PERFORMANCE ASSESSMENT FOR THE DUST RECYCLING SYSTEM DURING VITRIFICATION OF SIMULATED NON-RADIOACTIVE WASTE

摘要

For utilizing vitrification to treat low and intermediate level waste, industrial pilot plant was designed and constructed in October 1999 at Daejon, Korea through the joint research program among NETEC, MOBIS and SGN. More than 70 tests were performed on simulated IER, DAW, borate concentrates and sludges including key nuclide surrogate(Cs, Co); this plant has been shown to vitrify the target waste effectively and safely, however, some dust are generated from the HTF(High Temperature Filter) as a secondary waste. In this regard, we have needed to develop the special complementary system of the primary off-gas treatment system to recycle the dust from HTF to CCM(Cold Crucible Melter). Main concept of the dust recycling is to feed the dust to the CCM as a slurry state; this system is regarded as of an important position in the viewpoint of volume reduction, waste disposal cost and glass melt control in CCM. The role of DRS(Dust Recycling System) is to recycle the major glass components and key nuclides like B, Na, Li, Cs, Co; this system is served to lower glass viscosity and increase waste solubility by recycling B, Na, Li components into glass melt and also to re-entrain and incorporate into glass melt like Cs, Co. Therefore dust recycling is helpful to control the molten glass; it is unnecessary to consider a separate dust treatment system like a cementation equipment. During the pilot vitrification test, overall performance assessment was successfully performed; slurry type of DRS is found to be useful for the recycling the dust from HTF; the obtained operational data like slurry concentration, process variables with DRS and DRS operation experiences will be used as a basis of the commercial design.