A partial pressure sensor for an automated gas environment system (AGES) was not functioning correctly for pure hydrogen flow. While personnel were troubleshooting the problem, a burst disk ruptured resulting in a leak of hydrogen gas and actuation of a flammable gas alarm.

System troubleshooting involved the installation of a small hydrogen gas cylinder and temporary manual valve in an engineered ventilated enclosure adjacent to an instrument sample well. A burst disk associated with the temporary manual valve ruptured upon opening of the gas cylinder valve. The vented gas, exhausting through an engineered exhaust system, triggered the flammable gas detector. Personnel promptly evacuated the area in accordance with established procedures. Appropriate personnel responded to the view more

In the fall of 2007, the operations team began a procedure (a written procedure was being followed) to sample the liquid hydrogen (LH2) storage vessels ("tanks"), and associated transfer system. This procedure was being performed to determine the conditions within the system, and if necessary, to purge the system of any excess gaseous hydrogen (GH2) in preparation for reactivation of the system. The system had not been used since 2003.

The LH2 storage system contains two (2) spherical pressure vessels of 225,000 gallons in volume, with a maximum working pressure (MAWP) of 50 psig. Eight-inch transfer piping connects them to the usage point. Operations began with activation of the burnstack for the LH2 storage area. Pneumatic gaseous nitrogen (GN2) systems in the view more