The invention is related to equipment intended for feeding a steam generator connected into the primary and secondary circuit of a nuclear power plant and its convenient desing arrangement within the inside area of the body of the steam generator enables a significant reduction of the total time intended for shutting down the block of the nuclear power plant due to failure of the present feed tubing bz simplification of its fitting into the body of the steam generator while facilitating the visual inspection of the feed tubing contributes to the prevention of the occurance of leakeges of the feed tubing, followed by the undesirable effect of secondary water on the wall of the primary collector thus preventing damage caused to it, which leads to increased durability of this unit and to the increased operation life of this node of the nuclear plant.

State of the Art

Presently known are steam generators operated as heat exchagers between the first and second circuits of a nuclear power plant. The steam generator itself is formed of a cigar-shaped body whose inside area contains an inlet primary collector, an outlet primary collector, a supporting system of the tube bundle and the feed tubing itself. The feed tubing consists of a feed nozzle connected to the central distributing feed tubing led close along the wall of the inlet primary collector below the level of secondary water while in the bottom third of the steam generator two horizontal distributing tubes leading into the areas between tube bundle of heat exchanging tubes of the steam generator are connected to the central distributing feed tubing. The disadvantage of the above arrangement of individual steam generator nodes and particularly its feed system is in the fact that due to the considerable amount of continually let in feed water leakages or eventually cracks occur, due to

cavitation and erosion activity of water, in the bottom part of the distribution tubing just in the point of connection of horizontal distribution tubes where the direction and flow rate of feed water is changed. Such untightness is the cause of undesirable leakage of secondary water in close proximity of the inlet primary collector. The relatively cool feed water washing wall of the inlet primary collector from one entails the occurance of material stress due to non-uniform temperature loading over the circumference of the wall in the point in question thus leading, in the extreme case, to the occurance of cracks in the wall of the primary collector of the steam generator and to the premature shutting down of the entire block of the nuclear power plant. Another disadvantage is the unfeasibility of visual inspection of the feed system of the steam generator as its most exposed point, i.e. the point of connection of horizontal distribution tubes to the distribution tubing, located in the bottom third of the body of the steam generator, is surrounded by the tube bundle. A further disadvantage is that during repairs of the feed tubing it is necessary to perform demanding technological operations requiring long periods of putting the steam generator out of operation and thus also the block of the nuclear power plant while the present location of the feed tubing into the cramped area of the tube bundle makes its disassembly and eventual repair very difficult.

Summary of the Invention

The mentioned disadvantages are eliminated by the equipment intended for feeding the heat exchanger, particularly the steam generator, with secondary water, consisting of a feed nozzle attached to the top part of the steam generator body and partly of distribution feed water tubes. The substance of the invention is in the inlet of feed water to which a distribution piece is connected from a distribution tubing whose branches are led over the tube bundle of heat exchange tubes of the steam generator and

where a system of outlet tubes is extracted from the distribution tubing and led out above the tube bundle of heat exchange tubes and/or in the area between the tube bundle of steam generator heat exchange tubes. Its substance is also in that the free ends of oulet tubes are each provided with a blending box. Another substance is that at least one feed water flow rectifier is placed under a blending box.

An advantage of the equipment intended for feeding a heat exchanger, particularly a steam generator, with secondary water is that by location of the feed tubing above the tube bundle of the steam generator an explicit and rapid visual inspection of the steam generator feed system may be performed and the extent of eventual damage caused to this tubing evaluated to thus prevent undesirable leakage of cool feed water into the area close to the inlet primary collector, which is the reason for the occurance of material stress due to non-uniform heat loading over the circumference of the collector wall. Such timely evaluation of the technical condition of the feed tubing contributes to the prevention of the occurance of cracks in the wall of the primary collector and thus prevents undesirable failures of the primary circuit of the ^• nuclear power plant into which a steam generator is connected while this design solution consideraoly contributes to the enhancement of durability of this unit and to prolonged operation life of this node of the nuclear power plant. Another advantage of the invention is that during repairs of the feed tubing there is no need for the performance of demanding technological operations using special technology normally applied only in the replacement of defective parts of the present equipment in the cramped area inside the tube bundle. A further advantage is that the design of the equipment enables its very easy assembly and disassembly leading to the reduction of fitting time and thus to the total reduction of shut downs of blocks of nuclear power plants, leading out the feed water tubing in the top part of the steam generator body, eventually its leading out closely below the level of continually let in

feed water leads to' enhanced circulation of "boiler water" thus providing the required blending of inlet feed water with present boiler water.

BRIEF DESCRIPTION OF THE DRAWINGS

The enclosed Drawings show the equipment according to the invention where Fig. 1 a side view of the steam generator body. Fig. 2 is a top view into the steam generator body and Fig. 3 is a side view of the distribution tubing with the system of outlet tubes.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The equipment intended for feeding a heat exchanger, particularly a steam generator, with secondary water as shown in the construction example consists of a feed water inlet 4_ attached to the wall of the body 2 of the steam generator and an opposite inlet . part 3 of the primary steam generator collector. The inlet 1 of feed water is connected to a U-shaped distribution piece _^ while this distribution piece 4 is connected to a distribution tubing 5 whose one branch is led out between the inlet part 3 of the primary collector __ and the outlet part 6_ of the steam generator primary collector. The second ^• branch of the distribution tubing 5 is led around the inlet part 3 of the primary collector while both branches of the distribution tubing 5 are placed on and fixed to a supporting and dilatating structure T_ and run over the tube bundle 8 of steam generator heat exchange tubes. From the direct sections of the distribution tubing 5 a system of outlet tubes 9_ is led out in a reversed J shape into the area between two sections of the tube bundle 8 of heat exchange tubes of the steam generator.

Another alternative of this design is that the free ends of the outlet tubes _9 are provided with a blending box 10 formed of sideplates 11 _^ attached to ends of outlet tubes 9_ and a flow rectifier 12_ inntended for enhancing the blending of boiler water and feed water.