Preliminary Investigation of Sulfur Loading in Hanford LAW Glass

Vienna, John D.; Hrma, Pavel R.; Buchmiller, William C.; Ricklefs, Joel S.

doi:10.2172/893257

Cited by 15 publications

(27 citation statements)

References 11 publications

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“…8(c) as a representative component from this group. SO 3 , Cl, and F are the important components that contribute to segregated salt layer on glass melt surface [21,40,41] which Re/Tc preferentially partitions into and hence has a strong impact on Re/Tc retention.…”

Section: Component Groupsmentioning

confidence: 99%

Reactions during melting of low-activity waste glasses and their effects on the retention of rhenium as a surrogate for technetium-99

Jin

Kim

Tucker

et al. 2015

Journal of Non-Crystalline Solids

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a b s t r a c tVolatile loss of radioactive technetium-99 ( 99 Tc) to off-gas is a major challenge when vitrifying low-activity waste (LAW) at the U.S. Department of Energy's Hanford Site in Washington State. We investigated the partitioning and incorporation of rhenium (Re) (a nonradioactive surrogate for 99 Tc) into the glass melt during crucible melting of two simulated LAW feeds that have exhibited a large difference in 99m Tc/Re retention in glass from small-scale melter tests. Each feed was prepared from a simulated liquid LAW and additives (boric acid, silica sand, etc.). The as-mixed slurry feeds were dried at 105°C and heated to 600-1100°C at 5 K/min. The dried feeds and heat-treated samples were leached with deionized water for 10 min at room temperature followed by 24-h leaching at 80°C. Chemical compositions of the resulting solutions and insoluble solids were analyzed. Volume expansion measurements and X-ray diffraction (XRD) analyses were performed on dried feeds and heat-treated samples to characterize the progress of feed-to-glass conversion reactions. We found that incorporation of Re into the glass melt was virtually completed during the major feed-to-glass conversion reactions that occurred at ≤700°C. The results of our study suggest that the different compositions of the salt phases formed during early stages of melting at ≤700°C are responsible for the large difference in Re incorporation into the glass melt in these two feeds.

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Section: Component Groupsmentioning

confidence: 99%

Reactions during melting of low-activity waste glasses and their effects on the retention of rhenium as a surrogate for technetium-99

Jin

Kim

Tucker

et al. 2015

Journal of Non-Crystalline Solids

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“…Recent developments and the focus of current research on U.S. Defense waste vitrification are on (1) the development of glass composition that will allow current glass melters to tolerate higher crystal contents without adverse impacts, 80–84 (2) increased loading of high alumina wastes without nepheline formation, 67,68,73,85 and (3) increased salt contents without salt accumulation in the existing melters 53–57,62–65 …”

Section: Glass Formulationsmentioning

confidence: 99%

“…proposed a solubility product‐type of constraint where the product of the SO 3 and Na 2 O in wt% should not exceed 5 (wt% 2 ). Vienna and colleagues suggested that higher concentrations of sulfur (to over 1 wt% SO 3 ) could be processed with higher alkali concentrations 53–57,59 . The maximum concentrations obtained to date are in the range of 1.5 wt% in alkali‐boro‐silicate glasses 53,60…”

Section: Glass Formulationsmentioning

confidence: 99%

Nuclear Waste Vitrification in the United States: Recent Developments and Future Options

Vienna

2010

Int J of Appl Glass Sci

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188

130

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Nuclear power plays a key role in maintaining current worldwide energy growth while minimizing the greenhouse gas emissions. A disposition path for used nuclear fuel (UNF) must be found for this technology to achieve its promise. One likely option is to recycle UNF and immobilize the high‐level waste (HLW) by vitrification. Vitrification is the technology of choice for immobilizing HLW from defense and commercial fuel reprocessing around the world. Recent advances in both recycling technology and vitrification show great promise in closing the U.S. nuclear fuel cycle in an efficient fashion. This article summarizes the recent trends, developments, and future options in waste vitrification for both defense waste cleanup and closing the nuclear fuel cycle in the United States.

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“…• Case 3-High CaO/MgO: A feed with the same simulant as in the baseline case but with a modified target glass composition with higher concentrations of CaO and MgO that were expected to increase the sulfur loading in LAW glass (Vienna et al 2004). The concentration of CaO and MgO in glass was increased by ~2 wt% CaO (from 2.95 to 5.0 wt%) and by ~1 wt% MgO (from 1.44 to 2.5 wt%).…”

Section: Feeds and Pre-melted Glass Preparationmentioning

confidence: 99%

Investigation of Tc Migration Mechanism During Bulk Vitrification Process Using Re Surrogate

Kim¹,

Bagaasen²,

Crum³

et al. 2006

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SummaryAs a part of bulk vitrification (BV) performance enhancement tasks, laboratory scoping tests were performed in FY 2004FY -2005 to explore possible ways to reduce the amount of soluble Tc in the BV waste package. Theses scoping tests helped identify which mechanisms play an important role in the migration of Tc in the BV process (Hrma et al. 2005;Kim et al. 2005). Based on the results from these scoping tests, additional tests were identified that will improve the understanding of Tc migration and clearly identify the dominant mechanisms.The additional activities identified from previous studies were evaluated and prioritized for planning for Tasks 29 and 30 conducted in FY 2006. Task 29 focused on the improved understanding of Tc migration mechanisms, and Task 30 focused on identifying the potential process changes that might reduce Tc/Re migration into the castable refractory block (CRB). This report summarizes the results from the laboratory-and crucible-scale tests in the laboratory for improved understanding of the Tc migration mechanism using Re as a surrogate performed in Task 29. Other tests performed in Task 30, which specifically aimed at testing changes to the BV process that might reduce Tc/Re migration into the CRB, will be reported in a separate report. The FY 2004 work also showed that Re is an excellent surrogate for Tc. Therefore, Re was used for all the tests performed in this study because a broader set of non-radioactive Re tests could be conducted for less cost than radioactive Tc tests.The water and molten ionic salt (MIS) capillary experiments suggested that the capillary force is a dominant mechanism for MIS penetration in the CRB, which was also supported by the preliminary modeling results.Hot-stage microscopy observations of the feed-melting and liquid-formation processes showed that the behavior of a dry blended feed and a feed prepared from liquid simulant was significantly different. A dry blended feed seemed to form a higher fraction of liquid than a feed prepared from liquid simulant, which could cause an increase in MIS migration into CRB. This may suggest that the information obtained in the full-scale tests conducted with dry blended feed may need to be verified with drier prepared feed in future operations.Thin-section MIS/Re profile measurements with FS-38B CRB samples provided new information on how the MIS and Re penetrate as the melt progresses.• For the CRB above the melt line, Re penetrates into the CRB by a vapor disposition mechanism, i.e., Re deposits when the CRB is cold, becomes molten as the temperature increases, and then penetrates further into the CRB by capillary action. The extent of penetration and the concentration of Re above the melt line is small.• For the CRB at the melt line, Re penetrates into the CRB through both the vapor deposition at the early stages of processing and then liquid MIS formation and penetration at later processing stages. The CRB at the melt line close to the glass interface exhibited the highest soluble Re concentration.• For...

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Preliminary Investigation of Sulfur Loading in Hanford LAW Glass

Cited by 15 publications

References 11 publications

Reactions during melting of low-activity waste glasses and their effects on the retention of rhenium as a surrogate for technetium-99

Reactions during melting of low-activity waste glasses and their effects on the retention of rhenium as a surrogate for technetium-99

Nuclear Waste Vitrification in the United States: Recent Developments and Future Options

Investigation of Tc Migration Mechanism During Bulk Vitrification Process Using Re Surrogate

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