The next heaviest element in the periodic table, the inert gas helium, is used for detecting cracks in pressure vessels and the like.

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Items are now housed in a temperature and humidity-controlled strong-room protected by an inert gas fire protection system, which would douse the room in gas to kill flames instead of using water.

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Used fuel that has been cooled in a spent fuel pool for at least five years can be put into a container called a cask and surrounded with inert gas, providing leak-tight containment, according to the U.S. Nuclear Regulatory Commission.

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