Patent Number: 041486862
Section: summary

FIELD OF THE INVENTION The present invention relates to an auxiliary cooling device for a primary fluid heat exchanger of a rapid neutron nuclear reactor. The exchanger comprises at least one nest of tubes in which there flows cooling water (to be heated to superheated steam) and round whose tubes there flows a liquid alkaline metal constituting said primary fluid. BACKGROUND When a rapid neutron nuclear reactor is shut down, the power supplied does not die away instantaneously, but reduces gradually for some time before dying completely away. This residual power may be absorbed in special heat exchangers, to which the heated liquid alkaline metal is conveyed, instead of to the normal operation exchangers. Such special exchangers are however relatively expensive and are used for fairly short periods of operation. They therefore substantially increase the cost price of nuclear power stations using rapid neutron nuclear reactors. SUMMARY OF THE INVENTION Preferred embodiments of the present invention reduce this disadvantage and provide at a relatively low cost an auxiliary cooling device which is able to absorb the variable residual power of a rapid neutron reactor. The device according to the invention comprises an auxiliary cooling device for absorbing residual energy in a primary fluid heat exchanger of a nuclear reactor which continues to generate some 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. It also preferably has at least one of the following features: The auxiliary cooling fluid is air; PA1 The auxiliary heat exchange surfaces are spikes; PA1 The auxiliary cooling fluid inlet and outlet means include means for providing a forced flow of auxiliary cooling fluid; PA1 The auxiliary cooling fluid is free to flow by convection. The present invention also provides a heat exchanger including said cooling device and a reactor installation including said heat exchanger.