Editing Steam explosion (section)

{{Short description|Explosion created from a violent boiling of water}}
{{see also|Boiler explosion|Boiling liquid expanding vapor explosion}}
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[[Image:Littoral explosion at Waikupanaha 2.jpg|thumb|upright=1.5|[[littoral zone|Littoral]] explosion at Waikupanaha ocean entry at the big island of Hawaii was caused by the [[lava]] entering the [[ocean]]]]
A '''steam explosion''' is an [[explosion]] caused by violent boiling or flashing of water or ice into [[steam]], occurring when water or ice is either [[superheating|superheated]], rapidly heated by fine hot debris produced within it, or heated by the interaction of molten metals (as in a fuel–coolant interaction, or FCI, of molten nuclear-reactor [[fuel rod]]s with water in a [[nuclear reactor core]] following a [[nuclear meltdown|core-meltdown]]). Steam explosions are instances of [[explosive boiling]]. Pressure vessels, such as [[Pressurized water reactor|pressurized water (nuclear) reactors]], that operate above [[atmospheric pressure]] can also provide the conditions for a steam explosion. The water changes from a solid or liquid to a gas with extreme speed, increasing dramatically in volume. A steam explosion sprays steam and boiling-hot water and the hot medium that heated it in all directions (if not otherwise confined, e.g. by the walls of a container), creating a danger of [[scalding]] and burning.

Steam explosions are not normally [[chemical explosion]]s, although a number of substances react chemically with steam (for example, [[zirconium]] and superheated [[graphite]] (inpure [[carbon]], C) react with steam and air respectively to give off [[hydrogen]] (H<sub>2</sub>), which may [[Hydrogen safety|explode violently]] in air (O<sub>2</sub>) to form water or H<sub>2</sub>O) so that chemical explosions and fires may follow. Some steam explosions appear to be special kinds of [[boiling liquid expanding vapor explosion]] (BLEVE), and rely on the release of stored superheat. But many large-scale events, including foundry accidents, show evidence of an energy-release front propagating through the material (see description of FCI below), where the forces create fragments and mix the hot phase into the cold volatile one; and the rapid heat transfer at the front sustains the propagation.