A cooling device for use in a power plant, having at least two controllable fans, which are designed to produce an air flow having a specified flow direction during operation, at least two closing flaps, which close respective flow cross-sections, and a heat exchanger, which thermally interacts with the at least two air flows for heat exchange as a secondary medium, wherein the closing flaps are not operated by a mechanical adjusting device but rather are each to be opened merely by one of the two air flows as a result of the dynamic pressure when a minimum flow rate is reached. Furthermore at least two holding devices are provided, which hold the closing flaps in an open position when the closing flaps are opened.