Nuclear power plant containment building

It is considered the most characteristic building of a nuclear power plant and houses the reactor and all the elements containing radioactive material. In some cases, for safety reasons, the fuel handling area is also located in this building to avoid possible radiation to the outside.

It is an airtight structure of reinforced or prestressed concrete, which, as a general rule, is usually spherical or cylindrical in shape, topped by a hemispherical dome, the inner walls of which are covered with welded steel sheets to ensure water-tightness. Its architecture is designed to withstand its own weight, as well as accidental loads such as earthquakes or other natural phenomena or radioactive gas leaks that reach pressures of between 60 to 200 psi (4 to almost 14 atmospheres).

Its main mission is to isolate and protect the outside from the emission of radiation resulting from the operation of the reactor or, in the event of an accident. During normal operation, it is sealed, and access, for a limited time, is through hatches similar to those used on ships.

The containment building is the third barrier, the first being the actual sheath or rod in which the fuel pellets are enclosed and the second the vessel and piping assembly forming a reactor coolant pressure boundary (or primary circuit).