Distribution of studtite and metastudtite generated on the surface of U₃O₈: application of Raman imaging technique to uranium compound

Abstract

Studtite and metastudtite are uranyl peroxides formed on nuclear fuel in water through the reaction with H₂O₂ produced by the radiolysis of water. However, it is unclear how the two types of uranyl peroxides are generated and distributed on the surface of nuclear fuel. Here, we used Raman imaging technique to exemplify distribution data of the two uranyl peroxides formed on the surface of a U₃O₈ pellet through immersion in a H₂O₂ aqueous solution. As a result, we observed that studtite and metastudtite are heterogeneously distributed on the U₃O₈ surface. No clear correlation between the distributions of studtite and metastudtite was observed, suggesting that the two uranyl peroxides are independently generated on the surface of U₃O₈. We anticipate that this Raman imaging technique could reveal how these uranyl peroxides are generated and distributed on the surface of the nuclear fuel debris in the Fukushima-Daiichi nuclear power plants.