Hydrothermal dissolution of nonmetallic materials for nuclear fuel waste immobilization containers

Hydrothermal dissolution of nonmetallic materials was studied as part of a program to evaluate their potential use as container materials for the very long term containment of nuclear fuel waste under conditions of deep geological disposal. Samples of two grades of Al2O3, stabilized ZrO2, TiO2, porcelain and two concretes have been leached in Standard Canadian Shield Saline Solution (SCSSS), SCSSS plus 20% Na-bentonite and SCSSS plus 20% Na-bentonite/20% sand mixture under static conditions at 125 degrees Celsius and 150 degrees Celsius and 8.9 MPa pressure for periods up to 42 days. These studies have confirmed that some of these materials are highly resistant to corrosion. The highest resistance was exhibited by Al2O3 materials and MgO-stabilized ZrO2. The leach rates range from 0.48 x 10-10 kg·m-2·s-1 to 7.32 x 10-10 kg·m-2·-1 and 1.5 x 10-10 kg·m-2·s-1 to 21.9 x 10-10 kg·m-2·s-1, respectively. Evaluation of the leaching data showed that concrete materials are much less resistant to attack by hydrothermal solutions than are the other materials