US3175956A - Electric connectors for nuclear fuel cartridges - Google Patents

Description

March 30, 1965 J. LIERMANN 3,175,956

` ELECTRIC CONNECTORS FOR NUCLEAR FUEL CARTRIDGES Filed April 4, 1963 2 Sheets-Sheet l @Wmms L, .f/M//// March 30, 1965 J. LIERMANN 3,175,956

ELECTRIC CONNECTORS ECR NUCLEAR FUEL CARTRIDGES Filed April 4, 1955 2 sheets-sheet 2 United States Patent Oli ice 3,175,956 Patented Mar. 30, 1965 3,175,956 ELECTRIC CONNECTORS FOR NUCLEAR FUEL CARTRIDGES Jean Liermann, Paris, France, assignor to Commissariat IEnergie Atomique, Paris, France Filed Apr. 4, 1963, Ser. No. 270,676 Claims priority, application France, Apr. 10, 1962, 893,925 2 Claims. (Cl. 176-77) The present invention relates to a device for transmitting an electric potential difference from one nuclear fuel cartridge to the next when these two cartridges are in contact by their ends and approximately aligned.

It is applicable more especially to the transmission along a stack of cartridges of a potential diiference corresponding to a measurement, for example a temperature measurement obtained by means of a thermoelectric probe.

It is known to use for this application devices in which two contact studs insulated from one another are disposed at each of the ends of the cartridges. When the ends of two approximately aligned successive cartridges are in contact, the opposed studs create between them an electric connection. The geometric form of these studs is then such that no accidental electric connection can occur between two contacts which are not of like polarity. In one cartridge of the stack, the contacts of one end are connected to the terminals of the thermoelectric probe. In each of the other cartridges, the contacts provided on one of the ends are connected to the contacts of like nature at the other end, the cartridges thus equipped transmitting the voltage step-by-step along the stack.

Known devices of this type include notably those in which each cartridge end is provided with a central contact stud (of which the axis is identical with that of the cartridge) and With an annular stud concentric with the first and electrically insulated therefrom. When two successive cartridges are disposed end to end so as to bear one against the other, the central studs and the opposed peripheral studs, respectively, set up the necessary electric connections. However, these arrangements have a number of disadvantages. More especially, they require fairly considerable changes in the structure of the plugs by which the ends of the cartridges are closed, since their adoption involves a considerable increase in the length of the cartridges, which results in certain modifications in the very operation of the reactor and throughout the subsequent course of treatment of the fuel.

In order to obviate these disadvantages, the invention resides mainly in disposing on the end plug of each cartridge a fixed central contact stud and a peripheral stud supported by the upper edge of a resilient annular cup, which is slightly curved and substantially equal in diameter to the plug, the said cup being ixed to the plug concentrically with the central stud, in such manner that in the absence of stress the peripheral stud projects beyond the apparent contour of lthe remainder of the cartridge.

Among the advantages of the proposed arrangement, it is to be noted that it makes it possible to equip existing cartridges without substantial modication to the length of these cartridges. Moreover, owing to the use of a resilient cup of relatively large dimensions, it is possible to subject it only to relatively low stresses as compared with those applied to helical or spiral springs, for example, which are capable of undergoing the deformations in the longitudinal direction of the cartridge which are necessary for establishing two electric contacts.

It will be apparent that the cartridges in contact at their ends must be substantially aligned in order to ensure correct operation of such a device. This algnment may be automatically brought about with some geometrical forms of the cartridges and of the channel, while in other cases auxiliary elements may be provided to ensure alignment, which might be defective in the absence of such auxiliary elements. It is essential that these auxiliary elements should be such that the central portion of the plug of the fuel element, of which the device according to the invention is fitted, is left entirely free. There may with advantage be employed for correcting defective centering of the cartridges in relation to one another the device described in copending United States patent application Serial No. 268,395, iled March 27, 1963, also in the name of Commissariat a lEnergie Atomique.

Further advantages and features of the invention will be more readily apparent from the following description of an embodiment, which is given only by way of indication and has no limiting character.

In the accompanying drawings:

FIGURE 1 is a vertical sectional View of a nuclear reactor channel, Within which is stacked a set of fuel cartridges.

FIGURE 2 is a sectional view to a larger scale illustrating the details of the construction of the contact device according to the invention.

FIGURE 3 is a view from above of a fuel cartridge.

It should first of all be mentioned that the principle of the measurement of the temperature of a cartridge is applicable only if it is possible to use a thermoelect'ric probe of small dimensions which can be introduced into or secured to the very thin walls of the cartridge without any danger of breakage of the canning of the cartridge. Such a probe generally requires leading-out wires of very sroall diameter and it is diiicult to connect these to appropriate conductors which are capable of passing through a sealing system to the outside of the enclosed space of the reactor for an appropriate utilisation of the measurement. The particular conditions due to the circulation of the cooling iluid and to the effect of radiation during operation are incompatible with a simple connection of the wires of the probe to the said conductors. It is necessary to provide various systems, which are generally complex and diiiicult to produce with members of simple form which consist of materials capable of behaving correctly in the presence of the neutron liux.

The device according to the invention permits obviating the aforesaid disadvantages while aiording particularly appreciable reliability of operation.

In FIGURE 1, there is illustrated by way of example a nuclear reactor channel extending through the moderator structure 2 of the reactor. Of course, the invention could be applied in the same way in other reactor types, and notably in cases where the cartridges are stacked inside a tube in a reactor channel. The upper portion 3 of the channel, which is closed by a iluid-tight plug 4, extends, between the moderator structure 2 and the protective shield 5, through a free space 6 through which the cooling liquid circulating within the channel 1 can escape after having passed through apertures such as 7. Stacked in the channel under consideration is a number of cartridges such as 8 constituting what is conventionally called a train of cartridges. The end of this train comprises a false cartridge 9, i.e. an element having the same dimensions and geometrical characteristics as the cartridges 8, but containing no issile material.

The fuel cartridges comprise at each of their ends 10 Contact members designed in accordance with the invention, of which the constructional details will hereinafter be explained. One of the cartridges within the train, for example the cartridge 8a, is provided with a thermoelectric probe 11 secured to its canning, the leading-out wires of which probe are connected to a microcasing 12 fast with the body of the cartridge. The said microcasing is in turn connected to the Contact members supported by that end of the cartridge Sawhich is closer to the outlet of the channel, by means of two conductors such as 13. Each of the other cartridges 8 situated between the cartridge 8a and the outlet of the channel (in the figure, only one cartridge of this type and the false cartridge 9 are shown) comprises conductors 14 which provide the connection between the respective contact members mounted on each of their ends. The outlet plug 4 is provided with a fluidtight passage 15 for leading-out the connecting wires which, when connected to an appropriate measuring instrument, supply an exact reading of the voltage set up across the terminals of the thermoelectric probe 11.

FIGURE 2 shows in greater detail the ends of two successive cartridges within a channel and illustrates the particular construction of the contact members mounted respectively on each of the said cartridges. The latter, which are identical to one another, each comprise a canning terminated at both ends by plugs such as 21 which seal the canning in fluid-tight fashion with the aid of continuous weld beads 22. Rigidly secured to each of the plugs by means of screws or rivets such as 23 is a metal support 24. The Contact device proper comprises a central stud 25 secured along the axis of the cartridge by a screw 26 to the support 24 and a peripheral stud 27 secured by means of rivets such as 29 to a flexible cup 28 coaxially maintained around the stud 2S and bearing against the support 24 by means of a tubular casing 30 screwed on to the latter. Two ceramic cross-members or spacing members 31 and 32 provide appropriate electric insulation between the two studs 2S and 27 on the one hand and the studs and the canning on the other hand.

Each of the two aforesaid contact elements is connected by conductors 33 and 34 (33 in the case of the central stud and 34 in the case of the peripheral stud) respectively, either to studs of like nature secured to the opposite end of the cartridge, or to positive and negative elements of the thermoelectric probe through a microcasing, in the manner described with reference to FIGURE l.

The conductors 33 and 34 are disposed within insulating sheathings such as 35 maintained in contact with a longitudinal supporting lug 36 xedly mounted between the fins 37 of the canning 20 by any appropriate means, notably by welding. The sheathings 35 are aligned along the lug 36 by grooved guides 38 (FIGURE 3) situated at regular intervals along its length.

It will also be seen from FIGURE 2 that the aforesaid cartridges are provided at each of their ends with annular male and female members Whose function is on the one hand to ensure centering of one cartridge in relation to the next along the train of cartridges, and on the other hand to permit satisfactory contact between the studs of two successive cartridges, while preserving the weld of the conductor wires on the studs. These centering members, which are described in greater detail in the copending United States patent application already mentioned in the foregoing, are denoted by the references 39 for the male member and 40 for the female member in FIGURE 2. They are iixedly mounted on the ends of the cartridges and are so formed as to afford, when the cartridges have been positioned, a suicient lateral clearance to determine the closest possible Contact between the studs of like nature from one cartridge to the next. Extending through the elements 39 and 40 are ducts 41 and 42 for the passage of the cables 35, in which are disposed the connecting conductors 33 and 34.

In addition to the advantages already mentioned, it will be seen the device according to the invention makes it possible to transmit very reliably the items of information received from the thermoelectric probe, even if the alignment of the various cartridges is not perfect. Moreover, although the resilience of the cup 28 constantly ensures appropriate contact between the successive peripheral studs Y 27, the contact between the central studs 25 may also be further improved by forming them with a male profile and a female profile respectively which can slide one with respect to the other regardless of the relative disalignment of the cartridges.

It is also to be noted that the device according to the invention utilises as resilient element a cup having considerable radial development and small thickness. The stresses which are set upin the cup for a given longitudinal deformation are consequently much smaller than in the helical or spiral return spring which would have to be provided in association with, for example, a movable central stud. The consequences of the changes in the mechanical characteristics due to neutron irradiation are therefore much less serious.

Of course, the invention is in no way limited to the embodiments which have been described by way of example in the foregoing, but covers all variants thereof.

I claim:

1. A plurality of nuclear reactor fuel cartridges stacked end-to-end in a nuclear reactor channel the ends of the cartridges being closed by plugs and adjacent plugs having co-operating annular male and female aligning members respectively, a rigid support secured to each end of each of said plugs, a central electric contact stud secured to said support, a peripheral electric contact stud surrounding said central stud, a resilient cup supporting said peripheral stud and mounted on and electrically insulated from said support, means for electrically insulating said studs from each other, said peripheral stud normally extending beyond said central stud and sheathed electric conductors extending through said aligning members and connecting like studs for each fuel cartridge, said aligning members surrounding said studs.

2. Fuel cartridges as described in claim 1, including a thermo-electric probe secured to one of said cartridges, terminals for said probe, a micro-casing connecting said terminals andrsaid conductors for said cartridge, a longitudinal securing lug on each of said cartridges and guides on said lugs for aligning said conductors.

References Cited by the Examiner UNITED STATES PATENTS 3,104,215 9/ 63 Guneratne 176-79 FOREIGN PATENTS 226,454 1/ 60 Australia 176-79 614,279 2/61 Canada 176-68 1,252,173 12/60 France 176-19 875,462 8/61 Great Britain 176-77 CARL D. QUARFORTH, Primary Examiner.

Claims (1)

1. A PLURALITY OF NUCLEAR REACTOR FUEL CARTRIDGES STACKED END-TO-END IN A NUCLEAR REACTOR CHANNEL THE ENDS OF THE CARTRIDGES BEING CLOSED BY PLUGS AND ADJACENT PLUGS HAVING CO-OPERATING ANNULAR MALE AND FEMALE ALIGNING MEMBERS RESPECTIVELY, A RIGID SUPPORT SECURED TO EACH END OF EACH OF SAID PLUGS, A CENTRAL ELECTRIC CONTACT STUD SECURED TO SAID SUPPORT, A PERIPHERAL ELECTRIC CONTACT STUD SURROUNDING SAID CENTRAL STUD, A RESILIENT CUP SUPPORTING SAID PERIPHERAL STUD AND MOUNTED ON AND ELECTRICALLY INSULATED FROM SAID SUPPORT, MEANS FOR ELECTRICALLY INSULATING SAID STUDS FROM EACH OTHER, SAID PERIPHERAL STUD NORMALLY EXTENDING BEYOND SAID CENTRAL STUD AND SHEATHED ELECTRIC CONDUCTORS EXTENDING THROUGH SAID ALIGNING MEMBERS AND CONNECTING LIKE STUDS FOR EACH FUEL CARTRIDGE, SAID ALIGNING MEMBERS SURROUNDING SAID STUDS.

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