Passive containment cooling water supply system

The invention provides a passive containment cooling water supply system which comprises a first water tank, a second water tank, a third water tank and a nuclear island containment, the first water tank and the second water tank are located on a first horizontal plane, the third water tank is located on a second horizontal plane, and the nuclear island containment is located on a third horizontal plane; the first horizontal plane, the second horizontal plane and the third horizontal plane are stepped, and the terrains are sequentially reduced; the first outlet end of the first pool is connected with the first inlet end of the second pool through the first valve group, the first outlet end of the second pool is connected with the first inlet end of the third pool through the second valve group, and the first outlet end of the third pool is connected with the first inlet end of the nuclear island containment through the third valve group. According to the embodiment of the invention, the pool is far away from