Melting Behavior of Direct‐Feed High‐Level Waste Melter Feeds

ABSTRACT The direct‐feed high‐level waste (DFHLW) vitrification process at the Waste Treatment and Immobilization Plant will process millions of gallons of nuclear waste stored underground at the Hanford site. This study examines DFHLW melter feeds, with glass yields ranging from 222 to 754 g glass L −1 waste, investigating their melting behavior through feed expansion, evolved gas analysis, and thermal characterization. Water content was shown to have the largest effect on total conversion enthalpy and glass production rates. While foam onset temperature, bottom temperature, and total volume varied between the feeds, the impact on the final predicted glass production rate was considerably less than the impact of water content and resultant glass yield. These findings improve understanding melter feed performance based on glass yield and support refinement of models, including melt rate correlation for optimizing melter operation. Future scaled testing is recommended to validate results and optimize vitrification throughput.