WSRC-TR-2000-00144
Inverted Run Using the Cylindrical Induction Melter
D. H. Miller
Westinghouse Savannah River Company
Aiken, SC 29808
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I. Introduction
The base process for vitrification of the Am/Cm solution stored in F-canyon utilizes a process where cullet is initially charged to the melter followed by the addition of a batch from the precipitator. Task 3.05 of TTR-NMSS/SE-006, Additional Am-Cm Process Development Studies, requested the investigation of an upset condition in the process where the cullet was charged on top of the precipitate material. This report provides the process details for an inverted batch thereby satisfying Task 3.05.
II. Summary
The second 5" cylindrical induction melter (CIM5A) was used to perform the inverted run test. The run plan called for the precipitate batch to be added to the melter prior to charging the cullet. This situation could occur in MPPF by failing to add the cullet to the melter prior to batching the precipitate. The modified auto power program was used and the material was processed without incident. The small volume expansion that occurred was not noticeably different from that observed during a normal cullet run (cullet on bottom of melter with precipitate added to top). Pouring rates were similar to previous runs using the standard loading procedure.
III. Process Description
A ½" glass plug remained in the melter from the previous run. When oxalate batch CP-824 was dropped into the melter, the oxide bed height was 7-1/8" high with 2-3/8" free liquid. After the addition of 1315.4 grams of 25SrABS cullet, the solids bed height was 10" with 2" of free liquid. The solids bed height on a standard run is 8-1/2 to 9" with about 2" of free liquid. The modified power program, used since the new melter vessel was installed, was started to begin the drying process. The free liquid had boiled off by the 95 minute mark, which is within the normal operating window, but slightly longer than the most recent runs (85-90Min). The bed height was measured at 8-1/2" which is the normal value. Some oxides were visible on the cullet bed surface indicating a degree of mixing during the drying stage. The melter top was covered at the 251 minute mark with no problems observed to that point. At the 377 minute mark a small volume expansion occurred which brought the level to within 6-3/4" from the top of the melter. This occurs during standard runs and the surface of the foamy layer appeared similar to a standard run. The bubbler was inserted at the 381 minute mark with an argon flow of 1.5 scfh. At 389 minutes, the foamy layer was within 5" of the top which is normal. The layer quickly incorporated into the glass.
This run was selected to test the prototypic canister sealing technique, rather than pouring directly into a bucket of water. The weight scale was removed for easier access beneath the melter, so no pour rate data was collected. Pour initiation started 32 seconds after removal of the tip cooling air. The pour lasted approximately 6 and one half minutes and the melter contents were completely removed. The initiation and duration of the pour were similar to standard runs in the CIM5 vessel. Thirty grams of 49SrABS were added at the end to provide a glass seal for the drain tube..
Graphs showing the temperature profiles for the inverted run and a standard run are provided in the attached Figures 1 and 2. No significant differences are apparent.
IV. Recommendation
Although no detrimental effects were observed due to the inverted batching, the baseline process is still the preferred method. Administrative controls should be used to prevent a batching error. Since a camera is currently in the canyon design, visual verification of the presence of cullet before precipitate addition is recommended.
V. Attachments
VI. References