Gas bubble retention and its effect on waste properties: Retention mechanisms, viscosity, and tensile and shear strengths

Gauglitz, Phillip A.; Rassat, Scot D.; Powell, Michael R.

doi:10.2172/104988

Cited by 44 publications

(72 citation statements)

References 21 publications

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“…The small-scale studies on the mechanisms of gas retention and bubble behavior in tank waste have been the subject of a number of studies (see for example, Gauglitz et al 1994Gauglitz et al , 1995Gauglitz et al , 1996Gauglitz et al , 2001Gauglitz et al , 2009Stewart et al 1996;Rassat et al 1997Rassat et al , 1998Rassat et al , 1999Bredt et al 1995;Bredt and Tingey 1996;and Walker et al 1994). Gauglitz et al (2009) have recently summarized these studies.…”

Section: Previous Small-scale Studies Of Bubble Retentionmentioning

confidence: 99%

Strong-Sludge Gas Retention and Release Mechanisms in Clay Simulants

Gauglitz¹,

Buchmiller²,

Probert³

et al. 2012

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Executive SummaryThe Hanford Site has 28 double-shell tanks (DSTs) and 149 single-shell tanks (SSTs) containing radioactive wastes that are complex mixes of radioactive and chemical products. The mission of the Department of Energy's River Protection Project is to retrieve and treat the Hanford tank waste for disposal and close the tank farms. A key aspect of the mission is to retrieve and transfer waste from the SSTs, which are at greater risk for leaking, into DSTs for interim storage until the waste is transferred to and treated in the Hanford Waste Treatment and Immobilization Plant. There is, however, limited space in the existing DSTs to accept waste transfers from the SSTs, and approaches to overcoming the limited DST space will benefit the overall mission.The current safety basis for managing the waste in the tank farms provides controls to prevent spontaneous buoyant-displacement gas release events (BDGREs) and provide for ongoing safe storage of the waste. The current mission plan for future waste transfers assumes a relaxed set of BDGRE controls for selected wastes and DSTs based on a new experimental finding that shows relatively low gas retention for sediment materials that are sufficiently strong (shear strengths greater than about 1000 Pa). Based on these relaxed controls, waste from additional SSTs could be retrieved and transferred to DSTs while still avoiding the potential for BDGREs.The purpose of this study is to summarize and analyze the key previous experiment that forms the basis for the relaxed controls and to summarize progress and results on new experiments focused on understanding the conditions that result in low gas retention. The previous large-scale test used about 50 m 3 of sediment, which would be unwieldy for doing multiple parametric experiments. Accordingly, experiments began with smaller-scale tests to determine whether the desired mechanisms can be studied without the difficulty of conducting very large experiments.The previous large-scale gas retention test was conducted in a 3.5 m diameter test vessel with a sediment layer about 5 m deep. The average retained-gas volume fraction grew over a 25 day period to a peak value of about 7% and then decreased to about 5%. This is much lower than in previous small-scale tests.A key objective for the current gas-retention tests is to conduct tests that have slower gas generation rates and are larger than the previous small-scale tests. In the current study, small-scale tests were conducted with various mixtures of kaolin clay and Min-U-Sil 30 ®1 , which is finely ground silica with a median diameter of about 8 microns, in primarily 12.7 cm diameter test vessels with gas generation provided either by the decomposition of hydrogen peroxide to form oxygen bubbles or by the corrosion of iron to form hydrogen bubbles. The gas generation rates varied and resulted in gas retention that peaked after about 1 to 10 days. The volumes of retained gas and total generated gas were measured over time to determine the retained-gas fraction. Tests we...

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Section: Previous Small-scale Studies Of Bubble Retentionmentioning

confidence: 99%

Strong-Sludge Gas Retention and Release Mechanisms in Clay Simulants

Gauglitz¹,

Buchmiller²,

Probert³

et al. 2012

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“…The bubble-scale mechanisms of gas retention and bubble behavior in tank waste have been the subject of a number of studies (see, for example, Gauglitz et al 1994Gauglitz et al , 1995Gauglitz et al , 2001Rassat et al 1997Rassat et al , 1998Rassat et al , 1999Bredt et al 1995;Bredt and Tingey 1996;and Walker et al 1994). The principal mechanisms of bubble retention can be grouped into three categories:  bubbles retained by direct attachment to particles (often called armored bubbles)  bubbles retained by the strength of the surrounding waste  bubbles retained between particles by capillary forces.…”

Section: Mechanisms Of Bubble Retention At the Bubble Scalementioning

confidence: 99%

“…The difference between these two types of bubbles is illustrated in Figure 1.5. Whether a bubble is held by yield strength or capillary force is indicated by the Bond number criterion developed by Gauglitz et al (1994Gauglitz et al ( , 1995. This dimensionless number contains two parameters, a ratio of gravitational force to surface-tension force and a ratio of waste-strength force to surface-tension force.…”

Section: Mechanisms Of Bubble Retention At the Bubble Scalementioning

confidence: 99%

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An Approach to Understanding Cohesive Slurry Settling, Mobilization, and Hydrogen Gas Retention in Pulsed Jet Mixed Vessels

Gauglitz¹,

Wells²,

Fort³

et al. 2009

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“…The waste strength plays a central role in both the mechanisms of bubble retention and bubble release (Rassat et al 1997;Gauglitz et al 1995Gauglitz et al , 1996Stewart et al 1996b). While recent in-situ measurements with the ball rheometer (Stewart et al 1996a;Meyer et al 1997) have provided results for five of the DSTs, waste strength measurements are typically not available for any of the SSTs nor for those DSTs that have not been characterized with the ball rheometer.…”

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confidence: 99%

Waste behavior during horizontal extrusion: Effect of waste strength for bentonite and kaolin/ludox simulants and strength estimates for wastes from Hanford waste tanks 241-SY-103, AW-101, AN-103, and S-102

Gauglitz¹,

Aikin²

1997

Self Cite

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The Hanford Site has 149 single-shell tanks (SSTs) and 28 double-shell tanks (DSTs) containing radioactive wastes that are complex mixes of radioactive and chemical products. Some of these wastes are known to generate mixtures of flammable gases, including hydrogen, nitrous oxide, and ammonia. Nineteen of these SSTs and six of the DSTs have been placed on the Flammable Gas Watch List because they are known or suspected, in all but one case, to retain these flammable gases. Because these gases are flammable, their retention and episodic release pose a number of safety concerns. Understanding the physical mechanisms and waste properties that contribute to the retention and release of these gases will help to resolve the Flammable Gas Safety Issue.The strength of the waste plays a central role in the' mechanisms of both bubble retention and bubble release. While recent in-situ measurements from the ball rheometer have provided results for five of the DSTs, waste strength measurements are typically not available for any of the SSTs or for the DSTs that have not been characterized with the ball rheometer.The overall purpose of this study is to develop a method to obtain strength estimates for actual wastes from observations of the wastes' behavior during extrusion from core samplers. The first objective of the study was to quantify waste behavior during horizontal extrusion by documenting the extrusion behavior of simulants with known strengths; the second was to estimate the strength of actual waste based on these simulant standards.Results showed a reproducible extrusion behavior for bentonite clay and kaolin/Ludox" simulants over strengths ranging from 30 to 6,500 Pa. The extrusion behavior changed distinctively with variations in strength, forming the basis for creating visual standards. The extrusion behavior was documented with both video recordings and still images. Based on these visual standards, strength estimates were made for wastes from DSTs 241-SY-103, 241-AW-101, and 241-AN-103 and SST 241-S-102. These strength estimates were compared to available intank ball rheometer data and laboratory data, and the estimates from horizontal extrusions generally agreed within a factor of two with the ball rheometer data, which is acceptable accuracy for use in bubble retention models.iii Acknowledgments A number of staff at the Hanford Site have contributed to success of this project, and the authors would like to thank these individuals for their important contributions. Scot Rassat assisted with the simulant preparation and apparatus assembly. Mike Powell provided information on the earlier work on horizontal extrusion behavior, and this project evolved from a series of early conversations with Mike. In addition, Mike has been instrumental in developing and characterizing both the bentonite clay and kaolin/Ludox simulants used in this study. Bertrand Griffin II and Ray Akita of Hanford's 222-S hot cell facility were very helpful over the past two years in making available the video recordings of the core extrus...

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Gas bubble retention and its effect on waste properties: Retention mechanisms, viscosity, and tensile and shear strengths

Cited by 44 publications

References 21 publications

Strong-Sludge Gas Retention and Release Mechanisms in Clay Simulants

Strong-Sludge Gas Retention and Release Mechanisms in Clay Simulants

An Approach to Understanding Cohesive Slurry Settling, Mobilization, and Hydrogen Gas Retention in Pulsed Jet Mixed Vessels

Waste behavior during horizontal extrusion: Effect of waste strength for bentonite and kaolin/ludox simulants and strength estimates for wastes from Hanford waste tanks 241-SY-103, AW-101, AN-103, and S-102

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