HIGH LEVEL WASTE (HLW) SLUDGE BATCH 4 (SB4) WITH FRIT 418: RESULTS OF A PHASE II VARIABILITY STUDY

Fox, K ; Tommy Edwards, T ; David Peeler, D ; David Best, D ; Irene Reamer, I ; Phyllis Workman, P

Savannah River Site (S.C.)

关键词: Sludges;    Chemical Composition;    Waste Forms;    36 Materials Science;    Radioactive Waste Processing;   

DOI  :  10.2172/918141
RP-ID  :  WSRC-STI-2006-00329
RP-ID  :  DE-AC09-96SR18500
RP-ID  :  918141

美国|英语

来源: UNT Digital Library

【 摘 要 】

In early October 2006, the Liquid Waste Organization (LWO) began to consider decanting Tank 40 at the end of Sludge Batch 3 (SB3) processing and transferring the aqueous phase from the decant to Tank 51. This transfer would be done to remove water added to Tank 40 by a slurry pump bearing water leak. Tank 40 decant water would be used to decrease Tank 51 yield stress and facilitate a transfer of Tank 51 to Tank 40. The projected composition of Sludge Batch 4 (SB4) was adjusted by LWO to reflect the impact of the Tank 40 decant leading to new projected compositions for SB4, designated as the 10-04-06 and the 10-10-06 compositions. A comparison between these SB4 compositions and those provided in June 2006 indicated that the new compositions are slightly higher in Al2O3, Fe2O3, and U3O8 and slightly lower in SiO2. The most dramatic change, however, is the new projection's Na2O concentration, which is more than 4.5 wt% lower than the June 2006 projection. This is a significant change due to the frit development team's approach of aligning the Na2O concentration in a candidate frit to the Na2O content of the sludge. Questions surfaced regarding the applicability of Frit 503 to these revised compositions since the Savannah River National Laboratory (SRNL) recommended Frit 503 for use with SB4 based on the June 2006 compositional projection without the Tank 40 decant. Based on paper study assessments, the change in SB4's expected Na2O content had a significant, negative impact on the projected operating window for the Frit 503/SB4 glass system. Frit 418 had a slightly larger operating window for the 10-04-06 projection (as compared to a lower Na2O frit, Frit 503) and the Frit 418/10-04-06 glass system was no longer nepheline limited. Thus, strictly from the perspective of this paper study, Frit 418 was more attractive than Frit 503 for the new SB4 projected compositions. This comparison, however, did not reflect other aspects of interest for the glass systems such as their respective melt rates or the development of alternative frits to balance the projected operating windows, melt rate, waste throughput, and robustness to compositional variation. In discussions with Waste Solidification Engineering (WS-E) regarding the paper study results, their decision was to utilize Frit 418 for initial processing of SB4. This decision was not only based on the paper study assessments, but also on the fact that Frit 418 is currently being used to process SB3 and, perhaps more importantly, frit optimization efforts for SB4 may be premature given the uncertainties in tank transfers, volumes, and any operational issues associated with the decant transfer from Tank 40 to Tank 51 and the sludge transfer from Tank 51 to Tank 40. Given this decision and recognizing that a SB4/Frit 503 variability study had been initiated as part of the qualification process, questions regarding the need for a supplemental variability study to demonstrate applicability of the process control models for a Frit 418 based system surfaced. In response to the change in the projected composition for SB4 and the selection of Frit 418 by WS-E, SRNL complemented the SB4/Frit 503 variability study with 13 additional glasses using Frit 418. The composition region for the new glasses (or the SB4/Frit 418 variability study) was determined using the October 2006 projections of the SB4 composition.