Abandoned Reactor

You and your friends have decided that the annual excursion will take place in a cabin deep in the Krakow forest. The first day was a bit boring, but then you found the abandoned nuclear reactor in the forest. Tonight you are ready to go on the adventure of a lifetime. You enter the reactor, but wait..? It is not at all as dead as it seemed. Your adventure has now become a race to escape this sinister place as quickly as possible. But be careful! There is only enough oxygen for one hour...