The present paper is to describe the behavior of tritium in Flibe as a self-cooled liquid blanket of a fusion reactor quantitatively. In order to avoid the generation of corrosive TF, Flibe is maintained under reduction atmosphere to transform TF to T2 to keep a faster reaction rate compared with a residence time in a self-cooled blanket. The most important point is to clarify whether or not the redox control of Flibe can be achieved by Be rods inserted in a blanket within a limited contact time. The dissolution rate of a Be rod and the TF reduction reaction rate of Be + 2TF = BeF2 + T2 in Flibe were experimentally determined under the JUPITER-II collaboration work. Close agreement was obtained between experiment and our simplified complete-mixing model. Especially, the reaction between Be and F- ion immediately after the contact was found to be limited by diffusion of F- ion. The behavior of tritium generated in a Flibe fuel cycle was simulated under a Flibe flow condition of FFHR-2.