Reaction of hydrogen peroxide with uranium zirconium oxide solid solution – Zirconium hinders oxidative uranium dissolution

摘要

AbstractWe studied oxidative dissolution of uranium and zirconium oxide [(U,Zr)O2] in aqueous H2O2solution to estimate (U,Zr)O2stability to interfacial reactions with H2O2. Studies on the interfacial reactions are essential for anticipating how a (U,Zr)O2-based molten fuel may chemically degrade after a severe accident. The fuel's high radioactivity induces water radiolysis and continuous H2O2generation. Subsequent reaction of the fuel with H2O2may oxidize the fuel surface and facilitate U dissolution. We conducted our experiments with (U,Zr)O2powder (comprising Zr:U mole ratios of 25:75, 40:60, and 50:50) and quantitated the H2O2reaction via dissolved U and H2O2concentrations. Although (U,Zr)O2reacted more quickly than UO2, the dissolution yield relative to H2O2consumption was far less for (U,Zr)O2compared to that of UO2. The reaction kinetics indicates that most of the H2O2catalytically decomposed to O2at the surface of (U,Zr)O2. We confirmed th