DE1589663A1 - Core element for nuclear reactors and process for its manufacture - Google Patents

Description

β MONOHS B. OrrOSTRAaSE la TEUEFON COSIO BOMI

B. 2112.3 Munich, December 5, 1967

- - - Dr.M./F-h

C-IP 183/550

CoKifliasariat h 1'Energie Atomique in Paris / Prankreich Core element for nuclear reactors and processes EU its Manufacturing

The invention relates to a core element for nuclear reactors, in particular Reactors that work for bit-fast neutrons, which are driven by a vertical flow of an original Mertall ventilating coolant can be cooled by the core.

In the following, an arrangement is old from the expression "core slement" which contains at least one bundle loadIn, welohe Each from a stick of fissile or breeding material in one tight cover and arranged in a tubular Igen Qehäuse are that a channel for the flow of the fluids Metal forms and with which the HadeIn is tied at one of its ends «Ind. The term "Stak" «oll hler either» in the mmIvn Designate piece or a tablet column of short length. the one type is commonly used with metallic fuels (E.g. a uranium! Pluton lumlegia range), while * öd man

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the second type with ceramic fuels (e.g. oxides and Carbides) are used.

Such nuclear fuel elements are described in the applicant's French patent no. 1,291,633 dated March 10, 1961. This patent describes core elements with three needle bundles arranged one above the other in a housing with a hexagonal cross-section. The needles of a bundle are arranged in a centered hexagonal grid. Each bundle is supported by a grid or rails attached to the housing and the spacing required for the liquid metal to pass through is maintained by a rib or wire in a spiral shape fixed to the sheath. The housing ensures that the needles are held in place ₍ and directs the flow of the liquid metal used as coolant. The housing consists of a tubular jacket which, at its upper part, is essentially used for handling the core BlssMts by means of a loading machine has a certain head and a foot on the lower band with which the core-blement engages in a framework that supports the entirety of the elements "Fuel elements", which have a central needle bundle containing fissure material and two outer needle bundles containing brood material, describes the French patent 1,291,633 so-called "brood elements ¹¹ , which are used for the outer part of the core or the cover are intended and have a single loading bundle that extends over the entire lungs of the housing and contains breeding material.

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Various modifications of the elements described above are also known. According to such a configuration, the part containing the fissile material and the axially above and below the cover containing the breeding material are integrated in a single bundle consisting of needles of great length; According to another embodiment described and illustrated on pages 84 and 86 of July / August-November 1965 of the "Bulletin d ¹ Information Scientifiquee et Techniques", the arrangement also has a plug above the upper leutron radiation.

Have all of these, generally satisfactory, qualifications however, some disadvantages, and in particular the installation the needle bundle in the housing prove to be difficult Occurrence of vibration vibrations, resonants, terstems To prevent the needles etc., it is absolutely necessary to install the Nftdelbindel Ib housing without too much play. Under

Consideration of the property tolerances of the iadelbtodels 1st et

that
required / the transverse dimensions (too rare, split angle) and longitudinal dimensions (deflection, alignment) of the housing, which has a polygonal cross-section, are kept in a narrow area, ensuring a small clearance. However, this requires a balance between the requirements of production, assembly and good operation. In addition, the production costs of the housing are quite a bit high.

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The invention now aims to produce a core element lUr nuclear reactors, which meet the practical requirements in particular by more or less extensive elimination of the disadvantages indicated above, corresponds better than the known core elements.

The core element according to the invention with at least one bundle of Hadein arranged in a tubular jacket, in which the Sheath forms part of a housing that has a channel for the Represents coolant flow and in a handle head and a massive PuB ends, is characterized in particular by the fact that the jacket consists of a thin, spiral shape, inter alia, the bundle or the Bundle In close contact bit theeem wrapped thin netall ribbon with each turn of the ribbon being rigidly connected to the adjacent turn and the endings at the PuB or attached to the head of the element.

The invention also relates to a method of production such a Gore element.

The invention is particularly, but not exclusively, applicable to covering elements which only contain a breeding material filled Hade! bundle included;

for items that only come from a single loading bundle length, in which with fissile materials and frying materials equipped parts are integrated;

for nuclear fuel elements with a load-bearing central structure, as described in the applicant's simultaneous patent application * (Ae ....; corresponding to French patent application PV 86 219) are described.

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In the first two cases, the wound band takes care of the mechanical connection »wipe the head and the foot and the Rigidity of the gore element. In the latter case, ee is only used for Channeling the flow of the liquid metal used as a coolant.

In the following, two core elements according to the invention are used as Execution examples described. The description refers to eich

on the attached drawing. Point in here

Fig. 1 is an elevation of a core element, the central portion only partially shown and a portion of the dumbbell cut away is;

Fig. 2 is a detailed view of the lower part of a modified one

Embodiment of the core element of FIG. 1 in a larger size Scale.

The core element A shown in Fig. 1 has a housing 8, whose cross-section is a regular hexagon and which contains a single bundle of needles 10, either with brood material filled hadels or those that enclosed one of two zones filled with old breeding material, with fissile material have filled central zone, are.

The housing 8 is used to the Beatandteile of the core elements of the Fig. 1 to hold together and to handle them as ale block. That

Housing consists of a tubular jacket 12, which is attached to his

massive
is attached to both ends / work pieces, namely the foot and head 16 of the elements, the bit openings are provided for the passage of the liquid metal. The ladein elnd in a »

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centered hexagonal grid, and among other things each ladel 10 is a wire 18 helically arranged to the necessary Create a clearance for the liquid metals to pass through.

So that the needles can expand freely, they are only on attached to their lower part, where they are pushed onto parallel rails 20, which form a grid and are attached to the PuB 14 of the element are. At their upper end, the threads are simply passed through other soles 22 attached to the head 16, which Do not hinder the expansion of the load.

The PuQ 14 of the core element can have a Torrlohtvn (not shown) for elastic locking on the supporting structure, which is sloped in dash-dotted lines 24 of the reactor.

According to the invention, the tubular jacket 12 consists of one thin metal band that spirals with contiguous turns around the needle bundle 10, whereby it is the Needles touched closely to minimize play. The turns arranged edge to edge form a closed · tubulara workpiece, whose mechanical strength is due to LBt or welds 26 are obtained between adjacent turns. This soldering seam can either be continuous or be continuous if you want the jacket to be completely impermeable. The end turns are cut off at an angle so that a Edge perpendicular to the core element axis is created, and upside down 16 or the Pyfl 14 pulled up and attached to it by a sole seam 28,

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soldering or in some other way, for example by bidding, attached.

The core element according to the invention is produced according to a procedure which is derived from the above description: First, the needle bundle 10 is placed in the usual way Susanne and possibly connected to the PuU 14. This The needle blind el does not grow old in a rigid housing hexagonal cross-section introduced, but turn by turn by, for example, Tom Fuß starting spiral wrapping with a thin metal band progressing with the tubular Coat 12 cased. The turns are then firmly connected to one another, whereupon the PuQ and head are fastened in the usual way will.

The in Flg. 2 bowed embodiment «in which the Besugsseichen are the same as in Pig. 1, but with the addition of an index key »τοη the embodiment of the Flg. 1 only in a Punktι the metal band is with a lower Pitch than the axial width of the tape wound, so dofl an overlap old of the width r results. This training enables successive turns to be fastened to one another by means of rivets 30.

The shell 12 or 12 ¹ is produced in the case of a nuclear fuel element with three needle bundles, as in the above-mentioned German patent application on the same page (As ....; ent-

described, speaking of the frans. Patent application P? 86 219 V in similar

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Way, by utt-wiggling with the ribbon all of the bundles previously attached to their supporting structure.

The advantages of the invention are obvious: There are no difficulties in inserting a needle stick rigid housing more on; since the needles are assembled without play, disturbing vibrations are reduced; the thickness of the Volume karai be lower than that of a usual case, and the total shell of building materials in the core is smaller, so one can either use the mass for a given total mass Increase fission or breeding material or the assembly clearance between can enlarge neighboring core elements.

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Claims (7)

1.) Core element for nuclear reactors, especially those with fast ones Neutron powered nuclear reactors, which are cooled by means of a liquid metal flowing through the core, which has at least has a bundle of needles which are arranged in a tubular dumbbell forming a channel for the coolant flow » characterized in that the dumbbell (12) consists of a spiraling bit around the bundle or bundles and in close contact consists of this wound thin metal band, with each turn of the band being rigidly connected to the adjacent turns and the end turns at the foot (14 ·) moving head (16) of the Core elements (8) are attached. 2.) Core element according to claim 1, characterized in that the dumbbell consists of contiguous turns connected to one another by welding or LBt seams. 3.) Core element according to claim 1 »characterized in that the Dumbbell from overlapping, by welding, litten or Rivets (30) connected turns. 4.) core element according to one of claims 1, 2 or 3 »thereby characterized in that it contains only a single bundle of needles (10) filled with breeding material. 009845/0324 5.) Core element according to one of claims 1, 2 or 3 »thereby characterized in that it contains only a single bundle of very long needles (10), in which with fissure material and breeding material filled parts are integrated. 6.) core element according to claim 1, characterized in that it has a central support structure carrying the needles. 7.) Process for the production of a core element naoh one of the preceding claims, characterized in that the will Combine needles (10) into a bundle and this in a spiral shape is continuously ue-wrapped with a thin metal band, whereupon the turns are connected to one another and the end turns are attached to the PuQ or head of the core element. 009845/0324