Crystallization in High Level Waste (HLW) Glass Melters: Savannah River Site Operational Experience

Fox, Kevin M.; Peeler, David K.; Kruger, Albert A.

doi:10.1002/9781119190042.ch3

Cited by 3 publications

(5 citation statements)

References 22 publications

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“…A small volume of noble metal crystals is typical of DWPF HLW glasses. 5 A small number of platinum particles were also observed on the surface of the glass. These particles are likely residuals from the platinum boat used to catch the pour stream glass.…”

Section: Electron Microscopy Analysismentioning

confidence: 98%

“…Melter 2 entered service in March 2003 and has operated on a semi-continuous basis since then. Melter idling periods, some examples of which are described in detail elsewhere, 5 occur infrequently and are generally the result of maintenance activities or delays in melter feed preparation. Idling periods typically last for a few hours in the case of unplanned maintenance, a few days for feed delays, and up to about four weeks for planned maintenance outages.…”

Section: Melter Glass Sampling Dwpf Melter Idling Periodmentioning

confidence: 99%

“…As part of the road map, historical information from the DWPF flowsheet development and operational experience has been documented to provide insight into operational issues associated with crystallization within the melter, riser, pour spout, and glass. 5 However, additional information on the potential for crystal accumulation can be gained from glass samples collected from the DWPF melter pour stream after operation in off-normal conditions.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of High Level Nuclear Waste Glass Samples Following Extended Melter Idling

Peeler

Fox

Kruger

2015

Ceramic Transactions Series

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The Savannah River Site Defense Waste Processing Facility (DWPF) melter was recently idled with glass remaining in the melt pool and riser for approximately three months. This situation presented a unique opportunity to collect and analyze glass samples since outages of this duration are uncommon. The objective of this study was to obtain insight into the potential for crystal formation in the glass resulting from an extended idling period. The results will be used to support development of a crystal-tolerant approach for operation of the high level waste melter at the Hanford Tank Waste Treatment and Immobilization Plant (WTP).Two glass pour stream samples were collected from DWPF when the melter was restarted after idling for three months. The samples did not contain crystallization that was detectible by X-ray diffraction. Electron microscopy identified occasional spinel and noble metal crystals of no practical significance. Occasional platinum particles were observed by microscopy as an artifact of the sample collection method. Reduction/oxidation measurements showed that the pour stream glasses were fully oxidized, which was expected after the extended idling period.Chemical analysis of the pour stream glasses revealed slight differences in the concentrations of some oxides relative to analyses of the melter feed composition prior to the idling period. While these differences may be within the analytical error of the laboratories, the trends indicate that there may have been some amount of volatility associated with some of the glass components, and that there may have been interaction of the glass with the refractory components of the melter. These changes in composition, although small, can be attributed to the idling of the melter for an extended period. The changes in glass composition resulted in a 70-100 °C increase in the predicted spinel liquidus temperature (T L ) for the pour stream glass samples relative to the analysis of the melter feed prior to the outage. This indicates that the potential for spinel crystallization increased as a result of idling for an extended period. However, the predicted T L of the pour stream glasses remained 150-200 °C below the mean melt pool temperature of about 1125 °C during the idling period.Given the change in predicted T L over the three month outage, the results indicate that it is important to have a thorough understanding of spinel crystallization within the melter for WTP to operate with a volume percent crystallization constraint. This knowledge will enable process control routines to be developed that avoid bulk crystallization in the melter and allow for recovery from off-normal events. The current WTP crystal tolerant glass program will develop an improved understanding of spinel crystallization in the WTP melter to allow for operation at maximum waste loading in glass composition systems limited by predictions of spinel crystallization.

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Section: Electron Microscopy Analysismentioning

confidence: 98%

Section: Melter Glass Sampling Dwpf Melter Idling Periodmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Characterization of High Level Nuclear Waste Glass Samples Following Extended Melter Idling

Peeler

Fox

Kruger

2015

Ceramic Transactions Series

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“…Also, previous experiences with pour spout clogging in the SRS test melters and the DWPF melter highlight the need to avoid crystallization in the pour spout. 15,16 This is of particular importance given the inability to inspect and service the WTP melter discharge riser based on the current design.…”

Section: Assessment Of Wtp Hlw Melter Designmentioning

confidence: 99%

Road Map for Development of Crystal-Tolerant High Level Waste Glasses

Matyáš¹,

Vienna²,

Peeler³

et al. 2014

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The U.S. Department of Energy (DOE) is building a Tank Waste Treatment and Immobilization Plant (WTP) at the Hanford Site in Washington to remediate 55 million gallons of radioactive waste that is being temporarily stored in 177 underground tanks. Efforts are being made to increase the loading of Hanford tank wastes in glass while meeting melter lifetime expectancies and process, regulatory, and product quality requirements. This road map guides the research and development for formulation and processing of crystaltolerant glasses, identifying near-and long-term activities that need to be completed over the period from 2014 to 2019. The primary objective is to maximize waste loading for Hanford waste glasses without jeopardizing melter operation by crystal accumulation in the melter or melter discharge riser. The potential applicability to the Savannah River Site (SRS) Defense Waste Processing Facility (DWPF) will also be addressed in this road map.

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“…The results provide support for development of a crystal-tolerant glass approach for operation of the high level waste melter at WTP. Melter idling periods, some examples of which are described in detail elsewhere, 5 occur infrequently and are generally the result of maintenance activities or delays in melter feed preparation. Idling periods typically last for a few hours in the case of unplanned maintenance, a few days for feed delays, and up to about four weeks for planned maintenance outages.…”

Section: List Of Figuresmentioning

confidence: 99%

Evaluation of Defense Waste Processing Facility (Dwpf) Glass Samples After an Extended Melter Outage

Fox¹,

Peeler²,

Pareizs³

et al. 2014

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Crystallization in High Level Waste (HLW) Glass Melters: Savannah River Site Operational Experience

Cited by 3 publications

References 22 publications

Characterization of High Level Nuclear Waste Glass Samples Following Extended Melter Idling

Characterization of High Level Nuclear Waste Glass Samples Following Extended Melter Idling

Road Map for Development of Crystal-Tolerant High Level Waste Glasses

Evaluation of Defense Waste Processing Facility (Dwpf) Glass Samples After an Extended Melter Outage

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