Tailoring nuclear waste glass properties for joule heated ceramic Melter technique with bottom drain glass pouring

Detailed investigations during the glass formulation development for the future Diwopu plant are described. Three different glass formulations were developed including two base glasses for the different waste streams present at Diwopu site and a corresponding Start Glass that allows commissioning of the LFCM and later switch-over from glass production operation of the melter to idling mode for maintenance. The waste glasses have to possess similar physical properties to be processed within the same LFCM. Therefore, all three developed glasses were tailored to lie within given margins for rheological and electrical resistivity data as well as to allow a high waste glass loading and high chemical durability. Further in-depth research was conducted to clarify the crystallization behavior of the waste glasses as it is known that the crystallization tendency has to be minimized to exclude relevant impacts on the viscosity. Increase of the viscosity due to crystallization might otherwise lead to unfavorable conditions for the bottom drain up to blockage in the worst case.