Deuterium absorption in reduced activation ferritic/martensitic steel F82H under exposure to D2O vapor/water at room temperature

Eight samples of F82H ferritic/martensitic steel were irradiated at 300 K with 20 MeV W ions to the damage level of 0.54 displacements per atom at the damage peak. Three samples were afterwards annealed in vacuum at 423 K for 72 h and then at 373 K for 106 h. Three other samples were annealed in H2 atmosphere at 100 kPa at the same annealing temperatures and durations. All samples were exposed at room temperature to D2O vapor at the partial pressures in the range from 3 to 6 kPa for 365 to 1181 days. After termination of the D2O vapor exposure, the surfaces of the samples were partly covered by small (≤1 mm in diameter) drops of D2O water. Thus, the damaged samples were exposed to a mixture of D2O vapor and water. Trapping of deuterium at the ion-induced defects in the damage zone was examined by the D(3He, p)4He nuclear reaction. It has been found that the W-ion-induced defects generated in the F82H samples are decorated by deuterium diffusing from the surface.