Patent Number: 062698737
Section: claims

1. A method for controlling heat exchange in a nuclear reactor comprising the steps of: circulating a heated liquid through a conduit forming a closed loop extending from a heat exchanger in the nuclear reactor to at least one other heat exchanger immersed in a pool of relatively cold liquid located external of the nuclear reactor;  confining said at least one other heat exchanger within a container immersed in said pool of liquid, said container having an upper part forming an area surrounding said at least one other heat exchanger and an open lower part through which the liquid of said pool may freely pass;  forming a passageway in said upper part of said container to permit communication through said passageway from said area surrounding said at least one other heat exchanger and said pool; and  controlling the opening and closing of said passageway such that when the passageway is closed a vapor is formed in said area inhibiting further heat exchange with the heated liquid in the conduit and when the passageway is open heat exchange is maximized. 2. The method of claim 1, wherein said passageway forms an outlet located in the upper part of the container and controlling the opening and closing of the outlet using a thermal valve. 3. The method of claim 2 wherein at least two valves arranged in a parallel manner are located at said outlet. 4. The method of claim 2 wherein said open lower part of the container comprises one or more openings in said container for communicating with said pool. 5. The method of claim 1 wherein the heat exchanger contains a fluid entrance pipe and a fluid outlet pipe, said entrance and outlet pipes penetrating the lower part of the container. 6. The method of claim 5 wherein the fluid entrance pipe and the fluid outlet pipe are thermally insulated. 7. The method of claim 5 comprising using said loop for carrying a fluid, said loop being connected to: (a) the fluid entrance pipe through which a fluid is passed into the heat exchanger and (b) the fluid outlet pipe through which the fluid exits from the heat exchanger. 8. The method of claim 7 comprising using a pump in communication with the loop. 9. The method of claim 7 comprising using an expansion tank in communication with the loop, thereby causing any fluid present in the loop to be maintained under pressure. 10. The method of claim 1 wherein the heat exchanger contains a fluid entrance pipe and a fluid outlet pipe located such that the fluid entrance pipe and/or the fluid outlet pipe penetrate through a side or the top of the container. 11. The method of claim 10 wherein the fluid entrance pipe and the fluid outlet pipe are thermally insulated. 12. The method of claim 10 comprising using said loop for carrying a fluid, said loop being connected to: (a) the fluid entrance pipe through which a fluid is passed into the heat exchanger and (b) the fluid outlet pipe through which the fluid exits from the heat exchanger. 13. The method of claim 12 comprising using a pump in communication with the loop. 14. The method of claim 12 comprising using an expansion tank in communication with the loop, thereby causing any fluid present in the loop to be maintained under pressure.