Patent Number: 048636770
Section: summary

The invention relates to a nuclear power plant having a containment for containing activity carriers, the containment having an outlet in the form of an excess pressure safety device leading out of the containment and through a filter into the atmosphere. A nuclear reactor of this type is known, for example, from German Patent DE-PS 26 34 356, corresponding to U.S. Patent No. 4,151,689. The containment provided therein is in the form of a steel sphere that is enclosed by a concrete building. Outlet openings that can be closed off by an excess pressure valve are provided in the concrete building. Lines lead from the outlet openings into certain zones within a mound of soil that rises above the concrete building. A pile of coarse gravel in the mound is intended to carry out filtering and steam condensation, in the event of a malfunction in the interior of the concrete building that threatens to exceed its bursting strength. Outlet lines in which safety valves assure a certain response pressure also lead out of the containment. The outlet lines lead either into the concrete building or directly into the layer of gravel located outside the concrete building, so that pressure relief for the containment can be provided without damage to the integrity of the annular space between the containment and the concrete building. It is a disadvantage of this type of device that a mound of soil must be used. A particular problem in this respect is that the outlet medium includes aerosols, which because of their small size, on the order of approximately 1 .mu.m, are difficult to contain, especially if only one filter with a narrowly limited volume is available. It is accordingly an object of the invention to provide a nuclear power plant having a containment, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and which provides relief of the containment even if there is no mound of soil, enabling widely scattered distribution for receiving the outlet medium from the containment. With the foregoing and other objects in view there is provided, in accordance with the invention, a nuclear power plant, comprising a containment or containment shell for containing activity carriers, an outlet in the form of an excess pressure safety device or valve leading out of the containment, and a filter connecting the outlet to the atmosphere, the filter including a container, a washing fluid disposed in the container, a Venturi scrubber being integrated in or with the container and connected to the outlet, the container having an upper region or top with a gas outlet, and a stack connected to the gas outlet. According to the invention, while the existing pressure of the outlet medium is utilized in a Venturi scrubber, generally referred to as an atomizer, that is covered with washing fluid, the outlet medium is accelerated out of the containment in such a way that maximally effective aerosol moistening occurs passively, that is without auxiliary energy. Furthermore, iodine absorption can also be attained with the surrounding washing fluid that is aspirated at the same time. This can be further promoted by introducing suitable chemicals, such as alkaline substances, into the washing fluid. The aspiration of the washing fluid into the Venturi scrubber takes place not only by means of the negative pressure generated therein, but also by means of the pressure of the liquid column of washing fluid above the Venturi scrubber. In accordance with another feature of the invention, there is provided a jet pump upstream of the Venturi scrubber for feeding the washing fluid to the Venturi scrubber. A jet pump can advantageously be used for aspirating and precompressing the washing fluid if an even greater pressure difference is desired to increase the feed quantity. In accordance with a further feature of the invention, there is provided a mist collector disposed in the washing fluid in the container, the mist collector having a liquid outlet leading into the container. In accordance with an added feature of the invention, there is provided a mist collector connected between the gas outlet and the stack, the mist collector having a liquid outlet leading into the container. The outlet medium leaving the Venturi scrubber and hence having been washed can pass through a mist collector in order to filter out excess washing fluid. The washing fluid retained therein can then be returned to the washing fluid volume, along with the enriched iodine particles and aerosols therein. Subsequently, the outlet medium can be again passed through a hydraulic seal, as needed. In accordance with an additional feature of the invention, there is provided a gas distributor disposed in the washing fluid in the container, the gas distributor being fed by the Venturi scrubber. In accordance with yet another feature of the invention, there is provided a a mixing nozzle downstream of the gas outlet for diluting an outlet medium with ambient air. The de-moisturized and cleaned outlet medium may be carried directly to a stack. However, an admixture of ambient air can also be provided in order to obtain further dilution of any toxic gas components. It is also possible for the Venturi scrubber to be followed by a fiber packet filter, in order to attain even better filtering effectiveness. If especially stringent requirements are involved, then superheating by throttling the outlet medium is also possible. This is favorable if there is to be an ensuing cleaning in a superfine aerosol filter, such as an "S class" metal fiber filter. In terms of the heating of the washing fluid, the Venturi scrubber should be disposed just below the level of the fluid, for instance at a depth of 1 meter, so that it is located outside any possible boiling zone. In accordance with yet a further feature of the invention, there is provided at least one other Venturi scrubber connected in parallel with the first-mentioned Venturi scrubber, the Venturi scrubbers being disposed at different heights in the washing fluid. The fact that a plurality of Venturi scrubbers which are connected in parallel, that is connected to a common inlet line, are advantageously disposed at different levels, can be taken into consideration in dimensioning the column of liquid above the Venturi scrubber. This provision ensures that in the case of partial-load operation not all of the parallel-connected Venturi scrubbers operate uniformly, but instead optimal operating conditions for individual scrubbers are maintained. In accordance with yet an added feature of the invention, there is provided a heat exchanger connected upstream of the Venturi scrubber. The heat exchanger can be connected to the input side of the Venturi scrubber in order to vary the temperature conditions. In accordance with yet an additional feature of the invention, there is provided a pressure maintenance and limiting device connected upstream of the Venturi scrubber. In accordance with still another feature of the invention, the Venturi scrubber has a cooling device communicating with the washing fluid. One variation in the temperature conditions is a cooling of the outlet medium flowing to the scrubber from the containment, so that saturated steam is produced. In accordance with still a further feature of the invention, there is provided a pan disposed beneath the container. In accordance with a concomitant feature of the invention, there is provided a mist collector downstream of the Venturi scrubber, a throttle downstream of the mist collector, and a high-efficiency submicron particulate filter disposed downstream of the mist collector. Other features which are considered as characteristic for the invention are set forth in the appended claims. Although the invention is illustrated and described herein as embodied in a nuclear power plant having a containment, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.