Fuel corrosion processes under waste disposal conditions

Comparative study of the structural and electrochemical properties of noble metal inclusions in a UO2matrix

“…Between region A and B oxidation of UO 2 takes place which is due to the incorporation of O 2-into the oxide matrix and which results in the formation of UO 2+x [2]. Such incorporation involves an increase of mass which is expressed in a lower frequency of the oscillating electrode (QCMB image not shown here).…”

“…Thin films are deposited on the working electrode which is a planar AT-cut quartz crystal (diameter, d = 13.7 mm) having a resonance frequency of 8 MHz in air / vacuum with a gold deposition (d = 5.1 mm) on each side of the crystal (IJ Cambria Scientific Ltd., Carms). This gives a nominal electrode area of 0.204 cm 2 . An Ag/AgCl electrode (with 3 M KCl filling) with a potential of + 0.208 V (at room temperature) was used as reference electrode measured against a standard hydrogen electrode (SHE).…”

“…A higher frequency is monitored. Region E can be attributed to the reduction of U(VI) to U(IV) [2,15] and to the formation of secondary phases at the surface since the frequency is again decreased. With doping the UO 2 matrix new features appear in the CV for regions A, B and E. These features can be possibly attributed to the interaction of the surface with H 2 O (de-/sorption, decomposition).…”

“…Dissolution studies of spent nuclear fuel (SNF) represent one main contribution to the safety assessment of a nuclear waste repository since the leaching of radionuclides (RN) into the groundwater is associated with the risk of ecological and human exposure [1,2,3,4]. SNF is characterized as being a complex system composed of the fuel matrix UO 2 doped with a variety of components such as oxide precipitates of Rb, Cs, Ba, Zr, Nb, Mo, Tc or metallic precipitates -so called -particles -of Mo, Ru, Pd, Tc and Rh [5].…”

Cost-Effective Cementitious Material Compatible with Yucca Mountain Repository Geochemistry

“…7. The formation of this layer of alteration (or corrosion) products prevents further release of UO 2 particles, hence leading to a drop in the U release rate (Shoesmith 2000). Buck.…”