An Organic Rankine Cycle system includes a turbine driven by a working fluid and a generator driven by the turbine. The turbine includes a rotor volume that is at sub-atmospheric pressure, and the working fluid is sprayed into the rotor volume. The turbine can be arranged in a primary circuit that also includes, in flow series from the turbine, a condenser, a first pump, and an evaporator. The rotor volume can be arranged in a secondary cooling circuit that includes, in flow series from the rotor volume, a heat exchanger, a second pump, and a restriction valve located downstream of the second pump and upstream of the rotor volume.