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Title: Chemical flowsheet conditions for preparing urania spheres by internal gelation

Abstract

Small, ceramic urania spheres can be prepared for use as nuclear fuel by internal chemical gelation of uranyl nitrate solution droplets. Decomposition of hexamethylenetetramine (HMTA) dissolved in the uranyl nitrate solution releases ammonia to precipitate hydrated UO/sub 3/. Previously established flowsheet conditions have been improved and modified at ORNL and have been applied to prepare dense UO/sub 2/ spheres with average diameters of 1200, 300, and 30 ..mu..m. Acid-deficient uranyl nitrate (ADUN) solutions up to 3.4 M in uranium with NO/sub 3//sup -//U mole ratios of 1.5 to 1.7 are prepared by dissolution of U/sub 3/O/sub 8/ or UO/sub 3/. Continuous mixing of metered, cooled ADUN containing urea and HMTA solutions provides a smooth, regulated flow of the temperature-sensitive feed solution. The gelation times for solution drops in organic liquids at 45 to 95/sup 0/C depend on both the chemical reaction rates and the rates of heat transfer. The gel properties vary with temperature and other gelation variables. Gelation conditions were determined which allow easy washing, drying, firing, and sintering to produce dense UO/sub 2/ spheres of all three sizes. The 1200- and 300-..mu..m UO/sub 2/ spheres were pepared by gelation in trichloroethylene at 50 to 65/sup 0/C; 2-ethyl-l-hexanol wasmore » used as the gelation medium to prepare 30-..mu..m UO/sub 2/ spheres. Washing and drying requirements were determined. The gel dried to 225/sup 0/C contains about 95% UO/sub 3/; the remaining components are H/sub 2/O, NH/sub 3//sup -/, which are volatilized during firing to UO/sub 2/.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Oak Ridge National Lab., TN (USA)
OSTI Identifier:
6243665
Report Number(s):
CONF-790666-1
TRN: 79-016828
DOE Contract Number:  
W-7405-ENG-26
Resource Type:
Conference
Resource Relation:
Conference: 34. Northwest regional meeting of the American Chemical Society, Richland, WA, USA, 13 Jun 1979
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; 36 MATERIALS SCIENCE; FUEL PARTICLES; PRODUCTION; URANIUM DIOXIDE; CHEMICAL PREPARATION; AMINES; AQUEOUS SOLUTIONS; DECOMPOSITION; FLOWSHEETS; GELATION; MICROSPHERES; URANYL NITRATES; ACTINIDE COMPOUNDS; CHALCOGENIDES; CHEMICAL REACTIONS; DIAGRAMS; DISPERSIONS; MIXTURES; NITRATES; NITROGEN COMPOUNDS; ORGANIC COMPOUNDS; OXIDES; OXYGEN COMPOUNDS; SOLUTIONS; SYNTHESIS; URANIUM COMPOUNDS; URANIUM OXIDES; URANYL COMPOUNDS; 050700* - Nuclear Fuels- Fuels Production & Properties; 360201 - Ceramics, Cermets, & Refractories- Preparation & Fabrication

Citation Formats

Haas, P A, Begovich, J M, Ryon, A D, and Vavruska, J S. Chemical flowsheet conditions for preparing urania spheres by internal gelation. United States: N. p., 1979. Web.
Haas, P A, Begovich, J M, Ryon, A D, & Vavruska, J S. Chemical flowsheet conditions for preparing urania spheres by internal gelation. United States.
Haas, P A, Begovich, J M, Ryon, A D, and Vavruska, J S. Mon . "Chemical flowsheet conditions for preparing urania spheres by internal gelation". United States. https://www.osti.gov/servlets/purl/6243665.
@article{osti_6243665,
title = {Chemical flowsheet conditions for preparing urania spheres by internal gelation},
author = {Haas, P A and Begovich, J M and Ryon, A D and Vavruska, J S},
abstractNote = {Small, ceramic urania spheres can be prepared for use as nuclear fuel by internal chemical gelation of uranyl nitrate solution droplets. Decomposition of hexamethylenetetramine (HMTA) dissolved in the uranyl nitrate solution releases ammonia to precipitate hydrated UO/sub 3/. Previously established flowsheet conditions have been improved and modified at ORNL and have been applied to prepare dense UO/sub 2/ spheres with average diameters of 1200, 300, and 30 ..mu..m. Acid-deficient uranyl nitrate (ADUN) solutions up to 3.4 M in uranium with NO/sub 3//sup -//U mole ratios of 1.5 to 1.7 are prepared by dissolution of U/sub 3/O/sub 8/ or UO/sub 3/. Continuous mixing of metered, cooled ADUN containing urea and HMTA solutions provides a smooth, regulated flow of the temperature-sensitive feed solution. The gelation times for solution drops in organic liquids at 45 to 95/sup 0/C depend on both the chemical reaction rates and the rates of heat transfer. The gel properties vary with temperature and other gelation variables. Gelation conditions were determined which allow easy washing, drying, firing, and sintering to produce dense UO/sub 2/ spheres of all three sizes. The 1200- and 300-..mu..m UO/sub 2/ spheres were pepared by gelation in trichloroethylene at 50 to 65/sup 0/C; 2-ethyl-l-hexanol was used as the gelation medium to prepare 30-..mu..m UO/sub 2/ spheres. Washing and drying requirements were determined. The gel dried to 225/sup 0/C contains about 95% UO/sub 3/; the remaining components are H/sub 2/O, NH/sub 3//sup -/, which are volatilized during firing to UO/sub 2/.},
doi = {},
url = {https://www.osti.gov/biblio/6243665}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1979},
month = {1}
}

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