Fire during hydrogen transfer between CGH2 tube trailer and stationary storage

This event occurred at a plant fabricating nuclear fuel but affected only the hydrogen production and distribution system. A hydrogen leak ignited on a tube trailer connected to a pressure reducing station, while waiting for a hydrogen transfer.
The alert was given by personnel of the company cafeteria located nearby. The external rescue crews arriving at the site 15 min later reported a very sizeable gas leak ignited at the rear of the semitrailer, near the vertical bottle storage area.
The red-white heat at the end of the semitrailer platform raised fears over deterioration of the bottle valves. Other reasons of concern:
(1) the pressure reduction station to which the semi-trailer was connected (an older station used as a backup) was the site of numerous ignited leaks.
(2) Four other tube trailers were located on site, connected to a second (new) pressure reduction station: one was connected and awaiting transfer, two were connected and in use, and the last one was not connected.

The cylinder heads of the damaged semi-trailer were kept cool by water jets, and the other tube trailers were moved away. The whole hydrogen supply system was shut down. Eventually, emergency responders were able to approach them and close their valves.

[Note of HIAD event validator: ARIA report contains an incongruence which was corrected in the event description of HIAD. The nuclear fuel production site affected by the fire used hydrogen for the production process. It is plausible to assume that the hydrogen tube trailers were delivering hydrogen to the station, via the pressure reducing stations, not the other way around as mentioned by ARIA title. It would imply a hydrogen production unit plus a storage at high pressure, which then fill in tube trailers, for an unclear goal.]

The INITIATING CAUSE an unspecified hydrogen leak.

The IGNITION SOURCE is supposed having been lightning.

The fire revealed critical elements of the set-up and the operations which needed to be corrected. The pressure reducing station to which the semitrailer was connected had been the origin of many ignited leaks in the past, was used only as back up, nevertheless, still in use. A defective equipment should be left in operation, even if just as back-up, assuming that by using it less frequently the related risks are reduced. Moreover, the vicinity of several trailers and the absence of fire barrier between them, was raising the probability of an escalation. ROOT CAUSES are therefore related to a inadequate safety system and management of the operations.

tube, hose, pressure reducing station,

Hydrogen leakages and ignition had already previously occurred.

The definitive elimination of the damaged pressure reducing station (emergency centre) was used to resume distribution network operations the next day.
All of the semitrailer connection studs could be refurbished in a way that offsets the risk of destruction by heat.

The alert was sounded by personnel of the company cafeteria located nearby. The external rescue crews arriving at the site 15 min later reported a very sizeable gas leak ignited at the rear of the semitrailer, near the vertical bottle storage area. The excess red-white heat at the end of the semitrailer platform raised fears over deterioration of the bottle valves.

The first measures undertaken consisted of cooling, by flooding all bottle heads on the leaking semitrailer, and removing the other semitrailers. In addition, the hydrogen production equipment was shut off in order to isolate the distribution network.

Two hours later, with the pressure inside bottles on the damaged semitrailers having dropped, rescue personnel could get close enough to close the valves.

Lightning would have caused the accident.