DE2010233A1 - Moderator assembly for gas cooled reactors - Google Patents

Abstract

The building bricks of the moderator are arranged in layers each consisting of a number of polygonal blocks with groove and spring joints between their adjacent peripheral surface using keys of which a part engages the groove in at least one block. On each face of the block which has a groove there is at least one longitudinal slot separate from the groove but near to it. One such slot may be made on either side of the groove. Each spring engages the grooves opposite to each other in two adjoining blocks. The blocks may be alternately square and octagonal.

Description

Nuclear reactor moderator assembly The invention relates to a nuclear reactor moderator assembly of several moderate modules arranged in one layer or layer, one below the other are wedged with their outer circumferential surfaces by tongue and groove connections, wherein Each spring is provided in the outer circumferential surface of the moderator building blocks Engages grooves. Such a core structure usually consists of several such stacked layers, with the individual moderator modules of each layer with the moderator modules of the same type in the one above and / or below Position are aligned in such a way that the individual moderatoi.0 building blocks in vetical Columns are arranged, which vertical channels for receiving fuel elements, Form control rods and other plant parts of the nuclear reactor.

It is known that in nuclear reactor core structures of this type, the for example in "Magnox" and "Advanced Gas Cooled" nuclear reactors are embedded, the moderator blocks, if they are made of graphite, under the normal operating temperatures of the core structure a shrinkage with increasing Show radiation dose. This has a distortion deformation respectively. Rejection of the grooves as a result.

If, for example, the vertical channels for the fuel elements are formed by bores or recesses in certain moderator modules, so is the radiation dose on the inner wall surfaces in these moderator house stones larger than on the outer peripheral surfaces. Such moderator modules are therefore used A hoop tensile stress subjected to compressive stress on their outer peripheral sides. this causes a distortion or deformation of the grooves in such a way that they adhere to their outer peripheral side narrows, d. H.

that the grooves generally assume a dovetail shape.

The opposite is true for other moderator modules that do not have fuel elements included (although they are provided with holes or recesses in a similar way soin, which are used to hold control rods or other core system parts can) and which are therefore irradiated from the outside instead of from within, the irradiation desis is lower in its interior than in its outer peripheral surfaces; therefore, these moderator building blocks become inner L @@ ckkräfton and on their outer peripheral surfaces Annular tension clamps exposed, with the result that the provided in the outer peripheral surfaces Grooves deform in the sense of an inwardly progressive taper, d. H. that their width in the direction of the interior of the relevant moderator module @ decreases.

With regard to this groove deformations occurring during operation was it is necessary to wipe the grooves and tongues with a rinse for coupling @ di @@ Nut @ orformung @onzuschen.

This hot @och @ur Fole. d @ ß @es @rsaufhau @ie zeringei @ F @@ tlgkeit @ holds @@@@@@@ @ie @ wi @ chen d @@ Nut., and springs to be provided needed.

To remedy these disadvantages is a nuclear reactor moderator structure of the type mentioned provided according to the invention that in each case grooved outer peripheral surface of the building blocks adjacent to the groove and at a distance therefrom and running in the longitudinal direction of the groove at least one Slot provided ict.

According to a preferred embodiment, the arrangement can be made .o be that each provided on an outer peripheral surface of a moderator building blocks Groove in each case 2 at a distance from this and on both sides in the longitudinal direction extending slots are assigned.

It has been found that with such an arrangement, the distortion or deformation of the grooves ii irradiation state of the moderator modules quite considerably can be reduced without significantly reducing the strength of the grooves would; Furthermore, Bich has shown that daX as a result of the lower groove deformation of ilaus to be provided from only a smaller clearance between the grooves and tongues needs, whereby a greater initial $ or intrinsic strength can be achieved for the core construction is.

Preferably, the distance between each groove and the or the associated slot or slots substantially equal to the width of the relevant Groove; the slots have a depth between half and the full depth of the belonging en ut on; the width of the slots is so sufficient that the through the Deformations caused by ring stresses can be absorbed.

Individual, separate spring elements can be provided in this way that each spring element in engagement with grooves in two adjacent moderator modules one layer stands; alternatively it can be provided that the springs are each integral are formed with a moderator module and on its outer circumferential surface for engaging a corresponding groove in the outer peripheral surface of an adjacent one Survive the moderator module.

In the following an embodiment of the invention is based on the Drawing described; These show: FIG. 1 in a schematic top view Nuclear reactor structure according to the invention Fig. 2 in a perspective view Graphite brick used in the core reactor-core construction of Figure 1, the Pigo 3 and 4 sectional views of distorted grooves, to explain the invention.

The nuclear rescor gore structure shown in FIG. 1 has several similar structures Layers of graphite bricks on; each layer consists, as can be seen from FIG of bricks 10 with an octagonal cross-section, in a combined arrangement with bricks 11 of square cross section. The bricks 10 have openings or recesses 12 to accommodate fuel elements, and correspondingly the tiles 11 Ausnehwungan or holes 13 for receiving control rods and / or other core system parts on. The individual layers arranged one above the other are all of the same Kind in such a way that each brick 10 or 11 of a layer with a similar Brick 10 resp.

11 aligned in the layer above and / or below it is; the tiles of the core are thus in vertical octagonal or u-square Arranged columns with their aligned openings 12 or 13 form vertical channels.

The graphite bricks 10 and 11 are mutually centered projections or Wedges 14, which engage rivets 15 in the exterior surface of the brick. In the exemplary embodiment shown, there is one groove 15 in each outer surface.

the brick that has a corresponding surface of another Brick cooperates, provided; guard the lone islands get lost In each case in the longitudinal direction of the brick concerned; their centers are each in Radial planes running through the bricks that meet the Län. Because of this arrangement is each groove with the one in the adjacent outer surface of the relevant one adjacent tile provided hat aligned.

The grooves run continuously between adjacent drawing layers, in such a way that the grooves also serve as the bricks of adjacent layers with one another aligned to keep th. The grooves are preferably only on the end faces Ends of each brick provided.

In Figure 2, the character side of a brick 10 is in greater detail shown.

The bricks are made of graphite, which has the property at the temperatures to which it is exposed in normal operation, with increasing Radiation dose to shrink.

The bricks 10 are subject to a hoop tensile stress on their inner circumference and corresponding ring compressive stresses on their outer periphery; this has a distortion the grooves in the catfish cause them to narrow at their outer end, d. H.

adopt a dovetail cross-sectional configuration, such as shown somewhat exaggerated in FIG. Conversely, the bricks 11 are at their Inside a ring compressive stress and correspondingly on its outside a ring tensile stress exposes, which has a distortion of the grooves in such a way that they become taper inwards, d. H. towards the inside of the brick 11 one increasing have a smaller width; the distorted shape of these grooves is somewhat in Figure 4 shown exaggerated representation.

To reduce these delays, d @ auten @ is according to @er @rfind @g jeveils next to deier at in @er concerned circumferential area one Brick 10 or 11 in which the groove is provided, each at least one slot 16 at a distance from the relevant groove 15 and running in the longitudinal direction of the groove intended. Preferably, as in the embodiment shown in the drawing, each groove 15 has two slots 16 assigned to it, one on both sides of the b Groove at a distance from this. The two slots 16 run parallel to the associated one Groove 15. The two slots of each such slot pair are, as I said, to both Sides of the groove in question arranged. In the operation of the nuclear reactor, the slots have 16 the effect that they have the grooves at least partially against the effects shut off the ring tensions in the exterior surfaces of the brick, eliminating the distortion of the grooves 15 is reduced The distance between the grooves and the associated Slotting is preferably substantially equal to the width of the grooves; the depth the slot is preferably about half the depth of the grooves; their width is chosen so sufficiently that it eliminates the distortion caused by the hoop stresses be able to record.

It has been found that by this measure according to the invention Distortion of the grooves can be reduced quite considerably without being significant Impairment of the strength of the Xuten.

Of course, the invention is also suitable for use in Nuclear reactor core structures in which the moderator modules are different from have an octagonal or square cross-section. For example, the core structure consist of bricks or blocks of approximately hexagonal or circular cross-section.

Furthermore, as already mentioned, the spring elements 14 do not need necessarily to be separate, independent elements; much more can if necessary some or all of the springs may be formed in one piece with the bricks.

P a t e n t a n s p r ü c h e:

Claims (1)

P a t e n t a n s p r ü c h e 1. Nuclear reactor core construction from several I4oderator modules arranged in a layer and connected to one another by tongue and groove connections are wedged between their abutting outer peripheral surfaces, each a part in at least one on the outer circumferential surface of at least one moderator module Grooved into the intended groove, which means that each is adjacent to the outer peripheral surface of the building blocks (10, 11) with a groove (15) running at least to the groove and at a distance therefrom and in the longitudinal direction of the groove a slot (16) provided iSta 2. Nuclear reactor core structure according to claim 1, characterized g ek. It is noted that each on an outer circumferential surface of a moderator building blocks previous groove (15) each 2 at a distance from this and on both sides Slits (16) extending in the longitudinal direction are assigned. 3. Nuclear reactor core structure according to claim 1 or 2, characterized g e k e n n z i o h n e t that the springs are each integral with a moderator module are formed and on the outer circumferential surface for engagement in an Otrespondende Project groove in the outer circumferential surface of an adjacent moderator module. 4. Nuclear reactor core structure according to claim 1 or 2, characterized g e -k e n n W e i c h n e t that in each case each spring element (14) in engagement with in the adjacent Outer circumferential surface provided on two adjacent moderator modules of the layer Grooves. 5. Nuclear reactor core structure according to one or more of the claims 1 to 4, characterized in that the slots (16) are separated from the associated Groove (15) each have a distance substantially equal to the width of the groove. 6. Nuclear reactor core structure according to one or more of claims 1 to 5, characterized in that the slots (16) each have a depth have at least half the depth of the associated groove (15). 7. Nuclear reactor core construction according to one or more of the preceding Claims 1 to 6, characterized in that each layer does not exist The moderator structure consists of picking up moderator modules that are known to them Way octagonal and square cross-section, each with each octagonal moderator block except at the outer edge of the layer with 4 adjacent polygonal ones Blocks and 4 neighboring square blocks is wedged.