Abstract: In a nuclear-reactor power-generating installation having a main and an auxiliary steam-generating boiler, both arranged to receive heat from the reactor core (for example by circulation of reactor coolant gas), and having a turbogenerator which includes a multistage steam turbine through whose stages the steam from the main boiler passes in sequence, there being a steam reheater unit connected between two of the stages to provide reheating of the steam from the main boiler, the invention provides that the auxiliary boiler is connected to supply to the reheater unit steam which reheats the said steam from the main boiler.

Abstract: In a nuclear reactor installation comprising a fluid-cooled nuclear heat source within a primary pressure vessel, the latter is enclosed within a secondary containment means which comprises a lower wall portion surrounding the primary pressure vessel, an annular portion extending out from the lower wall portion, and an upper portion integral with the annular portion and extending over it and over the primary pressure vessel and housing handling means for lifting fuel and other reactor components through normally sealed vertical penetrations in the roof of the primary pressure vessel (giving access to the reactor core) and in the said annular portion (giving access to new and spent fuel stores and other auxiliary facilities disposed outside the secondary containment and wholly or partly below the said annular portion).

Abstract: A gas-cooled nuclear reactor has a main circulatory system for the gaseous coolant incorporating one or more main energy converting units, such as gas turbines, and an auxiliary circulatory system for the gaseous coolant incorporating at least one steam generating boiler arranged to be heated by the coolant after its passage through the reactor core to provide steam for driving an auxiliary steam turbine, such an arrangement providing a simplified start-up procedure also providing emergency duties associated with long term heat removal on reactor shut down.

Abstract: In a nuclear power installation comprising a fluid-cooled nuclear reactor, main boilers and main coolant circulators driven by steam turbines to circulate coolant fluid through the reactor core and the main boilers, the circulator-driving steam turbines are driven by steam from auxiliary boilers which are also heated by the hot reactor coolant. This steam, after then being reheated by the hot reactor coolant if desired, may also then drive auxiliary steam turbogenerators provided additionally to main steam turbogenerators driven from the main boilers. Preferably the reactor core is housed in a thick-walled concrete pressure vessel having in its wall thickness first cavities which each house a main boiler and associated steam-turbine-driven coolant circulator and second cavities which each house an auxiliary boiler, an associated auxiliary coolant circulator and a reheater, if such are provided, for steam exhausted from the steam turbines driving the main coolant circulators.