Cooling towers. Steam rising from the cooling towers of a nuclear power station. The tower cools water by allowing steam to evaporate into the atmosphere and carry away heat. A tower requires a flow of air and this may be induced by natural or mechanical means. Large cooling towers at power stations eliminate the problems of thermal pollution in masses of water. The water in the cooling towers is used to cool other cooling circuits within the power station. As it is not used to cool the reactor core directly, the water is not radioactively contaminated. Photographed at the Chaplecross Nuclear Power Station in Scotland.