CRUD resistant fuel cladding materials

Abstract

CRUD is a term commonly used to describe deposited corrosion products that form on the surface of fuel cladding rods during the operation of Pressurized Water Reactors (PWR). CRUD has deleterious effects on reactor operation and currently, there is no effective way to mitigate its formation. The Electric Power Research Institute (EPRI) CRUD Resistant Fuel Cladding project has the objective to study the effect of different surface modifications of Zircaloy cladding on the formation of CRUD, and ultimately minimize its effects. This modification will alter the surface chemistry and therefore the CRUD formation rate. The objective of this study was to construct a pool boiling facility at atmospheric pressure and sub-cooled boiling conditions, and test a series of samples in simulated PWR water with a high concentration of nanoparticulate CRUD precursors. After testing, ZrC was the only material out of six that did not develop dark, circular spots, which are hypothesized to be the beginnings of CRUD boiling chimneys. Further testing will be needed to confirm that it is indeed more CRUD resistant, even under realistic PWR conditions in a parallel testing facility.