Patent Number: 039473198
Section: description

In FIG. 1, the numeral 1 represents a nuclear reactor, provided with a core 2, inside which control rods 3 are accommodated. The control rods are moved with the aid of a control rod driving mechanism 4, which in turn is influenced by a control apparatus 5. The contents 6 of the reactor vessel are included in the primary circuit 7. This furthermore comprises a primary circulating pump 8 which is driven by an electric motor 9 with speed regulator. The medium, having been heated in the reactor vessel 1 by passing along the core 2, is pumped by the pump 8 to the heat exchanger 10. This heat exchanger transfers the heat to the secondary circuit 11 which is likewise provided with a pump 12 driven by an electric motor 13 with speed regulator. The secondary circuit comprises successively a superheater 14 and an evaporator 15. Before the superheater, a measuring flange 16 is included which allows the amount of flow of secondary medium to be measured. The heat exchangers 14 and 15 finally transfer the heat to the steam-water-circuit 17 which includes a steam turbine 18 which drives an electric generator 19. The exhaust steam of the steam turbine 18 is condensed in the condenser 20 and finally pumped through a condensate pump 21. A feed water pump 22 pressurizes this condensate so as to force it back to the steam generator. A number of feed water preheaters, not shown in the drawing, can be arranged between the condensate pump and the feed water pump. Such a feed water preheater is 23, which receives steam from the draining point 24 situated in the high pressure part of the steam turbine 18. After the feed water preheater 23, the feed water conduit contains the feed water control valve 25. This is followed by another preheater 26, which collects the condensate that has been separated in the external water separator 27. During normal operation, the valve 28 is closed, and the valves 29 and 30 are open. The steam water circuit likewise comprises a measuring flange, i.e. the flange 31 which measures the amount of steam which is conveyed through the main steam conduit to the turbine 18. The number 32 indicates a measuring point for measuring the steam pressure. The main shutoff valve of the turbine is indicated by 33, it being symbolically shown that this valve is influenced by a speed regulator 34. Control of the installation shown is performed as follows: A control impulse line 35, emitting a signal from a value which is a measure for the load, is supplied to the control circuit 5 of the reactor. The measured steam production in point 31 is supplied by the flow meter 37 to the control element 36. The same control element also receives an impulse through line 38 which comes from the pressure measurement 39. The control impulse emitted by the element 36 is conveyed to the electric motor 13 so as to adjust the pump 12 to the correct speed. This is accomplished with the aid of the control impulse line 40. The measuring flange 16, included in the secondary circuit 11, conveys an impulse to the flow meter 41. Besides giving an impulse through line 42 to the control circuit 5 of the reactor, it sends an impulse to the speed control of the pump motor 9 of the primary circulating pump 8 so as to regulate the speed of this pump. This is done with the aid of the impulse line 43. The control circuit 5, indicated symbolically in the figure, operates in such a way that it controls an outlet temperature at a point 44 near the outlet 45 of the reactor at a constant value with the aid of the control rods 3. The value to which this outlet temperature is adjusted can be influenced both by the impulse line 35 and by the impulse line 42. The line 52, besides comprising a measuring flange 46, also contains a control valve 47. This valve, operating by way of the control circuit 48 and the water level control 49, keeps the liquid level in 27 at a constant value. The measuring flange 46 conveys control impulses to the valve 25 by way of 50. There is a pressure drop across this valve 25, the magnitude of which is measured by the measuring element 51, which causes the result of measurement to act by way of line 53 upon the speed of the motor 54 which drives the pump 22. Shown in FIG. 2 is a portion of the diagram according to FIG. 1, but designated as a variant. The reactor circuit 7 with the nuclear reactor 1 is not entirely shown, because this has undergone no change with respect to FIG. 1. The parts of the diagram already discussed with regard to FIG. 1 are indicated in FIG. 2 by the same reference numerals. Shown here is an assembly with two circuits, i.e. the reactor circuit 7 and the steam-water-circuit 17, 21, 22, 26, 15, 14. The turbine 18 has three draining points for the feed water preheaters 23, 55 and 56. The feed water pump 22 is combined with a hydraulic turbine 60, through which part of the amount of feed water can flow. The magnitude of this partial amount is set with the bypass valve 57 contained in a bypass 61 of the turbine step. With the valve 57 entirely opened, only some of the feed water flow passes through the turbine 60, cooling this. With the valve 57 closed, the entire flow passes through turbine 60. The pressure drop which is required for control reasons can now be brought about economically and simply in the turbine 60, so that the valves 57 and 25 only need to dissipate a small amount of energy by throttling.