Over pressurisation of a LH2 trailer

A LH2 trailer had just delivered hydrogen to a customer and was travelling on a highway returning to the base, when the driver noticed that the pressure inside the tank was increasing rapidly.
The driver stopped at a rest stop to report incident. Local fire-fighters departments and the trailer company responded. The fire-fighters evacuated the rest stop area. Meanwhile, the trailer was venting hydrogen and reducing the internal pressure with no further problems. The cause appeared to be a mechanical problem, possibly a loss of vacuum on the vessel.

The INITIAL CAUSE was over-pressurisation of the LH2 tank, which triggered a hydrogen venting.
The ROOT CAUSE was probably due to a loss of the thermal insulation capacity of the tank, due to some mechanical events which partially disrupted the annular vacuum between the external and internal shells of the LH2 tank.

vacuum thermal insulation

The driver had terminated the delivery of LH2 to a customer's site. It can be assumed that the trailer was (almost) empty.

None

The local fire-fighters departments and the trailer company responded. The fire-fighters evacuated the rest stop area of the highway where the trailer was parked. Although not stated explicitly, it can be assumed that the emergency team strategy was to let the trailer venting till stabilisation of the internal pressure. It was anyhow almost empty.