JPS6345078B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reactor vessel for a hot gas-cooled pebble-vet nuclear reactor, such as is described, for example, in the May 1971 issue of the West German magazine "Atomwirtschaft".

The millions of spherical fuel deposits forming the core region of such a nuclear reactor are contained in a reactor vessel having a polygonal or circular plan shape and consisting of side walls and a funnel-shaped bottom. The fuel supplied from above and used up as it passes through the core region is discharged from the bottom of the funnel.

The cooling gas flows through the bulb from top to bottom, so that the operating temperature in the vicinity of the bottom and the lower parts of the side walls is, for example, 950°C. For this reason, the graphite blocks making up the bottom and side walls are exposed to large thermal expansions and contractions each time the reactor is started or shut down. In the case of sidewalls, the air gap between each block is such that it closes when the operating temperature is reached, resulting in a gas-tight furnace vessel, with the sidewall blocks having a radially displaced outer surface surrounding the furnace vessel. Prevented by support structures. In the area of the spherical body no problems arise due to thermal expansion of the side wall blocks. This is because the sphere behaves like a liquid under the action of external forces, ie in this case it can be deflected upwards and escape. A similar tightening profile on the side walls also occurs in the area of the bottom only if the bottom is of "soft" design. Conventionally, it has been thought that this can be achieved by providing a sufficiently large gap between each bottom block at room temperature. If the bottom blocks are placed relative to each other without constraint, after several expansions and contractions of the combination, each block will no longer be located precisely in its predetermined position in the bottom grid, and the gaps between each block will be reduced. The size changes unexpectedly from block to block. In individual cases, it is possible for the gap to remain closed even at room temperature, but this results in crushing of the composite or at least in large frictional forces during subsequent reheat expansion. Still other voids may be of considerable size due to the sum of multiple deviations of the target dimensions, and such excessively large voids may contain, for example, debris from damaged fuel or forced shutdown of the reactor. The well-known “small neutron absorption spheres” used for
This will prevent subsequent re-inflation of the block.

The object of the invention is to provide a furnace vessel in which the above-mentioned disadvantages are avoided, and the aim is to avoid different clamping conditions at the transition between the side wall and the bottom. . The aim is also to allow the bottom blocks to expand freely relative to each other, without the side walls being loaded with additional forces, and also to allow only a limited and calculable amount of air space between each bottom block. The aim is to make sure that this occurs.

According to the invention, this purpose is achieved by constructing a nuclear power plant consisting of side walls assembled from segment-shaped blocks and a bottom assembled from prismatic blocks, in which the reactor operating temperature is reached between the blocks of the side walls at room temperature. In the reactor vessel of a high-temperature gas-cooled pebble-vet reactor where there is a gap that closes when
Each bottom block is connected to the side wall block by means of adjustment springs or projections arranged in corresponding grooves of each block, said grooves and adjustment springs or projections forming a regular polygonal grid in a vertical plane. The air gap between each bottom block and the air gap between the bottom block and the side wall block are
This is achieved by not being completely closed even at operating temperatures. By arranging the bottom blocks relative to each other via adjustment springs or by projections formed on the blocks, it is possible to ensure that the thermal expansion of the blocks that occurs when the temperature rises occurs uniformly in all directions; maintains its set position in the grid even after cooling. By arranging the interlocking part in a vertical plane, it is achieved that the bottom block can expand vertically without hindrance. When the gap between the bottom blocks does not close completely even at operating temperatures, contact between the bottom blocks takes place only via adjusting springs or projections.

An advantageous embodiment of the present invention is defined in claim 2.
listed in section. The hexagonal shape of the bottom blocks and the arrangement of the interlocking parts in a triangular lattice provide a good guarantee of the intended uniform thermal expansion of each block in the desired direction. The triangular lattice continues into the side walls, where the grooves in the side walls also act.

Irregularities arise for geometrical reasons when transitioning from a bottom constructed of hexagonal blocks to essentially circular side walls. Claim 3 provides that the arrangement of specially formed filling blocks is omitted, but rather that the side wall blocks are formed to match the irregular outer contour of the bottom, and that the above-mentioned lattice can be used without any problem. Proposed.

Claims 4 to 7 refer to four of the side walls.
It lists two possible forms. Either of these embodiments is most useful in a particular case depending on the set of requirements set forth herein. The embodiment according to claim 5 provides, at high production costs, from an irregular inner contour to supports which are arranged at regular intervals from each other and support the furnace vessel to the outer clamping structure. Most suitable for forming transition areas.

Embodiments of the present invention shown in the drawings will be described below.

A spherical body 1 consisting of several million spherical fuel particles and forming the core region of a nuclear reactor is placed in a reactor vessel consisting of a substantially hollow cylindrical side wall 2 and a funnel-shaped bottom 3. There is. The side wall 2 has a graphite block 2 as shown in sector b of FIGS. 1 and 2.
It consists of two concentric rings assembled from 1 to 22. The base 3 is likewise assembled from graphite blocks 31, which in the illustrated example have the shape of a hexagonal prism. The inner surface of the side wall block 21 is shaped to match the irregular outer contour of the bottom 3.
During operation, new fuel is supplied to the upper end of the spherical volume 1 through the supply pipe 11.
is continuously supplied through the fuel tank 12, while exhausted fuel is discharged from the lower end via a counting and separating device 12. A cooling gas, preferably helium, is supplied to the upper end of the reactor vessel, flows through the bulb 1 from top to bottom and is delivered from the lower end to the load in a heated state up to the total operating temperature of approximately 950°C. . Since the cooling circuit has a well-known configuration, detailed illustration is omitted here. During normal operation, the nuclear reactor is controlled by control rods 6. The control rod 6 is moved up and down and inserted into the bulb 1 to shut down the reactor. In the event of a failure in this reactor shutdown system, a ball made of a neutron-absorbing material, for example a boron-containing material, is fed into the reactor vessel from a vessel (not shown here) via the supply pipe 11, for example.

Since the neutron-absorbing spheres are much smaller than the fuel spheres, they disperse into the sphere 1 and shut down the reactor. The neutron absorbing spheres are likewise ejected from the lower end of the reactor vessel in order to later restart the reactor. For this reason, the gaps between the bottom blocks 31, which occur particularly at room temperature, must be kept small so that neutron-absorbing spheres cannot reach into the gaps. For this purpose, grooves are provided on the bottom side of the bottom block 31 and the side wall blocks 21, which grooves are arranged in a regular triangular lattice (as indicated by the dash-dotted lines in FIG. 2). . Adjustment spring 311 or bottom block 31 inserted into this groove
The protrusions 312 formed in the bottom ensure that all the bottom blocks 31 maintain their correct location in the bottom assembly even during repeated expansions and subsequent deflations. Its geometry is the result of a French patent no.
This shape is similar to that proposed for moderator blocks in US Pat. No. 1,214,246, thereby allowing thermal expansion as well as unavoidable Wigner growth. To prevent flow loss due to voids,
It is of course important that this gap is completely closed during operation. However, in the case of this invention this is not a condition, but rather each bottom block 3
Adjusting the contact between spring 311 or protrusion 3
It is intended that the air gap between each bottom block 31 be maintained during operation in order to limit the contact surface to 12 predetermined contact surfaces. The shape of the bottom block 31 illustrated in the upper part of FIG. 3 allows it to be made from cylindrical stock with minimal material loss. In the sectors designated a, b, c, d in FIG. 2, various possibilities for the transition from an irregular inner contour of the side wall to an outer contour as uniform as possible are shown. The outer contour is
It is necessary to enable the furnace vessel to be supported on the metal support structure 4 via support rods 41 (which may be elastic bodies). In sector a, the dividing planes between each side wall block 21 each run radially outward from the recessed corner of the inner contour. This has the disadvantage that the division pitch of the outer contour is irregular. Therefore, around the inner ring of blocks 21 in sector b there are blocks 22
An outer ring consisting of is stretched, the outer ring having regular dividing pitches.
The blocks of both the inner and outer rings interlock with each other via adjustment springs or projections 221 arranged radially and fitted into corresponding grooves.
Here, the transition part is advantageously solved with increased construction costs. In sector c, the dividing surface extends radially inwardly starting from the regular pitch dividing surface of the outer contour, which results in the simplest shape for the side wall block 21, but because of this , where the dividing plane is unfavorable,
For example, in the region of the groove an inner contour is struck. In sector d, the dividing plane runs from the regularly subdivided outer contour to the recessed corner of the inner contour. This further makes it impossible for each sidewall block 21 to obtain the desired wedge shape.
During assembly, i.e. at room temperature, there is a gap between each side wall block 21 which closes when the operating temperature is reached, thereby forming an airtight container which is only tangentially tightened. There is. The entire reactor is placed in a pit in a radiation-shielding concrete structure 5.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a pebble-vet nuclear reactor, FIG. 2 is an enlarged sectional view taken along the - line in FIG. 1, and FIG. 3 is a further enlarged detailed view of FIG. 2. 1... Spherical volume, 2... Side wall, 3... Bottom, 21...
...Side wall block, 31...Bottom block, 311...
...adjustment spring, 312...protrusion.

Claims (1)

[Scope of Claims] 1. Consisting of a side wall assembled with segment-shaped blocks and a bottom assembled with prismatic blocks, there is a space between each block of the side wall at room temperature when the reactor operating temperature is reached. In the reactor vessel of a hot gas-cooled pebble-vet reactor in which there is a gap closed between the bottom blocks 31 and 21, each bottom block 31 is connected to the side wall block 21 by means of adjustment springs 311 or protrusions 312 disposed in corresponding grooves of each block. connected to the groove and the adjustment spring 311 or the protrusion 3
12 are arranged in a vertical plane forming a regular polygonal lattice, and the gaps between each bottom block 31 and the gaps between the bottom blocks 31 and the side wall blocks 21 do not close completely even at operating temperatures. A reactor vessel of a pebble-vet type nuclear reactor characterized by. 2. The bottom block 31 is hexagonal, and has a groove and an adjustment spring 311 or a protrusion 312.
2. The furnace vessel according to claim 1, wherein the lattice is triangular. 3. Claim 1 or 2, characterized in that the bottom 3 is formed of only a complete block 31, and the inside of the side wall 2 is adapted to the contour of the bottom 3.
Furnace vessel as described in section. 4. Furnace vessel according to any one of claims 1 to 3, characterized in that the dividing planes between each side wall block 21 each run radially outward from a recessed corner of the inner contour. . 5 The side wall 2 is divided into two concentric rings, the outer ring of which is divided into regular sectors, the blocks of the inner ring 21 being divided into outer rings 22
5. Furnace vessel according to claim 4, characterized in that it is connected to the block via an adjusting spring (221) arranged in a corresponding radial groove. 6. A furnace vessel according to any one of claims 1 to 3, characterized in that the dividing planes between each side wall block (21) run at regular intervals in the radial direction. 7. Claims 1 to 3 characterized in that the dividing planes between each side wall block 21 each run from a concave corner of the inner contour towards a regular pitch point of the outer contour. The furnace vessel described in any of the above.