Saltcake dissolution FY 1998 status report

Herting, D.L.

doi:10.2172/782279

Cited by 5 publications

(5 citation statements)

References 2 publications

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“…Among tank composite waste samples that have been tested, those from S-112 were found to be the most highly soluble in water (Herting and Edmonson 1998;Herting 1999Herting , 2000Herting , 2001Herting , 2002. This equates to a relatively high value for β LC and a correspondingly high value for the gas release rate, Q RG.…”

Section: Gas Release Model Inputs and Resultsmentioning

confidence: 99%

Flammable Gas Release Estimates for Modified Sluicing Retrieval of Waste from Selected Hanford Single-Shell Tanks

Huckaby¹,

Wells²

2004

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Section: Gas Release Model Inputs and Resultsmentioning

confidence: 99%

Flammable Gas Release Estimates for Modified Sluicing Retrieval of Waste from Selected Hanford Single-Shell Tanks

Huckaby¹,

Wells²

2004

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Section: Gas Release Model Inputs and Resultsmentioning

confidence: 99%

Flammable Gas Release Estimates for Modified Sluicing Retrieval of Waste from Selected Hanford Single-Shell Tanks

Huckaby¹,

Wells²

2003

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Executive SummaryThe high-level radioactive wastes in many single-shell tanks (SSTs) at the Hanford Site are to be retrieved by a modified sluicing method that uses water jets to dissolve the water-soluble waste and mobilize the water-insoluble waste. Retrieval operations will liberate any waste gases trapped in the wetted solid waste matrix, and these gases will be released into the tank headspaces. Because the trapped gases include the flammable species hydrogen, methane, and ammonia, a concern exists that a flammable mixture could be formed in the tank headspaces. This report combines conservative retained gas inventory estimates and tank data with anticipated waste retrieval rates to estimate the potential headspace flammability of selected SSTs during modified sluicing waste retrieval operations. Considered here are nine of the 12 tanks from the 241-S tank farm (241-S-107, 241-S-111, and 241-S 112 are not considered) and Tank 241-U-107.This report is intended to support the specification of process controls that ensure flammable conditions do not develop in the tank headspaces. Consequently, the physical scenarios considered, the models developed to estimate retained gas releases and the tank headspace compositions under these scenarios, and the model input data are intended to conservatively assess the potential to reach headspace flammability. The analyses are intended to address worst-case conditions and establish reasonable upper bounds on the achievable flammability of the tank headspaces. Flammable retained gas inventories, for example, are based on the 95th percentile developed by , giving 95% confidence that actual inventories are smaller than those used in the calculations.Gas releases and headspace flammability were evaluated for three general scenarios: a very aggressive dissolution and erosion of saltcake waste by water jets impinging on the waste surface, the drainage of interstitial liquids from saltcake during a shutdown of the retrieval process, and the dissolution of saltcake by unsaturated liquids during a shutdown of the retrieval process.The simple model of waste retrieval using the modified sluicing approach indicated that the flammable gas headspace concentrations can rapidly approach the action level of 25% of the lower flammability limit (LFL) when the tank is passively ventilated. While it is not necessary to use the portable exhauster to maintain the headspace hydrogen concentration below this action level, retrieval rates would probably be limited by the slow removal of flammable gases by passive ventilation. It was determined that using a portable exhauster anywhere in the assumed operating range of 270 to 450 cfm would prevent the headspaces from reaching the 25% of LFL action level even if the water jets are very effective at eroding the saltcake. Specific guidelines are developed to ensure that, in the event of a catastrophic loss of the retrieval pump and portable exhauster, headspace flammability will not reach the LFL. iv This report is Revision 2 of PNNL-14271. Revision 1 ...

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“…Of more use to this study is the methodology devised for a recent program involving actual-waste salt dissolution of numerous Hanford tanks. 11,12,13 This methodology involves saltcake-dissolution tests that fall into three general categories: series of single-wash tests, multiple-wash tests, and feed stability tests. The tests contained in this task plan are modeled after the first two of these categories of Hanford's saltcake dissolution experiments.…”

Section: Research Backgroundmentioning

confidence: 99%

“…The test design used aspects from previous saltcake dissolution studies performed at Hanford. 11,12,13 Table 1 contains the factors that were varied between each test and the levels of each factor. Two different saltcake simulants were prepared: "Average SRS" mimicked typical SRS waste and "Hanford S-112" represented a Hanford single-shell tank waste.…”

Section: Test Outlinementioning

confidence: 99%

Saltcake Dissolution Simulant Tests

Martino¹

2003

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Small-scale (15 to 50 mL) dissolution equilibrium tests were performed on surrogate waste representing typical saltcake at the Savannah River and Hanford Sites. The primary objectives of this study were to gain a better understanding of the solid-liquid equilibrium of simulated-waste saltcakes and chemistry of the dissolved salt solutions. These tests were performed in preparation for similar dissolution tests with actual-waste saltcakes.Two types of tests (single-wash and multiple-wash) were performed at two temperatures (25 °C and 50 °C) for each saltcake simulant. The compositions of the supernatant fluids are provided for both types of dissolution tests, and profiles of the elution of each salt component are provided for the multiple-wash tests.The conclusions from these tests follow:• For both salt waste surrogates, dissolution of the soluble components was achieved at less than a 2:1 mass ratio of inhibited water to saltcake during multiple-wash tests.• Dissolution of the Hanford S-112 simulant resulted in a relatively large weight percentage of residual insoluble material (4.2 wt. %), which was identified as a mixture of Al(OH) 3 phases (bayerite and gibbsite).• The profiles for the relative elution of anions from saltcake during dissolution exhibit distinctions that are dependent upon the dissolution temperature and the initial saltcake composition.

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Saltcake dissolution FY 1998 status report

Cited by 5 publications

References 2 publications

Flammable Gas Release Estimates for Modified Sluicing Retrieval of Waste from Selected Hanford Single-Shell Tanks

Flammable Gas Release Estimates for Modified Sluicing Retrieval of Waste from Selected Hanford Single-Shell Tanks

Flammable Gas Release Estimates for Modified Sluicing Retrieval of Waste from Selected Hanford Single-Shell Tanks

Saltcake Dissolution Simulant Tests

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