Characterization of Compaction and Dryout Properties of KE Basin Sludge During Long-Term Storage

Delegard, Calvin H.; Poloski, Adam P.; Schmidt, Andrew J.; Chenault, Jeffrey W.

doi:10.2172/15011820

Cited by 7 publications

(23 citation statements)

References 13 publications

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“…To investigate the influence of settling time and long-term storage, a 28-month study was conducted from May 2002 to September 2004 with six KE Basin sludge samples (Delegard et al 2005). These samples were kept under ~32 to 38°C hot cell conditions, immersed in liquid water and in a ~5 Rad/hour radiation field.…”

Section: Prior Sludge Strength Observationsmentioning

confidence: 99%

“…Aging processes occurred in the 31°C to 38°C (average ~34°C; Delegard et al 2005) hot cell storage. Imperfect cap closure allowed some samples to dry out and all samples to undergo air exposure.…”

Section: Sludge Strength Measurements For the Present Testingmentioning

confidence: 99%

“…The 0.5695 factor was derived based on evaluations provided in the Soiltest penetrometer description (Appendix A; see also Table 3.5 of Delegard et al 2005). Thus, a 7.00 kg f vertical load on the balance should compress the penetrometer by 0.5695 × 7.00 kg f = 3.99 or ~4.0 kg f /cm 2 .…”

Section: 5mentioning

confidence: 99%

“…Aging processes taking place in the 31°C to 38°C (average ~34°C; Delegard et al 2005) hot cell storage with imperfect cap closure allowed some samples to dry completely before water additions could be made during routine sludge maintenance activities. The imperfect closures also meant that all samples were exposed to air.…”

Section: Sludge Samplesmentioning

confidence: 99%

“…The elemental composition of the SNF Floor 60L PG sample is derived based on the weights of the KC Floor Comp sludge (as-settled wet basis) and crushed fuel used in the testing. Based on parallel measurements conducted in the Series III tests (Schmidt et al 2003), the crushed fuel was assumed to be 93 wt% uranium metal in the present analysis and in prior tests (Delegard et al 2005). In addition, and as postulated in prior tests (Delegard et al 2005), the 154 Eu, 241 Am, 238 Pu, and 239,240 Pu radionuclide contributions from the irradiated fuel per mass of uranium are presumed to be the same as found in the accompanying sludge because of the low solubility of these elements and their capture in the preponderant low-solubility uranium phases.…”

Section: 8mentioning

confidence: 99%

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Strength Measurements of Archive K Basin Sludge Using a Soil Penetrometer

Delegard¹,

Schmidt²,

Chenault³

2011

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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...

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Section: Prior Sludge Strength Observationsmentioning

confidence: 99%

Section: Sludge Strength Measurements For the Present Testingmentioning

confidence: 99%

Section: 5mentioning

confidence: 99%

Section: Sludge Samplesmentioning

confidence: 99%

Section: 8mentioning

confidence: 99%

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Strength Measurements of Archive K Basin Sludge Using a Soil Penetrometer

Delegard¹,

Schmidt²,

Chenault³

2011

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Effects of Time, Heat, and Oxygen on K Basin Sludge Agglomeration, Strength, and Solids Volume

Delegard¹,

Sinkov²,

Schmidt³

et al. 2011

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ph: (865) 576-8401 fax: (865) 576 5728 email: reports@adonis.osti.gov Available to the public from the National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Rd., Springfield, VA 22161 ph: (800) 553-6847 fax: (703) 605-6900 email: orders@nits.fedworld.gov online ordering: http://www.ntis.gov/ordering.htm Abstract viiThese findings indicate that for solids very rich in uranium (≳70 to 80 wt%, dry basis), long-term storage under aerated non-agitated conditions will form a thin metaschoepite crust that is readily broken. The underlying material may compact somewhat with time, but, because little appreciable change in settled solids strength was seen after nearly a year of settling at 51°C in laboratory tests, little increase in strength, beyond that associated with any compaction, is anticipated during lower temperature but longer term storage.The observations from the 28-month settling test with uranium-rich genuine sludge and the studies with the uraninite oxidation suggest that metaschoepite crystal ripening and intergrowth may have been responsible for the uncommon strength found in the genuine sludge. In this case, the presence of relatively high amounts of metaschoepite within the settled solids layer likely was necessary to produce the strong product material. Based on these findings, K Basin sludges rich in metaschoepite [≳70 to 80 wt% U as U(VI), dry basis] may self-cement by Ostwald ripening to produce strong agglomerates similar to the behavior shown by the 96-13 sludge in the 28-month settling tests. Because of the low solubility of UO 2 , similar gains in strength by Ostwald ripening for UO 2 -rich sludge cannot occur.  Under 51°C oxygenated conditions, a full KW containerized sludge simulant containing gibbsite, ferrihydrite, mordenite, organic ion exchange resin, Hanford sand, and ~50%/50% UO 2 /UO 3 ·2H 2 O decreased in settled solids volume by about 25% over 106 days while a parallel control test run in the absence of oxygen decreased only about 3%. The volume decrease coincided with the oxidation of UO 2 to UO 3 ·2H 2 O and may have been due to better solids packing or coagulation of non-uranium solids with the crystallizing UO 3 ·2H 2 O. However, even though the KW containerized sludge simulant compacted with time, the strength remained low. Under warm (30±5ºC) semi-oxic conditions, the uraninite in uranium-rich K Basin sludge samples oxidized to metaschoepite and other U(VI) phases after 9 years of hot cell storage (Delegard et al. 2007a).These findings mean that, unlike uraninite-rich sludges that form continuous layers or networks of product metaschoepite upon reaction with oxygen or which already have high metaschoepite concentrations, sludges more dilute in uraninite or metaschoepite likely will be unable to produce continuous metaschoepite layers that inhibit further oxidation or which self-cement to form highstrength agglomerates. Instead, the metaschoepite may act to coagulate non-uranium sludge solids and produce settled solids that are more tightly packed ...

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

Onishi¹,

Yokuda²,

Schmidt³

2010

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Characterization of Compaction and Dryout Properties of KE Basin Sludge During Long-Term Storage

Cited by 7 publications

References 13 publications

Strength Measurements of Archive K Basin Sludge Using a Soil Penetrometer

Strength Measurements of Archive K Basin Sludge Using a Soil Penetrometer

Effects of Time, Heat, and Oxygen on K Basin Sludge Agglomeration, Strength, and Solids Volume

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

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