Canyon dissolution of sand, slag, and crucible residues

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Description

An alternative to the FB-Line scrap recovery dissolver was desired for the dissolution of sand, slag, and crucible (SS{ampersand}C) residues from the plutonium reduction process due to the potential generation of hydrogen gas concentrations above the lower flammability limit. To address this concern, a flowsheet was developed for the F-Canyon dissolvers. The dissolvers are continually purged with nominally 33 SCFM of air; therefore the generation of flammable gas concentrations should not be a concern. Following removal of crucible fragments, small batches of the remaining sand fines or slag chunks containing less than approximately 350 grams of plutonium can be dissolved ... continued below

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12 p.

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Rudisill, T.S.; Gray, J.H.; Karraker, D.G. & Chandler, G.T. December 1, 1997.

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Description

An alternative to the FB-Line scrap recovery dissolver was desired for the dissolution of sand, slag, and crucible (SS{ampersand}C) residues from the plutonium reduction process due to the potential generation of hydrogen gas concentrations above the lower flammability limit. To address this concern, a flowsheet was developed for the F-Canyon dissolvers. The dissolvers are continually purged with nominally 33 SCFM of air; therefore the generation of flammable gas concentrations should not be a concern. Following removal of crucible fragments, small batches of the remaining sand fines or slag chunks containing less than approximately 350 grams of plutonium can be dissolved using the center insert in each of the four annular dissolver ports to address nuclear criticality safety concerns. Complete dissolution of the sand fines and slag chunks was achieved in laboratory experiments by heating between 75 and 85 degrees Celsius in a 9.3M nitric acid/0.013M (hydrogen) fluoride solution. Under these conditions, the sand and slag samples dissolved between 1 and 3 hours. Complete dissolution of plutonium and calcium fluorides in the slag required adjusting the dissolver solution to 7.5 wt% aluminum nitrate nonahydrate (ANN). Once ANN was added to a dissolver solution, further dissolution of any plutonium oxide (PuO2) in successive charges was not practical due to complexation of the fluoride by aluminum. During the laboratory experiments, well mixed solutions were necessary to achieve rapid dissolution rates. When agitation was not provided, sand fines dissolved very slowly. Measurement of the hydrogen gas generation rate during dissolution of slag samples was used to estimate the amount of metal in the chunks. Depending upon the yield of the reduction, the values ranged between approximately 1 (good yield) and 20% (poor yield). Aging of the slag will reduce the potential for hydrogen generation as calcium metal oxidizes over time. The potential for excessive corrosion in the dissolvers was evaluated using experimental data reported in the literature. Corrosion data at the exact flowsheet conditions were not available; however, the corrosion rate for 304L stainless steel (wrought material) corrosion coupons in 10M nitric acid/0.01M hydrofluoric acid at 95 degrees Celsius was reported as 21 mils per year. If the fluoride in the dissolver is complexed with aluminum, the corrosion rate will decrease to approximately 5 mils per year.

Physical Description

12 p.

Notes

INIS; OSTI as DE98051770

Source

  • Other Information: PBD: Dec 1997

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  • Other: DE98051770
  • Report No.: WSRC-TR--97-00367
  • Grant Number: AC09-96SR18500
  • DOI: 10.2172/574512 | External Link
  • Office of Scientific & Technical Information Report Number: 574512
  • Archival Resource Key: ark:/67531/metadc691242

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

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Creation Date

  • December 1, 1997

Added to The UNT Digital Library

  • Aug. 14, 2015, 8:43 a.m.

Description Last Updated

  • Feb. 9, 2016, 7:36 p.m.

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Rudisill, T.S.; Gray, J.H.; Karraker, D.G. & Chandler, G.T. Canyon dissolution of sand, slag, and crucible residues, report, December 1, 1997; Aiken, South Carolina. (digital.library.unt.edu/ark:/67531/metadc691242/: accessed September 18, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.