Patent Number: 048448575
Section: description

Referring now to the drawing and first, particularly, to FIG. 1 thereof, there is shown a pressurized water reactor having, as the most important component of the primary circuit thereof, a reactor pressure vessel 1, which encloses the otherwise non-illustrated reactor core, the pressure vessel being closed by an arched or dome-shaped cover 2. A pipeline 3 extends from the highest point of this cover 2 through a valve 4 and a temperature measuring point or station 5 to a T-branch 6. The line branches 7 and 8 extending from the T-fitting or joint 6 continue via shut-off of isolating valves 9 and 10 to two water-jet pumps 11 and 12 which are of identical construction, and, in fact, to the suction side 13 thereof, through which a nozzle 14 extends which is associated with a diffuser 15. Each diffuser 15 is connected via a respective valve 20, 21, to a respective pipeline 22, 23 of a volume control system 16, which extends, respectively, via recuperative heat exchangers 24 and 25 and branches 26, 27, 28 and 29 to four otherwise non-illustrated loops of the primary circuit of the pressurized water reactor. Also connected to the pipeline 22 is a respective pressure line 30, 31 leading to the nozzle 14 and having a respective valve 32, 33, in an arrangement wherein the jet-pumps 11 and 12 are disposed parallel to respective reducing valves 35 and 36 in the line 22 or 23. The following mode of operation thereby results: If, in a case wherein all the main coolant pumps of the pressurized water reactor fail, the water circulation in the reactor pressure vessel should be insufficient and, consequently, cooling thereby in insufficient, so that especially the hot water located below the cover 2 determines the pressure in the primary circuit and obstructs the feeding-in or emergency or auxiliary coolant, an outlet can be created by opening the valve 4 and the valve 9 or 10 which lead to the suction side of the respective water jet-pump 11 or 12. If the pumps 11 and 12 become operative by opening the valves 32 and 20, on the one hand, and valves 33, 21, on the other hand, while the valves 35 and 36, respectively, are at least partly or, preferably, completely closed, the hot coolant is sucked out of the reactor pressure vessel 1, and cooled by mixing with the water from the volume control system 16. The mixed liquid is then returned to the primary circuit, so that the water also reaches the reactor pressure vessel 1, and compensates there for the coolant loss caused by the removed coolant. This cooling of the coolant in the pressure-vessel cover 2 is effected without the use of additional high-pressure pumps and, primarily, without any danger that cold water is the reactor pressure vessel will cause thermal stresses. In the embodiment according to FIG. 2, the water-jet pumps 11 and 12 of FIG. 1 are replaced by motor-driven cenrifugal pumps 40 and 41, to the suction side of which, respective lines 7 and 8 are connected. With these pumps 40 and 41, the negative pressure required for shunting the coolant is ensured, and the coolant is pumped to the respective pipelines 22 and 23 of the volume control system 16. The embodiment according to FIG. 3 is provided with a fourfold branching of the outlet line 3. The individual brances are of identical construction. They include valves 44 and water-jet pumps 45, the pressure side of which is inserted via a valve 46 into a respective line of a boron-addition system 43, used as an auxiliary system. The outlet of the boron addition system 43, the lines of which extend through the wall 47 of the safety vessel, and are respectively connected via a three-way valve 48 to a line 49 which leads to a non-illustrated pressurizer of the primary circuit. Furthermore, the three-way valve 48, respectively, is connected via a valve 50 to a line 51 leading to a respective loop of the primary circuit of the reactor pressure vessel. Also in this case, the water-jet pumps 45 provide the required negative pressure in the reactor pressure vessel, and the desired discharge pressure, which assures the additional feeding of coolant into the primary circuit. The foregoing is a description corresponding to German Application P No. 31 16 443.9, dated Apr. 24, 1981, International priority of which is being claimed for the instant application, and which is hereby made part of this application. Any discrepancies between the foregoing specification and the aforementioned corresponding German application are to be resolved in favor of the latter.