Dissolution of Fissile Materials Containing Tantalum Metal

Rudisill, Tracy S.; Crowder, Mark L.; Bronikowski, Michael G.

doi:10.2172/910168

Cited by 4 publications

(14 citation statements)

References 3 publications

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“…It is also known that as the Pu concentration increases from 0 to 6.75 g/L Pu, the likelihood of forming a Pu-Gd-F precipitate decreases. [11] The lowtemperature Pu precipitation issue associated with the use of Gd does not occur for dissolutions performed with B; however, the B concentration must be maintained below the H 3 BO 3 solubility limit and the KF concentration must not exceed the value where B precipitates as KBF 4 .…”

Section: Figure 1-1 Estimated Times For the Dissolution Of A Nominalmentioning

confidence: 99%

“…The thickness was difficult to measure due to the irregular surface of the metal pieces; therefore a thickness of 0.8 mm was established based on the average of multiple measurements. Using this thickness, the calculated density of the metal pieces was 12-13 g/cm 3 . The dissolution vessel and offgas collection system were fabricated from borosilicate glass by the SRNL Glass Shop.…”

Section: Preparation Of Pu Metalmentioning

confidence: 99%

“…[12] Higher KF concentrations can be considered for the dissolution, although corrosion control issues and the precipitation of B as KBF 4 must also be taken into account. The precipitation of B as KBF 4 [5] The study also showed that dissolution rate decreased with increasing temperature in 0.13 M HF but increased with increasing temperature at 0.01 M and 0.07 M HF. It should be noted that the conclusions from Miner's work are based on calculated curves derived from measured values.…”

Section: Dissolution Rate Measurementsmentioning

confidence: 99%

“…[1][2][3][4][5][6][7] However, most of the testing was conducted at HNO 3 concentrations in the 3-5 M range and at temperatures < 90 C to limit the formation of plutonium dioxide and maximize the rate of dissolution. To support a new mission in H-Canyon, the development of a Pu metal dissolution flowsheet which utilizes 8-10 M HNO 3 solutions containing KF is desired. [8][9] The preferred flowsheet would use 8-10 M HNO 3 .…”

Section: Introductionmentioning

confidence: 99%

“…To support a new mission in H-Canyon, the development of a Pu metal dissolution flowsheet which utilizes 8-10 M HNO 3 solutions containing KF is desired. [8][9] The preferred flowsheet would use 8-10 M HNO 3 . [7] Based on Holcomb's calculations, a nominal alpha phase button would require a cumulative dissolution rate of ~20 mg/min-cm 2 to dissolve within 24 hours.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Dissolution of Plutonium Metal in 8-10 M Nitric Acid

Rudisill¹,

Pierce²

2012

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Section: Figure 1-1 Estimated Times For the Dissolution Of A Nominalmentioning

confidence: 99%

Section: Preparation Of Pu Metalmentioning

confidence: 99%

Section: Dissolution Rate Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Dissolution of Plutonium Metal in 8-10 M Nitric Acid

Rudisill¹,

Pierce²

2012

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Dissolution of Plutonium Metal Using Nitric Acid Solutions Containing Potassium Fluoride

Rudisill

Crowder

Bronikowski

2008

Separation Science and Technology

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The deinventory and deactivation of the Savannah River Site's (SRS's) FB-Line facility required the disposition of approximately 2000 items from the facility's vaults. Plutonium (Pu) scraps and residues which do not meet criteria for conversion to a mixed oxide fuel will be dissolved and the solution stored for subsequent disposition. Some of the items scheduled for dissolution are composite materials containing Pu and tantalum (Ta) metals. The preferred approach for handling this material is to dissolve the Pu metal, rinse the Ta metal with water to remove residual acid, and burn the Ta metal. The use of a 4 M nitric acid (HNO 3 ) solution containing 0.2 M potassium fluoride (KF) was initially recommended for the dissolution of approximately 500 g of Pu metal. However, prior to the use of the flowsheet in the SRS facility, a new processing plan was proposed in which the feed to the dissolver could contain up to 1250 g of Pu metal. To evaluate the use of a larger batch size and subsequent issues associated with the precipitation of plutonium-containing solids from the dissolving solution, scaled experiments were performed using Pu metal and samples of the composite material.In the initial experiment, incomplete dissolution of a Pu metal sample demonstrated that a 1250 g batch size was not feasible in the HB-Line dissolver. Approximately 45% of the Pu was solubilized in 4 h. The remaining Pu metal was converted to plutonium oxide (PuO 2 ). Based on this work, the dissolution of 500 g of Pu metal using a 4-6 h cycle time was recommended for the HB-Line facility. Three dissolution experiments were subsequently performed using samples of the Pu/Ta composite material to demonstrate conditions which reduced the risk of precipitating a double fluoride salt containing Pu and K from the dissolving solution. In these experiments, the KF concentration was reduced from 0.2 M to either 0.15 or 0.175 M. With the use of 4 M HNO 3 and a reduction in the KF concentration to 0.175 M, the dissolution of 300 g of Pu metal is expected to be essentially complete in 6 h. The dissolution of larger batch sizes would result in the formation of PuO 2 solids. Incomplete dissolution of the PuO 2 formed from the metal is not a solubility limitation, but can be attributed to a combination of reduced acidity and complexation of fluoride which slows the dissolution kinetics and effectively limits the mass of Pu dissolved.

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Low temperature dissolution flowsheet for Pu metal

Daniel

Almond

Rudisill

2017

Separation Science and Technology

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The Savannah River National Laboratory was requested to develop a Pu metal dissolution flowsheet at two reduced temperature ranges for implementation in the Savannah River Site H-Canyon facility. The dissolution and H 2 generation rates during Pu metal dissolution were investigated using a dissolving solution at ambient temperature (20-30 °C) and for an intermediate temperature of 50-60 °C. The Pu metal dissolution rate measured at 57 °C was approximately 20 times slower than at boiling (112 -116 °C). The dissolution rate at ambient temperature (24 °C) was approximately 80 times slower than the dissolution rate at boiling Hydrogen concentrations were less than detectable (<0.1 vol %). Low Temperature Dissolution Flowsheet for Pu Metal SRNL-STI-2016-00524 page 19 of 26 * Estimated dissolution rate(1) **Dissolving solution also contained 0.4 g/L Ni and 0.6 g/L Cr

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Dissolution of Fissile Materials Containing Tantalum Metal

Cited by 4 publications

References 3 publications

Dissolution of Plutonium Metal in 8-10 M Nitric Acid

Dissolution of Plutonium Metal in 8-10 M Nitric Acid

Dissolution of Plutonium Metal Using Nitric Acid Solutions Containing Potassium Fluoride

Low temperature dissolution flowsheet for Pu metal

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