Improvements to nuclear reactors

In some types of nuclear reactors the primary coolant, heated when going through the core, is cooled in heat exchangers (steam generators or intermediate exchangers) before being pumped back to the core. For various reasons the primary fluid is often returned, down stream of the exchangers, into a common tank where the flow from several exchangers can mix before being taken up by the pumps to be returned to the core. Pumps and exchangers are generally separate, forming two distinct components placed side by side at comparable levels in the vessel. The present invention consists in placing the pump at one end of the exchanger, whilst letting the flow from an exchanger mix in a common tank with the flows from the other exchangers, thus allowing all or part of the flow from an exchanger to be taken up by pumps other than that associated with it. This arrangement has a number of advantages compared with the conventional system where the exchangers and pumps are placed side by side. It enables the exchangers to be placed closer together and thus to build a smaller tank. The exchanger and the pump may be removed through the same aperture in the cover of the vessel and thus make it possible to reduce the number of orifices in the cover and thereby improve its rigidity. This reduction in the number of orifices in the cover therefore makes it possible to reduce the number of handling systems of the exchangers and their associated pumps