Patent Number: 
Section: claims

1. A nuclear reactor building passive cooling system disposed adjacent to an outer wall of a nuclear reactor building and capable of passively cooling the nuclear reactor building, the system comprising:a storage tank storing cooling water;a partition part arranged within the storage tank and dividing an inside of the storage tank into a first storage tank and a second storage tank to separate the cooling water;a first heat exchanger extending from the storage tank to the nuclear reactor building and cooling the nuclear reactor building on the basis of the cooling water;a unidirectional valve provided on the partition part and allowing the cooling water of the second storage tank to be introduced into the first storage tank when a water level of the first storage tank is reduced; andwherein the first heat exchanger comprises an inlet pipe into which the cooling water is introduced from the second storage tank, an outlet pipe along which the cooling water provided from the inlet pipe returns back into the first storage tank; and a heat exchange unit disposed between the inlet pipe and the outlet pipe. 2. The system of claim 1, wherein the unidirectional valve comprises at least one of a floating valve or a check valve. 3. The system of claim 1, wherein the first heat exchanger comprises an inlet pipe into which the cooling water is introduced from the first storage tank, an outlet pipe along which the cooling water provided from the inlet pipe returns back to the first storage tank, and a heat exchange unit disposed between the inlet pipe and the outlet pipe. 4. The system of claim 1, wherein a capacity of the first storage tank is smaller than a capacity of the second storage tank. 5. The system of claim 1, further comprising a second heat exchanger extending from the first storage tank to outside of the storage tank to cool the cooling water of the first storage tank. 6. The system of claim 5, further comprising an air inlet part provided on an outer surface of the storage tank to induce air to flow into the second heat exchanger. 7. The system of claim 6, wherein the air inlet part is disposed to surround the second heat exchanger and provided in a tube shape having an open top. 8. The system of claim 6, wherein the air inlet part is provided in a venturi tube shape having an open top. 9. A cooling water storage reservoir capable of passively cooling a nuclear reactor building, the cooling water tank comprising:a storage tank storing cooling water;a partition part arranged within the storage tank and dividing inside of the storage tank into a first storage tank and a second storage tank to separate the cooling water;a first heat exchanger extending from the storage tank to the building and cooling the nuclear reactor building based on the cooling water anda unidirectional valve, provided on the partition part and allowing the cooling water of the second storage tank to flow into the first storage tank when the water level of the first storage tank is reduced; andwherein the first heat exchanger comprises an inlet pipe into which the cooling water is introduced from the second storage tank, an outlet pipe along which the cooling water provided from the inlet pipe returns back into the first storage tank; and a heat exchange unit disposed between the inlet pipe and the outlet pipe.