EP0995198A1 - Device for modulating absorption, emission, moderation or reflection of radiation or of particle flow - Google Patents

Device for modulating absorption, emission, moderation or reflection of radiation or of particle flow

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Publication number
EP0995198A1
EP0995198A1 EP98935107A EP98935107A EP0995198A1 EP 0995198 A1 EP0995198 A1 EP 0995198A1 EP 98935107 A EP98935107 A EP 98935107A EP 98935107 A EP98935107 A EP 98935107A EP 0995198 A1 EP0995198 A1 EP 0995198A1
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European Patent Office
Prior art keywords
channels
fluid
cadmium
neutron
liquid
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Ceased
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EP98935107A
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German (de)
French (fr)
Inventor
Michel Emin
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Individual
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Individual
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Publication of EP0995198A1 publication Critical patent/EP0995198A1/en
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Classifications

    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C7/00—Control of nuclear reaction
    • G21C7/06—Control of nuclear reaction by application of neutron-absorbing material, i.e. material with absorption cross-section very much in excess of reflection cross-section
    • G21C7/22—Control of nuclear reaction by application of neutron-absorbing material, i.e. material with absorption cross-section very much in excess of reflection cross-section by displacement of a fluid or fluent neutron-absorbing material, e.g. by adding neutron-absorbing material to the coolant
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors

Definitions

  • the present invention relates to a device for modulating the absorption, emission, moderation or reflection of radiation or flux of particles, for example neutrons, with the aim, for example, of regulating the reactivity of nuclear system, to make it safe or to contain ionizing radiation, for example, from a reactor, a fuel cell, or a system for storing radioactive material, potentially radioactive material, or which is to undergo irradiation.
  • FIG. 1 of the accompanying schematic drawing shows a longitudinal sectional view of a nuclear reactor.
  • the vessel of which is designated by the reference 2 the radioactive elements 3 are arranged in the form of vertical piles, between which voids are formed.
  • the absorption of neutron fluxes for example, in order to shutdown the installation, is obtained by means of control bars 4, placed above the radioactive elements.
  • These control bars 4 are intended, to achieve the absorption of neutron fluxes, to be introduced into the spaces arranged between the radioactive elements. It follows that the height of the tank must be very large to allow the movement of the control bars between a position in which they are arranged between the radioactive elements and a position in which they are arranged above them.
  • the other disadvantages of this technique are:
  • the object of the invention is to provide a device of simple and compact structure, making it possible to modulate the nuclear power of a reactor or the absorption of particles without deformation of the axial neutron flux, and by having a homogeneity of the neutron absorption.
  • the device which it relates to of the type comprising a bundle of channels, tubes or the like permanently arranged in the reactor and intended to contain a neutron absorbing neutron fluid, is characterized in that it comprises means allowing to vary the number of absorbing channels according to the desired modulation.
  • Each channel containing a neutron absorbing fluid is either in the fully filled position or in the entirely empty position, the different channels being able to be filled or emptied in a differentiated manner, independently, or by series of channels. It is thus possible to modulate the power of a reactor, without deformation of the axial neutron flux.
  • the channels containing neutron absorbing fluid remain permanently filled, and are associated with channels intended to form a screen, which may or may not be filled, on command, with a neutron reflecting liquid. The filling or not of a certain number of channels with a neutron reflecting liquid makes it possible to achieve a modulation of the power of the reactor.
  • This solution is particularly advantageous if it is desired to have safety means to cause the reaction to stop quickly, this stop being obtained by simultaneous emptying of all the channels containing liquid reflecting the neutrons.
  • the neutron absorbing fluid comprises at least one liquid metal charged with particles of materials absorbing or reflecting neutrons of the same density as the liquid. This arrangement provides a homogeneous neutron absorption or reflection.
  • the particles of materials absorbing or reflecting the neutrons are obtained by alloying or sintering.
  • the neutron absorbing fluid is chosen from the following compositions:
  • MoB molybdenum monoboride
  • the neutron reflecting liquid intended to supply the screen forming channels is chosen from mixtures containing heavy water D2O or other hydrogenated liquids, optionally charged with particles such as reflective beryllium neutrons.
  • This reflecting liquid can be used in combination with an absorbent fluid having one of the preceding compositions, or else based on hafnium or on hafnium diboride.
  • the different absorbent channels can be filled with the same neutron absorbing liquid, or with different neutron absorbing liquids, they can have the same section, constant or not, or have different sections.
  • the channels each consist of a U-shaped tube or by two concentric tubes communicating at one of their ends, the fluid filling of which is carried out by a pneumatic device, a vacuum source, or a device circulation by a pump or a piston.
  • the corresponding ends of several parallel tubes can be connected to the same channel, one end of each channel containing fluid being connected to a balloon provided with two swan necks, in order to avoid untimely emptying of liquid and to ensure the stability thereof with respect to temperature variations in the reactor.
  • this device further comprises channels, intended to receive a fluid containing a radioactive element placed under conditions allowing the transmutation of this element to another radioactive element.
  • transmutation channel without generating an imbalance in the neutron flux. It is advisable to control the neutron flux received by the channel containing the body to be transmuted, by integrating a local neutron measurement system which can be placed outside the reactor, and perform the measurement of absorption of the materials contained either in the transmutation channel. , or in a nearby channel. This installation allows, thanks to the possibilities of modulation by absorption or reflection, to adapt the neutron flux to carry out the transmutation operation.
  • FIG. 1 is a sectional view of a traditional nuclear reactor
  • FIG. 2 is a very schematic sectional view of a nuclear reactor according to the invention
  • - Figure 3 is a longitudinal sectional view of a channel containing a neutron absorbing fluid, and of two channels forming a screen
  • FIG. 4 is a cross-sectional view of these channels along the line IV-IV of FIG. 3,
  • FIGS. 5 and 6 are two views illustrating two methods of mounting channels containing a neutron absorbing fluid
  • FIG. 7 is a very schematic view in section of a device for crossing the cover of a reactor vessel.
  • FIG. 2 very schematically represents a nuclear reactor comprising a tank 6, inside which are disposed vertical piles 7 of combustible material between which are provided free spaces.
  • a bundle of channels 8 in the form of U-shaped pins, the first ends of the pins 8 being connected to a channel 9 and the second ends of the pins 8 being connected to a channel 10.
  • the pins 8 and channels 9 and 10 form a circuit inside which circulates a neutron absorbing fluid consisting for example of liquid cadmium added with micro-balls of tungsten boride W2B5, alloyed by sintering with indium-silver alloy.
  • the channel 9 is connected by means of a swan neck forming a siphon 12 to a pressurized balloon 13 located inside the reactor vessel, which maintains the temperature of the fluid.
  • the flask could be located outside the tank, but should in this case be reheated.
  • the channel 10 is, for its part, connected by means of a 3-way solenoid valve 14, on the one hand to a source of pressurized air 15 and on the other hand to the open air 16
  • the balloon 13 communicates for its part, via a channel 17, the end of which is equipped with a swan neck, and on which is mounted an electro-valve 18, with an analysis device 19 fluids, from which fluids can be sent via conduits 20, 22 to treatment or replacement devices.
  • the solenoid valve 14 When the solenoid valve 14 allows the admission of pressurized air, the pressure causes the neutron absorbing fluid to rise inside the balloon 13, and the channels 8 tend to empty. To maintain these channels in the filled position, which is the aim sought by the invention, it is necessary to tilt the solenoid valve 18 in the position to which it puts the channels in communication with the exhaust 16. The pressure falling, the neutron absorbing fluid is driven out by the pressure prevailing in the balloon and fills the channels.
  • FIG. 2 represents only one group of channels 8. It is possible to have several groups of channels, the channels being controlled independently of one another, to be either filled or emptied, which makes it possible to carry out a different modulation in different places of the reactor.
  • the modulation of the reactor power is obtained by varying the number of groups of full and empty channels.
  • the reactor stops when all the channels are filled with neutron absorbing fluid.
  • the power variation is obtained by keeping certain channels filled while others are empty.
  • Figures 3 and 4 show an alternative embodiment of this device.
  • a channel 23 is permanently filled with neutron absorbing fluid.
  • This channel 23 is surrounded by channels 24 which may or may not be filled with a neutron reflecting fluid.
  • Figures 5 and 6 show two embodiments of channels 8 containing a neutron absorbing fluid.
  • the channels are grouped by series and have different sections from one channel to another.
  • the channels are arranged in a cross, and can optionally be grouped by two or more, to form U-shaped pins.
  • FIG. 7 very schematically shows a cover 25 of the reactor vessel having an opening 26, traversed by a bell-shaped part 27, the lower part 28 of which is flared, and situated inside the vessel.
  • This bell is used for the passage of tubes 29, 30, 31 ensuring the circulation of neutron-absorbing and / or reflecting fluids, penetration through the cover of the tank being made by a multichannel tube 32, guided by a sphere 33 situated inside the flared part of the bell 27.
  • the invention brings a great improvement to the existing technique by providing a device of simple structure, avoiding any mechanical action to regulate the nuclear power of a reactor, having a small footprint, as well as a high reliability.
  • the invention is not limited to the sole embodiments of this device described above by way of examples, on the contrary, it embraces all of its variants.
  • the arrangement of the different channels inside a reactor could be different from the indicated arrangements, or else that the means of circulation of the neutron absorbing fluid or of the neuton reflecting fluid could be different and obtained either by a vacuum source, either by a circulation device by a pump, by a piston, or by an intermediate control fluid, without departing from the scope of the invention.

Abstract

The invention concerns a device comprising a network of channels (8, 23), tubes or the like permanently arranged in the reactor and designed to contain a neutron absorbing fluid absorbing the neutrons. Said device further comprises means for varying the number of absorbing channels (8, 23) according to the desired modulation.

Description

DISPOSITIF PERMETTANT DE MODULER L'ABSORPTION, L'EMISSION, LA MODERAΗON OU LA REFLEXION DE RAYONNEMENTS OU DE FLUX DE PARTICULESDEVICE FOR MODULATING THE ABSORPTION, EMISSION, MODERATION OR REFLECTION OF PARTICLE RADIATION OR FLOWS
La présente invention a pour objet un dispositif permettant de moduler l'absorption, l'émission, la modération ou la réflexion de rayonnements ou de flux de particules, par exemple de neutrons, dans le but, par exemple, de régler la réactivité d'un système nucléaire, de le rendre sûr ou de contenir le rayonnement ionisant, par exemple, d'un réacteur, d'une pile à combustible, ou d'un système de stockage de matière radioactive, potentiellement radioactive, ou devant subir une irradiation.The present invention relates to a device for modulating the absorption, emission, moderation or reflection of radiation or flux of particles, for example neutrons, with the aim, for example, of regulating the reactivity of nuclear system, to make it safe or to contain ionizing radiation, for example, from a reactor, a fuel cell, or a system for storing radioactive material, potentially radioactive material, or which is to undergo irradiation.
La figure 1 du dessin schématique annexé montre une vue en coupe longitudinale d'un réacteur nucléaire. Dans un tel réacteur, dont la cuve est désignée par la référence 2, les éléments radioactifs 3 sont disposés sous forme de piles verticales, entre lesquelles sont ménagés des vides. L'absorption des flux neutroniques, par exemple, pour réaliser l'arrêt de l'installation, est obtenue grâce à des barres de contrôle 4, disposées au-dessus des éléments radioactifs. Ces barres de contrôle 4 sont destinées, pour réaliser l'absorption des flux neutroniques, à être introduites dans les espaces disposés entre les éléments radioactifs. Il en résulte que la hauteur de la cuve doit être très importante pour permettre le débattement des barres de contrôle entre une position dans laquelle elles sont disposées entre les éléments radioactifs et une position dans laquelle elles sont disposées au-dessus de ceux-ci. Les autres inconvénients de cette technique résident :Figure 1 of the accompanying schematic drawing shows a longitudinal sectional view of a nuclear reactor. In such a reactor, the vessel of which is designated by the reference 2, the radioactive elements 3 are arranged in the form of vertical piles, between which voids are formed. The absorption of neutron fluxes, for example, in order to shutdown the installation, is obtained by means of control bars 4, placed above the radioactive elements. These control bars 4 are intended, to achieve the absorption of neutron fluxes, to be introduced into the spaces arranged between the radioactive elements. It follows that the height of the tank must be very large to allow the movement of the control bars between a position in which they are arranged between the radioactive elements and a position in which they are arranged above them. The other disadvantages of this technique are:
- d'une part, dans les dangers liés aux risques de coincement d'une barre de contrôle, au saut d'un pas du mécanisme de commande de ces barres, et à la non descente d'une barre de contrôle lors d'un arrêt d'urgence d'un réacteur, et- on the one hand, in the dangers linked to the risks of jamming of a control bar, the jump of a step of the control mechanism of these bars, and the non-descent of a control bar during a emergency shutdown of a reactor, and
- d'autre part, dans les difficultés d'exploitation des installations nucléaires consécutives à l'usure inégale du combustible et à la dissymétrie du flux neutronique résultant notamment de l'empoisonnement des combustibles et de l'effet xénon samarium.- on the other hand, in the difficulties of operating nuclear installations consecutive to the uneven wear of the fuel and the asymmetry of the neutron flux resulting in particular from the poisoning of the fuels and the xenon samarium effect.
Ces derniers points imposent l'utilisation de bore pour régler la réactivité et entraînent une consommation imparfaite du combustible.These last points require the use of boron to regulate reactivity and lead to imperfect fuel consumption.
En outre, cette technologie étant sensible aux mouvements et aux accélérations, pose des problèmes dans le cas d'installations mobiles ou embarquées sur des navires ou dans des sous-marins. Les documents GB 803 701 , FR 1 269 659 et DE 1 125562 décrivent des dispositifs de modulation de la puissance nucléaire d'un réacteur, mettant en oeuvre un réseau de tubes contenant un liquide absorbant les neutrons. Dans les différents cas, la modulation est obtenue en faisant varier le niveau de liquide absorbant les neutrons. Il en résulte une déformation du flux neutronique axial.In addition, this technology being sensitive to movements and accelerations, poses problems in the case of mobile or on-board installations on ships or in submarines. The documents GB 803 701, FR 1 269 659 and DE 1 125562 describe devices for modulating the nuclear power of a reactor, using a network of tubes containing a neutron absorbing liquid. In the different cases, the modulation is obtained by varying the level of liquid absorbing the neutrons. This results in a deformation of the axial neutron flux.
Le but de l'invention est de fournir un dispositif de structure simple et compacte, permettant de moduler la puissance nucléaire d'un réacteur ou l'absorption de particules sans déformation du flux neutronique axial, et en disposant d'une homogénéité de l'absorption des neutrons.The object of the invention is to provide a device of simple and compact structure, making it possible to modulate the nuclear power of a reactor or the absorption of particles without deformation of the axial neutron flux, and by having a homogeneity of the neutron absorption.
A cet effet, le dispositif qu'elle concerne, du type comportant un faisceau de canaux, tubes ou similaires disposés en permanence dans le réacteur et destinés à contenir un fluide neutrophage absorbant les neutrons, est caractérisé en ce qu'il comprend des moyens permettant de faire varier le nombre de canaux absorbants en fonction de la modulation souhaitée.To this end, the device which it relates to, of the type comprising a bundle of channels, tubes or the like permanently arranged in the reactor and intended to contain a neutron absorbing neutron fluid, is characterized in that it comprises means allowing to vary the number of absorbing channels according to the desired modulation.
Chaque canal contenant un fluide neutrophage se trouve soit en position entièrement remplie, soit en position entièrement vide, les différents canaux pouvant être remplis ou vidés de façon différenciée, indépendamment, ou par série de canaux. Il est ainsi possible de moduler la puissance d'un réacteur, sans déformation du flux neutronique axial. Suivant une autre forme d'exécution, les canaux contenant du fluide neutrophage demeurent remplis en permanence, et sont associés à des canaux destinés à former écran, pouvant être remplis ou non, sur commande, par un liquide réfléchissant les neutrons. Le remplissage ou non d'un certain nombre de canaux par un liquide réfléchissant les neutrons permet de réaliser une modulation de la puissance du réacteur.Each channel containing a neutron absorbing fluid is either in the fully filled position or in the entirely empty position, the different channels being able to be filled or emptied in a differentiated manner, independently, or by series of channels. It is thus possible to modulate the power of a reactor, without deformation of the axial neutron flux. According to another embodiment, the channels containing neutron absorbing fluid remain permanently filled, and are associated with channels intended to form a screen, which may or may not be filled, on command, with a neutron reflecting liquid. The filling or not of a certain number of channels with a neutron reflecting liquid makes it possible to achieve a modulation of the power of the reactor.
Cette solution est particulièrement intéressante si l'on souhaite disposer de moyens de sécurité pour provoquer l'arrêt rapide de la réaction, cet arrêt étant obtenu par une vidange simultanée de tous les canaux contenant du liquide réfléchissant les neutrons.This solution is particularly advantageous if it is desired to have safety means to cause the reaction to stop quickly, this stop being obtained by simultaneous emptying of all the channels containing liquid reflecting the neutrons.
Suivant une caractéristique de l'invention, le fluide neutrophage comprend au moins un métal liquide chargé de particules de matériaux absorbant ou réfléchissant les neutrons de même densité que le liquide. Cet aménagement permet de disposer d'une absorption ou d'une réflexion neutronique homogène.According to a characteristic of the invention, the neutron absorbing fluid comprises at least one liquid metal charged with particles of materials absorbing or reflecting neutrons of the same density as the liquid. This arrangement provides a homogeneous neutron absorption or reflection.
Suivant une caractéristique de l'invention, les particules de matériaux absorbant ou réfléchissant les neutrons sont obtenues par alliage ou frittage.According to a characteristic of the invention, the particles of materials absorbing or reflecting the neutrons are obtained by alloying or sintering.
Avantageusement le fluide neutrophage est choisi parmi les compositions suivantes :Advantageously, the neutron absorbing fluid is chosen from the following compositions:
- Cadmium et microbilles de monoborure de molybdène (MoB) de même densité que le cadmium (8,65) ; - Mélange indium/cadmium, étain/cadmium ou étain/indium/cadmium ajusté à la densité du samarium (7,54) ;- Cadmium and microbeads of molybdenum monoboride (MoB) with the same density as cadmium (8.65); - Indium / cadmium, tin / cadmium or tin / indium / cadmium mixture adjusted to the density of the samarium (7.54);
- Mélange indium/cadmium, étain/cadmium ou étain/indium/cadmium ajusté à la densité du gadolinium (7,895) ;- Indium / cadmium, tin / cadmium or tin / indium / cadmium mixture adjusted to the density of gadolinium (7.895);
- Cadmium liquide additionné de microbilles de borure de tungstène W2B5, allié par frittage avec un alliage indium-argent.- Liquid cadmium supplemented with microbeads of tungsten boride W2B5, alloyed by sintering with an indium-silver alloy.
Suivant une autre caractéristique de l'invention, le liquide réfléchissant les neutrons et destiné à alimenter les canaux formant écrans est choisi parmi les mélanges contenant de l'eau lourde D2O ou d'autres liquides hydrogénés, éventuellement chargés de particules telles que le béryllium réfléchissant les neutrons. Ce liquide réfléchissant peut être utilisé en association avec un fluide absorbant possédant l'une des compositions précédentes, ou encore à base d'hafnium ou de diborure d'hafnium.According to another characteristic of the invention, the neutron reflecting liquid intended to supply the screen forming channels is chosen from mixtures containing heavy water D2O or other hydrogenated liquids, optionally charged with particles such as reflective beryllium neutrons. This reflecting liquid can be used in combination with an absorbent fluid having one of the preceding compositions, or else based on hafnium or on hafnium diboride.
Les différents canaux absorbants peuvent être remplis par le même liquide neutrophage, ou par différents liquides neutrophages, ils peuvent posséder la même section, constante ou non, ou posséder différentes sections.The different absorbent channels can be filled with the same neutron absorbing liquid, or with different neutron absorbing liquids, they can have the same section, constant or not, or have different sections.
Ces différentes possibilités permettent de parfaitement adapter le dispositif de modulation au réacteur à équiper, qui peut être un réacteur déjà existant.These different possibilities make it possible to perfectly adapt the modulation device to the reactor to be equipped, which may be an already existing reactor.
Suivant une possibilité, les canaux sont constitués chacun par un tube en forme de U ou par deux tubes concentriques communiquant à l'une de leurs extrémités, dont le remplissage en fluide est réalisé par un dispositif pneumatique, une source de vide, ou un dispositif de circulation par une pompe ou un piston. Les extrémités correspondantes de plusieurs tubes parallèles peuvent être reliées à un même canal, l'une des extrémités de chaque canal contenant du fluide étant reliée à un ballon muni de deux cols de cygne, dans le but d'éviter les vidanges intempestives de liquide et d'assurer la stabilité de celui-ci vis à vis des variations de température dans le réacteur. Dans le cas d'un réservoir interne à la cuve du réacteur qui, par conséquent, subit un bombardement neutronique, il est important de prévoir un écran réfléchissant les neutrons pour conserver l'efficacité du liquide. Suivant une forme d'exécution, ce dispositif comprend en outre des canaux, destinés à recevoir un fluide contenant un élément radioactif placé dans des conditions permettant la transmutation de cet élément vers un autre élément radioactif.According to one possibility, the channels each consist of a U-shaped tube or by two concentric tubes communicating at one of their ends, the fluid filling of which is carried out by a pneumatic device, a vacuum source, or a device circulation by a pump or a piston. The corresponding ends of several parallel tubes can be connected to the same channel, one end of each channel containing fluid being connected to a balloon provided with two swan necks, in order to avoid untimely emptying of liquid and to ensure the stability thereof with respect to temperature variations in the reactor. In the case of a tank internal to the reactor vessel which, consequently, undergoes neutron bombardment, it is important to provide a screen reflecting the neutrons in order to maintain the efficiency of the liquid. According to one embodiment, this device further comprises channels, intended to receive a fluid containing a radioactive element placed under conditions allowing the transmutation of this element to another radioactive element.
Il est possible d'intégrer un canal de transmutation sans engendrer de déséquilibre du flux neutronique. Il convient de contrôler le flux neutronique reçu par le canal contenant le corps à transmuter, en intégrant un système de mesure neutronique local qui peut être disposé en dehors du réacteur, et effectuer la mesure d'absorption des matières contenues soit dans le canal de transmutation, soit dans un canal proche. Cette installation permet, grâce aux possibilités de modulation par absorption ou réflexion, d'adapter le flux neutronique pour réaliser l'opération de transmutation.It is possible to integrate a transmutation channel without generating an imbalance in the neutron flux. It is advisable to control the neutron flux received by the channel containing the body to be transmuted, by integrating a local neutron measurement system which can be placed outside the reactor, and perform the measurement of absorption of the materials contained either in the transmutation channel. , or in a nearby channel. This installation allows, thanks to the possibilities of modulation by absorption or reflection, to adapt the neutron flux to carry out the transmutation operation.
Il est possible d'effectuer des opérations de contrôle pour vérifier périodiquement l'efficacité du ou des fluides absorbants. Une certaine quantité de fluide est prélevée, les particules étant récupérées par filtration ou centrifugation, ou piégeage chimique ou magnétique.It is possible to carry out control operations to periodically check the effectiveness of the absorbent fluid (s). A certain quantity of fluid is removed, the particles being recovered by filtration or centrifugation, or chemical or magnetic trapping.
De toute façon l'invention sera bien comprise à l'aide de la description qui suit, en référence au dessin schématique annexé représentant, à titre d'exemples non limitatifs, plusieurs formes d'exécution de ce dispositif.In any case, the invention will be clearly understood with the aid of the description which follows, with reference to the appended schematic drawing representing, by way of nonlimiting examples, several embodiments of this device.
- Figure 1 est une vue en coupe d'un réacteur nucléaire traditionnel,- Figure 1 is a sectional view of a traditional nuclear reactor,
- Figure 2 est une vue très schématique, en coupe, d'un réacteur nucléaire selon l'invention, - Figure 3 est une vue en coupe longitudinale d'un canal contenant un fluide neutrophage, et de deux canaux formant écran, - Figure 4 est une vue en coupe transversale de ces canaux selon la ligne IV-IV de figure 3,- Figure 2 is a very schematic sectional view of a nuclear reactor according to the invention, - Figure 3 is a longitudinal sectional view of a channel containing a neutron absorbing fluid, and of two channels forming a screen, FIG. 4 is a cross-sectional view of these channels along the line IV-IV of FIG. 3,
- Figures 5 et 6 sont deux vues illustrant deux modes de montage de canaux contenant un fluide neutrophage, - Figure 7 est une vue très schématique et en coupe d'un dispositif de traversée du couvercle d'une cuve d'un réacteur.- Figures 5 and 6 are two views illustrating two methods of mounting channels containing a neutron absorbing fluid, - Figure 7 is a very schematic view in section of a device for crossing the cover of a reactor vessel.
La figure 2 représente très schématiquement un réacteur nucléaire comportant une cuve 6, à l'intérieur de laquelle sont disposées des piles 7 verticales de matériau combustible entre lesquelles sont ménagés des espaces libres.FIG. 2 very schematically represents a nuclear reactor comprising a tank 6, inside which are disposed vertical piles 7 of combustible material between which are provided free spaces.
Entre les piles de matériau combustible est installé un faisceau de canaux 8 en forme d'épingles en U, les premières extrémités des épingles 8 étant reliées à un canal 9 et les secondes extrémités des épingles 8 étant reliées à un canal 10. Les épingles 8 et les canaux 9 et 10 forment un circuit à l'intérieur duquel circule un fluide neutrophage constitué par exemple de cadmium liquide additionné de micro-billes de borure de tungstène W2B5, allié par frittage avec de l'alliage indium- argent.Between the piles of combustible material is installed a bundle of channels 8 in the form of U-shaped pins, the first ends of the pins 8 being connected to a channel 9 and the second ends of the pins 8 being connected to a channel 10. The pins 8 and channels 9 and 10 form a circuit inside which circulates a neutron absorbing fluid consisting for example of liquid cadmium added with micro-balls of tungsten boride W2B5, alloyed by sintering with indium-silver alloy.
Le canal 9 est relié par l'intermédiaire d'un col de cygne formant syphon 12 à un ballon sous-pression 13 situé à l'intérieur de la cuve du réacteur, ce qui assure le maintien en température du fluide. Le ballon pourrait être situé à l'extérieur de la cuve, mais devrait, dans un tel cas, être réchauffé. Le canal 10 est, pour sa part, relié par l'intermédiaire d'une électro-vanne 14 à 3 voies, d'une part à une source d'air sous- pression 15 et d'autre part à l'air libre 16. Le ballon 13 communique pour sa part, par l'intermédiaire d'un canal 17, dont l'extrémité est équipée d'un col de cygne, et sur lequel est montée une électro-vanne 18, avec un dispositif 19 d'analyse des fluides, à partir duquel les fluides peuvent être envoyés par des conduits 20, 22 vers des dispositifs de traitement ou de remplacement.The channel 9 is connected by means of a swan neck forming a siphon 12 to a pressurized balloon 13 located inside the reactor vessel, which maintains the temperature of the fluid. The flask could be located outside the tank, but should in this case be reheated. The channel 10 is, for its part, connected by means of a 3-way solenoid valve 14, on the one hand to a source of pressurized air 15 and on the other hand to the open air 16 The balloon 13 communicates for its part, via a channel 17, the end of which is equipped with a swan neck, and on which is mounted an electro-valve 18, with an analysis device 19 fluids, from which fluids can be sent via conduits 20, 22 to treatment or replacement devices.
Lorsque l'électro-vanne 14 permet l'admission d'air sous- pression, la pression fait monter le fluide neutrophage à l'intérieur du ballon 13, et les canaux 8 ont tendance à se vider. Pour maintenir ces canaux en position remplie, ce qui est le but recherché par l'invention, il convient de basculer l'électro-vanne 18 dans la position vers laquelle elle met les canaux en communication avec l'échappement 16. La pression chutant, le fluide neutrophage est chassé par la pression régnant dans le ballon et remplit les canaux.When the solenoid valve 14 allows the admission of pressurized air, the pressure causes the neutron absorbing fluid to rise inside the balloon 13, and the channels 8 tend to empty. To maintain these channels in the filled position, which is the aim sought by the invention, it is necessary to tilt the solenoid valve 18 in the position to which it puts the channels in communication with the exhaust 16. The pressure falling, the neutron absorbing fluid is driven out by the pressure prevailing in the balloon and fills the channels.
La figure 2 ne représente qu'un groupe de canaux 8. Il est possible de disposer de plusieurs groupes de canaux, les canaux étant commandés indépendamment les uns des autres, pour être soit remplis, soit vidés, ce qui permet de réaliser une modulation différente en différents endroits du réacteur.FIG. 2 represents only one group of channels 8. It is possible to have several groups of channels, the channels being controlled independently of one another, to be either filled or emptied, which makes it possible to carry out a different modulation in different places of the reactor.
La modulation de la puissance du réacteur est obtenue en faisant varier le nombre de groupes de canaux pleins et vides. Le réacteur s'arrête lorsque tous les canaux sont remplis de fluide neutrophage. La variation de puissance est obtenue en maintenant certains canaux remplis alors que d'autres sont vides.The modulation of the reactor power is obtained by varying the number of groups of full and empty channels. The reactor stops when all the channels are filled with neutron absorbing fluid. The power variation is obtained by keeping certain channels filled while others are empty.
Les figures 3 et 4 représentent une variante d'exécution de ce dispositif. Dans cette forme d'exécution, un canal 23 est rempli en permanence de fluide neutrophage. Ce canal 23 est entouré par des canaux 24 pouvant être ou non remplis d'un fluide réfléchissant les neutrons.Figures 3 and 4 show an alternative embodiment of this device. In this embodiment, a channel 23 is permanently filled with neutron absorbing fluid. This channel 23 is surrounded by channels 24 which may or may not be filled with a neutron reflecting fluid.
Lorsque tous les canaux 24 sont remplis, il n'y a pas d'absorption par le fluide contenu dans le canal 23. Lorsque l'on recherche une modulation, il est possible de vider certains des canaux 24 pour permettre une absorption par le fluide contenu dans le canal 23. Pour commander l'arrêt du réacteur, il convient de vider simultanément et totalement tous les canaux 24.When all the channels 24 are filled, there is no absorption by the fluid contained in the channel 23. When a modulation is sought, it is possible to empty some of the channels 24 to allow absorption by the fluid contained in channel 23. To control the reactor shutdown, all channels 24 must be emptied simultaneously and completely.
Les figures 5 et 6 montrent deux formes d'exécution de canaux 8 contenant un fluide absorbant les neutrons. Dans la forme d'exécution de la figure 5, les canaux sont regroupés par série et possèdent différentes sections d'un canal à un autre. Dans la forme d'exécution représentée à la figure 6, les canaux sont disposés en croix, et peuvent être éventuellement regroupés par deux ou plus, pour former des épingles en U.Figures 5 and 6 show two embodiments of channels 8 containing a neutron absorbing fluid. In the embodiment of Figure 5, the channels are grouped by series and have different sections from one channel to another. In the embodiment shown in Figure 6, the channels are arranged in a cross, and can optionally be grouped by two or more, to form U-shaped pins.
La figure 7 représente, de façon très schématique, un couvercle 25 de cuve de réacteur comportant une ouverture 26, traversée par une pièce 27 en forme de cloche dont la partie inférieure 28 est évasée, et située à l'intérieur de la cuve. Cette cloche sert au passage de tubes 29, 30, 31 assurant la circulation des fluides neutrophages et/ou réfléchissants, la pénétration à travers le couvercle de la cuve se faisant par un tube 32 multicanaux, guidé par une sphère 33 située à l'intérieur de la partie évasée de la cloche 27.FIG. 7 very schematically shows a cover 25 of the reactor vessel having an opening 26, traversed by a bell-shaped part 27, the lower part 28 of which is flared, and situated inside the vessel. This bell is used for the passage of tubes 29, 30, 31 ensuring the circulation of neutron-absorbing and / or reflecting fluids, penetration through the cover of the tank being made by a multichannel tube 32, guided by a sphere 33 situated inside the flared part of the bell 27.
Comme il ressort de ce qui précède, l'invention apporte une grande amélioration à la technique existante en fournissant un dispositif de structure simple, évitant toute action mécanique pour régler la puissance nucléaire d'un réacteur, possédant un faible encombrement, ainsi qu'une grande fiabilité.As is apparent from the above, the invention brings a great improvement to the existing technique by providing a device of simple structure, avoiding any mechanical action to regulate the nuclear power of a reactor, having a small footprint, as well as a high reliability.
Comme il va de soi, l'invention ne se limite pas aux seules formes d'exécution de ce dispositif décrites ci-dessus à titre d'exemples, elle en embrasse au contraire toutes ies variantes. C'est ainsi notamment que la disposition des différents canaux à l'intérieur d'un réacteur pourrait être différente des dispositions indiquées, ou encore que les moyens de circulation du fluide absorbant les neutrons ou du fluide réfléchissant les neutons pourraient être différents et obtenus soit par une source de vide, soit par un dispositif de circulation par une pompe, par un piston, ou par un fluide de commande intermédiaire, sans que l'on sorte pour autant du cadre de l'invention. It goes without saying that the invention is not limited to the sole embodiments of this device described above by way of examples, on the contrary, it embraces all of its variants. Thus, in particular, the arrangement of the different channels inside a reactor could be different from the indicated arrangements, or else that the means of circulation of the neutron absorbing fluid or of the neuton reflecting fluid could be different and obtained either by a vacuum source, either by a circulation device by a pump, by a piston, or by an intermediate control fluid, without departing from the scope of the invention.

Claims

REVENDICATIONS
1 - Dispositif permettant de moduler la puissance nucléaire d'un réacteur ou l'absorption de particules sans déformation du flux neutronique axial, comportant un faisceau de canaux (8, 23), tubes ou similaires disposés en permanence dans le réacteur et destinés à contenir un fluide neutrophage absorbant les neutrons, caractérisé en ce qu'il comprend des moyens permettant de faire varier le nombre de canaux absorbants (8, 23) en fonction de la modulation souhaitée.1 - Device for modulating the nuclear power of a reactor or the absorption of particles without deformation of the axial neutron flux, comprising a bundle of channels (8, 23), tubes or the like permanently arranged in the reactor and intended to contain a neutron absorbing neutron fluid, characterized in that it comprises means making it possible to vary the number of absorbing channels (8, 23) according to the desired modulation.
2 - Dispositif selon la revendication 1 , caractérisé en ce qu'il comprend des moyens permettant, sur commande, de vider ou de remplir en totalité chaque canal (8) en fluide neutrophage.2 - Device according to claim 1, characterized in that it comprises means allowing, on command, to empty or completely fill each channel (8) with neutron absorbing fluid.
3 - Dispositif selon la revendication 1 , caractérisé en ce qu'il comprend des canaux (23) formant écrans qui, associés aux canaux (23) contenant du fluide neutrophage qui demeurent remplis en permanence, peuvent être remplis, sur commande, par un liquide réfléchissant les neutrons.3 - Device according to claim 1, characterized in that it comprises channels (23) forming screens which, associated with the channels (23) containing neutron absorbing fluid which remain permanently filled, can be filled, on command, with a liquid reflecting neutrons.
4 - Dispositif selon l'une quelconque des revendications 1 à 3, caractérisé en ce que le fluide neutrophage comprend au moins un métal liquide chargé de particules de matériaux absorbant ou réfléchissant les neutrons de même densité que le liquide.4 - Device according to any one of claims 1 to 3, characterized in that the neutron absorbing fluid comprises at least one liquid metal charged with particles of materials absorbing or reflecting neutrons of the same density as the liquid.
5 - Dispositif selon la revendication 4, caractérisé en ce que les particules de matériaux absorbant ou réfléchissant les neutrons sont obtenues par alliage ou frittage.5 - Device according to claim 4, characterized in that the particles of materials absorbing or reflecting the neutrons are obtained by alloying or sintering.
6 - Dispositif selon l'une quelconque des revendications 4 et 5, caractérisé en ce que le fluide neutrophage est choisi parmi les compositions suivantes :6 - Device according to any one of claims 4 and 5, characterized in that the neutron absorbing fluid is chosen from the following compositions:
- Cadmium et microbilles de monoborure de molybdène (MoB) de même densité que le cadmium (8,65) ;- Cadmium and microbeads of molybdenum monoboride (MoB) with the same density as cadmium (8.65);
- Mélange indium/cadmium, étain/cadmium ou étain/indium/cadmium ajusté à la densité du samarium (7,54) ;- Indium / cadmium, tin / cadmium or tin / indium / cadmium mixture adjusted to the density of the samarium (7.54);
- Mélange indium/cadmium, étain/cadmium ou étain/indium/cadmium ajusté à la densité du gadolinium (7,895) ;- Indium / cadmium, tin / cadmium or tin / indium / cadmium mixture adjusted to the density of gadolinium (7.895);
- Cadmium liquide additionné de microbilles de borure de tungstène W2B5, allié par frittage avec un alliage indium-argent. 7 - Dispositif selon la revendication 3, caractérisé en ce que le liquide réfléchissant les neutrons et destiné à alimenter les canaux (24) formant écrans est choisi parmi les mélanges contenant de l'eau lourde D2O ou d'autres liquides hydrogénés, éventuellement chargés de particules telles que le béryllium réfléchissant les neutrons.- Liquid cadmium added with microbeads of tungsten boride W2B5, alloyed by sintering with an indium-silver alloy. 7 - Device according to claim 3, characterized in that the liquid reflecting the neutrons and intended to supply the channels (24) forming screens is chosen from mixtures containing heavy water D2O or other hydrogenated liquids, possibly charged with particles such as beryllium reflecting the neutrons.
8 - Dispositif selon l'une quelconque des revendications 1 à 7, caractérisé en ce que tous les canaux (8, 23) sont remplis par le même liquide neutrophage.8 - Device according to any one of claims 1 to 7, characterized in that all the channels (8, 23) are filled with the same neutron absorbing liquid.
9 - Dispositif selon l'une quelconque des revendications 1 à 7, caractérisé en ce que les canaux (8, 23) sont remplis par différents liquides neutrophages. 10 - Dispositif selon l'une quelconque des revendications 1 à 9, caractérisé en ce que tous les canaux (8, 23) remplis de fluide neutrophage possèdent la même section.9 - Device according to any one of claims 1 to 7, characterized in that the channels (8, 23) are filled with different neutron-absorbing liquids. 10 - Device according to any one of claims 1 to 9, characterized in that all the channels (8, 23) filled with neutron absorbing fluid have the same section.
1 1 - Dispositif selon l'une quelconque des revendications 1 à 9, caractérisé en ce que les canaux (8, 23) remplis de fluide neutrophage possèdent différentes sections.1 1 - Device according to any one of claims 1 to 9, characterized in that the channels (8, 23) filled with neutron absorbing fluid have different sections.
12 - Dispositif selon l'une quelconque des revendications 1 à 1 1 , caractérisé en ce que les canaux (8, 23) sont constitués chacun par un tube en forme de U ou par deux tubes concentriques communiquant à l'une de leurs extrémités, dont le remplissage en fluide est réalisé par un dispositif pneumatique (15), une source de vide, ou un dispositif de circulation par une pompe ou un piston.12 - Device according to any one of claims 1 to 1 1, characterized in that the channels (8, 23) each consist of a U-shaped tube or by two concentric tubes communicating at one of their ends, the fluid filling of which is carried out by a pneumatic device (15), a vacuum source, or a circulation device by a pump or a piston.
13 - Dispositif selon l'une quelconque des revendications 1 à 12, caractérisé en ce que les extrémités correspondantes de plusieurs canaux parallèles (8) sont reliées à un même canal (9, 10). 14 - Dispositif selon l'une quelconque des revendications13 - Device according to any one of claims 1 to 12, characterized in that the corresponding ends of several parallel channels (8) are connected to the same channel (9, 10). 14 - Device according to any one of claims
1 à 12, caractérisé en ce que l'une des extrémités de chaque canal (9) contenant du fluide est reliée à un ballon (13), muni de deux cols de cygne dans le but d'éviter les vidanges intempestives de liquide et d'assurer la stabilité de celui-ci vis à vis des variations de température dans le réacteur. 15 - Dispositif selon l'une quelconque des revendications1 to 12, characterized in that one of the ends of each channel (9) containing fluid is connected to a balloon (13), provided with two swan necks in order to avoid untimely emptying of liquid and d '' ensure the stability thereof with respect to temperature variations in the reactor. 15 - Device according to any one of claims
1 à 14, caractérisé en ce qu'il comprend en outre des canaux, destinés à recevoir un fluide contenant un élément radioactif placé dans des conditions permettant la transmutation de cet élément vers un autre élément radioactif. 1 to 14, characterized in that it further comprises channels, intended to receive a fluid containing a radioactive element placed under conditions allowing the transmutation of this element to another radioactive element.
EP98935107A 1997-07-07 1998-07-06 Device for modulating absorption, emission, moderation or reflection of radiation or of particle flow Ceased EP0995198A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR9708818A FR2765722B1 (en) 1997-07-07 1997-07-07 DEVICE FOR MODULATING THE ABSORPTION, EMISSION, MODERATION OR REFLECTION OF PARTICLE RADIATION OR FLOWS
FR9708818 1997-07-07
PCT/FR1998/001443 WO1999003109A1 (en) 1997-07-07 1998-07-06 Device for modulating absorption, emission, moderation or reflection of radiation or of particle flow

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FR2817649B1 (en) * 2000-12-06 2004-05-14 Michel Gerard Emin VACUUM EFFECT DEVICE FOR MODULATING OR ENHANCING THE ABSORPTION, EMISSION OR MODERATION OF PARTICLE RADIATION OR FLOWS AND REGENERATING FUEL
FR2832846B1 (en) 2001-11-26 2005-12-09 Commissariat Energie Atomique COMPACT NUCLEAR WATER REACTOR UNDER PRESSURE
FR2850786B1 (en) * 2003-02-04 2008-06-13 Michel Gerard Emin NUCLEAR REACTOR AND ITS MEANS OF INSERTION OF NEUTROPHAGE IN THE HEART
FR2855310B1 (en) * 2003-02-04 2008-06-13 Michel Emin NUCLEAR REACTOR AND ITS MEANS OF INSERTION OF LIQUID NEUTROPHAGE IN THE HEART

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GB803701A (en) * 1955-08-11 1958-10-29 Parsons C A & Co Ltd Improvements in and relating to nuclear reactors
DE1125562B (en) * 1958-04-03 1962-03-15 Rhein Westfael Elect Werk Ag Device for regulating nuclear reactors
NL242149A (en) * 1958-08-08
FR1269659A (en) * 1960-06-16 1961-08-18 Elettronucleare Naz Senn Soc Nuclear fission reactor control system based on the use of neutron absorbing fluids
US3228847A (en) * 1963-01-29 1966-01-11 Parkinson Thomas Franklin Reactor control system
US3300848A (en) * 1963-12-24 1967-01-31 Jr Carl F Leitten Method of preparing oxides for neutronic reactor control
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FR2765722B1 (en) 1999-09-24
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WO1999003109A1 (en) 1999-01-21

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