Patent Number: 
Section: claims

1. A steel concrete structure for a reactor containment facility comprising a pair of steel plates composed of an inner steel plate having a first thickness and exposed to a high temperature environment and an outer steel plate having a second thickness and mutually opposingly arranged at an interval, a plurality of studs arranged on a surface of each steel plate in touch with concrete, and the concrete filled between the steel plates,wherein a discharging opening for discharging steam is provided in the outer steel plate having the second thickness, andwherein the outer steel plate has a thickness greater than the second thickness arranged around the discharging opening in the outer steel plate. 2. The steel concrete structure for a reactor containment facility according to claim 1,wherein a steam discharging pipe in touch with the rear surface of the inner steel plate and leading steam to outside the concrete through a pipe opening arranged in the outer steel plate is provided,wherein a gap is provided between the pipe opening in the outer steel plate and the steam discharging pipe, andwherein the outer steel plate has a thickness greater than the second thickness arranged around the pipe opening in the outer steel plate. 3. The steel concrete structure for a reactor containment facility according to claim 2, wherein the steam discharging pipe is provided with plural small openings for enabling steam flow therethrough. 4. The steel concrete structure for a reactor containment facility according to claim 2, wherein the thickness of the outer steel plate greater than the second thickness of the outer steel plate is provided only in the vicinity of the discharging opening and the pipe opening in the outer steel plate. 5. The steel concrete structure for a reactor containment facility according to claim 1,wherein vertical partitions connecting the opposing inner steel plate and outer steel plate are provided,horizontal reinforcements for preventing buckling are provided in the inner steel plate and the outer steel plate, andopenings for letting concrete flow in are provided in the horizontal reinforcements. 6. The steel concrete structure for a reactor containment facility according to claim 5 wherein,the horizontal reinforcements are formed of horizontal partitions connecting the opposing inner steel plate and outer steel plate, andopenings for letting concrete flow in are provided in the horizontal partitions. 7. A reactor containment vessel having the steel concrete structure for a reactor containment facility according to claim 1. 8. A reactor containment facility internal structure employing the steel concrete structure for a reactor containment facility according to claim 1.