Fire on a hydrogen vehicle prototype

[Note of HIAD Validator: this event description is unsatisfactory. Details on the prototype and the incident evolution are missing].

The incident affected a prototype light hydrogen vehicle in a hydrogen research centre of a university. The vehicle was a kind of a four-wheeled scooter. The fire started on the vehicle while being filled. Apparently, the hydrogen storage system was a hydrogen hydride.
The site was evacuated and the building isolated from its hydrogen supply. The firefighters attacked the fire with a hose and extinguished it one hour later.
Temperature and visual checks were carried out at the level of the vehicle, to check the potential persistence of invisible flame. The building containing the vehicle was ventilated and the fire panel and the automatic hydrogen detection were put back into operation.
A plug was placed on the tank to isolate it from the external element such as air or water. The safety valve is unscrewed to prevent any rise in pressure in the event of possible desorption of the hydride.
The vehicle's lithium battery was submerged in a tank of water and remains under the supervision of a company security guard overnight.

The fire started during a test on the prototype vehicle. According to the sources, a valve broke on the tank during a test consisting in its pressurisation with an inert gas (helium). It is impossible to deduce from this scarce and vague information the real cause of the loss of confinement and the fire. It is not even known if the involved substance(s) was gaseous hydrogen or a hydride.

on-board hydrogen hydride tank, on-board battery

DESCRIPTION OF THE UNIT
The 4-wheeled scooter can store on-board approximately 300 g hydrogen in the form of metal hydride, providing 4 hours f autonomy at a speed between 40 and 50 km/h.

The vehicle is destroyed. Five people were slightly injured, three of whom were taken to hospital. All experiments planned for in the hydrogen laboratory are stopped and the hangar remains closed until the investigation results are available. The offices were reopened for employees.