The uncontrolled release of hydrogen occurred as a result of the rupture of the No. 6 hydrogen storage tube’s burst disc. This disc failed in response to being overloaded by mechanical stresses developed as water expanded and formed ice while in…

1. Revise fire protection operations surveillance tests to include a maximum of 110% of the agent net weight to prevent over-filled cylinders from being placed in service.
2. Identify cylinders currently in service that exceed the 110…

Refueling operations need to be conducted in a careful and attentive manner, and operators need to be aware of the potential consequences of their actions.

• Verify that all PRDs contain fuse-backed adapters.
• Explore elimination of rupture disk PRDs and substitution of spring-style relief valves.
• Develop new hydrogen unloading procedure using a written checklist. * Add…

Metallurgical examination of the two failed disks by light optical microscopy (LOM), scanning electron microscopy (SEM), and energy-dispersive x-ray spectroscopic analysis (EDS) found them to be fabricated from pure nickel with evidence of…

1. Place signs on all liquid hydrogen tanks indicating that no water is to be put on the vent stack.
2. An additional secondary backup vent stack was added to liquid hydrogen tanks. This secondary stack is designed to be used only if…

The ignition of the fireball could have been caused by any of the following mechanisms:

• The inverse Joule-Thompson effect of hydrogen (i.e., heating upon expansion)
• Some of the oil and light ends were above their auto-…

Three root-causes were noted during the investigation: (1) the use of incompatible materials in the manufacturing of the PRD valve, (2) improper assembly resulting in over-torquing of the inner assembly, and (3) over-hardening of the inner…