The Effect of Rare Earth Dopants on UO2 Oxidation

Conference · Sun Jun 01 04:00:00 EDT 2003

OSTI ID:891157

Hanson, Brady D; Cumblidge, Stephen E; Scheele, Randall D; Sell, Rachel L

Recent work by Hanson [1] has demonstrated a clear dependence of the oxidation of Light Water Reactor spent fuel on burnup. Oxidation of spent fuel was shown to proceed via the two-step reaction UO2?UO2.4?UO2.67+x, where the U3O8-like phase does not form until conversion to UO2.4 is complete. The temperature-dependent activation energy (Ea) of the transition from UO2.4 to the hyperstoichiometric U3O8 was found to be {approx}150 kJ mol-1. Each MWD/kg M burnup added {approx}1.0 kJ mol-1. The work of McEachern et.al. [2], Choi et. al. [3], and You et. al. [4] have all verified this oxidation dependence on SIMFUEL or unirradiated doped-UO2. All present work agrees that the soluble actinides or fission products that substitute in the U matrix act to delay the onset of U3O8. However, no single model exists to explain the observed behavior, including the fact that most dopants actually allow an earlier onset for UO2.4 formation. The present work is part of a Nuclear Energy Research Initiative project attempting to develop a UO2-based matrix capable of achieving extended burnups by including soluble dopants. The resulting fuel should be highly oxidation and dissolution resistant, which will be beneficial during accident scenarios or for disposal in a geologic repository. In addition, the stabilized matrix may help delay the onset of fuel restructuring that occurs at higher burnups. Initial results of the oxidation tests to quantify effects as a function of ionic radii and charge of the dopant are presented.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 891157
• Report Number(s): PNNL-SA-38078
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
29 ENERGY PLANNING, POLICY, AND ECONOMY
ACCIDENTS
ACTINIDES
ACTIVATION ENERGY
BURNUP
DISSOLUTION
FISSION PRODUCTS
NUCLEAR ENERGY
OXIDATION
RARE EARTHS
SPENT FUELS
UO2 oxidation
URANIUM OXIDES U3O8
WATER
dopants