DE3909446A1 - Pressure container for a nuclear reactor - Google Patents

Abstract

Published without abstract.

Description

The invention relates to a pressure vessel for Nuclear reactor with enclosed in the pressure vessel Reactor core, in particular for a high-temperature reactor, with concrete walls, especially those with reinforced concrete walls Container walls.

In the case of high-temperature reactors, the entire primary circuit integrated. The pressure vessel consists of prestressed concrete for reactors with higher output. To Achieving gas tightness against that under pressure standing primary coolant helium is the pressure vessel inside with a lining made of steel, the so-called liner. The liner has gas side a thermal insulation and cooling channels on the concrete side one or more water cooling systems are connected (see DE-PS 35 26 377, US-PS 42 92 134).

With the liner cooling system described above, the Temperatures in a core heating up accident at which all active heat recovery systems fail and also a total Loss of cooling gas occurs with a suitable core geometry limited non-critical values. This is the reluctance of Fission products in the fuel elements guaranteed and also maintain the integrity of the pressure vessel. Would, however in such a case the liner cooling would fail the temperature of the core, the graphite reflector and  of the concrete continue to increase over time. This would have been Consequence that the pressure vessel would be destroyed. It should also penetration of water released from the concrete and Carbon dioxide in the hot core are feared d. H. it large amounts of explosive gases would arise. Farther would result in a massive release of fission products from the Fuel elements take place.

The invention has for its object a nuclear reactor of the type mentioned in such a way that in one Nuclear heating accident, destruction of the pressure vessel and thus the formation of large quantities of highly explosive gases is prevented or at least significantly delayed.

This object is achieved by a Pressure vessels of the type mentioned above with the following Features resolved:

• (a) at least in the container side walls are additional Lich poured heat conductive body;
• (b) the heat conducting bodies in the container side walls extend in height or are in height distributed at least over the active area of the Reactor core;
• (c) the heat conducting bodies extend radially Direction from the inside of the area Reinforced concrete walls over more than half of them Thickness;
• (d) the heat conducting bodies consist of a material that a better one compared to the concrete material Thermal conductivity and heat penetration number (cf.  dtv-Lexikon der Physik, Volume 10, 1971, page 38);
• (e) the heat conducting bodies are dimensioned and / or arranged in such a way that the inner area of the Reinforced concrete walls of the pressure vessel in the of the Surface areas occupied by heat-conducting bodies relieved of temperature in a core heating-up accident becomes.

With the help of such additional in the reinforced concrete walls of the Pressure vessel cast-in heat sink can in a heat from the core insofar as highly stressed areas close to the core in further external wall areas are derived. With that also these outer wall areas for reinforced Heat absorption used with the consequence that the Peak temperatures in the core area considerably be reduced. Due to the enlarged Difference in temperature can also generate more heat from the hot core drain, which is faster Temperature drop in the core. Overall will thereby the passive safety of the nuclear reactor for the Case that all protection systems, especially that Liner cooling system, fail, significantly improved.

Another proposal to solve the problem is in a pressure vessel with the following features:

• (a) are at least in the container side walls additionally cast in heat-conducting body;
• (b) the heat conducting bodies in the container side walls extend in height or are in height distributed at least over the active area of the  Reactor core;
• (c) the heat conducting bodies extend at least in the area of the inside (s) of the pressure vessel;
• (d) the heat conducting bodies consist of a material which is in the A better comparison to the concrete material Has thermal conductivity and heat penetration number;
• (e) the heat conducting bodies have cooling channels for the Passage of a cooling medium on;
• (f) the heat conducting bodies are dimensioned and / or arranged that the inner area of the concrete walls of the Pressure vessel in the from the heat sink occupied areas at a Core heating accident is relieved in terms of temperature.

The cooling channels should preferably be vertical run and have ribs on the inside.

According to the invention, the heat-conducting bodies have this Proposed solution for cooling channels through which a cooling medium can be passed through, the cooling channels expediently connected to supply and discharge pipes are. In the simplest case, heating up creates the Thermally conductive body in the cooling channels Convection flow, through which the heat sink absorbed heat can be dissipated. In addition there is of course the possibility of a To provide forced cooling by air or other gases or even liquids, such as water, in the Cooling channels are introduced or injected.  

With this proposed solution, because of the additional heat dissipation by the cooling medium, it is not necessary for the heat-conducting bodies to extend in the radial direction in accordance with feature ( c ) of the first proposed solution, even if this is possible.

In both proposed solutions, the aim is to distribute the heat-conducting bodies as evenly as possible over the cross-section in which they are arranged. The active area of the reactor core in the sense of feature ( b ) is to be understood as the cylindrically averaged height of the ball cluster or a corresponding height for other types of nuclear reactors. In the event of a core heating-up accident, the pressure vessel is exposed to particularly high heat in this height range, so that the arrangement of heat-conducting bodies in this height range is particularly recommended in order to relieve the temperature of the concrete walls of the pressure vessel when heat is applied from the inside in such a way that the peak temperatures are caused by rapid Heat dissipation in the outer areas of the concrete walls or in the cooling medium flowing through the cooling channels can be reduced.

The heat-conducting bodies can be designed in many forms. For the first solution it is essential that they on the one hand very close to the inside of the Reach container walls, on the other hand a large one radial extension over more than half the wall thickness to have. Preferably, the extension should be as close as possible to the outside of the container walls to high heat penetration volume through the thermal conductors To make available and thereby also the outside Areas of the container walls for heat absorption and storage.  

Possible heat conductors include, for example Variety of radially aligned plates or the like Heat conducting bodies. As far as space exists, however also the possibility of using blocks as thermal conductors use because with them a high compared to concrete Heat storage capacity is provided. It is expedient that the heat-conducting body additionally ribs have to the heat transfer surface to the concrete material enlarge. These ribs can, for example, in Extend circumferential direction.

The heat-conducting body should, if possible, cover the entire height the container side walls, d. H. about the amount of by the space enclosed by the pressure vessel. It is even more advantageous if the heat-conducting body even about the height of the container side walls extend.

In a further embodiment is according to the invention provided that the concrete material of the reinforced concrete walls mixed at least in the inner area with granulate material is that from a heat compared to the concrete material better conductive material such as iron or steel consists. This also helps that the heat goes faster into the less polluted areas led to the outside and the heat storage capacity in the highly stressed area is increased. This measure is also regardless of the arrangement of heat conducting bodies feasible and increases the safety of the nuclear reactor.

As for the second proposed solution, he can also in the form can be realized that the heat sink as concentric ring wall are formed, the ring  not according to the geometry of the pressure vessel circular, but also square, for example can. The ring wall should be on the inside of the Concrete wall of the pressure vessel arranged and on the A liner must be hung on the inside of the ring wall. At the protection of the concrete wall is special in this arrangement effective. In addition, the heat dissipation on the Supported outside of the liner. If the liner is there The gap should be at a distance from the ring wall filled with a material between the liner and the ring wall be, whose thermal conductivity is better than that of concrete is. This could be, for example Trade metal granules or similar metal waste.

The ring wall should improve the heat dissipation have ribs on the inside. Accordingly, the Have ribs on the outside. Another improvement the heat dissipation is achieved in that the ribs of the Ring wall contact to the liner and / or the ribs of the Liners are in contact with the ring wall.

This could result in the liner being suspended from the ring wall be realized that the liner vertically on the Has T or double T profiles on the outside, the outside flanges in matching hammer head grooves in surround the ring wall.

The ring wall is expediently vertical in Split ring segments. This makes manufacturing easier transportation and assembly. The Ring segments on their vertical faces one in Have a radial connection, for example a tongue and groove connection. In this way has the ring wall compressive strength and can  Shrinkage forces of the concrete and prestressing forces if necessary intercept the pressure vessel and in this way the liner relieve.

In the drawing, the invention is schematic with reference to illustrated embodiments illustrated in more detail. Show it:

Figure ( 1 ) is a vertical section through the pressure vessel of a high temperature reactor;

Figure ( 2 ) is a horizontal section through the pressure vessel of Figure ( 1 );

Figure ( 3 ) shows a cross section through one half of another pressure vessel and

Figure ( 4 ) partial cross section through a modified embodiment of the pressure vessel according to Figure ( 3 ).

The pressure vessel ( 1 ) shown in Figures ( 1 ) and ( 2 ) is made as a prestressed concrete structure and has a circular cross section. A cylindrical free space ( 2 ) is provided on the inside, which is provided for receiving the reactor core, the graphite reflector and the devices and systems for the coolant guide.

The inside of the pressure vessel ( 1 ) is provided with a liner ( 3 ). This is a steel lining. A liner insulation ( 4 ) is provided on the inside, which consists of a plurality of metal foils arranged one behind the other with air spaces in between. On the outside, the liner ( 3 ) is connected to cooling channels - designated by ( 5 ) for example. A cooling liquid is passed through these cooling channels ( 5 ) via a pump system.

In the ring-shaped part of the pressure vessel ( 1 ), ie over the height of the free space ( 2 ), heat-conducting bodies - designated by way of example ( 6 ) - are arranged. In figure (2), only three of them are located. However, they extend in a corresponding arrangement over the entire circumference of the pressure vessel ( 1 ). They are made of gray cast iron, so they have a significantly better thermal conductivity and heat penetration capacity. They extend with their inward-facing sides as close as possible to the cooling channels ( 5 ) of the liner ( 3 ) and extend radially into the outer area. They are provided with ribs extending in the circumferential direction - designated by way of example with ( 7 ) - in order to substantially increase the heat transfer area to the concrete material.

Due to the arrangement of the heat-conducting bodies ( 6 ) shown, the heat flowing into the concrete of the pressure vessel ( 1 ) in the event of a core heating failure in the event of cooling of the liner ( 3 ) failing is conducted quickly and effectively into the outer regions of the pressure vessel ( 1 ) and these areas are used for heat absorption. In this way it is avoided that the areas of the pressure vessel ( 1 ) close to the core reach critical temperatures.

At the same time, this increases the temperature difference between the free space ( 2 ) and the concrete of the pressure vessel ( 1 ), with the result that the heat dissipation into the heat-conducting body ( 6 ) and into the concrete of the pressure vessel ( 1 ) is intensified.

In the heat-conducting bodies ( 6 ) extend vertically cooling channels - designated by way of example ( 8 ) - which are connected to the interior of the reactor protection building (not shown here) via feed pipes ( 9 , 10 ) and discharge pipes ( 11 , 12 ). When the heat-conducting bodies ( 6 ) are heated in the event of a core heating-up accident, a natural convection flow occurs in the cooling channels ( 8 ), as a result of which the heat absorbed by the heat-conducting bodies ( 6 ) is effectively dissipated. This natural flow can of course be actively supported by pumps or compressors. It is also possible to inject cooling liquids, for example water, into the cooling channels ( 8 ) in order to intensify the heat dissipation.

The pressure vessel ( 13 ) shown in Figure ( 3 ) also has a circular cross section. A cylindrical free space ( 14 ) is provided on the inside, which is provided for receiving the reactor core, the graphite reflector and the devices and systems for the coolant guide.

The inside of the pressure vessel ( 13 ) is provided with a steel liner ( 15 ). A liner insulation ( 16 ) is attached to the inside. On the outside, vertical cooling channels - designated by way of example with ( 17 ) - are applied, through which cooling liquid is passed during operation.

The majority of the pressure vessel ( 13 ), ie more than half of its thickness, is formed by an annular concrete wall ( 18 ). On the inside there is a heat-conducting wall ( 19 ) which is divided into individual ring segments - designated by ( 20 ) for example. The individual ring segments ( 20 ) are positively connected on their vertical end faces via tongue-and-groove connections - identified by way of example with ( 21 ). On their outer sides, the ring segments ( 20 ) carry T-shaped anchors - designated by way of example with ( 22 ) - via which the ring segments ( 20 ) are cast into the concrete wall ( 18 ).

The ring segments ( 20 ) of the heat-conducting wall ( 19 ) are provided with vertical cooling channels - identified by way of example ( 23 ) - in which a natural convection flow occurs when heated in the event of a core heating-up accident, as a result of which the heat absorbed by the heat-conducting wall ( 19 ) is effectively dissipated. The individual ring segments ( 20 ) of the heat conducting wall ( 19 ) consist of cast steel or gray cast iron, so they have a considerably better thermal conductivity and heat penetration capacity.

There is a gap between the inside of the heat-conducting wall ( 19 ) and the liner ( 15 ), which is filled with a highly heat-conductive material, for example iron granulate ( 24 ). This iron granulate ( 24 ) can additionally be mixed with a hardenable binder which enables uniform load transfer from the liner ( 15 ) to the heat conducting wall ( 19 ).

The outside of the liner ( 15 ) is provided at regular intervals with supports which extend in the vertical direction and are T-shaped in cross section - designated by way of example ( 25 ). These carriers ( 25 ) fit into suitable hammer head grooves - designated by way of example with ( 26 ) - in the ring segments ( 20 ). By appropriate dimensioning of the hammer head grooves ( 26 ) and the carrier ( 25 ) both the game and the distance between the liner ( 15 ) and the ring segments ( 20 ) can be defined so that the cooling channels ( 17 ) on the liner ( 15 ) are not can come into contact with the ring segments ( 20 ).

The embodiment shown in Figure ( 4 ) differs from that of Figure ( 3 ) only by an additional detail, so that the same reference numerals are used for the same parts. This additional detail is formed by a multiplicity of ribs ( 27 ) which extend radially and are integrally formed on the inside of the heat-conducting wall ( 19 ). These ribs ( 27 ) ensure a larger heat transfer area and thus better heat transport into the ring segments ( 20 ).

Claims (22)

1. Pressure vessel for a nuclear reactor with a reactor core enclosed in the pressure vessel, in particular for a high-temperature reactor, with concrete walls, in particular vessel walls having reinforced concrete walls, characterized by the following features:

• (a) heat-conducting bodies ( 6 ) are cast in at least into the container side walls ( 1 );
• (b) the heat conducting bodies ( 6 ) in the container side walls extend in height or are distributed in height at least over the active region of the reactor core;
• (c) the heat-conducting bodies ( 6 ) extend in the radial direction from the region of the inside of the concrete walls ( 1 ) over more than half of their thickness;
• (d) the heat-conducting bodies ( 6 ) consist of a material which has a better thermal conductivity and heat penetration number than the concrete material;
• (e) the heat-conducting bodies are dimensioned and / or distributed such that the inner area of the concrete walls of the pressure vessel ( 1 ) is relieved of temperature in the area occupied by the heat-conducting bodies ( 6 ) in the event of a core heating-up accident.

2. Pressure vessel for a nuclear reactor with a reactor core enclosed in the pressure vessel, in particular for a high-temperature reactor, with concrete walls, in particular vessel walls having reinforced concrete walls, characterized by the following features

• (a) heat-conducting bodies ( 6 , 19 , 20 ) are additionally cast in at least into the side walls of the container;
• (b) the heat conducting bodies ( 6 , 19 , 20 ) in the container side walls ( 1 , 13 ) extend in height or are distributed in height at least over the active region of the reactor core;
• (c) the heat conducting bodies ( 6 , 19 , 20 ) extend at least in the area of the inside (s) of the pressure vessel ( 1 , 13 );
• (d) the heat conducting bodies ( 6 , 19 , 20 ) consist of a material which has a better thermal conductivity and heat penetration number than the concrete material;
• (e) the heat-conducting bodies ( 6 , 19 , 20 ) have cooling channels ( 8 , 23 ) for the passage of a cooling medium;
• (f) the heat-conducting bodies ( 6 , 19 , 20 ) are dimensioned and / or arranged in such a way that the inner region of the concrete walls ( 18 ) of the pressure vessel ( 1 , 13 ) in the surface areas occupied by the heat-conducting bodies ( 6 , 19 , 20 ) is relieved of temperature in a core heating-up accident.

3. Pressure vessel according to claim 2, characterized in that the cooling channels ( 8 , 23 ) run vertically. 4. Pressure vessel according to claim 2 or 3, characterized in that fins in the cooling channels protrude. 5. Pressure vessel according to one of claims 1 to 4, characterized in that the heat-conducting body ( 6 , 19 , 20 ) consist of metal. 6. Pressure vessel according to one of claims 1 to 5, characterized in that the heat conducting body as Plates are formed. 7. Pressure vessel according to one of claims 1 to 5, characterized in that the heat-conducting body ( 6 , 19 , 20 ) are designed as blocks. 8. Pressure vessel according to one of claims 1 to 7, characterized in that the heat-conducting body ( 6 ) have ribs ( 7 ). 9. Pressure vessel according to claim 8, characterized in that the ribs ( 7 ) extend in the circumferential direction. 10. Pressure vessel according to claim 1, characterized in that the heat-conducting body ( 6 ) extend over the height of the container side walls ( 1 ). 11. Pressure vessel according to one of claims 1 to 7, characterized in that the concrete material of the Concrete walls in the inner area with granulate material is mixed, that one against the concrete material the heat is more conductive material. 12. Pressure vessel according to at least claim 2, characterized in that the heat-conducting body ( 19 , 20 ) are designed as a concentric ring wall. 13. Pressure vessel according to claim 12, characterized in that the ring wall ( 19 , 20 ) on the inside of the concrete wall ( 18 ) of the pressure vessel ( 13 ) is arranged and that on the inside of the ring wall ( 19 , 20 ) a liner ( 15 ) is hung. 14. Pressure vessel according to claim 13, characterized in that the liner ( 15 ) is at a distance from the ring wall ( 19 , 20 ) and the space between the liner ( 15 ) and ring wall ( 19 , 20 ) is filled with a material ( 24 ) whose Thermal conductivity is better than that of concrete. 15. Pressure vessel according to claim 14, characterized in that the material filled in the intermediate space contains metal granules ( 24 ) or the like. 16. Pressure vessel according to one of claims 13 to 15, characterized in that the ring wall ( 19 , 20 ) has ribs ( 27 ) on the inside. 17. Pressure vessel according to one of claims 13 to 16, characterized in that the liner on the outside Ribs. 18. Pressure vessel according to claim 16 or 17, characterized in that the ribs of the ring wall Contact to the liner and / or the ribs of the liner contact to the ring wall. 19. Pressure vessel according to one of claims 13 to 18, characterized in that the liner ( 15 ) has vertically running on the outside T or double T profiles ( 25 ), the outside flanges in matching hammer head grooves ( 26 ) in the ring wall Border ( 19 , 20 ). 20. Pressure vessel according to one of claims 13 to 19, characterized in that the ring wall ( 19 ) is divided vertically into ring segments ( 20 ). 21. Pressure vessel according to claim 20, characterized in that the ring segments ( 20 ) with their vertical end faces have a positive connection in the radial direction ( 21 ). 22. Pressure vessel according to one of claims 13 to 21, characterized in that on the outside of the ring wall ( 19 , 20 ) anchors ( 22 ) are arranged which are cast into the concrete wall ( 18 ).