Internal vessel explosions ruptures

Ruptures or Internal Vessel Explosions - An catastrophic opening of a container (i.e., tank, vessel or pipe), commonly from overpressure or metallurgical failure, resulting in the immediate release of its contents. 

Internal Detonations or Explosions An internal detonation or explosion may occur due to several scenarios. Air leakage into the system may cause a combustible mixture to form, undesired chemical reactions may occur, and extremely rapid vapor expansion may occur. These almost instantaneous events have to be carefully protected against as many overpressure devices do not react quickly enough to prevent the vessel from rupturing. 

Explosions or ruptures of vessels or process equipment from internal deflagrations, runaway reactions or pressure explosions with possible damaging shock wave and missile ejection. 

The energy of explosion on vessel rupture depends on its internal pressure. That is determined by the boundary conditions of the accident, as described above. The higher the internal pressure the stronger is the explosion. 

This appendix considers one of the more extreme solutions against severe accidents (see Chapter 5) which consists of a steel-reinforced concrete cage built around a PWR vessel with the purpose of absorbing, by plastic deformation, the energy released by a steam explosion (internal or external to the vessel) and which causes its rupture and the violent projection of its pieces into the surrounding space. 

Description of hazard. A pressure vessel is a cylindrical or spherical metal container capable of withstanding pressures exerted by the contained material. Many liquids and gases must be stored under high pressure in such vessels. Safety codes have been developed that specify the container design for specified conditions, with special emphasis on the strength of the vessel to prevent rupture and subsequent explosions. All shells, test chambers, tanks, and model parts designed for internal pressures greater than 15 pounds per square inch (psi) are considered pressure vessels. 

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