A turbine includes an inner casing to which at least a stator vane of a turbine section is mountable, and an outer casing arranged around the inner casing in such a way that an outer cooling channel is formed between the inner casing and the outer casing. The outer cooling channel includes a fluid inlet through which a cooling fluid is injectable from an outer volume of the turbine into the outer cooling channel. The cooling channel includes a fluid outlet such that the cooling fluid is exhausted into an inner volume of the turbine. The fluid inlet is located with respect to the fluid outlet such that the cooling fluid inside the outer cooling channel includes a flow direction which has a component that is orientated in opposite direction with respect to a main flow direction of a working fluid of the turbine.