Grain boundary corrosion and alteration phase formation during the oxidative dissolution of UO{sub 2} pellets

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:459982

Wronkiewicz, D J; Buck, E C; Bates, J K

Alteration behavior of UO{sub 2} pellets following reaction under unsaturated drip-test conditions at 90 C for up to 10 years was examined by solid phase and leachate analyses. Sample reactions were characterized by preferential dissolution of grain boundaries between the original press-sintered UO{sub 2} granules comprising the samples, development of a polygonal network of open channels along the intergrain boundaries, and spallation of surface granules that had undergone severe grain boundary corrosion. The development of a dense mat of alteration phases after 2 years of reaction trapped loose granules, resulting in reduced rates of particulate U release. The paragenetic sequence of alteration phases that formed on the present samples was similar to that observed in surficial weathering zones of natural uraninite (UO{sub 2}) deposits, with alkali and alkaline earth uranyl silicates representing the long-term solubility-limiting phases for U in both systems.

• Research Organization: Argonne National Lab., IL (United States)
• Sponsoring Organization: USDOE Office of Civilian Radioactive Waste Management, Washington, DC (United States)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 459982
• Report Number(s): ANL/CMT/CP--90413; CONF-961202--73; ON: DE97003219
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
DISSOLUTION
FUEL PELLETS
RADIOACTIVE WASTE FACILITIES
SIMULATION
SOURCE TERMS
SPENT FUEL STORAGE
SPENT FUELS
UNDERGROUND DISPOSAL
URANIUM DIOXIDE