Corrosion of Glass-Bonded Sodalite as a Function of pH and Temperature

Abstract

This paper reports the results of corrosion tests with glass-bonded sodalite, a ceramic waste form (CWF) that is being developed to immobilize radioactive electrorefiner salt used to condition spent sodium-bonded nuclear fuel, and with sodalite and binder glass, the two major components of the CWF. These tests were performed with dilute pH-buffered solutions in the pH range of 5-10 at temperatures of 70 and 90°C to determine the pH dependences of the forward dissolution rates of the CWF and its components. The tests show that the pH dependences of the dissolution rates of sodalite, binder glass, and glass-bonded sodalite are similar to the pH dependence of dissolution rate of borosilicate nuclear waste glasses, with a negative pH dependence in the acidic region and a positive pH dependence in the basic region. The dissolution rates are higher at 90°C than at 70°C. Our results on the forward dissolution rates and their temperature and pH dependences will be used as components of a waste form degradation model to predict the long-term behavior of the CWF in a nuclear waste repository.