Accident　tolerant　fuel　(ATF)　concepts　are　at　present　still　in　the　engineering　design　stage.　FeCrAl,　which　has　great　oxidation　resistance　in　high　temperature　steam　environment,　is　an　ATF　potential　cladding　material　with　higher　research　priority.　However,　considering　its　features,　including　high　thermal　expansion,　low　creep　rate　and　strong　absorption　of　neutron,　further　evaluation　on　its　in-pile　behaviors　is　still　necessary　for　future　industrial　application.　To　address　this　issue,　the　self-developed　fuel　performance　analysis　code,　FROBA,　was　further　developed　into　a　new　version　named　FROBA-ATF.　A　transient　heat　transfer　model　was　added　into　the　code＇s　thermo-hydraulic　module　for　transient　simulation,　the　rigid　mechanical　model　was　rewritten　into　unrigid　for　ATF　cladding　and　material　properties　of　FeCrAl　cladding　were　also　added.　These　updated　modules　were　introduced　and　the　updated　code　was　assessed　in　this　paper.　On　this　basis,　a　comparative　study　on　in-pile　behaviors　of　UO2-FeCrAl　fuel　rod　and　UO2-Zr4　fuel　rod　under　normal　and　accident　conditions　were　performed　in　this　paper.　Even　through　the　performance　analysis　revealed　that　FeCrAl　cladding　could　greatly　reduce　the　oxidation　thickness,　the　thermal　performance　of　UO2-FeCrAl　fuel　rod　was　unsatisfactory　due　to　its　higher　thermal　expansion　and　lower　creep　rate,　especially　at　beginning　of　life.　With　geometry　optimization,　the　steady-state　performance　of　UO2-FeCrAl　fuel　rod　was　enhanced.　What＇s　more,　the　thermal　and　mechanical　performance　of　the　improved　UO2-FeCrAl　was　evaluated　and　compared　under　Loss　of　coolant　accident　(LOCA)　and　Reactivity　Initiated　Accident　(RIA)　conditions.　The　results　showed　that　the　optimized　ATF　had　better　thermal　performance,　lower　cladding　hoop　stress,　and　could　provide　more　coping　time　under　accident　conditions.　©　2020　Elsevier　B.V.