A cryogenic liquid expansion turbine has a turbine wheel mounted on a rotary shaft, at least one radial inlet for cryogenic liquid to be expanded in the expansion turbine for the rotary shaft, and a dry gas sealing means at a position along the rotary shaft between the turbine wheel and the bearings. There is a thermal barrier member between the turbine wheel and the dry gas sealing means, a gas chamber on the dry gas sealing means side of the thermal barrier member, and an internal passage for cryogenic gas to the said gas chamber. A method is also provided.