Hydrogen isotope exchange at the surface of C-W mixed material layer on tungsten by gas exposure

•Hydrogen isotope exchange behavior on C-W mixed material was studied by TDS.•The temperature dependence showed that hydrogen isotope exchange was the most effective at 523 K.•It can be said that hydrogen isotope replacement is efficient to remove retained tritium on the surface region of mixture layer. Hydrogen isotope exchange behavior on carbon (C)- tungsten (W) mixed material layer on W was studied as a function of gas exposure time and temperature. It was found that hydrogen isotope exchange enhanced the reduction of residual hydrogen effectively compared by only heating. The temperature dependence showed that hydrogen isotope exchange was the most effective at 523 K and above 573 K, thermal annealing reduced the total hydrogen isotope retention. It can be said that hydrogen isotope replacement is efficient to remove retained tritium on the surface region of mixture layer.