Development of nuclear fuels with enhanced accidenttolerance (ATF) is one of the main current objectives ofresearchers worldwide. The contribution focuses onchromium-based PVD coated cladding concept (Cr andCrN+Cr) developed in cooperation of UJP PRAHA a.s.and Czech Technical University in Prague. The resultspresented in the past showed high oxidation resistance ofthin Cr and multicomponent CrN+Cr coatings andimproved cladding ductility of samples after hightemperaturetransients. A more complex approach tosimulate LOCA transient is applied in the presentedstudy. A set of experiments was performed to understandthe behavior of chromium-based coated claddings duringthe whole LOCA phenomena. The presented results showthe influence of studied coatings on high-temperaturecladding creep and related phenomena such asballooning size, time to burst, cracking of coating, hightemperatureoxidation through cracked and intactcoatings. Secondary oxidation and hydriding from theinner uncoated surface after cladding failure is discussedas well. Microhardness and microstructure analysis of thematerial after testing revealed local cladding damage.The mechanical properties of cladding after LOCA canlocally deteriorate due to cracks in coating, but theinfluence on the bulk mechanical behavior of the wholefuel cladding and cladding bundles needs to be furtherinvestigated.
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