DE3445485A1 - Nuclear power station with closed coolant gas circuit for generating process heat - Google Patents

Abstract

The invention relates to a nuclear power station for generating process heat in a helium-cooled high-temperature reactor, the said heat being extracted by means of a plurality of He/He heat exchangers. These heat exchangers are arranged around the high-temperature reactor in the central cavern of a reinforced concrete pressure vessel. The object of the invention is to design the He/He heat exchangers in such a way that the heat exchanger tubes are accessible for inspection and blanking-off work without special protective measures and a great amount of time. This is achieved by each He/He heat exchanger comprising a cluster of U-tubes arranged in two coaxial annular spaces and surrounding a tube-free central channel, and also comprising an annular inlet header and a central tubular outlet header. The two headers of each He/He heat exchanger are installed in an explosion-proof steel cylinder, mounted on the reinforced concrete pressure vessel, and each are connected to a laterally extending supply line and discharge line, respectively. Arranged above the two headers in each steel cylinder is the primary helium blower with drive motor for the leg of the circuit concerned.

Description

Nuclear power plant with closed cooling gas circuit

for generating process heat The invention relates to a nuclear power plant with a closed cooling gas circuit for generating process heat, which is at least a helium-powered secondary circuit is decoupled, with a helium-cooled one High-temperature reactor in a central cavern of a prestressed concrete pressure vessel housed and surrounded on all sides by a thermal shield, and with He / He heat exchangers, on a pitch circle around the pressure vessel axis in the annulus between the thermal side shield and the cavern wall are installed, with the cooling gas circuit jPrimary circuit) is divided into several equal strands, each connected in series comprise a He / He heat exchanger and a fan.

A nuclear power plant of this type is described in DE-OS 33.37 415. In this nuclear power plant, the ends of the heat exchanger tubes are in the immediate vicinity Radiation area of the reactor core, which has the consequence that the detection and stopping Damaged heat exchanger tubes is extremely difficult to carry out and takes a long time Time needed. The fan for the primary helium in each circuit is in each case in an opening provided above the associated heat exchanger installed in the prestressed concrete pressure vessel ceiling. The drive motors for the fans are also located in the aforementioned openings. To work on To be able to make the heat exchanger tubes, it is therefore necessary to do the relevant Remove the fan with the drive motor; i.e. for checking and tapping The primary circuit must be opened if the heat exchanger pipes are damaged. Another The disadvantage of the known nuclear power plant is that every He / He heat exchanger from two parts connected in series, a high-temperature and a low-temperature part, exists side by side in the annulus between the cavern wall and the thermal Side shield are arranged and of which only the high-temperature part (after removal fan and drive motor and implementation of radiation protection measures) directly is accessible.

From DE-PS 24 11 039 is another nuclear power plant for generation known from process heat, in which the cooling gas circuit is also in several identical Strands is divided, each one in series in a high-temperature part and a low-temperature part divided He / He heat exchange unit and a fan include. Here all components are installed in vertical shafts that are inside the wall of the prestressed concrete pressure vessel are provided. The high temperature and low-temperature parts of all heat exchanger units each in a separate shaft housed, and the fans are located below the low temperature parts, so that all heat exchanger parts can be removed for themselves. Allerring goes the division of the He / He heat exchangers into two parts connected in series and the separate accommodation of the parts in shafts in the pressure vessel wall at the expense of the compactness of the entire system. (The use of an advantageous Single-cavity reactor pressure vessel is not possible).

In addition, maintenance and repair work can be carried out on the heat exchanger pipes can only be carried out when the primary circuit is open.

To the prior art, DE-OS 26 50 922 is also mentioned, which is also an He / Re heat exchanger for the extraction of heat generated in a high-temperature reactor Shows warmth. Here the one-piece heat exchanger is also in a vertical shaft installed in the wall of a prestressed concrete pressure vessel, and the poisonous fan for the primary helium is in another Manhole. Here, too, it is not a matter of a system with only one cavern, to which the present invention relates. In addition, the heat exchangers & pipes, which are combined into a large number of straight tube bundles, also here only after opening of the primary circuit accessible.

The invention is based on the stated prior art the task is based on a nuclear power plant according to the generic term by special Design of the He / He heat exchangers Blanking work on damaged heat exchanger pipes to be able to carry out special protective measures and a great deal of time.

According to the invention, this object is achieved by the following features solved: a) each He / He heat exchanger comprises a U-tube bundle, which in two of one outer boundary cylinder, a middle separating cylinder and an inner separating cylinder formed annulus is arranged, through which hot primary helium is passed; b) the inner separating cylinder of each He / He heat exchanger encloses a tube-free, central channel through which hot primary helium flows from bottom to top; c) the U-tube bundle each He / He heat exchanger starts from an annular inlet header for the Secondary helium and opens into the end wall of one of the inlet header enclosed tubular outlet header for the secondary helium; i) with everyone He / He heat exchangers are the inlet collector and the outlet collector for the secondary helium arranged within a burst-proof steel cylinder that is placed on the prestressed concrete pressure vessel is placed on and anchored in this; the inlets and outlets of the two collectors exit laterally from each steel cylinder, arranged one above the other, in burst-proof expansion compensation bushings are installed; f) above the derivative for the outlet collector, the fan for the primary helium is in each steel cylinder installed with the associated drive motor.

The inlet and outlet alarms are located in the nuclear power plant according to the invention the He / He heat exchanger for the secondary helium in an area with very weak radiation and are (to a limited extent) accessible, so that it is relatively easy to repair damaged heat exchanger tubes to be recognized and blinded. An expansion of the fans for the primary helium and theirs Drive motors are not required for this; the primary circuit needs to be not open to become.

The good accessibility of the fans and theirs is also advantageous Easily expandable, as they are also in an area with only low radiation exposure are arranged.

Further advantages are that the U-tubes are at their hottest Make no bends and that the annular inlet headers and the tubular outlet headers are accessible from the inside, whereby the unplugging tasty U-tubes is made easier again.

The use of He / He heat exchangers in U-tube design has the Advantage that a smaller overall cross-section is required than with heat exchangers in a different design, e.g. in helix design. Because the He / He heat exchanger is also one-piece there is so much space in the cavern between the He / He heat exchangers present that arranged at these points heat exchangers for the removal of the residual heat that lie in the primary circuit. This causes a minor unavailability achieved in comparison to the requirement of the residual heat removal devices DE-OS 33 37 415, in which as a result of dividing the He / He heat exchanger into high-temperature and low-temperature parts no space in the cavern for primary helium-side residual heat removal devices is available. In the known nuclear power plant, the residual heat is via the operational secondary circuits of part of the He / He heat exchangers, which results in a higher unavailability of the residual heat removal devices (which results from the necessity, among other things, of the fans for the secondary helium to have in the company). For the He / He heat exchangers, there are high temperature transients additional thermal loads that adversely affect the service life of this Affect the heat exchanger.

It should also be mentioned that the He / He heat exchangers of the ore in accordance with the invention Nuclear power plant can be installed and removed in a simple manner by means of a crane can; In the known nuclear power plant, the low-temperature parts of the He / He heat exchangers must be moved transversely for assembly and disassembly in the cavern, including special facilities required are.

Advantageous further developments of the invention are set out in the subclaims and the following description of an exemplary embodiment in connection with refer to the schematic drawings. The figures show in detail: figure 1 shows a longitudinal section through a nuclear power plant according to the invention, in which only one Circuit line is shown, Figure 2 shows the He / He heat exchanger shown in Figure 1 on a larger scale, also in longitudinal section.

The figure L leaves a burst-proof cylindrical prestressed concrete pressure vessel 1, the high-temperature reactor in a central cavern 2 is a halium-cooled high-temperature reactor 3 with spherical fuel assemblies and a graphite reflector contains. The one on the side Part 4 of the graphite reflector is forming an annular space 9 of a thermal Surrounding side plate 5. A hot gas collecting space 6 is provided below the reactor core, to which a plurality of initially horizontally running hot gas ducts 8 are connected.

The heated helium passes through holes in the bottom part 10 of the Graphite reflector in the hot gas collecting space 6. Located above the reactor core a cold gas collecting space 7, which is in communication with the annular space 9. Between the thermal side plate 5 and the wall of the cavern 2 is another annular space 11 provided for receiving He / He heat exchangers 12, as will be described below.

The cooling gas or primary circuit is divided into several equal strands, which are coupled via the high-temperature reactor 3.

Each line contains an He / He heat exchanger connected in series 12 and a blower i3 which is driven by a motor 14. The He / He heat exchangers 12 are arranged on a pitch circle around the pressure vessel axis, whereby they are through the annular space 11 and each through an opening 15 in the ceiling la des Prestressed concrete pressure vessel 1 and extend into a recess 16 in the cavern floor.

The continuation of the He / He heat exchangers 12 to below the cavern floor, which is specifically provided in this embodiment enables the accommodation additional heat exchanger surface. If there is a further increase in the heat exchanger surface Should it be necessary, the He / He heat exchangers can even run through the entire area Extend the bottom of the prestressed concrete pressure vessel 1 and beyond. In this case are the heat exchanger parts that extend beyond the outer boundary surface of the floor are each arranged in a burst-proof steel cylinder. Like one Steel cylinder can be formed later in connection with the collector system the He / He heat exchanger 12 is described.

In the embodiment shown here, two adjacent He / He heat exchanger 12 is supplied with hot helium via one of the hot gas channels 8. The hot gas channels 8 each emerge between two He / He heat exchangers 12 from the Hot gas collection chamber 6 and run first horizontally, then vertically downwards, they are arranged within the cavern floor in a further recess; they branch out at the level of the heat exchanger ends, and so do each section is connected to one of two neighboring He / He heat exchangers 12 (not shown).

In the annular space 11 there is sufficient space between the He / He heat exchangers 12 is available, and this space is used for the installation of one of several auxiliary heat exchangers 17 with fans 18 existing residual heat removal device exploited. The blowers 18 with their drive motors are each located in a horizontal recess 19 in the wall of the cavern 2. The connections of the auxiliary heat exchanger 17 to the high-temperature reactor 3 are not shown.

Each He / He heat exchanger 12 is formed with an annular channel 20 enclosed by a guide cylinder 21 which extends through the ceiling la of the prestressed concrete pressure vessel 1 extends into the recess 16, so the heat exchanger also in the annular space 11 surrounds. The ring channels 20 are used to return the cold primary helium the bottoms of the He / He heat exchangers 12, where the cold gas is in each case an annular channel 22 is fed, each surrounding a hot gas channel 8 coaxially. The ring channels 22 are to the annular space 9 between the thermal side plate 5 and the lateral graphite reflector 4 connected.

One of the He / He heat exchangers 12 will now be described in detail.

As can be seen in FIG. 2, there is the heat exchanger surface of the He / He-W heat exchanger 12 from a U-tube bundle 23, which is in two coaxial annular spaces is arranged. The two legs of a U-tube 24 do not lie in a meridian plane, but are offset from one another in the circumferential direction of the He / He heat exchanger 12 positioned (not shown). The inner annular space 25 is from an inner Separating cylinder 27 and a central separating cylinder 28 formed; the kisser annulus 26 has. as a limit the middle separating cylinder 28 and an outer limiting cylinder 29. The annular channel 20 is provided around the limiting cylinder 29. All three cylinders are provided with thermal insulation 30 on the inside. Downwards are those two annular spaces 25, 26 closed with a base plate 31, which is also internally insulated is.

The inner separating cylinder 27 encloses a tube-free central channel 32, into which hot primary helium flows in from below via a mixing device 33. The hot primary helium that comes from one of the hot gas channels 8 is at the top The end of the U-tube band 23 is deflected by a guide device 34 by 1800 and occurs above into the inner annular space 25. Only then does it flow through the inner annular space 25 and then the outer annular space 26. The guide device 34 is by means of ribs 35 attached to the inner separating cylinder 27. On the middle separating cylinder 28 stepped spacers 36 are attached; they are both in the inner annulus 25 as well as in the outer annular space 26. Fixing the spacers 36 allows the U-tubes 24 to be threaded in only on the central separating cylinder 28 during the assembly of the heat exchanger (if the cylinders 27 and 29 and still missing base plate 31).

The U-tube bundle 23 goes from an annular inlet header 37 for the secondary helium, which has an elliptical cross section; it flows out in a tubular outlet header 38, which is enclosed by the inlet header 37 is. The tubular outlet header 38 is at its lower end in diameter expanded and has in the cambered end face of the extension 39 an upward drawn conical neck 41. The U-tubes 24 only enter the remaining one annular end wall 40, but not into the neck 41. Elbows are here not present in the U-tubes 24. Reached by means of the conical neck 41 the annular end wall 40 has a sufficiently high thermal elasticity, as above all is necessary for stronger temperature transients of the secondary helium (the relative thin walls of the conical neck 41 adapt quickly to changed helium temperatures which avoids excessive additional thermal voltages).

The outer limiting cylinder 29 as well as the middle separating cylinder 28 are attached to the annular inlet header 37.

This results in a good stability of the He / He heat exchanger 12. The middle separating cylinder 28 has perforations in its uppermost area 42 for the passage of the cold primary helium, its warmth in the annulus 25 and 26 to the secondary arhelium. It arrives now in an annular connecting channel 43, which is partly between the inlet header 37 and the outlet collector 38 and in which the cold primary helium goes to the Fan 13 is transported. The inlet collector is in the area of the connecting channel 43 37 and the outlet header 38 are connected to one another by ribs 44 which are arranged in a radial direction Direction have a certain elasticity. This will cause excessive thermal Tensions between the two collectors 37, 38 avoided in this direction, and Sufficient stability is achieved in the axial direction, the outlet header 38 has two thermal insulations which overlap in the axial direction. One - an outer insulation 45 - is on the extension 39 as well as on the conical Neck 41 provided; the other - an inner insulation 46 - is on the tubular part of the outlet collector adjoining the extension 39 at the top 38. The two insulations 45 and 46 gradually reduce the wall temperature from the temperature of the hot secondary helium (900 oC) to the temperature of the cold Primary helium (approx. 300 OC) in the conical or cylindrical wall area of the outlet collector 38 allows.

The cold primary helium enters the fan after it has been compressed 13 into the annular channel 20, in which it - as already described - flows downwards and is returned in the annular channel 22 to the high-temperature reactor 3 (cf. Figure 1).

As can be seen in FIG. 1, the inlet collector is located 37, the outlet collector 38 and the fan 13 and the associated drive motor 14 outside the prestressed concrete pressure vessel 1 in a burst-proof steel cylinder 47, which is on the ceiling 1a of the container 1 is placed. The supply line 48 to the inlet collector 37 or. The discharge 49 of the outlet collector 38 occur laterally from the steel cylinder 47, wherein they are arranged one above the other. Fan 13 and drive motor 1 & are above the two inlets and outlets 48, 49 installed.

The supply line 48 has at least a clear diameter of 600 mm to make the inlet collector 37 accessible.

The steel cylinder 47 is through peripheral tension cables 50 and longitudinal tension cables 51 secured, the longitudinal tensioning cable 51 in the ceiling la of the prestressed concrete pressure vessel 1 are anchored. This makes the concept even though a steel cylinder is used Maintain full burst safety of the system. The end of the steel cylinder 47 at the top forms a double cover 52; So there is also burst protection here. If necessary, the steel cylinder 47 can also be secured by means of tension cables Cover to be completed. In addition, the steel cylinder 47 is still further Tensioning cables 53, which are anchored in the prestressed concrete pressure vessel 1, against the effects secured by earthquakes.

Also in the inlet and outlet lines 48, 49 of the two collectors 37, 38 Burst security is guaranteed, as it is in burst-proof expansion compensation bushes 54 are relocated. The expansion compensation bushings 54 also carry peripheral tension cables 55, and a clamping ring 56 is placed on each of their outer ends, which means horizontal tensioning cable looping around the steel cylinder 47 is tensioned (not shown).

The secondary helium to be heated flows through the feed line 48 in the inlet collector 37 and is here on the individual U-tubes 24 of the U-tube bundle 23 distributed. As the secondary helium flows through the U-tube bundle, it is released from to him in primary helium flowing in the opposite direction to the two annular spaces 25 and 26 heated and then reaches the outlet collector 38. Through the discharge line 49 is it eventually led out of the nuclear power plant.

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Claims (22)

Claims: le nuclear power plant with closed cooling gas circuit for the generation of process heat, which is operated with helium via at least one Secondary circuit is decoupled, with a helium-cooled high-temperature reactor, which is housed in a central cavern of a prestressed concrete pressure vessel and is surrounded on all sides by a thermal shield and has He / He heat exchangers, die.on a partial circle around the pressure vessel axis in the annulus between the thermal Side shield and the cavern wall are installed, whereby the cooling gas circuit (primary circuit) is divided into several equal strands, each one in series Have He / He heat exchangers and a blower characterized by the following Features: a) each He / He heat exchanger (12) comprises a U-tube bundle (23), which in two of an outer limiting cylinder (29), a middle separating cylinder (28) and annular spaces (25, 26) formed by an inner separating cylinder (27) are arranged, through which hot primary helium is passed; b) the inner separating cylinder (27) each He / He heat exchanger (12) encloses a tube-free one, from bottom to top central channel (32) through which hot primary helium flows; c) the U-tube bundle (23) each He / He heat exchanger (12) goes from an annular inlet header (37) for the secondary halium and opens into the end wall (40) of one tubular outlet header (38) enclosed by the inlet header (37) for the secondary helium; d) in every He / He heat exchanger (12) are the inlet collectors (37) and the outlet collector (38) for the secondary helium within a burst-proof Steel cylinder (47) arranged, which is placed on the pre-stressed concrete pressure vessel (1) and is anchored in this; e) the supply and discharge lines (48, 49) of the two collectors (37, 38) emerge laterally from each steel cylinder (47), arranged one above the other, where they are laid in burst-proof expansion compensation bushes 154); f) above the discharge line (49) for the outlet collector (38) is in each steel cylinder (47) installed the fan (13) for the primary helium with the associated drive motor (14). 2. Nuclear power plant according to claim 1, characterized in that each tubular outlet header (38) expanded in diameter at its lower end is and the end wall (40) of the extension (39th) an upwardly drawn conical Has a neck (41) into which no U-tubes (24) open. 3. Nuclear power plant according to claim 1, characterized in that each annular inlet collector (37) an elliptical or elliptical cross-section having. 4. Nuclear power plant according to claims 1, 2 and 3, characterized in that that in each He / He heat exchanger (12) one Connecting duct (43) for the transport of the cold primary helium from the outer annulus (26) to the fan (13) is provided, the stretches between the annular inlet header (37) and the tubular outlet header (38) runs. 5. Nuclear power plant according to claim 4, characterized in that each tubular outlet collector (38) in the area of the extension (39) and in the conical Collar (41) has a thermal outer insulation (45) and that the top adjoining area is provided with a thermal inner insulation (46), wherein the two insulations (45, 46) overlap. 6. Nuclear power plant according to claims 1 and 4, characterized in that that the inlet header (37) and the outlet header (38) of each He / He heat exchanger (12) in the area of the connecting channel (43) for the cold primary helium by elastic Ribs (44) are interconnected. 7. Nuclear power plant according to claim 1 or 3, characterized by dad-urch, that the central separation cylinder (28) of each He / He heat exchanger (12) on the annular Inlet collector (37) is attached and at its upper end perforations (42) for the passage of the cold primary helium. 8. Nuclear power plant according to claims 1, 2 and 7, characterized in that that the outer limiting cylinder (29) of each He / He heat exchanger (12) also is attached to the annular inlet header (37). 9. Nuclear power plant according to claim 1 or 7, characterized in that the U-tube bundle (23) in the inner (25) and in the outer annular space (26) preferably has stepped spacers (36) in the two annular spaces (25, 26) on the middle separating cylinder (28) are attached. 10. Nuclear power plant according to claim 1, characterized in that on the inner separation cylinder (27) of each He / He heat exchanger (12) a guide device (34) is attached to divert the hot primary helium, the top into the central channel (32) protrudes. 11. Nuclear power plant according to claim 1, characterized in that at each He / He heat exchanger (12) the two legs of a U-tube (24) in the circumferential direction of the He / He heat exchanger (12) are arranged offset from one another. 12. Nuclear power plant according to claim 1, characterized in that the Feed line (48) to the annular inlet header (37) of each He / He heat exchanger (12) has a diameter of at least 600 mm. 13. Nuclear power plant according to claim 1, characterized in that the burst-proof steel cylinders (47) of each He / He heat exchanger (12) by means of longitudinal tensioning cables (51) and peripheral tensioning cable (50) is tensioned, the longitudinal tensioning cable (51) are anchored in the prestressed concrete pressure vessel (1). 14. Nuclear power plant according to claims 1 and 13, characterized in that that each burst-proof steel cylinder (47) completed with a double cover (52) is. 15. Nuclear power plant according to claims 1 and 13, characterized in that that each anti-rupture steel cylinder top with a vertical tension cable secured lid is complete. 16. Nuclear power plant according to claims 1 and 13, characterized in that that the expansion compensation bushings (54) for the supply and discharge lines (48, 49) of the two collectors (37, 38) of each He / He heat exchanger (12) by peripheral tension cables (55) are pretensioned and each have a clamping ring (56) at their outer ends and that the two clamping rings (56) are braced with horizontal tensioning cables, which enclose the steel cylinder (47). 17. Nuclear power plant according to claims 1 and 13, characterized in that that each burst-proof steel cylinder (47) additionally through in the prestressed concrete pressure vessel (1) anchored tensioning cable (53) is secured against earthquake damage. 18. Nuclear power plant according to claim 1, characterized in that each He / He heat exchanger (12) forming an annular channel (20) from a guide cylinder (21) is enclosed, which extends through the ceiling (la) of the prestressed concrete pressure vessel (1) and the entire cavern (2) extends, and that through the annular channel (20) the cold primary helium is led down. 19. Nuclear power plant according to claim 18, characterized in that each He / He heat exchanger (12) extends into a recess in the cavern floor (16) extends and the associated guide cylinder (21) also into the recess (16) is extended into it. 20. Nuclear power plant according to claim 19, characterized in that for two adjacent He / He heat exchangers (12) on below the reactor core the high-temperature reactor (3) exiting hot gas duct (8) is provided which first runs horizontally, then in one between the recesses (16) for the two Ee / He heat exchangers (12) provided further recess up to the level the heat exchanger ends is led down and there for the connection to the two heat exchangers (12) branched. 21. Nuclear power plant according to claim 1, characterized in that the He / He heat exchangers extend through the entire floor of the prestressed concrete pressure vessel and are also led out beyond its outer boundary surface, this latter being the latter Part of each is arranged in a burst-proof steel cylinder. 22. Nuclear power plant according to claim 1 and one or more of the preceding Claims, characterized in that in the annular space (11) of the central cavern (2) between the He / He heat exchangers (12) in a manner known per se at least two auxiliary heat exchangers (17) are arranged for removing residual heat from the reactor core are.