Nuclear plant and method for the pressure relief in a nuclear plant
A nuclear installation has a reactor containment which is connected to a pressure relief line. A Venturi scrubber, which is arranged in a vessel containing a washing liquid, and a throttle device are connected in series in the pressure relief line. The novel system restrains, with particularly high reliability, fine air-transported activities or aerosols during decompression such that release thereof into the environment is practically impossible. The Venturi scrubber and the throttle device are dimensioned in such a way that, in the case of a critical drop in pressure of an air-vapor mixture flowing in the decompression line, a flow speed of said air-vapor mixture of more than 150 m/s, preferably more than 200 m/s, can be adjusted with respect to the throttle device in the Venturi scrubber.
1. A nuclear plant, comprising:
a containment;
a pressure relief line communicating with said containment;
a throttle device and a Venturi scrubber connected in series in said pressure relief line, said Venturi scrubber being disposed in a vessel with a washing liquid;
said Venturi scrubber and said throttle device being dimensioned to establish, in the event of a critical depressurization of an air/vapor mixture flowing in said pressure relief line and through said throttle device, a flow velocity of the air/vapor mixture of more than 150 m/s in the Venturi scrubber.
2. The nuclear plant according to claim 1 , wherein said Venturi scrubber and said throttle device are dimensioned to establish a flow velocity through said Venturi scrubber of more than 200 m/s.
3. The nuclear plant according to claim 1 , wherein said Venturi scrubber comprises a multiplicity of Venturi tubes having outlets, a comparatively large number of said Venturi tubes are disposed with the respective said outlets above an intended setpoint level of the scrubbing liquid, and a comparatively small number of said Venturi tubes are disposed with an outlet direction directed downward.
4. The nuclear plant according to claim 3 , wherein up to approximately 10% of said Venturi tubes are disposed with the outlet direction directed downward.
5. The nuclear plant according to claim 1 , wherein said Venturi scrubber comprises a plurality of Venturi tubes having a throat cross-sectional area and an inlet cross-section area for the scrubbing liquid, and a ratio of said throat cross-sectional area to said inlet area is less than 10:1.
6. The nuclear plant according to claim 5 , wherein said ratio is approximately 3:1.
7. The nuclear plant according to claim 1 , wherein said Venturi scrubber comprises a plurality of substantially round Venturi tubes with a throat width of less than about 80 mm.
8. The nuclear plant according to claim 7 , wherein said throat width of said Venturi tubes is less than about 40 mm.
9. The nuclear plant according to claim 1 , wherein said Venturi scrubber comprises a plurality of substantially flat Venturi tubes with a throat width of less than about 100 mm.
10. The nuclear plant according to claim 1 , wherein said Venturi scrubber comprises a plurality of Venturi tubes with a height to throat width ratio of more than 5.
11. The nuclear plant according to claim 1 , wherein said Venturi scrubber comprises a plurality of Venturi tubes with a height to throat width ratio of more than 10.
12. The nuclear plant according to claim 1 , which further comprises a washing liquid reservoir connected to said vessel on a scrubbing liquid side thereof.
13. The nuclear plant according to claim 1 , which further comprises a feedback line connecting a scrubbing liquid side of said vessel to an interior of said containment.
14. The nuclear plant according to claim 13 , wherein said feedback line is connected via said pressure relief line to the interior of said containment.
15. The nuclear plant according to claim 14 , wherein said vessel is disposed geodetically lying at least approximately 5 m higher than an exit point of said pressure relief line from said containment.
16. The nuclear plant according to claim 15 , wherein said vessel is disposed at least 10 m above said exit point.
17. The nuclear plant according to claim 1 , wherein the washing liquid in said vessel has a pH of at least 9.
18. The nuclear plant according to claim 1 , which further comprises, following said Venturi scrubber in a flow direction, a molecular sieve coated with silver compounds.
19. The nuclear plant according to claim 1 , wherein said throttle device is integrated into said vessel.
20. A method for depressurizing a nuclear plant according to claim 1 , which comprises subjecting the Venturi scrubber to a flow velocity of the medium carried in the pressure relief line of more than 150 m/s.
21. The nuclear plant according to claim 20 , which comprises setting the flow velocity to more than 200 m/s.