In recent years, there has been considerable interestin the nuclear industry to implement a cladding that canprovide more tolerance under accident scenarios. Acoating applied on the surface of existing Zircaloy or Zralloybased fuel cladding has been considered as anoption that is achievable in the near future. In parallel,debris fretting causing fuel rod failures remains an activemechanism in Boiling Water Reactors and, to a lesserextent, in Pressurized Water Reactors. A surface coatingon fuel cladding has been considered as part of measuresthat could be taken to mitigate such failures. There istherefore interest in a coating that serves both purposes.This paper describes a coating on Zircaloy fuel claddingtubes that has been developed to address improved debrisfret resistance as well as providing enhanced accidenttolerance. GNF’s proprietary coating is called ARMOR,named for its Abrasion Resistant, More OxidationResistant characteristics.A number of tests have been conducted to support thedevelopment of ARMOR. The accident tolerancecharacteristic was demonstrated through testing in steamunder design basis accident conditions at between 1000and 1200 oC. Additionally, mechanical tests wereperformed to check the influence of the coating on thetensile properties of coated tubes, and on the strainbearing performance of the coated fuel rod. Results froman experiment to assess the likelihood of the coatingbecoming a source of debris are also described.
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