The Behavior of Analogues for RIS-affected AGR Cladding under Conditions Relevant to Wet Interim Storage

摘要

Due to radiation induced segregation (RIS) thatoccurs during fuel use in-reactor, portions of spent fuelcladding are predicted to have enhanced corrosionsusceptibility during wet interim storage. The NationalNuclear Laboratory UK have produced thermallysensitized analogues (20/25/Nb SS and 304H SS) for RISaffectedcladding to allow study of this effect withoutradiological risk. Here, we present a study of thecorrosion properties of these simulants in order to gaininsight into the behavior of real cladding underconditions relevant to wet storage.First, the degree of sensitization of the RIS-affectedcladding analogues was verified. In these tests significantsusceptibility to localized corrosion was observed. Theeffect of such vulnerability was analyzed under alkalicorrosion conditions. Under open circuit conditions, XPSdata indicates that the protective layer formed on thesurface of thermally aged SS consists predominately of Feand Cr oxides/hydroxides, with Fe oxide/hydroxide beingthe more dominant of the two especially in the case of304H SS. Despite increased vulnerability and thedecrease in Cr oxide/hydroxide in the surface layer, bothheat treated samples were found to protected under pondwater conditions and it would be expected that real RISaffectedcladding would be similarly passive under thesame conditions.