Reactor building

In a case where there is a base rock deeply in the underground at a site of a reactor power plant, most of reactor buildings are buried underground. A secondary containing facility for containing reactor containers has a structure of two reactor-integrated type reactor building. Pipelines and a valve chamber are disposed to the circumference of the reactor containers. The outer walls of building, the bulk head for partitioning adjacent secondary containing facilities for two reactors, pipelines and the valve chamber are constituted, for example, by concrete walls. The bulk head has a one-wall structure serving both as a structural wall (earthquake proof wall) required for ensuring strength relative to earthquakes and pressure of soils and as a bulk head required for keeping independence of each of the secondary containing facilities (shielding property, air tightness and pressure resistance). A communication port for communication between the secondary containing facilities is disposed to the bulk head. An airtight door for opening/closing the communication port has a double-walled structure which ensures an access space for operators. (I.N.)