The effects of the second refining process, Electro-Slag Remelting (ESR), were investigated on Ta rich inclusion formation in the Vacuum Induction Melted (VIM) Reduced Activation Ferritic/Martensitic steel (RAFM), F82H (Fe-8Cr-2W-V-Ta). The Ta rich oxides such as TaO_x and TaO_x-Al₂O₃ are major inclusion in VIMed F82H, and those were correlated with the reduction of the Charpy impact property, as those were found at the crack initiation points. It was revealed that the ESR process was effective on removing those Ta rich oxides. On the other hand, ESR process increased MnS and Al₂O₃ instead, and these inclusions were found at the crack initiation points. These could explain the little difference on Ductile-Brittle Transition Temperature (DBTT) of as-VIMed and ESRed F82H.