95 provided with a probe 94 from the auxiliary installation building 18 is associated with the exhaust air line 20 a further exhaust air line 96 which is provided with a probe 97 leads into the containment 1 at which dampers 98 and 99 are provided on both sides in the interior a damper 100 leads to a suction inlet 101 by means of which the operating space 14 can be exhausted a direct suction line for the equipment space 10 is connected via a line 102 it leads to an outside air line 103 by which part of the air of the equipment space 10 is transported by a blower 104 through two filters 105 in series and via a check valve 106 to the outside air line is further connected a connecting line 107 serving as a standby which leads to the blower 51 a further outside air line 108 in the operating space 14 serves for venting the chamber 15 here air is drawn in by a blower 109 via rare gas filters 17 and is pushed into the chamber via a check valve 110 therefore the chamber 15 is always accessible without precautionary measures it may for instance also be utilized as a room for the personnel the lines 111 and 112 are merely spare lines provided for emergencies up.