Evaluation of Shear Strength Threshold of Concern for Retrieval of Interim-Stored K-Basin Sludge in the Hanford Site

Onishi, Yasuo; Yokuda, Satoru T.; Schmidt, Andrew J.

doi:10.2172/1004826

Cited by 3 publications

(2 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figure 2.3 shows three different modes of solids settling, possibly due to solids floc or agglomerate settling, hindered settling, and solids consolidation in that sequence over 50 days (MacLean 1999). Onishi et al (2009) developed a unified settling velocity calculation method to seamlessly cover the solids settling through a range of an individual particle settling, solids flocculation, and hindered settling, as discussed below.…”

Section: Hindered Solids Settlingmentioning

confidence: 99%

Hanford Waste Physical and Rheological Properties: Data and Gaps

Wells¹,

Kurath²,

Mahoney³

et al. 2011

Self Cite

103

View full text Add to dashboard Cite

Executive SummaryThe Hanford Site in Washington State manages 177 underground storage tanks containing approximately 250,000 m 3 of waste generated during past defense reprocessing and waste management operations. These tanks contain a mixture of sludge, saltcake and supernatant liquids. The insoluble sludge fraction of the waste consists of metal oxides and hydroxides and contains the bulk of many radionuclides such as the transuranic components and 90 Sr. The saltcake, generated by extensive evaporation of aqueous solutions, consists primarily of dried sodium salts. The supernates consist of concentrated (5-15 M) aqueous solutions of sodium and potassium salts. The 177 storage tanks include 149 single-shell tanks (SSTs) and 28 double-shell tanks (DSTs).Ultimately the wastes need to be retrieved from the tanks for treatment and disposal. The SSTs contain minimal amounts of liquid wastes, and the Tank Operations Contractor is continuing a program of moving solid wastes from SSTs to interim storage in the DSTs. The Hanford DST system provides the staging location for waste feed delivery to the Department of Energy (DOE) Office of River Protection's (ORP) Hanford Tank Waste Treatment and Immobilization Plant (WTP). The WTP is being designed and constructed to pretreat and then vitrify a large portion of the wastes in Hanford's 177 underground waste storage tanks.The retrieval, transport, treatment and disposal operations involve the handling of a wide range of slurries. Solids in the slurry have a wide range of particle size, density and chemical characteristics. Depending on the solids concentration the slurries may exhibit a Newtonian or a non-Newtonian rheology.The extent of knowledge of the physical and rheological properties is a key component to the success of the design and implementation of the waste processing facilities. These properties are used in engineering calculations in facility designs. Knowledge of the waste properties is also necessary for the development and fabrication of simulants that are used in testing at various scales. The expense and hazards associated with obtaining and using actual wastes dictates that simulants be used at many stages in the testing and scale-up of process equipment. The results presented in this report should be useful for estimating process and equipment performance and provide a technical basis for development of simulants for testing.The purpose of this document is to provide an updated summary of the Hanford waste characterization data pertinent to safe storage, retrieval, transport and processing operations for both the tank farms and the WTP and thereby identify gaps in understanding and data. Important waste parameters for these operations are identified by examining examples of relevant mathematical models of selected phenomena including: The data sets in (UDS composition and particle density, UDS primary particle size and shape, UDS particle size distributions [PSDs], and estimated particle size and density distributions [PSDDs]) and Poloski et al. (2007) ...

show abstract

Section: Hindered Solids Settlingmentioning

confidence: 99%

Hanford Waste Physical and Rheological Properties: Data and Gaps

Wells¹,

Kurath²,

Mahoney³

et al. 2011

Self Cite

103

View full text Add to dashboard Cite

show abstract

“…Shear strength is one of the key properties to determine the energy of water jets needed to mobilize sludge from the STSCs (Onishi et al 2010). Among other factors, shear strength is affected by its time at rest.…”

Section: Prior Sludge Strength Observationsmentioning

confidence: 99%

Strength Measurements of Archive K Basin Sludge Using a Soil Penetrometer

Delegard¹,

Schmidt²,

Chenault³

2011

Self Cite

View full text Add to dashboard Cite

SummaryThe K East (KE) and the K West (KW) Basin fuel storage pools near the Columbia River at the U.S. Department of Energy (DOE) Hanford Site were used from the 1980s until 2004 for storage of a portion of the spent nuclear fuel from the Hanford N Reactor. Over this period, the spent fuel storage and packaging operations generated radioactive sludge in both basins. Transfer of sludge from the KE Basin to the KW Basin was completed in 2007. Sludge from both basins now resides in six large underwater engineered containers in the KW Basin.Under the Sludge Treatment Project (STP), K Basin sludge disposition will be managed in two phases. The first phase is to retrieve the sludge that currently resides in the six engineered containers. The retrieved sludge will be hydraulically loaded into sludge transport and storage containers (STSCs) and transported to an interim storage facility in the Central Plateau. In the second phase of the STP, sludge will be retrieved from interim storage and treated and packaged in preparation for eventual shipment to the Waste Isolation Pilot Plant (WIPP) in New Mexico.During the period the STSCs are stored, the strength of K Basin sludge is expected to increase because of chemical reactions and intergrowth of sludge phase crystals whose rates increase with increasing temperature. Sludge strength also can increase by compaction and dewatering due to settling. Changes in sludge strength with time can impact the specialized equipment and the mechanical intensity of its operation when sludge is retrieved from STSCs for final sludge treatment and packaging.Under current plans, water jets will be used to help mobilize K Basin sludge for retrieval from the STSCs after interim storage. It is important to determine whether water jets can mobilize and erode the stored K Basin sludge from the STSCs. Shear strength is known to be a key property to determine whether water jets can mobilize sludge from the STSCs. Accordingly, the unconfined compressive strengths of archive K Basin sludge samples and sludge blends were measured using a pocket penetrometer modified for hot cell use. Based on known correlations, the unconfined compressive strength (UCS) values measured by the pocket penetrometer were converted to shear strengths. Using inventory logs, twenty-six sludge samples were identified and selected as potential candidates for sludge strength measurement. These samples had been stored in hot cells for varying numbers of years since last being disturbed. Valid UCS measurements could only be made for twelve samples with the remaining materials not being suitable for UCS measurements due to quantity, geometry, or texture limitations. Significantly, valid measurements were made for all seven of the key archive samples that have been maintained for future testing. The samples for which valid measurements were made were moist or water-immersed solids and at least ½-inch deep in their storage jars. Two of the samples were measured in quadruplicate, seven in triplicate, two in duplicate, and one had a s...

show abstract

Development of K-Basin High-Strength Homogeneous Sludge Simulants and Correlations Between Unconfined Compressive Strength and Shear Strength

Onishi¹,

Baer²,

Chun³

et al. 2011

Self Cite

View full text Add to dashboard Cite

iii Executive Summary K-Basin sludge will be stored in the Sludge Transport and Storage Containers (STSCs) at an interim storage location on Central Plateau before being treated and packaged for disposal. During the storage period, sludge in the STSCs may consolidate/agglomerate, potentially resulting in high-shear-strength material. The Sludge Treatment Project (STP) plans to use water jets to retrieve K-Basin sludge after the interim storage.STP has identified shear strength to be a key parameter that should be bounded to verify the operability and performance of sludge retrieval systems. Determining the range of sludge shear strength is important to gain high confidence that a water-jet retrieval system can mobilize stored K-Basin sludge from the STSCs. The shear strength measurements will provide a basis for bounding sludge properties for mobilization and erosion. Thus, it is also important to develop potential simulants to investigate these phenomena.Long-term sludge storage tests conducted by Pacific Northwest National Laboratory (PNNL) show that high-uranium-content K-Basin sludge can self-cement and form a strong sludge with a bulk shear strength of up to 65 kPa. Some of this sludge has "paste" and "chunks" with shear strengths of approximately 3~5 kPa and 380~770 kPa, respectively. High-uranium-content sludge samples subjected to hydrothermal testing (e.g., 185°C, 10 hours) have been observed to form agglomerates with a shear strength up to 170 kPa. These high values were estimated by measured unconfined compressive strength (UCS) obtained with a pocket penetrometer. Due to its ease of use, it is anticipated that a pocket penetrometer will be used to acquire additional shear strength data from archived K-Basin sludge samples stored at the PNNL Radiochemical Processing Laboratory (RPL) hot cells.It is uncertain whether the pocket penetrometer provides accurate shear strength measurements of the material. To assess the bounding material strength and potential for erosion, it is important to compare the measured shear strength to penetrometer measurements and to develop a correlation (or correlations) between UCS measured by a pocket penetrometer and direct shear strength measurements for various homogeneous and heterogeneous simulants.This study developed 11 homogeneous simulants, whose shear strengths vary from 4 to 170 kPa. With these simulants, we developed correlations between UCS measured by a Geotest E-280 pocket penetrometer and shear strength values measured by a Geonor H-60 hand-held vane tester and a more sophisticated bench-top unit, the Haake M5 rheometer. This was achieved with side-by-side measurements of the shear strength and UCS of the homogeneous simulants.The homogeneous simulants developed under this study consist of kaolin clay, plaster of Paris, and amorphous alumina CP-5 with water. The simulants also include modeling clay. The shear strength of most of these simulants is sensitive to various factors, including the simulant size, the intensity of mixing, and the curing time, even wi...

show abstract

Evaluation of Shear Strength Threshold of Concern for Retrieval of Interim-Stored K-Basin Sludge in the Hanford Site

Cited by 3 publications

References 46 publications

Hanford Waste Physical and Rheological Properties: Data and Gaps

Hanford Waste Physical and Rheological Properties: Data and Gaps

Strength Measurements of Archive K Basin Sludge Using a Soil Penetrometer

Development of K-Basin High-Strength Homogeneous Sludge Simulants and Correlations Between Unconfined Compressive Strength and Shear Strength

Contact Info

Product

Resources

About