Strength Measurements of Archive K Basin Sludge Using a Soil Penetrometer

Abstract

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...

Capability of Pocket Penetrometer to Evaluate Unconfined Compressive Strength of Baghdad Clayey Soil

“…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 [3]. 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 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 [3]. In the test procedure for manual for description identification of soils presented by Texas department of transportation, August 1999, this text depends the penetrometer reading for describe the soil consistency as seen in the Plate-1- [4].…”