTERMEDIATE-LEVEL WASTE FROM NUCLEAR POWER PLANTS - PART II. CHEMICAL STABILITY OF VITRIFIED PRODUCTS IN ACIDIC SOLUTIONS
 
Hlaváč Jan, Michajlovič Jaroslav, Škrovánková-Rohanová Dana
 
Institute of Chemical Technology, Department of Glass and Ceramics, Technická 5, 166 28 Prague 6

Leaching of glasses of the basic system SiO₂-B₂O₃-Al₂O₃-Na₂O in water and in solutions of mineral acids was studied. All of the tests were carried out on ground samples (0.315-0.50 mm). The solutions were analyzed for SiO₂ and Na₂O content and their pH was measured. The static tests showed that the intensity of leaching was raised in acidic solutions having pH=2 compared to leaching in water. More detailed investigations using the flow method and acidic solutiouns of pH 2, 3 and 4 demonstrated a substantial increase in the leaching rate of alkalies with decreasing pH of the solution; at the same time, the SiO₂:Na₂O ratio in the solution changed. With weakly acidic solutions, their pH is shifted to the alkaline region by the extracted alkalies. A significant decrease of resistance to acidic solutions occurs at pH < 4; at pH = 2, the extracted amounts of Na₂O are much higher than those in water.


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