PNNL

Abstract

Spinel sludge, which forms while vitrifying high-level waste, obstructs the flow of molten glass and damages the melter. The effectiveness of removing spinel sludge from a high-level waste glass melter depends on its rheological behavior. We prepared spinel sludge in a laboratory crucible by allowing spinel to settle from molten glass and measured the response of the sludge to shear using a rotating spindle viscometer. The shear stress increased nonlinearly with the velocity gradient (the shear rate) and with time at a constant velocity gradient, as is typical for a pseudoplastic rheopectic liquid. The apparent viscosity of the sludge substantially increased when RuO-2 needles were present.