Improvements in design and operation of bubblers in the Savannah river site defense waste processing facility melter - 15163
In order to accelerate the closing of High Level Waste (HLW) tanks at the Savannah River Site (SRS), it was necessary to process more waste throughout the SRS liquid waste facilities. Therefore the Defense Waste Processing Facility (DWPF) needed to increase its production rate of radioactive waste glass filled canisters. To attain the increased production rate, four bubblers were installed in the DWPF Melter in September 2010 to agitate the DWPF Melter glass pool. The four bubblers were designed to be installed in existing nozzles on the top-head of the DWPF Melter. After a few years of successful operation with the original design, several changes have been made to the bubblers. The main change allows for the lower end (inside melter) of the bubbler to be replaced while the top end (outside melter) of the bubbler can be reused. This minimizes cost and waste at the DWPF. Material testing of the Inconel 690 bubbler pipes of used lower bubblers has been performed. Based on the material testing and issue with the integrity of some lower bubbler pipes used in the melter, a protective sleeve at the melt line was also added. Other changes for operational improvement or cost savings have also been made. Overall, performance of the bubblers continues to be excellent as canister production records have been achieved at the DWPF due in large part to the use of bubblers. (authors)