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Title: MEASUREMENT OF SURFACE AREA OF URANIUM DIOXIDE POWDER AND SINTERED PELLETS

Abstract

The surface areas of sintered uranium dioxide pellets (individual pellets ranging from 50 to 2000 cm/sup 2/) were measured with a precision of 1.3% and a reproducibility of about 4% with a BET adsorption apparatus, using krypton as the adsorbate. Powder samples (10 to 50 mg) of uranium dioxide, anatase, zirconia, and ceria were measured with a precision of 0.5% and a reproducibility of about 3%. An excellent correlation was found between the surface area and the average particle diameter, as measured with a Fisher Sub-Sieve Sizer. An equation, relating the surface area(S) and the average particle diameter(D) (S= 1.67/D, as compared to S = 0.547/D (if the particles were spherical)) shows the powder has a shape factor of about 3. (auth)

Authors:
Publication Date:
Research Org.:
Atomics International. Div. of North American Aviation, Inc., Canoga Park, Calif.
Sponsoring Org.:
USDOE
OSTI Identifier:
4123540
Report Number(s):
NAA-SR-5319
NSA Number:
NSA-15-000620
DOE Contract Number:
AT-11-1-GEN-8
Resource Type:
Technical Report
Resource Relation:
Other Information: Orig. Receipt Date: 31-DEC-61
Country of Publication:
United States
Language:
English
Subject:
METALS, CERAMICS, AND OTHER MATERIALS; ADSORPTION; ANATASE; BET METHOD; CERIUM OXIDES; EQUATIONS; GRAIN SIZE; INSTRUMENTS; KRYPTON; LABORATORY EQUIPMENT; MEASURED VALUES; PELLETS; POWDERS; SINTERED MATERIALS; SURFACES; TITANIUM OXIDES; URANIUM DIOXIDE; ZIRCONIUM OXIDES

Citation Formats

Smith, T. MEASUREMENT OF SURFACE AREA OF URANIUM DIOXIDE POWDER AND SINTERED PELLETS. United States: N. p., 1960. Web. doi:10.2172/4123540.
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Smith, T. MEASUREMENT OF SURFACE AREA OF URANIUM DIOXIDE POWDER AND SINTERED PELLETS. United States. doi:10.2172/4123540.
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Smith, T. Sat . "MEASUREMENT OF SURFACE AREA OF URANIUM DIOXIDE POWDER AND SINTERED PELLETS". United States. doi:10.2172/4123540. https://www.osti.gov/servlets/purl/4123540.
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@article{osti_4123540,
title = {MEASUREMENT OF SURFACE AREA OF URANIUM DIOXIDE POWDER AND SINTERED PELLETS},
author = {Smith, T.},
abstractNote = {The surface areas of sintered uranium dioxide pellets (individual pellets ranging from 50 to 2000 cm/sup 2/) were measured with a precision of 1.3% and a reproducibility of about 4% with a BET adsorption apparatus, using krypton as the adsorbate. Powder samples (10 to 50 mg) of uranium dioxide, anatase, zirconia, and ceria were measured with a precision of 0.5% and a reproducibility of about 3%. An excellent correlation was found between the surface area and the average particle diameter, as measured with a Fisher Sub-Sieve Sizer. An equation, relating the surface area(S) and the average particle diameter(D) (S= 1.67/D, as compared to S = 0.547/D (if the particles were spherical)) shows the powder has a shape factor of about 3. (auth)},
doi = {10.2172/4123540},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Oct 01 00:00:00 EDT 1960},
month = {Sat Oct 01 00:00:00 EDT 1960}
}
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Technical Report:
View Technical Report (5.43 MB)
DOI:  10.2172/4123540
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  • The specifications are outlined in terms of chemical and isotopic composition, grinding, blending, physical properties, microstructure, sintering characteristic s, and inspections. Appendixes include methods for: determination of oxygen-to-uranium ratio in sintered UO/sub 2/ pellets; microexamination of the sintered pellets; and corrosion testing of the pellets. (B.O.G.)

  • Sintered uranium dioxide pellets, ignited to U/sub 3/O/sub 8/, and uranium dioxide powder without pretreatment are dmssolved in sulfuric acid in the presence of hydrogen peroxide. Boron is separated by distillation as methyl borate and determined absorptiometrically as rosocyanine. The range of the method is 0.1 to l.5 micrograms boron, and is applicable to uranium dioxide powder containing 0.1 to 1.5 ppm boron and to sintered uranium dioxide pellets containing 0.02 to 0.3 ppm boron calculated on a uranium basis. Standard deviation (95% confidence limits) at the 0.1 to 1 ppm levels is plus or minus 10%. (auth)

  • S>Sintered uranium dioxide pellets, ignited to U/sub 3/O/sub 8/, and uranium dioxide powder without pretreatment are dissolved in sulfuric acid in the presence of hydrogen peroxide. Boron is separated by distillation as methyl borate and determined absorptiometrically as rosocyanine. The range of the method is 0.1 to 1.5 Aicrograms boron, and, as written, is applicable to uranium dioxide powder containing 0.1 to 1.5 ppm boron and to sintered uranium dioxide pellets containing 0.02 to 0.3 ppm boron calculated on a uranium basis. Standard deviation at the 0.1 to 1 ppm levels is plus or minus 10%. (auth)

  • Oxidation of uranium dioxide sintered pellets with oxygen at 3 to 800 mm Hg, 0 to 450 gas-cooled C and with a 0 to 5% concentration of fission product oxides (fissia) was studied in an effort to elucidate the kinetics and mechanism of the reactions involved. A mechanism is postalated for processes that control the oxidation from UC/sub 2/ to U/sub 3/O/sub 8/ in terms of the following reactions: chemisorption of oxygen on the UO/sub 2/ surface, followed by adsorption of oxygen on the chemisorbed layer STAR/sub 1/ = 5.5 x 10/sup -7/ P exp (-l2,800 2,800/RT) moles O/cm/sup 2/-sec,more » where P is oxygen pressure in mm Hg!; diffusion through a thin layer (224 74 A) of U/sub 3/O/sub 7/ or U/ sub 4/O/sub 9/ (depending on the temperature) with a diffusion coefficient D = 5.5 x 10/sup -5/ exp (-21,900 1400/RT) cm/sup 2//sec for pure UO/sub 2/ and D = 12.2 x 10/sup -5/ exp (-28,100 1100/RT) cm/sup 2//sec for pellets with fissia; formation of U/sub 3/O/sub 8/ in the grain boundaries, which causes the surface layer to spall off, and thereby pulverize the pellet. (auth)« less

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