Method for qualifying canisters of vitrified high-level waste for disposal

A method for controlling and predicting the composition of high-level nuclear waste borosilicate glass produced in a liquid-fed ceramic melter process has been investigated by simulating process operations. A control algorithm was developed in which upstream sampling of the waste was used to determine the amounts of glass-forming compounds to add to the waste to adjust the decay heat loading and boron loading in the glass to desired levels. In the simulation, the predicted glass composition was based on samples taken of the melter feed (the combined glass former and waste mixture). The error found between the predicted and true (e.g., resulting from the simulation) compositions of various glass components was 2 to 8%, depending on the feed sampling strategy used and on estimated standard deviations of stochastic process parameters. Such errors are estimated to increase the error in the predicted long-term durability of the glass by 7 to 64%.