The present invention relates to a
reactor design technology, and specifically to a passive direct
evaporation type cooling
system for a double-layer concrete containment. The
system comprises a
heat exchanger arranged inside a containment, a cooling water tank arranged outside the containment, and a steam water separation device. According to the present invention, the
retention time of cooling water in the
heat exchanger is increased to force the cooling water to generate a
phase change, and a large amount of heat inside the containment is taken away through
phase change latent heat of the water; when the temperature of the containment is less than 100 DEG C, natural circulation flow of the
system is low or zero; when the severe accident is generated in the
nuclear power station and the containment temperature is more than 100 DEG C, water inside the
heat exchanger is heated and expands until the water is evaporated, the separated water returns back to the cooling water tank, the steam is discharged into the
atmosphere outside the containment, the system is put into operation, and the natural circulation is formed. With the system of the present invention, the whole process does not require intervention by
nuclear power station operators, and whether the system is put into operation is automatically selected according to the containment temperature, such that the passive system is completely achieved, the human intervention factor during accident generation is substantially reduced, and the containment cooling function is achieved independent of
external energy sources.