Patent Number: 041486862
Section: claims

1. An auxiliary cooling device for absorbing residual energy in a primary fluid heat exchanger of a nuclear reactor which continues to generate energy after shut down, said exchanger comprising a casing for conveying a flow of primary fluid heated in the reactor and a nest of tubes disposed inside the casing for conveying a secondary cooling fluid in thermal contact with the primary fluid, said auxiliary cooling device comprising a jacket disposed around the casing and including inlet means and outlet means for an auxiliary cooling fluid, and auxiliary heat exchange surfaces projecting from said casing into the space around the casing inside said jacket. 2. An auxiliary cooling device according to claim 1 wherein the auxiliary cooling fluid is air. 3. An auxiliary cooling device according to claim 1 wherein the auxiliary heat exchange surfaces are constituted by spikes. 4. An auxiliary cooling device according to claim 1 wherein the auxiliary cooling fluid inlet and outlet means include means for providing a forced flow of auxiliary cooling fluid. 5. An auxiliary cooling device according to claim 1 wherein the auxiliary cooling fluid is free to flow by convection. 6. An assembly of auxiliary cooling devices according to claim 4 comprising a plurality of primary heat exchangers connected in parallel each equipped with an auxiliary cooling device wherein the auxiliary cooling devices are connected to a common source of forced flow for the auxiliary cooling fluid. 7. A primary fluid heat exchanger for a nuclear reactor which continues to generate energy after shut down, said exchanger comprising a casing for conveying a flow of primary fluid heated in the reactor and a nest of tubes disposed inside the casing for conveying a secondary cooling fluid in thermal contact with the primary fluid and the auxiliary cooling device of claim 1. 8. A primary fluid heat exchanger according to claim 7 wherein the secondary cooling fluid is water which is heated to superheated steam. 9. A primary fluid heat exchanger according to claim 7 including a primary fluid jacket over portions of the casing adjacent each of its ends, the jacket of the auxiliary cooling device being disposed intermediate the portions of the primary fluid jacket. 10. A rapid neutron nuclear reactor installation including the heat exchanger of claim 7. 11. A reactor installation according to claim 10 wherein the primary fluid heated by the reactor is an alkaline metal. 12. An auxiliary cooling device according to claim 1 including a primary fluid jacket over portions of the casing adjacent each of its ends, the jacket of the auxiliary cooling device being disposed intermediate the portions of the primary fluid jacket. 13. An auxiliary cooling device according to claim 1 wherein the secondary cooling fluid is water which is heated to superheated steam.