Accidental hydrogen explosions

Also the Chernobyl accident resulted in a significant metal-water reaction with hydrogen generation, but no final conclusions could be made so far concerning the H2 behavior and its contribution to the accident [16]. 

Hydrogen-oxygen offgas explosions have occurred in some older boiling water reactors where no treatment of such gases was given. The explosions took place in various components from the condenser air injector downstream to the vent stack and 

5 Offgases released into the primary coolant during norma] operation consist of air leaked into the turbine condenser, activated gases, fission gases, and Hj and Oj from radiolytic decomposition of steam. A typical mixture could contain roughly a 6 - 8 % share of hydrogen. 

Hydrogen-air-steam combustion experiments have been conducted to simulate local detonations in confined structures and to validate the respective numerical detonation codes. 

A hazardous potential was thought to exist in the AVR HTGR, Julich, with a hydrogen-carbon monoxide-helium-air mixture, which could evolve in a water ingress accident scenario with an estimated 8 % H2 + CO concentration resulting from the corrosive reaction between steam and hot fuel element graphite. Ignition experiments in a combustion chamber were conducted in 1971 to examine the lower combustibility limit in respective gas mixtures. The tests have shown that a mixture with 22 % H2 + CO was not flammable at temperatures up to 120 °C [54], 

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Due to the low density of H2, an accidental hydrogen emission creates a high probability of forming highly explosive volumes in the upper part of a confined or semi-confined space. A characteristic of the near-ceiling HAM volumes is a free region in the combustible bay basement and, probably, along the sides of a gas-polluted space. 

HBr reacts with metals, producing highly explosive hydrogen gas. If aleak or spill occurs, exposure to the vapors should be avoided. If a high concentration of aqueous acid is accidentally spilled, it should be diluted immediately with water to reduce fuming prior to neutralization. Hydrobromic acid may be neutralized with soda ash or lime sprinkled over the contaminated area. An aqueous solution of sodium hydroxide may also be used to neutralize the diluted acid. 

When this reaction has occuiTcd accidentally sufficient hydrogen chloride has been liberated to explosively burst the vessel. The purest form of hydrogen chloride is made by the action of water on silicon tetrachloride ... 

Acetone was accidentally introduced into a reactor containing a sulphuric acid/nitric acid/hydrogen peroxide mixture. This led to an explosion due to acetone oxidation by the peroxymonosulphuric acid formed by the oxidising mixture. 

Accidental addition of a little acetone to the residue from wet-ashing a polymer with mixed nitric-sulfuric acids and hydrogen peroxide caused a violent explosion [1]. The peroxoacid would be produced under these conditions, and is known to react with acetone to produce the explosive acetone peroxide [2], but direct oxidation of acetone may have been responsible. 

A massive explosion in Pasadena, Texas, on October 23,1989, resulted in 23 fatalities, 314 injuries, and capital losses of over 715 million. This explosion occurred in a high-density polyethylene plant after the accidental release of 85,000 pounds of a flammable mixture containing ethylene, isobutane, hexane, and hydrogen. The release formed a large gas cloud instantaneously because the system was under high pressure and temperature. The cloud was ignited about 2 minutes after the release by an unidentified ignition source. 

Hydrogen was most likely produced accidentally by ancient alchemists who knew it as a gas that burned. The first recorded event of its discovery was by Theophrastus Bombastus von Hohenheim (known as the alchemist and physician Paracelsus 1493-1541). It was a well-known explosive gas produced by pouring acids over zinc metal. Paracelsus was unaware that the gas produced by this chemical reaction was hydrogen—the name had not yet been designated. 

Accidental contact of 50% sodium hydroxide solution with residual trichloroethanol in a pump caused an explosion. This was confirmed in laboratory experiments. Chlorohydroxyacetylene, or the isomeric chloroketene, or chlorooxirene may have been formed by elimination of hydrogen chloride. 

The risk to the public during consumer end use of hydrogen derives from the possibility of accidental fire and explosion, a direct consequence of the physical and chemical properties of hydrogen. These properties help to define the kinds of safety issues that must be addressed, the fundamental design goals for hydrogen systems, and the operational limitations of these systems. Table 9-1 summarizes the properties of hydrogen in contrast with those of other commonly used fuels. 

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