in part of combustible materials can support internal fire propagation. Such fires can become very intense, due to the high surface-volume ratio of the towers, and fires can be further intensified by natural convection or fan-assisted draft. The resulting damage can be sufficiently severe to require the replacement of the entire cell or tower structure. For this reason, some codes and standards recommend that combustible cooling towers be provided with an automatic fire sprinkler system. Fires can propagate internally within the tower structure when the cell is not in operation (such as for maintenance or construction), and even while the tower is in operation, especially those of the induced-draft type, because of the existence of relatively dry areas within the towers. Structural stability Being very large structures, cooling towers are susceptible to wind damage, and several spectacular failures have occurred in the past. At Ferrybridge power station on 1 November 1965, the station was the site of a major structural failure, when three of the cooling towers collapsed owing to vibrations in winds. Although the structures had been built to withstand higher wind speeds, the shape of the cooling towers caused westerly winds to be funneled into the towers themselves, creating a vortex. Three out of the original eight cooling towers were destroyed, and the remaining five were severely damaged. The towers were later rebuilt and all eight cooling towers were strengthened to tolerate adverse weather conditions. Building codes were changed to include improved structural support, and wind tunnel tests were introduced to check tower structures and configuration. See also List of tallest cooling towers Alkali soils Architectural engineering Deep lake water cooling Evaporative cooler Evaporative cooling Fossil fuel power plant Heating, ventilating and air conditioning Hyperboloid structure Mechanical engineering Nuclear power plant Power station Spray pond Water cooling Willow Island disaster References External links What is a cooling tower? – Cooling Technology Institute "Cooling Towers" – includes diagrams – Virtual Nuclear Tourist Wet cooling tower guidance for particulate matter, Environment Canada. Striking pictures of Europe’s abandoned cooling towers by Reginald Van de Velde, Lonely Planet, 15 February 2017 (see also excerpt from radio interview, World Update, BBC, 21 November 2016) Building engineering Heating, ventilation, and air conditioning Nuclear power plant components Cooling technology