Accidental release of hydrogen from a cryogenic tank Original Research Article

Liquid hydrogen at 20 K was harmlessly released at Turin’s Porta Susa station over a period of seven hours on 9 July 1991 through the safety valve of a dewar-type tank on a railway wagon following the loss of the vacuum between its two walls. Commercially available programs were unable to model this type of release in the unusual conditions in which this hydrogen had been stored. A model illustrating the course of the accident was therefore worked out. A start was made by examining the changes in the physical and thermodynamic properties of the hydrogen progress in the dewar to find out how long it had taken to build up the pressure needed to open the safety valve.