Sealing device between a tube and a column passing through the latter, method for mounting same

The invention relates to a sealing device (30) intended to be fixed against an edge of a tube and against a column. According to the invention, the body (3060) thereof comprises guides (3030), distributed around its cavity (316) between an inner side (3064) that opens into the cavity (316) and an outer side (3062) that opens out against a concentric clamping ring (305), mounted so as to rotate about the axis (A), fingers (303) integral with outer actuating members (3031) being guided in the guides (3030), the ring (305) having actuating zones (3051) that are able to be positioned against the members (3031) so as make the fingers (303) protrude into the cavity (316) by sliding in order to clamp the fingers (303) against the edge of the tube when the ring (305) and the base (306) are in a first position of relative rotation, the ring (305) and the base (306) being able to pass, by rotation about the axis (A), between the first position and a second position in which the zones (3051) are spaced apart from the members (3031) so as to allow the fingers (303) to be returned into the body (3060).

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a national phase entry under 35 U.S.C. § 371 of International Application No. PCT/EP2016/078070, filed Nov. 17, 2016, which claims priority from French Patent Application No. 1561211 filed Nov. 20, 2015, all of which are hereby incorporated herein by reference.

The invention relates to a sealing device intended to be fixed against an end edge of a tube and against a column needing to pass through the tube, as well as a method for mounting this device.

One field of the invention relates in particular to thermocouple columns disposed on a tube of a cover of a pressurized-water reactor vessel, such as for example a nuclear reactor of a nuclear power plant, these thermocouples needing to measure, through the column entering inside of the vessel, the temperature within it.

Document JPA-10062583 describes a sealing device including a base having three cams for clamping a vertical thermocouple column, including two fixed cams and a cam that is movable by turning a horizontal outer bolt screwed into the base. One disadvantage of this known device is that it carries out clamping of the movable cam against the fixed cams, leading to asymmetries in clamping and therefore in the force applied to the seals, with a risk of jamming Another disadvantage of this device is that the user must take care to avoid having the cams be tilted around the column. Another disadvantage of this device is that the user requires a great deal of time to tighten the bolt so as to clamp the column, which is penalizing in environments with strong constraints on personnel, such as for example a nuclear power plant, inside which personnel can be subjected to ionizing radiation.

Document JP-A-10062584 describes a sealing device including a base having three cams for clamping a vertical thermocouple column, including one fixed cam and two cams movable by the rotation of two handles fixed to them around two vertical axes fixed to the base. One disadvantage of this known device is that it carries out clamping of the movable cams against a fixed cam, leading to asymmetries in clamping and therefore in the force applied to the seals, with a risk of jamming Another disadvantage of this device is that the user must take care to avoid having the cams be tilted around the column. Another disadvantage of this device is that the user must exert considerable force several times to have each of the handles turn, which is penalizing in environments with strong constraints on personnel, such as for example a nuclear power plant, inside which personnel can be subjected to ionizing radiation.

Document JP-A-10048383 describes a sealing device including a base having cams for clamping a vertical thermocouple column, these cams being movable by rotation of two handles fixed to them around two horizontal axes fixed to the base. This device has disadvantages similar to those indicated above for the device known from document JPA-10062584.

The invention aims to obtain a sealing device and a method for its mounting which palliate the disadvantages of the prior art.

To this end, a first subject matter of the invention is a sealing device intended to be fixed against an end edge of a tube and against a column which must pass along an axis of the column through an opening in the tube, delimited by this edge, the device including a base having a feedthrough for the axial passage of the column, a first sealing member capable of being activated to be pressed against the column in the feedthrough, a body surrounding around the axis a cavity for receiving the edge of the tube and a second sealing member intended to be pressed against the edge of the tube in the cavity, the feedthrough communicating axially with the cavity,

characterized in that the body includes a plurality of guides, which are distributed around the cavity and which extend between an inner side which opens into the cavity and an outer side which opens against a concentric clamping ring, rotatably mounted around the axis with respect to the base,

a plurality of inner fingers integral with a plurality of outer actuating members being guided respectively in the plurality of guides around the cavity, the ring including a plurality of actuation zones which are mutually distant and which are capable of being positioned against respectively the plurality of outer actuating members to cause the inner fingers to slide and to protrude in the cavity for clamping the fingers against the edge of the tube when the ring and the base are, with respect to one another, in a first relative rotational position, called first tube edge clamping position,

the ring and the base being capable of passing, by rotation with respect to one another around the axis, between one and the other of the first relative rotational position and a second relative rotational position, called tube edge unclamping position, in which the plurality of actuation zones is at a distance from the plurality of outer actuating members to allow the fingers to be retracted into the body.

Thanks to the invention, clamping reliability and the intervention time of personnel to implement the fixing of the device are improved, which is particularly advantageous in environments with strong constraints on personnel, such as for example a nuclear power plant, inside which personnel can be subjected to ionizing radiation. The invention thus allows, with a single manipulation of rotation from the second to the first position, to uniformly and almost simultaneously clamp all the fingers against the tube, thus avoiding any jamming or incorrect positioning.

According to one embodiment of the invention, the plurality of guides extends radially with respect to the axis for the radial guidance of the fingers with respect to the axis.

According to one embodiment of the invention, the base and/or the body is integral with at least a first handle, and the ring is integral with at least a second handle.

According to one embodiment of the invention, the base includes a lock for blocking the ring and the body in their first relative rotational position, the lock being connected to a manual actuation means allowing the lock to be unlocked to allow passage from the first relative rotational position to the second relative rotational position.

According to one embodiment of the invention, the plurality of actuation zones comprises respectively a plurality of portions of the inner surface of the ring, separated from one another around the axis by a plurality of recesses of this inner surface, which are farther from the axis than its portions and which are used for the reception, respectively, of the plurality of outer actuating members in the second relative rotational position.

According to one embodiment of the invention, each recess has a first slope, starting from the portion of the inner surface of the ring and extending away from the axis until a bottom of the recess, for guiding the outer actuating member between one and the other of a first position retracted into the guide in the first relative rotational position and a second position protruding in the bottom in the second relative rotational position.

According to one embodiment of the invention, each outer actuating member comprises a cam having a second slope turned toward the ring and rising in the same direction as the first slope.

According to one embodiment of the invention, each guide includes a biasing element for biasing the outer actuating member to move toward the ring.

According to one embodiment of the invention, the first sealing member includes a first dynamic seal, adjoining the feedthrough and capable of being activated by inflation by injection of a fluid via an endpiece of the base to press a portion of the first seal against the column in the feedthrough.

According to one embodiment of the invention, the sealing includes movement transmission means for pressing the second sealing member against the edge of the tube, when the ring and the base pass from the second relative rotational position to the first relative rotational position.

According to one embodiment of the invention, the second sealing member includes a second seal turned in a first direction of the axis toward a first surface of the edge of the tube, the movement transmission means include on each finger a second support surface for bearing against a second surface of the edge, which is axially distant from the first surface, this second support surface rising in a second direction, which is reverse of the first direction and runs from the inside to the outside, to press the second seal toward the first surface, when the finger slides in the cavity from the outside to the inside until the first tube edge clamping position.

According to one embodiment of the invention, at least three fingers are provided, of which at least two are positioned in a first 180° angular sector around the axis and of which at least one other is positioned in a second 180° angular sector complementary to the first sector in the first tube edge clamping position.

According to one embodiment of the invention, the sealing device includes removable fixing means of at least one plug to plug the feedthrough in the absence of a column in the latter.

A second subject matter of the invention is a method for mounting the sealing device as described above against an end edge of a tube and against a column which must pass through an opening in the tube, delimited by this edge, along an axis of the column, the sealing device including movement transmission means for pressing the second sealing member against the edge of the tube, when the ring and the base pass from the second relative rotational position to the first relative rotational position for clamping against the edge of the tube, a method in which the ring and the base are rotated with respect to one another around the axis from the second relative rotational position to the first relative rotational position, for clamping the base against the edge (281) of the tube and for pressing the second sealing member against the edge of the tube, then the first sealing member is activated to press it against the column in the feedthrough.

First described below with reference toFIGS. 1 and 2, is a context to which the sealing device according to the invention and the mounting method according to the invention can be applied. Of course, the invention can be applied to different contexts.

FIG. 1shows a nuclear power plant. Thermal energy is produced by its nuclear reactor (6) formed by fissile fuel (2) cooled by water (16), all placed in the vessel (1).FIG. 2shows a fissile fuel element (5). The hot water (7) produced passes through a steam generator (8) through hundreds of inverted-U-shaped loops (9) with a very great height (H) with respect to the reactor, in particular with respect to the seal plane (10) of the vessel (1) on which the cover (3) rests. The heat of the loops will bring the water of a secondary circuit (11) to the vapor state (13), which will actuate turbines (14), themselves driving generators (15) producing electricity.

The tube (28) is welded to the cover (3). Inside the tube (28) passes a thermocouple column (27) passing through the cover (3) inside of the tube (28).

In use, it is important to control the power of the reactor (6) by monitoring in particular the temperature of the fuel assemblies (5) of the core (2) and more precisely the temperature of the water (16) that cools it. To this end, an internal instrumentation (17), called the upper instrumentation, above the core as shown inFIG. 2, allows power control and temperature measurement by thermocouples (26) movable in the top of the core. These thermocouples (26) are guided in the columns (27) which pass through the cover (3) and which are retained by tubes (28) which pass through the cover (3), which are welded to the latter while emerging in the outer portion of the latter, i.e. in the enclosure (18) of the reactor building.

The water of the reactor being under 155 bars pressure, it is indispensable that sealing between the columns (27) and the tubes (28) be ensured during operation, certain sealing systems, hereafter called dedicated sealing systems and not shown, being previously mounted to this end on the columns (27) and the tubes (28) for sealing between them during the operation of the reactor. When the reactor is shut down, the cover (3) is removed, which mechanically imposes the removal of these dedicated sealing systems between the columns (27) and tubes (28).

Yet, a particular maintenance operation called Vacuumization of the primary circuit for filling it with water necessitates the temporary replacement of the cover (3) on the vessel (1). As in this case, the thermocouple column (27) has been stripped of its dedicated sealing systems, the sealing function must again be provided for. Sealing must again be provided for between the column (27) and the tube (28) or the flange (40). When the reactor is shut down for the Vacuumization, the pressure of the core is at atmospheric pressure compared with the 155 bars during operation and the sealing function is generally provided by another sealing device, and not by the dedicated sealing systems. In fact, the parts of the dedicated sealing systems are sensitive to manipulation and impose additional dosimetry. But this temporary solution is not satisfactory. It leads to operations that are penalizing overall; first as regards duration, hence cost, and consequently unnecessarily increases individual and collective personnel dosimetry, while remaining within the authorized limits for working exposed to radiation.

One of the problems resolved by the present invention is to improve this situation during the Vacuumization test of the primary circuit of a nuclear power plant, carrying out the cover (3) of the vessel. The sealing device according to the invention allows the sealing function of the thermocouple columns to be provided during Vacuumization (MSV) tests of the primary circuit, with core unloaded, of a nuclear power plant. The solution is applicable when the use of the real cover (that is the cover (3) used during the operation of the reactor) for vacuumization is unavoidable for different reasons, for example the unavailability of a dummy cover in another embodiment of the vacuumization. The invention improves and makes reliable the sealing accomplished around the thermocouple columns (27) and simplifies the insertion mode by eliminating human interventions in the bottom of the pool, near the cover of the vessel, and costly in integrated collective dosimetry.

The principles of the procedure for vacuumization (called MSV below) are recalled below, and the sealing function of the thermocouple columns (27), during operation and in the test situation of filling the primary circuit during Vacuumization according to the prior art.

Once the reactor is shut down, the cover (3) is removed from the vessel (1) and set aside. The fuel (5) is unloaded.

Before loading the new core, it is necessary to fill the primary circuit and to leave no air volume inside it. During the filling of a reactor loop, at atmospheric pressure, the hydrostatic equilibrium of the water levels does not allow the height of the vessel seal plane (10) to be exceeded, due to the height (H) which separates the vessel seal plane (10) and the top (19) of the loops (9).

To complete the filling and to fill with water the upper portion of the loops, and therefore to drive out the air which is trapped there, a Vacuumization (MSV) operation is carried out.

Document FR-A-2 921 510 describes in detail this method implemented on a dummy cover. This method is applicable to the “real cover” (3).

The Vacuumization (MSV) method includes the following steps.

After the shutdown of the reactor and resetting the primary circuit pressure to Atmospheric Pressure,The cover (3) is removed, the dedicated sealing system of the devices (27,28) is replaced, according to the prior art practice, with caps for protection of the female flanges (40).The core is unloaded, the primary circuit is purged for maintenance of the stop of the nuclear plant unit.When maintenance is finished, the primary circuit must be filled.The cover (3) is placed, by depositing it on a silicone seal on the vessel seal plane (10) which seals the primary circuit at atmospheric pressure, a provisional sealing system is installed around the thermocouple columns (27) and a vacuum is created in the primary circuit, to approximately 300 mb; this depressurization increases the sealing effect at the silicone seal.The primary circuit is filled to the highest possible level in the loops, leaving air pockets present, however (filling step).Vents are then opened to break the vacuum, which causes the water to circulate toward the top of the loops; the water level in the vessel drops. The pressure returns to Atmospheric pressure.The water is partially purged up to the vessel seal plane (10), the provisional sealing system is withdrawn, then the protection caps are placed again. The vessel seal plane is in the vicinity of the bottom level of the pool.The cover (3) is withdrawn, the filling of the vessel continues.The core is loaded.The cover (3) is placed again and bolted to the vessel.The protection caps are removed, then the normal seals used for operation are placed again.

These steps in the MSV impose the sealing of the thermocouple columns. As shown byFIG. 2, the water filling step leads to filling the totality of the vessel (1) and its cover (3) with water; said water being able to infiltrate the feedthroughs of the cover from which the tubes (28) welded to the cover (3) emerge. During the installation or the removal of the cover (3), the column slides to some extent inside the tube (28), this after having withdrawn all the other devices ensuring sealing disposed in the upper portion.

Described below with reference toFIGS. 3 to 8is the sealing device according to the invention.

The sealing device30according to the invention is intended to be attached against an end edge281of a tube28and against a column27. The column27must pass through, along an axis A of the column27, an opening285of the tube28, this opening285being delimited by this edge281. The column27has for example an outer cylindrical surface, possibly circularly cylindrical around the axis A. The column27can be any column allowing measuring instrumentation for measuring one or more parameters to pass, from the end edge281of the tube28into the space situated at the other end of the tube28(inside of the vessel1in the application example mentioned above), such as for example one or more temperatures, for example by one more thermocouples, or other parameters.

The sealing device30includes a base306having a feedthrough3061for the passage of the column27along the axis A. The sealing device30further includes a first sealing member310for providing sealing against the column27in the feedthrough3061. According to one embodiment, the first sealing member310is capable of being activated to be pressed against the column27in the feedthrough3061. When the first sealing member310is not activated, the column27can slide along the axis A in the feedthrough3061.

The sealing device30further includes a body3060, which surrounds, around the axis A, a cavity316used to receive the edge281of the tube28. The sealing device30further includes a second sealing member304intended to be pressed against the edge281of the tube28in the cavity316. The feedthrough3061is connected, in a direction running parallel to the axis A, with the cavity316. The feedthrough3061has a transverse dimension (for example a transverse diameter) which is less than the transverse dimension (for example a transverse diameter) of the cavity316, the transverse direction being taken with respect to the axis A passing through this transverse direction, which is for example perpendicular to the axis A.

According to the invention, the body3060includes a ring305rotatably mounted around the body3060, this ring305serving to concentrically clamp a plurality of fingers303guided in guides3030against the edge281of the tube28. The body3060includes a plurality of guides3030, which are distributed around the cavity316and which extend between an inner side3064of the body3060, which opens into the cavity316and an outer side3062which opens against the ring305. The ring305is rotatably mounted around the axis A with respect to the base306. The ring305surrounds the body3060and is therefore situated outside this body3060. The ring305has for example an annular shape. The ring305is for example rotatably mounted in a peripheral groove3066of the body3060, delimited by an upper wall3067aand a lower wall3067b, separated from one another along the axis A. The ring305can for example be made in the form of two halfrings around the axis A.

Hereafter, the direction running from the outside to the inside is a direction approaching the axis A or the column27or the cavity316.

A plurality of inner fingers303is provided, which are integral respectively with a plurality of outer actuating members3031. The plurality of outer actuating members3031are guided respectively in the plurality of guides3030around the cavity316. The ring305comprises a plurality of mutually distant actuation zones3051capable of being positioned against, respectively, the plurality of outer actuating members3031to cause the fingers303to slide and to protrude in the cavity316for clamping the fingers303against the edge281of the tube28, when the ring305and the base306are in a first relative rotational position relative to one another, called the first tube28edge281clamping position, shown inFIG. 6.

The ring305and the base306are capable of passing, by rotation with respect to one another around the axis A, between one and the other of the first relative rotational position and a second relative rotational position, called the tube28edge281unclamping position. In this second relative rotational position, shown inFIG. 7, the plurality of actuation zones3051is at a distance from the plurality of outer actuating members3031to allow the fingers303to be retracted into the body3060. It is in this second unclamping position that the sealing device30can be slid around the column27and the edge281or be removed from them.

Thus, the ring305is a concentric ring305for clamping the fingers against the edge281of the tube28. The ring305thus allows a uniform distribution of the clamping force around the tube28to be ensured, by carrying out a single rotation action around the column27. This invention thus allows saving manipulation and installation time of the sealing device30, as well as reliability in clamping and reliability in sealing.

The body3060can for example have a generally annular shape around the axis A and the cavity316. The base306includes for example an upper portion3063delimiting the feedthrough3061and connected or fixed or in a single piece with the body3060. The upper portion3063can for example have an annular shape around the axis A and around the feedthrough3061. The upper portion3063can be formed for example by a first overriding plate and fixed to a second plate forming the body3060, these plates extending transversely and for example perpendicular to the axis A.

In the embodiment shown in the figures, the inner side3064of the body3060is cylindrical around the axis A, for example circularly cylindrical around the axis A. The outer side3062of the body3060is for example cylindrical around the axis A, for example circularly cylindrical around the axis A. The ring305is for example cylindrical around the axis A, for example circularly cylindrical around the axis A.

The guides3030are arranged to ensure guidance of their respective finger303from the outside to the inside with respect to the axis A, that is to cause the fingers303to approach for example this axis A, and in the reverse direction. In the embodiment shown inFIGS. 6 and 7, the guides303are rectilinear. Of course, in other embodiments not shown, the guides303could be curved. According to the embodiment shown inFIGS. 6 and 7, the plurality of guides3030extends radially with respect to the axis A for the radial guidance of the fingers303with respect to the axis A. Of course, the guides3030may not extend radially with respect to the axis A and can extend obliquely.

According to the embodiment ofFIG. 4, it can be provided under the lower portion of the body3060, that is under its portion distant from the sealing members310,304along the axis A, a ring3065delimiting the guides3030and allowing, when the ring3037is dismantled, the insertion of the fingers303, the actuating members3031and the parts fixed to them in the guides3030. The ring3065can be fixed to the body3030by removable fixing means, for example by bolts3038or by nonremovable fixing means, for example by rivets3038.FIGS. 6 and 7are shown without showing the lower wall3067band the portion3065, so as to show the elements present in the guides3030.

According to one embodiment, the base306and/or the body3060is integral with at least one first handle314, while the ring305is integral with at least one second handle301. Thus, the handles301and314allow the user to cause the ring305and the base306to turn with respect to one another around the axis A to cause the fingers303to pass from one to the other of the first clamping position to the second unclamping position. For example, the handle301is fixed to the ring305through an outer arm3010.

According to one embodiment, the base306includes a lock307for blocking the ring305and the body3060in their first relative rotational position. The lock307is connected to a manual actuation means3070, for example in the form of a cylindrical button overriding the lock307, this means3070allowing the lock307to be unlocked to allow passage from the first relative rotational position to the second relative rotational position. Thus, the lock307allows the fingers303to be blocked in the first tube28edge281clamping position. The lock307includes for example a first lock portion3071capable of retracting into a hollow3072of the ring305or of an outer arm3010fixed to it, to block this ring305in the first clamping position. The manual actuation means3070is provided to raise the first portion3071of the lock and remove it from the hollow3072so as to unlock the lock307. A preloading means can be provided on the first portion3071of the lock to load it toward the ring305or toward the arm3010, so that this portion3071is automatically engaged in the hollow3072in the first clamping position.

According to one embodiment, the plurality of actuation zones3051comprises respectively a plurality of first portions3052of the inner surface3053of the ring305. These portions3052of the inner surface3053of the ring305are separated from one another by a plurality of recesses3054of this inner surface3053. These recesses3054are farther from the axis A than the first portions3052of the inner surface3053of the ring305and are used for the reception, respectively of the plurality of outer actuating members3031in the second relative rotational position, that is in the unclamping position.

According to one embodiment, each recess3054has a first slope, which begins in the first adjacent portion3052and which moves away from the axis A until a bottom3055, to guide the outer actuating member3031between one and the other of a first position retracted in the guide3030in the first relative rotational position, that is the clamping position, and a second protruding position in the bottom3055of the recess3054in the second relative rotational position, that is in the second unclamping position. Thus, when the ring305is rotated in a first clamping direction of rotation S1around the axis A with respect to the body3060or to the base306, that is from the second position to the first position, each actuating member3031slides against the second portion3056of the inner surface3053delimiting the recess3054, from the bottom3055to the first portion3052, which constrains the actuating member3031and therefore the finger303fixed to it, to slide in the guide3030from the outside to the inside to approach the axis A and thus cause the finger303to extend beyond the inner side3064in the cavity316. When the ring305is rotated with respect to the body3060or to the base306in an unclamping direction of rotation S2, the reverse of the first direction S1, around the axis A, each actuating member3031is made free to slide toward the outside in the guide3030against the second portion3056of the surface3053delimiting the recess3054, to pass from the first portion3052to the bottom3055and cause the finger303to slide from the inside to the outside until this finger303no longer extends beyond the inner side3064and no longer protrudes into the cavity316in the second unclamping position.

According to one embodiment, each outer actuating member3031comprises a cam3032having a second slope turned toward the ring305and rising in the same direction as the first slope. Thus, the cam3032can slide along the first slope of the second portion3056delimiting the recess3054. Of course, the first slope may not be identical to the second slope, as is shown inFIGS. 6 and 7.

According to one embodiment, each guide3030includes a biasing element3033for biasing the outer actuating member3031to move toward the ring305, that is from the inside to the outside. This biasing element3033is therefore provided to constrain the finger303to move from the cavity316to the outside, in other words to retract the finger303into the body3030. This biasing element3033can be formed from one or more spring(s). For example, the outer actuating member3031is fixed to its respective finger303through a stem3034. The biasing element3033can be provided between an abutment part3035fixed to the body3060in the guide3030and the outer actuating member3031, for example by including a compression spring between the abutment part3035and the member3031. As a variant, the biasing element3033can be provided between an abutment part3035fixed to the body3060in the guide3030and the finger303, for example by including a draw spring between the abutment part3035and the finger303. Thus, the actuating member3031is pressed by the biasing element3033against the inner surface3053of the ring305, namely against its first portion3052closer to the axis A in the first clamping position, against the second portion3056during passage from the first clamping position to the second unclamping position and against the bottom3055of the recess3054in the second unclamping position.

According to one embodiment, the first sealing member310includes a first dynamic seal300, which adjoins the feedthrough3061and which is capable of being activated by inflation by injection of a fluid via an endpiece302of the base306to press a portion311of the first seal300against the column27in the feedthrough3061. This dynamic seal300is for example annular in the feedthrough to surround the column27around the axis A. The endpiece302communicates through inner recesses312with the first seal300, to allow a fluid to be sent into this seal300from the endpiece302. The endpiece302is able to be connected to an outer duct for sending fluid. The injection of the fluid through the endpiece302from the outside duct fills the dynamic seal300and deforms it to cause a movement of its portion311in the centripetal direction, that is toward the column27, so that the portion311of the seal300is supported against the column27so as to provide a sealing barrier around it.

According to one embodiment, the sealing device30includes movement transmission means3036to press the second sealing member304against the edge281of the tube28, when the ring305and the base306pass from the second relative rotational position to the first relative rotational position, that is to clamp the edge281of the tube28.

According to one embodiment, the second sealing member304includes a second seal3040, which is turned in a first direction A1of the axis A toward a first surface282of the edge281of the tube28, this surface282being transverse to the axis A and in particular perpendicular to the axis A. The movement transmission means3036include a second support surface3037, situated on each finger303. The second support surface3037of each finger303is used to press against a second surface284of the edge281, the surface284being for example parallel to the surface3037. This second surface284is distant from the first surface282along the axis A. This second support surface3037rises when approaching the first surface282while moving away from the axis A. This second support surface3037rises in a second direction A2of the axis A (the reverse of the first direction A1) running from the inside to the outside, to press the second seal304toward the first surface282, when the finger303slides in the cavity316from the outside to the inside until the first edge281clamping position. The second support surface3037rises for example in the same direction as the surface284which is for example a rear surface284of the rim of the edge281, axially distant from the first surface282. Thus, the movement from the outside to the inside of the finger303to arrive in the first clamping position causes, through the support surface3037, the movement of the second seal3040in the first direction A1toward the first surface282of the edge281. In addition, the edge281includes a lateral outer surface283, which is for example parallel to the axis A and which is connected, on the one hand, to the surface282and on the other hand to the surface284. The finger303includes for example another surface3037bfarther from the axis A than its surface3037and parallel to the axis A, for support against the lateral outer surface283.

According to one embodiment, at least three fingers303are provided as fingers303, hence at least two303a,303bare positioned in a first 180° angular sector SEC1around the axis A, and at least one303cis positioned in a second 180° angular sector SEC2complementary to the first sector SEC1in the first tube28edge281clamping position, as shown inFIG. 6. Three fingers303can for example be provided. Of course, four fingers303or a greater number of fingers303can be provided.

According to one embodiment, fingers303are distributed in an equiangular manner around the axis A in the first clamping position. Thus, in the case of three fingers303, these can be regularly distributed at 120 degrees from one another around the axis A. In the case of four fingers303, these can be distributed at 90 degrees to one another around the axis A.

The sealing device30can be used with or without EIS (lower inner equipment) that is with or without a column27. In one embodiment inFIG. 8, in the case of use without EIS, that is without the column27, but where the sealing device30must be clamped around the edge281of the tube28, one or more plugs3068can be installed and fixed to the base306for plugging the feedthrough3061, as shown inFIG. 8. The plug3068is fixed to the upper portion3063, for example by removable fixing means3069, which can be of the bolting type or another.

The invention also relates to a method for mounting the sealing device30described above against an end edge281of a tube28and against a column27which must pass through an opening285of the tube28along axis A, delimited by this edge281, the sealing device30including the movement transmission means3036described above.

According to this method, during a first step, the ring305and the base306are rotated with respect to one another around the axis A from the second relative rotational position to the first relative rotational position (i.e. in the first clamping direction S1), for clamping the base306against the edge281of the tube28and for pressing the second sealing member304against the edge281of the tube28.

Then, during a second step, the first sealing member310is activated to press it against the column27in the feedthrough3061.

The sealing device30according to the invention and the method for mounting it according to the invention can be used to be fixed around and accomplish sealing on the edge281of a tube28fixed to the cover3of a vessel1of a nuclear reactor, as shown inFIGS. 1 and 2and as described above and on the thermocouple column27of this vessel1.

In the preceding, the edge281to which the sealing device must be fixed according to the invention can be a flange40, itself welded to the tube28, itself welded to the cover3, the flange40and the tube28having the column27passing through them as shown inFIG. 9, the flange40including the portions281,282,283,284and285described above. The tube28can be an adapter tube28, adapted to allow the sealed exit of a column27within which are located movable probes26having the function of thermocouples.

Thus, the vacuumization procedure of this vessel1of a nuclear reactor using the sealing device30according to the invention can be the following.

At the time when the dedicated sealing systems are withdrawn, when the cover3is still on the vessel1after the stop of the nuclear plant unit, the sealing device30is placed and locked to the edge281of the tube28in the first clamping position, by rotation of the base306and the ring306in the first direction S1of one with respect to the other.

Then, the cover3is removed with respect to the vessel1and this cover3is set aside. In another embodiment, these first two steps can be congruent, the installation and the locking being able to be accomplished once the cover is set aside.

The mouthpiece of a pression fluid duct is then disposed on the endpiece302of the device30.

Then, the cover3is put back on the seal plane10of the vessel1to begin the vacuumization operation, the device30being equipped with its duct for the injection of fluid under pressure.

Then, from a distant console, a vacuumization action of the duct is commanded to inflate the dynamic seal300and insure sealing around the column27.

Afterward, a rest period is provided to observe any deviation of pressure, which would be a sign of a leak or a malfunction of the dynamic seal300.

Then, the MSV and filling of the primary circuit procedure as described above is implemented.

At the end of this MSV and filling of the primary circuit procedure, the vacuum of the primary circuit being broken and considering the return to atmospheric pressure, the dynamic seal300is remotely operated to be unclamped by releasing the compression fluid.

Then, in order to guarantee total release of the column27, a slight depression is created in the dynamic seal300.

Then, the cover3comprising the device30installed on it is set aside, and the loading of the core can begin.

The injection duct is then removed from the endpiece302.

The sealing device30is then unlocked with respect to the edge281of the tube28in the second unclamping position, by rotation of the base306and of the ring306in the second direction S2with respect to one another. The device30is then removed with respect to the tube28and the column27.

The cover, without the device30, can then be remounted on the seal plane10of the vessel1.

The present invention contributes to improving the current situation, in particular it reduces to less than a minute the exposure time to ionizing radiation. It allows time to be saved over the critical path by operating in hidden time. It makes environmental systems lighter by allowing scaffolding customarily provided in the prior art at the bottom of the pool surrounding the vessel1to be dispensed with, and as a result it reduces costs for the operator.

The main application of the present invention is the achievement of sealing around the thermocouple columns27passing through the cover3of the vessel1for the purpose of achieving a vacuumization of the primary circuit following the filling of the loops, in the context described above with reference toFIGS. 1 and 2.

A secondary use of the invention consists of using the sealing device30as a protective sealing surfaces. Indeed, these sealing surfaces are very sensitive and their possible repairs prove to be very delicate.

The invention allows a reduction in the exposure time of personnel to ionizing radiation, with particularly a reduction in the overall time spent in the bottom of the pool (scaffolding assemblers, vessel work operators) and a gain of approximately 3.5 mSv/vacuumization (estimated values).

The invention allows a reduction of the intervention time of personnel, with in particular improved reliability and safety of sealing around the columns27, installation of the tooling in hidden time, a gain of approximately 3 hours and 45 minutes/vacuumization.

The invention allows an improvement in safety, with in particular elimination of the need for access to the cover3by scaffolding at the bottom of the pool, which would generate a fall risk, elimination of the mounting of scaffoldings (manual handling).