If one needs to work with 3rd stage on the laser amplifier, one needs to make the safety patrol inspection before closing the bunker.

for that, it is mandatory to switch 2 keys on the "key board" in the control room, just before or just after the safety patrol :
- the THOMX key to 1
- the "EXPLOITATION LASERFP" key to 1

for the safety patrol, one has to push the "blinking white" buttons on the walls of the bunker, in the order from 1 to 6, and finish by the south entrance door button.
message " ronde en cours" is shouted during the process.
at the end of the safety patrol, an alarm is triggered for 30sec approx. and then stop.
now, the special keys located at the south entrance door are green and one has to take them (at least 2) to enter the bunker without breaking the safety patrol.