Effect of carbon impurity during the sintering of MOX fuels

Conference · Fri Jul 01 00:00:00 EDT 2016

OSTI ID:22764092

Vaudez, S.; Marlot, C.; Chambon, C. ^[1]; Lebreton, F. ^[2]

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1. CEA - Centre de Marcoule, DEN, DTEC, SECA, LFC, F-30207 Bagnols sur Ceze (France)
2. CEA - Centre de Marcoule, DEN, DTEC, SECA, LCC, F-30207 Bagnols sur Ceze (France)

UO{sub 2} and PuO{sub 2} powders are currently used as raw materials for the industrial fabrication of mixed uranium plutonium oxide (MOX) for light-water reactors. The mixture is pelletized before being sintered at 1700 Celsius degrees under a reducing atmosphere of Ar/4%H{sub 2} with 1200 vpm H{sub 2}O. At the end of the oxide ceramic sintering process, a swelling phenomenon sometimes occurs and could be responsible for the fuel non-compliance with safety specifications. This phenomenon is often caused by the presence of carbon impurities in the raw materials. In this paper, it will be shown how carbon impurities (naturally present or deliberately introduced) in the raw materials affect MOX fuel densification by sintering. For that purpose, MOX densification has been monitored by dilatometric measurements and the gases released during sintering have been continuously qualitatively and quantitatively analyzed. Gases released or trapped in the fuel during densification have been studied, as well as the sintered fuel characteristics (density, microstructure, U/Pu distribution). Results confirm that carbon impurities can play a major role in the fuel swelling: the oxides react with carbon and form gaseous CO molecules that could be trapped in the closed pores during sintering. This leads to a pressure increase within pores responsible for an irreversible swelling by creep deformation. (authors)

• Research Organization: American Nuclear Society - ANS, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
• OSTI ID: 22764092
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
CARBON
CARBON MONOXIDE
CREEP
FISSION POISONS
FISSION PRODUCT RELEASE
FUEL DENSIFICATION
IMPURITIES
MICROSTRUCTURE
MIXED OXIDE FUELS
PLUTONIUM
PLUTONIUM OXIDES
RAW MATERIALS
SINTERING
SWELLING
TEMPERATURE RANGE 1000-4000 K
TRAPPING
URANIUM
URANIUM DIOXIDE
WATER COOLED REACTORS
WATER MODERATED REACTORS