Particle Property Analyses of High Level Waste (HLW) Tank Sludges [SEC 1 Thru 7]

Bechtold, D.B.

doi:10.2172/807714

Cited by 2 publications

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“…However, in the case of these agglomerate particles, measurements of both the mass and volume are confounded by the risk of destroying the structure of the particles when separating them from the surrounding liquid. An attempt to measure the effective density indirectly from settling-rate measurements (Bechtold et al 2002) was not successful, probably because the particles were broken up by the stirring action used to suspend them.…”

Section: Non-newtonian Discussionmentioning

confidence: 99%

Deposition Velocities of Newtonian and Non-Newtonian Slurries in Pipelines

Poloski

Adkins

Abrefah

et al. 2009

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Executive SummaryThe External Flowsheet Review Team (EFRT) expressed concern about the potential for Waste Treatment and Immobilization Plant (WTP) pipe plugging. Per the review's executive summary, "Piping that transports slurries will plug unless it is properly designed to minimize this risk. This design approach has not been followed consistently, which will lead to frequent shutdowns due to line plugging." To evaluate the potential for plugging, critical-velocity tests were performed on several physical simulants to determine if the design approach is conservative. Critical velocity is defined as the point where particles begin to deposit to form a moving bed of particles on the bottom of a straight horizontal pipe during slurry transport operations. The critical velocity depends on the physical properties of the particles, fluid, and system geometry.This report gives the results from critical-velocity testing and provides an indication of slurry stability as a function of fluid rheological properties and transport conditions that are typical of what the plant will see. The experimental results are compared to the WTP design guide on slurry-transport velocity in an effort to confirm minimum waste-velocity and flushing-velocity requirements as established by calculations and critical-velocity correlations in the design guide. The major findings of this testing are as follows:Experimental results indicate that for Newtonian fluids, the design guide is conservative. The design guide is based on the Oroskar and Turian (1980) correlation, a traditional industry-derived equation that focuses on particles larger than 100 m in size. Slurry viscosity has a greater effect on particles with a larger surface area to mass ratio, i.e. smaller particles. The increased viscous forces on small particles result in a smaller critical velocities. Since the Hanford slurry particles generally have large surface area to mass ratios, the reliance on such equations in the 24590-WTP-GPG-M-0058, Rev 0 design guide (Hall 2006) is conservative. Additionally, the use of the 95% percentile particle size as an input to this equation is conservative. The design guide specifies the use of the d 95 density, this term is ambiguous and needs clarification in the design guide. Nonetheless, this value is interpreted to mean the density of the d 95 particle. This density value is irrelevant for critical velocity calculations. Often this value is unknown, and Equation 1 of the 24590-WTP-GPG-M-0058, Rev 0 design guide (Hall 2006) will be used for design purposes. This equation calculates an average or composite density of all solids in the slurry. However, test results indicate that the use of an average particle density as an input to the equation is not conservative. Particle density has a large influence on the overall critical-velocity result returned by the correlation. The viscosity correlation used in the WTP design guide has been shown to be inaccurate for Hanford waste feed materials. Additionally, the recommendation of a 30% minimum margi...

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Section: Non-newtonian Discussionmentioning

confidence: 99%

Deposition Velocities of Newtonian and Non-Newtonian Slurries in Pipelines

Poloski

Adkins

Abrefah

et al. 2009

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“…A light-scattering particle size distribution (PSD) analysis was conducted on AY-102 samples (Bechtold et al 2002). Two PSD measurements were conducted on the core sample composite.…”

Section: Settled Solids Layer Particle Sizementioning

confidence: 99%

Feasibility Study on Using Two Mixer Pumps for Tank 241-AY-102 Waste Mixing

Onishi¹,

Wells²

2004

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The current waste retrieval plan for Hanford double-shell Tank 241-AY-102 (AY-102) calls for using two mixer pumps to mix the waste stored within it. The objective of this evaluation was to determine whether two rotating 300-hp pumps located 22 ft (6.7 m) from the center of the tank could adequately mix the AY-102 waste. The tank now contains 248 in. (6.3 m) of high-level radioactive waste consisting of 62 in. (1.58 m) of sludge and 186 in. (4.72 m) of supernatant liquid. Based on the available data, AY-102 waste properties were determined, including the densities of the liquid and the mostly agglomerated settled (bulk) solids (the sludge) and solid particles, the solid volume fraction in the settled solids, the solid particle size distribution, the liquid and slurry viscosities, and the yield stress in shear (shear strength) of the settled solids layer. To evaluate the likely and bounding cases of AY-102 waste mixing, sludge erosion modeling was performed with a median value of 1,090 Pa (likely condition) and a conservative (more difficult to erode) 97.5 percentile value of 2,230 Pa for shear strength. According to the AY-102 model predictions, the two rotating mixer pumps would erode 89% of the sludge that has a shear strength of 1,090 Pa up to 41 ft (12.5 m) away from the mixer pumps. However, due to the tank wall effect, they would not mobilize the sludge next to the tank wall, which is more than 26 ft (7.9 m) from the pumps. Moreover, the pumps would not mobilize the bottom 2.5 in. (0.06 m) of sludge. Once the sludge was mobilized, the solids were predicted to be uniformly suspended within the tank within a 1-vol% concentration variation (99% uniformity), except those within few inches of the bottom. The two pumps would erode 85% of the sludge with a shear strength of 2,230 Pa, slightly less than the 89% in the 1,090-Pa shear strength case. In this case, the pump jets would mobilize sludge up to 38 ft (11.6 m) away from the pumps. Like the 1,090-Pa shear strength case, the mixer pumps would leave the sludge at the tank wall that is 20 ft (6.1 m) or farther from the pumps due to the wall effect. The model predicts that the bottom 2.5 in. (0.06 m) of sludge remains. Similar to the 1,090-Pa shear strength case, the solids were predicted to be uniformly suspended except within a few inches of the tank bottom. These results indicate that the greater the sludge shear strength, the less the mixer pumps can erode, although the differences are small between the 1,090 and 2,230 Pa cases in erosion amount and maximum erosion distance from the pumps. v

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Particle Property Analyses of High Level Waste (HLW) Tank Sludges [SEC 1 Thru 7]

Cited by 2 publications

References 0 publications

Deposition Velocities of Newtonian and Non-Newtonian Slurries in Pipelines

Deposition Velocities of Newtonian and Non-Newtonian Slurries in Pipelines

Feasibility Study on Using Two Mixer Pumps for Tank 241-AY-102 Waste Mixing

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