EP0072736B1 - Heat exchanger with double barrier - Google Patents

Heat exchanger with double barrier Download PDF

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Publication number
EP0072736B1
EP0072736B1 EP82401472A EP82401472A EP0072736B1 EP 0072736 B1 EP0072736 B1 EP 0072736B1 EP 82401472 A EP82401472 A EP 82401472A EP 82401472 A EP82401472 A EP 82401472A EP 0072736 B1 EP0072736 B1 EP 0072736B1
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EP
European Patent Office
Prior art keywords
matrix
heat exchanger
primary
exchanger according
conduit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP82401472A
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German (de)
French (fr)
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EP0072736A1 (en
Inventor
Jean Edmond Chaix
Jean Claude Chaix
Jean Louis Chaix
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Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
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Commissariat a lEnergie Atomique CEA
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Publication of EP0072736A1 publication Critical patent/EP0072736A1/en
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Publication of EP0072736B1 publication Critical patent/EP0072736B1/en
Expired legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D7/00—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
    • F28D7/0008—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits for one medium being in heat conductive contact with the conduits for the other medium
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D21/00—Heat-exchange apparatus not covered by any of the groups F28D1/00 - F28D20/00
    • F28D2021/0019—Other heat exchangers for particular applications; Heat exchange systems not otherwise provided for
    • F28D2021/0054—Other heat exchangers for particular applications; Heat exchange systems not otherwise provided for for nuclear applications
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F2265/00—Safety or protection arrangements; Arrangements for preventing malfunction
    • F28F2265/16—Safety or protection arrangements; Arrangements for preventing malfunction for preventing leakage
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F2275/00—Fastening; Joining
    • F28F2275/02—Fastening; Joining by using bonding materials; by embedding elements in particular materials
    • 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
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S165/00—Heat exchange
    • Y10S165/001—Heat exchange with alarm, indicator, recorder, test, or inspection means
    • Y10S165/008—Leakage

Definitions

  • the subject of the present invention is a double barrier heat exchanger more specifically intended for refrigerating radioactive primary water from a sampling circuit of a water reactor and making it possible in particular to detect a leak of the primary liquid at said exchanger.
  • a number of auxiliary circuits are connected to the primary circuit of a nuclear reactor, making it possible to verify the proper functioning of this circuit and, if necessary, to adjust the characteristics of the primary fluid.
  • the sampling circuit used to take samples of the primary liquid for analysis, it is necessary to cool the primary liquid coming from the heart before taking the sampling. For this, it is cooled via a secondary refrigeration circuit.
  • Most of the exchangers currently used do not provide total protection of the secondary circuit against the risks of pollution by the primary fluid and, in general, do not allow rapid detection of an accidental leak of the latter.
  • the object of the present invention is precisely a heat exchanger which not only makes it possible to protect the secondary circuit against the risks consecutive to a deterioration of the primary circuit, but which also makes it possible to quickly detect a leak of the primary liquid.
  • the radioactive primary fluid circulating in a primary sheath and the secondary fluid circulating in a secondary sheath comprises a junction matrix, disposed between the two sheaths and in contact with them, this matrix being in the form of a compact metallic mass and comprising at least one element capable of diffusing into the primary fluid when it is in contact with it and of being made radioactive under l action of an activation source.
  • the junction matrix is metallic and is in compact form ensures good thermal conductivity between the primary and secondary sheaths and gives good mechanical resistance to the entire device.
  • the element capable of being made radioactive when it is entrained by the primary fluid is silver.
  • an exchanger consists of two "barriers", one between the primary sheath and the matrix, the other between the matrix and the secondary sheath.
  • the device according to the invention has increased security because it makes it possible to detect an anomaly at the level of the first barrier (for example leakage of the primary liquid) well before the second is attacked in turn.
  • the primary liquid attacks the matrix and silver ions begin to diffuse in the primary circuit of the reactor: during the passage through the core, they are activated in silver 110 under the action of the neutron flux.
  • This anomaly can then be detected in the form of an increase in the peak of this radioelement in the radiochemical spectrum carried out periodically on primary samples: the rupture of the first barrier of the exchanger can therefore be detected very quickly by monitoring this peak .
  • the secondary sheath has a coefficient of thermal expansion substantially equal to that of the junction matrix, which makes it possible to avoid the drawbacks due to the phenomena of thermal expansion.
  • the primary circuit 1 of a nuclear reactor allowing the primary fluid to pass from the core 2 where it heats up in contact with the fuel claddings to a heat exchanger 4 where it cools contact of the fluid circulating in the secondary circuit 6 of the reactor before returning to the core.
  • a sampling circuit 8 On the primary circuit, and downstream of the exchanger 4, is connected a sampling circuit 8 making it possible to take samples of the primary fluid for analysis.
  • the primary fluid is still too hot to be able to take these samples and it is necessary to cool it with a fluid circulating in a secondary refrigeration circuit 10, this cooling taking place in a heat exchanger. heat 12.
  • Various embodiments are possible for such an exchanger, depending on the geometry of the sheath primary and secondary sheath.
  • the primary sheath has the form of a straight tube 14 surrounded by an annular enclosure 16 in which circulates the secondary coolant, the primary tube 14 and the annular enclosure 16 being separated by a space 18 filled with the junction matrix used in the context of the present invention.
  • the primary sheath still has the shape of a cylindrical tube 20, but the secondary sheath 22 has the shape of a serpentine surrounding the primary sheath and embedded inside a matrix 24 placed all around the tube 20 and in contact with it.
  • the primary sheath 26 which has the shape of a coil embedded in a junction matrix 28, the latter being placed between two external and internal cylindrical walls referenced 30 and 32 respectively on the face.
  • the secondary fluid circulates on the one hand in the tubular space 34 delimited by the internal wall 32 and on the other hand in an annular space 36 delimited by the external wall 30 and an external wall 38.
  • FIG. 5 it illustrates a particular embodiment of an exchanger according to the invention in which the primary sheath has the shape of a coil while the secondary liquid circulates in the spaces defined by the threads of two screws to not square.
  • the primary liquid arrives in the exchanger, which has a cylindrical shape and has the general reference 11 in the drawing, through an inlet orifice 42 located at one end and leaves at the other end through an outlet orifice 44 after have circulated in a coil 46 whose axis is substantially coincident with that of the tube 11.
  • This coil is embedded in a junction matrix 47 which is made of an alloy of silver and copper.
  • a cylindrical wall48 Inside the cylinder defined by the coil 46, and in contact with the matrix 47, is arranged a cylindrical wall48, called “internal cylindrical wall in the remainder of this text, of the same axis as the tube 11, while a piece 49, externally threaded, is placed inside the wall 48 so that its thread is in contact with the internal face of the latter.
  • the longitudinal section of the thread of the piece 49 has substantially the shape of a square and that is why this piece is called "square pitch screw".
  • the matrix 47 On the outside of the cylinder defined by the coil 46, the matrix 47 is in contact with a second cylindrical wall 50, called “external cylindrical wall", which is none other than the internal face of a second threaded square screw 51 externally, and inside which are arranged the matrix 47, the coil 46 and the first square-pitch screw 49. Finally, an external wall 52 is in contact, on the one hand with the thread of the screw 51 and, on the other hand, with the external envelope 53 of the tube 11.
  • the secondary fluid enters through an orifice 54 located at the end of the tube 11 through which the primary liquid is discharged into a hole 55 formed inside the part 49 and substantially along its axis.
  • An orifice 56 places the hole 55 in communication with the spaces delimited on the one hand by the threads of the screws 49 and 51, on the other hand by the walls 48 and 52.
  • the secondary fluid therefore follows a double helical path around the primary coil 46 before being evacuated to the other end of the tube 10 by an outlet orifice 58.
  • This arrangement makes it possible to have a good heat exchange coefficient and gives the device good rigidity, which makes it possible to reduce the thickness internal and external cylindrical walls.
  • the matrix 47 is a binary alloy of copper and silver, obtained by casting a ternary eutectic alloy of silver, copper and cadmium, the latter volatilizing at the time of casting.
  • the primary coil is made of an alloy with a high nickel content (for example Inconel 800 or Incoloy) so as not to deteriorate the primary sheath when the casting -
  • the other parts of the exchanger, and in particular the square pitch screws constituting the secondary sheaths are made of 316 L stainless steel. The use of this steel grade makes it possible to avoid problems of expansion since the coefficient of thermal expansion of stainless steel is 17.
  • this matrix constitutes an excellent thermal bridge between the primary and secondary sheaths thanks to the good conductivity of silver and copper.
  • this alloy has good mechanical strength, which makes it possible to reduce the thickness of the primary tube and the secondary sheaths, the thickness of these elements being determined solely as a function of corrosion problems.
  • Two cavities 60 and 61 are provided at each end of the tube 11 in order to recover the primary or secondary liquid which can escape in the event of a leak.
  • the outer casing 53 of the tube 11 is protected against overpressure following a leak by a safety valve 62.
  • the detection of leaks with such a device is done as follows: if the primary tube 46 is pierced, the primary fluid comes into contact with the alloy constituting the junction matrix, attacking it, and silver ions will diffuse in the primary circuit and activate silver 110 after passing through the reactor core. The primary sheath leak is therefore detected by observing the peak of the silver on the radiochemistry spectrum carried out periodically.
  • the primary water escaping from the coil 46 can make its way along it and reach the end pieces bearing the reference 63 in the drawing and, from there, enter the cavities 60 or 61.
  • the liquid circulating in the primary coil 46 being under high pressure, it follows an increase in pressure in the cavity 61, and therefore a displacement of the valve 62, which frees the evacuation orifice 65: it is therefore possible to detect the operating anomaly for example by means of a alarm which is triggered when the liquid leaves through this orifice 65.
  • the primary liquid can also attack the junction matrix and thus reach the wall limiting the secondary sheath. At this time, under the effect of the pressure, the matrix may become detached or the liquid progress along the interface and the primary fluid flows along this interface to the end pieces.
  • the leak can still be detected thanks to the safety valve 62.
  • the attack phenomenon of the junction matrix is sufficiently slow to allow the detection of the anomaly by observation of the silver peak 110, generally well before the fluid reaches the cavities 60 or 61: we can therefore intervene quickly to replace the defective device before complete destruction of it .
  • the device according to the invention has particularly advantageous advantages since it allows good heat exchange between the primary liquid and the secondary liquid, good mechanical strength of the assembly even with thin walls, and also allows rapid detection. a leak at the primary sheath, since in the event of piercing of the latter, one of the elements constituting the junction matrix diffuses into the primary liquid and can be easily detected by spectrographic control.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Monitoring And Testing Of Nuclear Reactors (AREA)
  • Examining Or Testing Airtightness (AREA)

Description

La présente invention a pour objet un échangeur de chaleur à double barrière plus spécialement destiné à réfrigérer l'eau primaire radioactive d'un circuit de prélèvement d'un réacteur à eau et permettant notamment de détecter une fuite du liquide primaire au niveau dudit échangeur.The subject of the present invention is a double barrier heat exchanger more specifically intended for refrigerating radioactive primary water from a sampling circuit of a water reactor and making it possible in particular to detect a leak of the primary liquid at said exchanger.

Sur le circuit primaire d'un réacteur nucléaire sont branchés un certain nombre de circuits auxiliaires permettant de vérifier le bon fonctionnement de ce circuit et, s'il le faut, d'ajuster les caractéristiques du fluide primaire. En ce qui concerne l'un de ces circuits, dit « circuit de prélèvement », utilisé pour prélever des échantillons du liquide primaire pour analyse, il est nécessaire de refroidir le liquide primaire provenant du coeur avant d'effectuer le prélèvement. Pour cela, on le refroidit par l'intermédiaire d'un circuit secondaire de réfrigération. La plupart des échangeurs actuellement utilisés n'assurent pas une protection totale du circuit secondaire contre les risques de pollution par le fluide primaire et, en général, ne permettent pas de détecter rapidement une fuite accidentelle de ce dernier.A number of auxiliary circuits are connected to the primary circuit of a nuclear reactor, making it possible to verify the proper functioning of this circuit and, if necessary, to adjust the characteristics of the primary fluid. With regard to one of these circuits, known as the “sampling circuit”, used to take samples of the primary liquid for analysis, it is necessary to cool the primary liquid coming from the heart before taking the sampling. For this, it is cooled via a secondary refrigeration circuit. Most of the exchangers currently used do not provide total protection of the secondary circuit against the risks of pollution by the primary fluid and, in general, do not allow rapid detection of an accidental leak of the latter.

La présente invention a justement pour objet un échangeur de chaleur qui permet non seulement de protéger le circuit secondaire contre les risques consécutifs à une détérioration du circuit primaire, mais qui permet également de détecter rapidement une fuite du liquide primaire.The object of the present invention is precisely a heat exchanger which not only makes it possible to protect the secondary circuit against the risks consecutive to a deterioration of the primary circuit, but which also makes it possible to quickly detect a leak of the primary liquid.

Selon la principale caractéristique de l'échangeur de chaleur objet de l'invention, le fluide primaire radioactif circulant dans une gaine primaire et le fluide secondaire circulant dans une gaine secondaire, cet échangeur comporte une matrice de jonction, disposée entre les deux gaines et en contact avec celles-ci, cette matrice se présentant sous la forme d'une masse métallique compacte et comprenant au moins un élément susceptible de diffuser dans le fluide primaire lorsqu'il est au contact de celui-ci et d'être rendu radioactif sous l'action d'une source d'activation. Ainsi, le fait que la matrice de jonction soit métallique et se présente sous forme compacte assure une bonne conductibilité thermique entre les gaines primaire et secondaire et confère une bonne résistance mécanique à l'ensemble du dispositif.According to the main characteristic of the heat exchanger which is the subject of the invention, the radioactive primary fluid circulating in a primary sheath and the secondary fluid circulating in a secondary sheath, this exchanger comprises a junction matrix, disposed between the two sheaths and in contact with them, this matrix being in the form of a compact metallic mass and comprising at least one element capable of diffusing into the primary fluid when it is in contact with it and of being made radioactive under l action of an activation source. Thus, the fact that the junction matrix is metallic and is in compact form ensures good thermal conductivity between the primary and secondary sheaths and gives good mechanical resistance to the entire device.

Selon une autre caractéristique de l'invention, l'élément susceptible d'être rendu radioactif lorsqu'il est entraîné par le fluide primaire est de l'argent. Ainsi, un tel échangeur se compose de deux «barrières», l'une entre la gaine primaire et la matrice, l'autre entre la matrice et la gaine secondaire. Le dispositif selon l'invention présente une sécurité accrue car il permet de détecter une anomalie au niveau de la première barrière (par exemple fuite du liquide primaire) bien avant que la seconde ne soit attaquée à son tour.According to another characteristic of the invention, the element capable of being made radioactive when it is entrained by the primary fluid is silver. Thus, such an exchanger consists of two "barriers", one between the primary sheath and the matrix, the other between the matrix and the secondary sheath. The device according to the invention has increased security because it makes it possible to detect an anomaly at the level of the first barrier (for example leakage of the primary liquid) well before the second is attacked in turn.

En effet, si une fuite se produit, par exemple suite à un percement de la gaine primaire, le liquide primaire attaque la matrice et des ions argent se mettent à diffuser dans le circuit primaire du réacteur : lors du passage dans le coeur, ils sont activés en argent 110 sous l'action du flux de neutrons. Cette anomalie peut alors être détectée sous forme d'une augmentation du pic de ce radioélément dans le spectre de radiochimie effectué périodiquement sur des prélèvements primaires : la rupture de la première barrière de l'échangeur peut donc être décelée très rapidement par surveillance de ce pic.Indeed, if a leak occurs, for example following a piercing of the primary sheath, the primary liquid attacks the matrix and silver ions begin to diffuse in the primary circuit of the reactor: during the passage through the core, they are activated in silver 110 under the action of the neutron flux. This anomaly can then be detected in the form of an increase in the peak of this radioelement in the radiochemical spectrum carried out periodically on primary samples: the rupture of the first barrier of the exchanger can therefore be detected very quickly by monitoring this peak .

Selon une autre caractéristique de l'invention, la gaine secondaire a un coefficient de dilatation thermique sensiblement égal à celui de la matrice de jonction, ce qui permet d'éviter les inconvénients dus aux phénomènes de dilatation thermique.According to another characteristic of the invention, the secondary sheath has a coefficient of thermal expansion substantially equal to that of the junction matrix, which makes it possible to avoid the drawbacks due to the phenomena of thermal expansion.

D'autres caractéristiques et avantages de l'invention ressortiront de la description qui va suivre, donnée à titre purement illustratif et nullement limitatif, en référence aux dessins annexés dans lesquels :

  • la figure 1 est une vue schématique montrant un échangeur de chaleur selon l'invention placé dans un circuit de prélèvement relié au circuit primaire d'un réacteur,
  • la figure 2 est une vue schématique en coupe d'un mode de réalisation d'un échangeur conforme à l'invention dans lequel la gaine primaire a la forme d'un tube droit et la gaine secondaire une forme annulaire,
  • la figure 3 est une vue schématique en coupe d'un autre mode de réalisation dans lequel la gaine primaire a la forme d'un tube droit et la gaine secondaire la forme d'un serpentin,
  • la figure 4 est une vue schématique en coupe montrant une troisième forme de réalisation avec la gaine primaire en forme de serpentin, la gaine secondaire ayant une forme annulaire, et
  • la figure 5 est une vue schématique en coupe d'un échangeur de chaleur selon l'invention dans lequel la gaine primaire a la forme d'un serpentin séparé par une matrice d'une gaine secondaire délimitée par les filets de deux vis à pas carré.
Other characteristics and advantages of the invention will emerge from the description which follows, given purely by way of illustration and in no way limiting, with reference to the appended drawings in which:
  • FIG. 1 is a schematic view showing a heat exchanger according to the invention placed in a sampling circuit connected to the primary circuit of a reactor,
  • FIG. 2 is a schematic sectional view of an embodiment of an exchanger according to the invention in which the primary sheath has the form of a straight tube and the secondary sheath has an annular shape,
  • FIG. 3 is a schematic sectional view of another embodiment in which the primary sheath has the shape of a straight tube and the secondary sheath has the shape of a coil,
  • FIG. 4 is a schematic sectional view showing a third embodiment with the primary sheath in the form of a coil, the secondary sheath having an annular shape, and
  • Figure 5 is a schematic sectional view of a heat exchanger according to the invention in which the primary sheath has the shape of a coil separated by a matrix from a secondary sheath delimited by the threads of two square pitch screws .

Sur la vue schématique de la figure 1, on voit le circuit primaire 1 d'un réacteur nucléaire permettant au fluide primaire de passer du coeur 2 où il s'échauffe au contact des gaines combustibles à un échangeur de chaleur 4 où il se refroidit au contact du fluide circulant dans le circuit secondaire 6 du réacteur avant de retourner dans le coeur. Sur le circuit primaire, et en aval de l'échangeur 4, est branché un circuit de prélèvement 8 permettant de prélever des échantillons du fluide primaire pour analyse. Cependant, même à la sortie de l'échangeur4, le fluide primaire est encore trop chaud pour pouvoir effectuer ces prélèvements et il est nécessaire de le refroidir par un fluide circulant dans un circuit secondaire de réfrigération 10, ce refroidissement ayant lieu dans un échangeur de chaleur 12. Divers modes de réalisation sont possibles pour un tel échangeur, suivant la géométrie de la gaine primaire et de la gaine secondaire.In the diagrammatic view of FIG. 1, we see the primary circuit 1 of a nuclear reactor allowing the primary fluid to pass from the core 2 where it heats up in contact with the fuel claddings to a heat exchanger 4 where it cools contact of the fluid circulating in the secondary circuit 6 of the reactor before returning to the core. On the primary circuit, and downstream of the exchanger 4, is connected a sampling circuit 8 making it possible to take samples of the primary fluid for analysis. However, even at the outlet of the exchanger 4, the primary fluid is still too hot to be able to take these samples and it is necessary to cool it with a fluid circulating in a secondary refrigeration circuit 10, this cooling taking place in a heat exchanger. heat 12. Various embodiments are possible for such an exchanger, depending on the geometry of the sheath primary and secondary sheath.

Dans l'exemple représenté à la figure 2, on voit que la gaine primaire a la forme d'un tube droit 14 entouré d'une enceinte annulaire 16 dans laquelle circule le liquide secondaire de refroidissement, le tube primaire 14 et l'enceinte annulaire 16 étant séparés par un espace 18 rempli par la matrice de jonction utilisée dans le cadre de la présente invention.In the example shown in Figure 2, we see that the primary sheath has the form of a straight tube 14 surrounded by an annular enclosure 16 in which circulates the secondary coolant, the primary tube 14 and the annular enclosure 16 being separated by a space 18 filled with the junction matrix used in the context of the present invention.

Dans le cas de la figure 3, la gaine primaire a encore la forme d'un tube cylindrique 20, mais la gaine secondaire 22 a la forme d'un serpentin entourant la gaine primaire et noyé à l'intérieur d'une matrice 24 placée tout autour du tube 20 et en contact avec celui-ci.In the case of FIG. 3, the primary sheath still has the shape of a cylindrical tube 20, but the secondary sheath 22 has the shape of a serpentine surrounding the primary sheath and embedded inside a matrix 24 placed all around the tube 20 and in contact with it.

Dans l'exemple représenté à la figure 4, c'est la gaine primaire 26 qui a la forme d'un serpentin noyé dans une matrice de jonction 28, celle-ci étant placée entre deux parois cylindriques externe et interne référencées 30 et 32 respectivement sur la figure. Le fluide secondaire circule d'une part dans l'espace tubulaire 34 délimité par la paroi interne 32 et d'autre part dans un espace annulaire 36 délimité par la paroi externe 30 et une paroi extérieure 38.In the example shown in Figure 4, it is the primary sheath 26 which has the shape of a coil embedded in a junction matrix 28, the latter being placed between two external and internal cylindrical walls referenced 30 and 32 respectively on the face. The secondary fluid circulates on the one hand in the tubular space 34 delimited by the internal wall 32 and on the other hand in an annular space 36 delimited by the external wall 30 and an external wall 38.

Quant à la figure 5, elle illustre un mode particulier de réalisation d'un échangeur selon l'invention dans lequel la gaine primaire a la forme d'un serpentin tandis que le liquide secondaire circule dans les espaces définis par les filets de deux vis à pas carrés.As for FIG. 5, it illustrates a particular embodiment of an exchanger according to the invention in which the primary sheath has the shape of a coil while the secondary liquid circulates in the spaces defined by the threads of two screws to not square.

Le liquide primaire arrive dans l'échangeur, qui a une forme cylindrique et porte la référence générale 11 sur le dessin, par un orifice d'entrée 42 situé à une extrémité et en ressort à l'autre extrémité par un orifice de sortie 44 après avoir circulé dans un serpentin 46 dont l'axe est sensiblement confondu avec celui du tube 11. Ce serpentin est noyé dans une matrice de jonction 47 qui est réalisée en alliage d'argent et de cuivre. A l'intérieur du cylindre défini par le serpentin 46, et en contact avec la matrice 47, est disposée une paroi cylindrique48, appelée «paroi cylindrique interne dans la suite du présent texte, de même axe que le tube 11, tandis qu'une pièce 49, filetée extérieurement, est placée à l'intérieur de la paroi 48 de telle sorte que son filet soit en contact avec la face interne de cette dernière. La section longitudinale du filet de la pièce 49 a sensiblement la forme d'un carré et c'est pourquoi cette pièce porte le nom de « vis à pas carré ».The primary liquid arrives in the exchanger, which has a cylindrical shape and has the general reference 11 in the drawing, through an inlet orifice 42 located at one end and leaves at the other end through an outlet orifice 44 after have circulated in a coil 46 whose axis is substantially coincident with that of the tube 11. This coil is embedded in a junction matrix 47 which is made of an alloy of silver and copper. Inside the cylinder defined by the coil 46, and in contact with the matrix 47, is arranged a cylindrical wall48, called “internal cylindrical wall in the remainder of this text, of the same axis as the tube 11, while a piece 49, externally threaded, is placed inside the wall 48 so that its thread is in contact with the internal face of the latter. The longitudinal section of the thread of the piece 49 has substantially the shape of a square and that is why this piece is called "square pitch screw".

Du côté extérieur au cylindre défini par le serpentin 46, la matrice 47 est en contact avec une deuxième paroi cylindrique 50, dite « paroi cylindrique externe », qui n'est autre que la face interne d'une deuxième vis à pas carré 51 filetée extérieurement, et à l'intérieur de laquelle sont disposés la matrice 47, le serpentin 46 et la première vis à pas carré 49. Enfin, une paroi extérieure 52 est en contact, d'une part avec le filet de la vis 51 et, d'autre part, avec l'enveloppe externe 53 du tube 11.On the outside of the cylinder defined by the coil 46, the matrix 47 is in contact with a second cylindrical wall 50, called "external cylindrical wall", which is none other than the internal face of a second threaded square screw 51 externally, and inside which are arranged the matrix 47, the coil 46 and the first square-pitch screw 49. Finally, an external wall 52 is in contact, on the one hand with the thread of the screw 51 and, on the other hand, with the external envelope 53 of the tube 11.

Le fluide secondaire pénètre par un orifice 54 situé à l'extrémité du tube 11 par laquelle est évacué le liquide primaire dans un trou 55 ménagé à l'intérieur de la pièce 49 et sensiblement le long de son axe. Un orifice 56 met le trou 55 en communication avec les espaces délimités d'une part par les filets des vis 49 et 51, d'autre part par les parois 48 et 52. Le fluide secondaire suit donc un double chemin hélicoïdal autour du serpentin primaire 46 avant d'être évacué à l'autre extrémité du tube 10 par un orifice de sortie 58. Cette disposition permet d'avoir un bon coefficient d'échange thermique et confère au dispositif une bonne rigidité, ce qui permet de réduire l'épaisseur des parois cylindriques interne et externe.The secondary fluid enters through an orifice 54 located at the end of the tube 11 through which the primary liquid is discharged into a hole 55 formed inside the part 49 and substantially along its axis. An orifice 56 places the hole 55 in communication with the spaces delimited on the one hand by the threads of the screws 49 and 51, on the other hand by the walls 48 and 52. The secondary fluid therefore follows a double helical path around the primary coil 46 before being evacuated to the other end of the tube 10 by an outlet orifice 58. This arrangement makes it possible to have a good heat exchange coefficient and gives the device good rigidity, which makes it possible to reduce the thickness internal and external cylindrical walls.

Dans le cas particulier décrit ici, la matrice 47 est un alliage binaire de cuivre et d'argent, obtenu par coulée d'un alliage eutectique ternaire d'argent, de cuivre et de cadmium, ce dernier se volatilisant au moment de la coulée. Cette opération étant effectuée sous atmosphère neutre et à une température d'environ 930 °C, on réalise le serpentin primaire en alliage à forte teneur en nickel (par exemple Inconel 800 ou Incoloy) afin de ne pas détériorer la gaine primaire au moment de la coulée- Les autres pièces de l'échangeur, et en particulier les vis à pas carré constituant les gaines secondaires, sont réalisées en acier inoxydable 316 L. L'utilisation de cette nuance d'acier permet d'éviter les problèmes de dilatation puisque le coefficient de dilatation thermique de l'acier inoxydable est de 17 . 10-6 tandis que celui de l'alliage argent-cuivre utilisé pour faire la matrice de jonction est de 16,5 - 10-6. De plus cette matrice constitue un excellent pont thermique entre les gaines primaire et secondaire grâce à la bonne conductibilité de l'argent et du cuivre. Enfin, cet alliage a une bonne résistance mécanique, ce qui permet de réduire l'épaisseur du tube primaire et des gaines secondaires, l'épaisseur de ces éléments étant déterminée uniquement en fonction des problèmes de corrosion.In the particular case described here, the matrix 47 is a binary alloy of copper and silver, obtained by casting a ternary eutectic alloy of silver, copper and cadmium, the latter volatilizing at the time of casting. This operation being carried out under a neutral atmosphere and at a temperature of approximately 930 ° C., the primary coil is made of an alloy with a high nickel content (for example Inconel 800 or Incoloy) so as not to deteriorate the primary sheath when the casting - The other parts of the exchanger, and in particular the square pitch screws constituting the secondary sheaths, are made of 316 L stainless steel. The use of this steel grade makes it possible to avoid problems of expansion since the coefficient of thermal expansion of stainless steel is 17. 10- 6 while that of the silver-copper alloy used to make the junction matrix is 16.5 - 10- 6. In addition, this matrix constitutes an excellent thermal bridge between the primary and secondary sheaths thanks to the good conductivity of silver and copper. Finally, this alloy has good mechanical strength, which makes it possible to reduce the thickness of the primary tube and the secondary sheaths, the thickness of these elements being determined solely as a function of corrosion problems.

Deux cavités 60 et 61 sont ménagées à chaque extrémité du tube 11 afin de récupérer le liquide primaire ou secondaire qui peut s'échapper en cas de fuite.Two cavities 60 and 61 are provided at each end of the tube 11 in order to recover the primary or secondary liquid which can escape in the event of a leak.

L'enveloppe externe 53 du tube 11 est protégée contre les surpressions consécutives à une fuite par une soupape de sûreté 62. La détection des fuites avec un tel dispositif se fait de la manière suivante : si le tube primaire 46 est percé, le fluide primaire entre en contact avec l'alliage constituant la matrice de jonction, attaquant celui-ci, et des ions argent vont diffuser dans le circuit primaire et s'activer en argent 110 après passage dans le coeur du réacteur. On détecte donc la fuite de la gaine primaire en observant le pic de l'argent sur le spectre de radiochimie effectué périodiquement.The outer casing 53 of the tube 11 is protected against overpressure following a leak by a safety valve 62. The detection of leaks with such a device is done as follows: if the primary tube 46 is pierced, the primary fluid comes into contact with the alloy constituting the junction matrix, attacking it, and silver ions will diffuse in the primary circuit and activate silver 110 after passing through the reactor core. The primary sheath leak is therefore detected by observing the peak of the silver on the radiochemistry spectrum carried out periodically.

D'autre part, l'eau primaire s'échappant du serpentin 46 peut se frayer un chemin le long de celui-ci et parvenir jusqu'aux pièces d'extrémité portant la référence 63 sur le dessin et, de là, pénétrer dans les cavités 60 ou 61. Le liquide circulant dans le serpentin primaire 46 étant sous forte pression, il s'ensuit une augmentation de pression dans la cavité 61, et donc un déplacement de la soupape 62, ce qui libère l'orifice d'évacuation 65 : on peut donc détecter l'anomalie de fonctionnement par exemple grâce à une alarme qui se déclenche lorsque le liquide sort par cet orifice 65. Le liquide primaire peut également attaquer la matrice de jonction et parvenir ainsi jusqu'à la paroi limitant la gaine secondaire. A ce moment-là, sous l'effet de la pression, on peut avoir décollement de la matrice ou progression du liquide le long de l'interface et le fluide primaire s'écoule le long de cette interface jusqu'aux pièces d'extrémité 63 et débouche à nouveau dans la cavité 61 : la fuite peut encore être détectée grâce à la soupape de sûreté 62. Cependant, il faut remarquer que, dans tous les cas, le phénomène d'attaque de la matrice de jonction est suffisamment lent pour permettre la détection de l'anomalie par observation du pic de l'argent 110, généralement bien avant que le fluide ne parvienne dans les cavités 60 ou 61 : on peut donc intervenir rapidement pour remplacer l'appareil défectueux avant destruction complète de celui-ci.On the other hand, the primary water escaping from the coil 46 can make its way along it and reach the end pieces bearing the reference 63 in the drawing and, from there, enter the cavities 60 or 61. The liquid circulating in the primary coil 46 being under high pressure, it follows an increase in pressure in the cavity 61, and therefore a displacement of the valve 62, which frees the evacuation orifice 65: it is therefore possible to detect the operating anomaly for example by means of a alarm which is triggered when the liquid leaves through this orifice 65. The primary liquid can also attack the junction matrix and thus reach the wall limiting the secondary sheath. At this time, under the effect of the pressure, the matrix may become detached or the liquid progress along the interface and the primary fluid flows along this interface to the end pieces. 63 and again opens into the cavity 61: the leak can still be detected thanks to the safety valve 62. However, it should be noted that, in all cases, the attack phenomenon of the junction matrix is sufficiently slow to allow the detection of the anomaly by observation of the silver peak 110, generally well before the fluid reaches the cavities 60 or 61: we can therefore intervene quickly to replace the defective device before complete destruction of it .

Ainsi, le dispositif selon l'invention présente des avantages particulièrement intéressants puisqu'il permet un bon échange thermique entre le liquide primaire et le liquide secondaire, une bonne tenue mécanique de l'ensemble même avec des parois minces, et permet également de détecter rapidement une fuite au niveau de la gaine primaire, puisqu'en cas de percement de celle-ci, l'un des éléments constituant la matrice de jonction diffuse dans le liquide primaire et peut être facilement détecté par contrôle spectrographique.Thus, the device according to the invention has particularly advantageous advantages since it allows good heat exchange between the primary liquid and the secondary liquid, good mechanical strength of the assembly even with thin walls, and also allows rapid detection. a leak at the primary sheath, since in the event of piercing of the latter, one of the elements constituting the junction matrix diffuses into the primary liquid and can be easily detected by spectrographic control.

Claims (11)

1. Heat exchanger of the double barrier type, for heat exchange between a radioactive primary fluid circulating in a first conduit (20) and a secondary fluid circulating in a secondary conduit (22), characterized in that it comprises a junction matrix (24), located between and in contact with the two conduits (20,22), said matrix (24) being in the form of a compact metallic mass, and comprising at least one element capable of diffusing into the primary fluid when in contact therewith, and of becoming radioactive when exposed to a radiation source.
2. Heat exchanger according to claim 1, characterized in that the coefficient of thermal expansion of the secondary conduit (22) is substantially equal to that of the junction matrix (24).
3. Heat exchanger according to claim 2, characterized in that the element of matrix (24) that is capable of becoming radioactive is silver.
4. Heat exchanger according to claim 3, characterized in that the matrix (24) comprises a binary alloy of silver and copper.
5. Heat exchanger according to claim 4, characterized in that the matrix (24) is obtained by casting, in an inert atmosphere, an eutectic ternary alloy of silver, copper and cadmium, the latter volatilizing during casting.
6. Heat exchanger according to any one of claims 1 to 5, characterized in that the primary conduit (20) comprises an alloy having a high nickel content.
7. Heat exchanger according to any one of claims 1 to 6, characterized in that the secondary conduit (22) comprises stainless steel.
8. Heat exchanger according to any one of claims 1 to 7, characterized in that the primary conduit comprises a straight tube (14) surrounded by a junction matrix (18), which is itself surrounded by a secondary conduit (16) of annular form.
9. Heat exchanger according to any one of claims 1 to 7, characterized in that the primary conduit comprises a straight tube (20) surrounded by a matrix (24), in the interior of which is located the secondary conduit in the form of a coil (22).
10. Heat exchanger according to any one of claims 1 to 7, characterized in that the primary conduit has the form of a coil (26) embedded in a matrix (28) which is itself in contact with a secondary conduit (36) of annular form.
11. Heat exchanger according to any one of claims 1 to 7, characterized in that the primary conduit has the form of a coil (46) embedded in a matrix (47), which is itself in contact with two cylindrical walls, viz. an internal wall (48) and an external wall (50), the internal cylindrical wall (48) separating the matrix (47) from the thread of a first externally-threaded cylindrical member (49), the external cylindrical wall (50) forming the internal wall of a second externally-threaded cylindrical member (51), the secondary fluid circulating in the spaces defined, on the one hand, by the thread of the first threaded member (49) and the internal cylindrical wall (48) and, on the other hand, by the thread of the second threaded member (51) and an external wall (52).
EP82401472A 1981-08-10 1982-08-04 Heat exchanger with double barrier Expired EP0072736B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8115451A FR2511139A1 (en) 1981-08-10 1981-08-10 DOUBLE BARRIER HEAT EXCHANGER
FR8115451 1981-08-10

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EP0072736A1 EP0072736A1 (en) 1983-02-23
EP0072736B1 true EP0072736B1 (en) 1984-07-04

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EP (1) EP0072736B1 (en)
JP (1) JPS5837494A (en)
DE (1) DE3260330D1 (en)
FR (1) FR2511139A1 (en)

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Publication number Priority date Publication date Assignee Title
FR2511139A1 (en) * 1981-08-10 1983-02-11 Commissariat Energie Atomique DOUBLE BARRIER HEAT EXCHANGER
GB2361054B (en) * 2000-02-04 2003-11-26 Nnc Ltd Heat exchanger
US7220381B2 (en) * 2001-06-15 2007-05-22 Avure Technologies Incorporated Method for high pressure treatment of substances under controlled temperature conditions
JP3524083B2 (en) * 2001-11-16 2004-04-26 核燃料サイクル開発機構 Helical heat exchanger with intermediate heat carrier
US20060205332A1 (en) * 2005-03-11 2006-09-14 Flow International Corporation Method to remove meat from crabs
ITBL20090003A1 (en) * 2009-02-04 2010-08-05 Al Ca S R L COMPACT APPLIANCE WITH HEAT PUMP, PARTICULARLY TO HEAT THE DOMESTIC SANITARY WATER.
JP5128544B2 (en) * 2009-04-20 2013-01-23 株式会社神戸製鋼所 Plate fin heat exchanger
AT519081B1 (en) * 2016-09-06 2018-06-15 Andritz Hydro Gmbh METHOD FOR COOLING THE ROTOR OF AN ELECTRIC GENERATOR
GB2586145A (en) * 2019-08-07 2021-02-10 Ibj Tech Ivs Improvements in or relating to heat exchangers

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DE2550329A1 (en) * 1975-11-08 1977-05-18 Interatom THREE-FUEL HEAT EXCHANGER
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FR2511139A1 (en) * 1981-08-10 1983-02-11 Commissariat Energie Atomique DOUBLE BARRIER HEAT EXCHANGER

Also Published As

Publication number Publication date
US4625789A (en) 1986-12-02
FR2511139A1 (en) 1983-02-11
JPS6361599B2 (en) 1988-11-29
DE3260330D1 (en) 1984-08-09
FR2511139B1 (en) 1983-11-10
EP0072736A1 (en) 1983-02-23
JPS5837494A (en) 1983-03-04

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