Apparently, the squares in the ceiling were for measuring the radiation after the reactor was decommisioned. These days, they say the radiation is low enough for the earth itself to actually be more radioactive.
Went to #emergingsensation with @ttyr. Pretty magical experience to be in a decomissioned nuclear reactor together with trippy fabric/AR creations.
Especially the lower parts of KTH R1 give a very post-apocalyptic feeling.