Patent Number: 043740839
Section: description

Referring now to the figures of the drawing, and first, particularly to FIG. 1 thereof, there is seen a line 1 which comes from the non-illustrated primary loop of a pressurized water reactor, and leads to a volume control surge tank 2. The lower part 3 of the volume control surge tank is filled with cooling water. The liquid level is measured with a measuring device 4 which acts on a control 5. The latter controls a delivery valve 6 in the line 1 and the make-up or refill through a line 7 with a valve 8. The end 9 of the line 1 is below the liquid level. In the volume control surge tank 2, the gas space 10 above the volume of liquid is inserted into an exhaust gas system, not shown in detail. To this end, a line 12 leads from the exhaust gas system to the volume control surge tank 2 past a valve 13. The opening of the valve 13 is controlled by a control device in dependence on a measuring point 15, for instance, for constant throughput. Another line branch 18, which also has a control valve 19, leads from the gas space 10 to the exhaust gas system. Its control device 20, however, is set for constant pressure by a measuring point 21. The gas space 10 is thereby flushed continuously and is simultaneously brought to a definite pressure of, for instance, 3 bar. The pressure should be above the partial hydrogen pressure for the desired hydrogen content. The volume control surge tank 2 is connected through a suction line 25 to three high-pressure pumps 26, 27 and 28. These high-pressure pumps are connected in parallel through mixing sections 30, 31 and 32, and valves 35, 36 and 37, in series therewith. They transport the cooling water back into the primary cooling loop, from which the line 1 branches off. A bypass line 40 which leads from the line 1 to the liquid-filled suction line or loop section 25 and can be shut off by a hand-operated valve 41 is connected parallel to the volume control surge tank. At the bypass line 40, a feed-in point for hydrogen (H.sub.2) is provided. The feed-in point comprises a check valve 44 and a control valve 45. The control valve 45 is controlled by a control device 46. The values of the hydrogen content in the cooling water and the known operating state of the degassification system, are fed to the control device 46 in a manner which is therefore not specifically shown. The measuring lines therefor are indicated at 47 and 48. Between the feed-in point or hydrogen introducing means 43 to the liquid-filled loop section and a connecting line 50 of the suction line 25 itself to the three high-pressure pumps 26, 27 and 28, a mixing section 51 is disposed. The mixing section 51 comprises, for instance, four individual members 52, 53, 54 and 55. By means of the mixing section 51, the fed-in hydrogen is thoroughly mixed with the cooling water, so that the hydrogen is dissolved in the water as completely as possible. In the embodiment example according to FIG. 2, the mixing section 51 is followed by a gas separator 58, the gas exhaust 59 of the separator 58 is connected through a control valve 60 to an exhaust gas system. In this manner, it is assured that no free hydrogen is present after or downstream of the mixing section 51, which might lead to gas bubbles or to cavitation in the area of the high-pressure pumps 26, 27 and 28. The control valve 60 can be opened by a control system 61 if gas appears in the gas separator 58. The control 46, on the other hand, feeds-in hydrogen from a central source to between 2 ppm and 4 ppm hydrogen content in the coolant; the throughput is taken into consideration in the delivery of the pumps 26 to 28. The pressure in the volume control surge tank 2 is set for a partial hydrogen pressure of 4 ppm. Thus, it is impossible for the hydrogen content behind or upstream of the separator 58 to exceed 4 ppm and therefore no strict requirements need to be met as to monitoring the hydrogen concentration. For this reason, intermittent monitoring may be entirely sufficient. In the embodiment example according to FIG. 3, the feed-in point 43 is followed by a gas separator 58' having a dome 64. Two diaphragm compresors 65 and 66 are connected in parallel to the dome 64. The diaphragm compressors 65 and 66 pump through a line 68 into the feed-in point 43. Therefore, excess hydrogen accumulated in the gas separator 58' is returned into the line 40. Simultaneously, the gas content in the separator 58' is determined by a control device 70 through a measuring device 71. In this way, the control valve 45 is actuated, as indicated by the dotted line 72, representing a functional connection. The feeding of hydrogen at the valve 45 from a non-illustrated hydrogen source is thus made directly dependent on the hydrogen content in the coolant, which is determined after the mixing section 51. In the embodiment example according to FIG. 4, the feed-in point 43' is associated with the suction lines of the pumps 26, 27 and 28 in parallel. The feed-in point ends in ceramic filter cartridges 75 and comprises control valves 45' which are connected to a control device 76. The control device 76 takes into consideration, as reference inputs, the operation of each of the active pumps 26 to 28, as is indicated by the dotted functional connection lines 77. In addition, the hydrogen content which is present after or downstream of the pumps and is being determined continuously, is processed in the control device 76, as indicated by the dotted functional connection lines 78. The control devices 46, 76 may be gas analyzers. Suitable apparatus and installation instructions therefor may be found in the August 1974 issue of Siemens-Betriebsanleitung (Siemens Instruction Book) MP 1.3 A 38/1 D.