Patent Number: 039376524
Section: summary

This invention relates to nuclear power installations, and more particularly such installations including a nuclear reactor in which the reactor core is cooled by a fluid such as carbon dioxide or helium which is circulated by one or more coolant fluid circulators. In such an installation, it may be advantageous to drive the coolant circulators by means of steam turbines; and, in cases where the heat removed from the reactor core by the coolant is used to generate high-pressure steam in one or more main boilers which supply the steam to one or more main turbo-generators, it has been proposed to drive the coolant circulators by steam turbines supplied with steam from this main system, preferably from the cold reheat line thereof (i.e. at an intermediate stage in the main turbine expansion process) since this minimises the loss in thermodynamic efficiency. In cases of this kind, and in which steam reheat in the main steam system is effected within the reactor vessel by heat exchange with the hot coolant, the connection of the circulator turbines in the steam reheat line is quite convenient since this latter is returned to the reactor vessel (where the circulators are located) in any event. However, in a case where a steam-to-steam reheat cycle is used (i.e. in which either live or bled steam is used for reheat purposes), it would be expensive to return steam to the reactor merely for driving the coolant circulators. According to the present invention, there is provided a nuclear power installation comprising a nuclear reactor which includes a reactor core, at least one main boiler, at least one main coolant circulator arranged to circulate coolant fluid through the core and through the main boiler, and a circulator-driving steam turbine arranged to drive said main coolant circulator, wherein the installation further comprises at least one auxiliary boiler which is arranged to be heated by the coolant fluid and to generate steam and which is connected to supply said steam to said circulator-driving steam turbine. The invention may be incorporated in reactor systems such as are described and claimed in U.S. Ser. No. 178525 filed on Aug. 30, 1971 and now abandoned comprising a main boiler system and an auxiliary boiler system both heated by heat transferred to them from the reactor core by fluid coolant circulated by coolant circulators, the auxiliaary boilers providing steam for essential electrical power and having a capacity, typically, of some 20% of the maximum station output.