A previously identified generator hydrogen gas leakage into the stator cooling water system exceeded the predetermined maximum operational allowance and the nuclear plant was shut down from 100 percent power in accordance with plant operating procedures. The leak was identified by monitoring the stator water cooling system detraining tank. Following reactor shut down and generator rotor removal, a small hole was located in the collector end winding area of a slot on the top stator bar.
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.
A distillate dewaxing unit at an oil refinery was undergoing hot hydrogen regeneration of the catalyst when an explosion occurred. Catalyst regeneration is a periodically performed procedure, in which the normal liquid hydrocarbon feed is stopped and a hydrogen-rich gas mixture is fed through the catalyst bed for which the normal operating temperature is raised from 700F to 800F. During the catalyst regeneration process the reactor pressure is increased from normal operating levels just below 600 psig to about 640 psig.