Thermal shock resistance of a simulated high-level waste glass

Thermal shock resistance of a simulated high-level waste glass was examined by water quenching in the range of the temperature difference up to 6000C. The observation of cracks revealed that there existed two critical temperature differences. One was the threshold temperature difference of 740C above which surface cracks appeared. The other was the temperature difference of 6000C at which cracks were propagated markedly and the specimen broke down into many pieces. In the range of the temperature difference of 740C to 6000C, the surface area of cracks on the surface of the quenched specimens increased with increasing temperature difference. However, the fractional release of sodium and cesium from the quenched specimens was almost constant in the range of the temperature difference up to 5000C, and it increased markedly at the temperature difference of 6000C. These facts indicate that sodium and cesium do not leach out from the cracks when the separation of fracture surfaces is small