The surface rate constants of deuterium in the reduced activating martensitic steel OPTIFER-IVb

Abstract

A gas permeation technique has been used to obtain the deuterium surface rate constants for adsorption σK 1 and recombination σK 2 in the martensitic steel OPTIFER-IVb. The measurements were performed over the temperature range 523–723 K with deuterium driving pressures ranging from 5×10 2 to 5×10 5 Pa. The deuterium surface rate constants obtained are: σK 1 ( mol m −2 s −1 Pa −1)=2.998×10 −8 exp(−29230/RT) , σK 2 ( mol −1 m 4 s −1)=2.838×10 −7 exp(−28679/RT) , R in J/ K mol −1 . An intermediate gas transport regime has been accounted for over the experimental range. The transport regime was found close to the surface-limited regime as the deuterium driving pressure is lowered and the temperature increased. Permeability Φ has been derived together with surface rate constants: Φ ( mol m −1 Pa −1/2 s −1)=5.311×10 −8 exp(−44988/RT) . This is in very good agreement with the permeability previously measured using a different gas evolution method, evidencing the consistency of the obtained results.