The disclosure relates to a radially fed axial steam turbine with a cold inlet duct, axially displaced from a hot inlet duct such that is it further away from a first blade row than the hot inlet duct. The cold inlet duct receives a cold steam from a cold inlet spiral and directs it into the hot inlet duct in such a way that a boundary layer of cold steam is formed over the rotor circumferential surface between the outlet end of the cold inlet duct and the blade and vane rows. The rotor circumferential surface is also adapted to promote and maintain the boundary layer. In this way, a maximum temperature to which the rotor is exposed can be reduced.