Patent Number: 
Section: claims

1. A boiling water reactor comprising:a reactor building including,a top wall defining a penetration therein,a bottom wall, andat least one side wall, the top wall, the bottom wall, and the at least one side wall defining a chamber in the reactor building;a reactor cavity pool adjacent the reactor building;a primary containment vessel, at least a portion of the primary containment vessel is in the chamber of the reactor building; anda passive containment cooling system configured to receive water and expel hot water, the passive containment cooling system including,at least one thermal exchange pipe including,an outer pipe having a first outer pipe end and a second outer pipe end, the first outer pipe end being closed and the second outer pipe end being open, the first outer pipe end being within the primary containment vessel, and the second outer pipe end extending through the penetration in the top wall of the reactor building and into the reactor cavity pool such that the outer pipe is in fluid communication with the reactor cavity pool, the outer pipe including,a side pipe wall defining an opening therein, andan inner pipe at least partially within the outer pipe, the inner pipe having a first inner pipe end and a second inner pipe end, the first inner pipe end and the second inner pipe end being open, and the second inner pipe end extending out of the outer pipe and into the reactor cavity pool such that the second inner pipe end is in fluid communication with the reactor cavity pool, the inner pipe including,a curved portion between the first inner pipe end and the second inner pipe end, the curved portion extending through and past the opening in the side pipe wall and into the reactor cavity pool. 2. The boiling water reactor of claim 1, wherein the outer pipe has a diameter of 200 mm to 520 mm. 3. The boiling water reactor of claim 1, wherein the inner pipe has a diameter of 50 mm to 200 mm. 4. The boiling water reactor of claim 1, wherein the inner pipe and the outer pipe comprise stainless steel. 5. The boiling water reactor of claim 1, further comprising:at least one seal around the outer pipe and adjacent the penetration in the top wall of the reactor building. 6. The boiling water reactor of claim 1, wherein the passive containment cooling system includes a plurality of thermal exchange pipes. 7. The boiling water reactor of claim 6, wherein the passive containment cooling system includes two to twenty thermal exchange pipes. 8. The boiling water reactor of claim 1, further comprising:at least one support within the primary containment vessel, the support configured to support the first outer pipe end of the thermal exchange pipe. 9. The boiling water reactor of claim 8, wherein the support comprises a spring support, the spring support configured to allow vertical movement of the thermal exchange pipe caused by expansion due to absorption of heat. 10. The boiling water reactor of claim 1, wherein the passive containment cooling system is valve-free, pump-free, or both valve-free, and pump-free. 11. A passive containment cooling system comprising:a thermal exchange pipe including,an outer pipe having a first outer pipe end and a second outer pipe end, the first outer pipe end being closed and the second outer pipe end being open, the first outer pipe end being within a primary containment vessel of a boiling water reactor, the second outer pipe end extending into a reactor cavity pool such that the outer pipe is in fluid communication with the reactor cavity pool, the outer pipe including,a side pipe wall defining an opening therein, andan inner pipe at least partially within the outer pipe, the inner pipe having a first inner pipe end and a second inner pipe end, the first inner pipe end and the second inner pipe end being open, and the second inner pipe end extending out of the outer pipe and into the reactor cavity pool such that the second inner pipe end is in fluid communication with the reactor cavity pool, the inner pipe including,a curved portion between the first inner pipe end and the second inner pipe end, the curved portion extending through and past the opening in the side pipe wall and into the reactor cavity pool. 12. The passive containment cooling system of claim 11, wherein the outer pipe has a diameter of 200 mm to 520 mm. 13. The passive containment cooling system of claim 11, wherein the inner pipe has a diameter of 50 mm to 200 mm. 14. The passive containment cooling system of claim 11, wherein the inner pipe and the outer pipe comprise stainless steel. 15. A method of installing the passive containment cooling system of claim 11 comprising:placing the thermal exchange pipe at least partially in the primary containment vessel, such that a portion of the thermal exchange pipe extends into the reactor cavity pool.