FR3048116A1 - TANK PENETRATION ASSEMBLY OF A NUCLEAR REACTOR - Google Patents

Abstract

The invention relates to a penetration assembly (100, 300, 400, 500) of a tank (10) of a nuclear reactor that can be installed in a vessel orifice (20) (10) of a nuclear reactor, said penetration assembly comprising: a through body (110) passing through said vessel port (20), said through body (110) having a first end adapted to be positioned within the vessel (10) and a second end capable of to be positioned outside the tank (10); a radial clamping device (120, 320, 420, 520) radially clamping said through body (110) and forming a sealing barrier of the bushing; said penetration assembly (100) being characterized in that the radial clamping device (120, 320, 420, 520) is formed by: a conical member (123, 323) having a top and a base, said top being oriented towards the interior of the vessel (10) of the reactor; a screwing element (122, 322, 422, 522) exerting a compressive force on said conical element (123, 323) to provide radial clamping of said through body (110) and the sealing of the penetration.

Description

TANK PENETRATION ASSEMBLY OF A NUCLEAR REACTOR

TECHNICAL FIELD OF THE INVENTION

The invention relates to the field of penetration assemblies, such as for example assemblies of electrical penetrations (EPA for electrical penetration assembly) through the nuclear reactor vessels.

The invention finds a particularly interesting application in the field of integrated nuclear reactors and small modular reactors also called SMR (for Small & Modular Reactor in English) with many actuators / sensors in tank creating specific needs of tank penetrations, such as electrical penetrations. An application in conventional pressurized reactors is possible replacing the fingers of gloves known from the state of the art.

The electrical penetrations of the tank must meet several criteria. They must be dismountable for the dismantling operations of the tank internals at the outage, guarantee a continuity of the containment barrier with the principles of the regulations of design, manufacture, inspection and control in service, and not cause significant gaps in the event of breakage of the penetration (electric cable or thermowell).

SUMMARY OF THE INVENTION

In this context the invention seeks to provide a tank penetration assembly of a dismountable nuclear reactor to ensure the continuity of the confinement barrier while allowing to reduce the size of the breach in case of rupture at the level of of the body passing through.

To this end, the invention relates to a vessel penetration assembly of a nuclear reactor adapted to be installed in a reactor vessel orifice, said penetration assembly comprising: a through-body passing through said vessel orifice, said through body having a first end adapted to be positioned inside the vessel and a second end adapted to be positioned outside the vessel; - A radial clamping device radially clamping said through body and forming a sealing barrier of the bushing; said penetration assembly being characterized in that the radial clamping device is formed by: - a conical element having a top and a base, said top being directed towards the inside of the reactor vessel; - A screw member exerting a compressive force on said conical element to ensure the radial clamping of said through body and the sealing of the penetration.

The penetration assembly according to the invention may also have one or more of the features below taken individually or in any technically possible combination: the body through has an outer envelope acting as a second barrier for confining the primary fluid ; said outer casing is secured by welding on said screw element; said screw member comprises a ferrule adapted to be secured to the vessel; the body passing through is an electrical cable surrounded by a sheath forming said outer envelope; the through body is a thermowell having an outer wall, the outer wall of the thermowell forming said outer casing.

The invention also relates to a nuclear reactor vessel characterized in that it comprises: - an orifice for the passage of a through body, said orifice having: - a first portion of cylindrical shape having an opening end outside the tank; - A second portion of cylindrical shape having an end opening into the vessel and having a diameter smaller than the first portion; a third portion of conical shape connecting the first part to the second part; a penetration assembly according to the invention comprising: a through body passing through said tank orifice; - A radial clamping device radially clamping said body through and forming a barrier against penetration.

Advantageously, the first cylindrical portion of said orifice comprises a thread and the peripheral periphery of said screw member comprises a thread complementary to said thread formed inside the first cylindrical portion of said orifice.

The invention also relates to a nuclear reactor comprising a vessel according to the invention.

[0010] Advantageously, the reactor is an integrated reactor or a small modular reactor.

The invention also relates to a method of mounting a penetration assembly according to the invention in an orifice of a vessel of a nuclear reactor, said penetration assembly comprising a body passing through said vessel orifice and a radial clamping device, said method being characterized in that it comprises: a step of introducing said through body through said orifice from the inside to the outside of the tank; a step of positioning in said orifice of said radial clamping device formed by a conical element and by a screwing element, the positioning being effected by the outside of the tank; a step of clamping said radial clamping device by the outside of the tank so as to mechanically real estate said through body, said clamping being able to withstand the pressure of the primary fluid.

Advantageously, the clamping step is performed by rotation of said screw member towards the inside of the orifice, said rotation generating a translation of the radial clamping device until the generation of a compression force of said element screwing on said conical element, said compression force being able to elastically deform said conical element so that said conical element ensures a radial clamping of said through body.

Advantageously, said method comprises a step of securing the outer casing of the through body on said screw element at the end of said through body positioned outside the vessel.

Advantageously, prior to said step of securing the outer casing of the through body to said screw member, the method comprises a step of deforming said outer casing of the through body at the end positioned outside. of the tank.

Advantageously, the deformation step of said outer casing of the through body is made by stamping in situ of said outer casing by means of a punch and a matrix.

Advantageously, said method comprises a step of securing said screw member to said tank.

BRIEF DESCRIPTION OF THE FIGURES

Other features and advantages of the invention will become apparent on reading the description which follows, with reference to the accompanying figures.

[0018] Figure 1 illustrates a sectional view of a nuclear reactor vessel portion comprising a first embodiment of a vessel penetration assembly according to the invention.

Figure 2 illustrates a block diagram illustrating the main steps of the mounting method according to the invention.

FIG. 3 illustrates a sectional view of a portion of a nuclear reactor vessel comprising a second embodiment of a vessel penetration assembly according to the invention.

[0021] Figure 4 illustrates a sectional view of a nuclear reactor vessel portion comprising a third embodiment of a vessel penetration assembly according to the invention.

FIG. 5 illustrates a sectional view of a nuclear reactor vessel portion comprising a fourth embodiment of a vessel penetration assembly according to the invention.

In all the figures, the common elements bear the same references unless otherwise specified.

The terms upstream and downstream used in the patent application are defined by considering the direction of flow of the primary fluid in case of leakage, that is to say from the inside to the outside of the tank of the nuclear reactor.

DETAILED DESCRIPTION OF AN EMBODIMENT

FIG. 1 illustrates a sectional view of a first embodiment of a penetration assembly 100 according to the invention installed in an orifice 20 of a tank 10 of a nuclear reactor, of integrated type, or SMR, allowing the passage of a through body 110 while sealing the crossing and respecting the spirit of the design regulations imposed in the field of pressurized reactors and SMR in particular, namely the prevention of primary leaks and limiting the consequences of possible failures.

The tank penetration assembly according to the invention is for example an electrical penetration tank assembly (V-EPA for Vessel Electrical Penetration Assembly) 100 for the passage of an electric cable 110. The electric cable 110 is for example a cable comprising a plurality of conductors 111 isolated from each other by a mineral insulator 112. The assembly is enclosed in a sheath 113 forming an outer envelope, the outer envelope serving as an extension of the second confinement barrier.

The penetration assembly 100 further comprises a radial clamping device 120 inserted into the orifice 20 of the tank 10 to immobilize the electrical cable 110 in position in the bushing, to ensure immobilization of the electrical cable to conditions of pressure and temperature of the primary liquid and to ensure a double barrier of sealing of the crossing.

The orifice 20 formed in the vessel 10 of the reactor is composed of: a first part 21 substantially cylindrical in shape opening out of the vessel and having a diameter referenced De, a second portion 22 substantially of cylindrical shape opening inside the vessel and having a diameter Di, the diameter Di of the second portion 22 being smaller than the diameter De of the first portion 21 and substantially equivalent to or slightly greater than the outer diameter of the electric cable 110 or the body passing through the tank 10; a third portion 23 located between the first portion 21 and the second portion 22, the third portion having a conical shape connecting the first portion 21 and the second portion 22 of the orifice 20.

In the first embodiment shown in Figure 1, the radial clamping device 120 is formed by a conical element 123 defined by a base and a top, also called conical olive, cooperating at its base with an element. The clamping element 122 has the function of a nut and has a substantially cylindrical shape having a thread formed on its periphery. A complementary thread is provided inside the first portion 21 of the orifice 20 so that the rotation of the screwing element in the first portion 21 of the orifice generates a longitudinal translation along the axis of revolution. of the orifice 20 thereof and the conical element 123.

Thus, during the clamping of the radial clamping device 120, the conical element 123 is intended to come into contact with the conical portion 23 of the orifice 20.

The radial clamping device 120 is a device mounted by the outside of the tank and ensures the primary containment barrier of the nuclear reactor and the holding in position of the cable 110. The clamping of the radial clamping device 120 makes it possible to withstand the pressure conditions of the primary liquid inside the reactor.

The radial clamping device 120 also ensures the second containment barrier of the reactor when it is in place. For this purpose, the radial clamping device 120 comprises a first weld between the outer casing of the electric cable 110, ie the sheath 113 of the electric cable 110, and the screwing element 122 as well as between the screwing element 122 and the tank 10 of the reactor.

[0033] Figure 2 illustrates a block diagram illustrating the main steps of a method for mounting a penetration assembly described above in Figure 1 in a nuclear reactor vessel port.

In a first step 201, the through body, for example an electric cable 110 with a stainless steel sheath and a mineral insulator as described above is slid into the orifice 20 by the hot side, ie by the interior of the nuclear reactor.

A second step 202 consists in positioning in the orifice 20 the radial clamping device 120 formed by the conical element 123 and by the screwing element 122. The radial clamping device is inserted through the outside of the tank 10.

A third step 203 consists in mechanically immobilizing the electrical cable 110 in the orifice 20. For this, the radial clamping device 120 is put in place in the orifice 20 by the outside of the orifice 20 and around. of the electric cable 110. In this step 202, the screwing element 122 is screwed inside the orifice 20 generating a translation of the conical element 123 towards the inside of the reactor vessel. When the conical element 123 comes into contact with the conical wall of the conical portion 23 of the orifice 20, an additional tightening of the screwing element 122 exerts a pressure at the base of the conical element 123 which is constrained radially by the conical wall. The tightening of the radial clamping device 120 thus makes it possible, via the conical element 123, to clamp the electrical cable 110 radially. The conical element 123 being immobilized in translation on the one hand by the conical part of the orifice 20 and on the other by the clamping element 122 mechanically held by the cooperation of the threads, the electric cable 110 is thus also immobilized in the orifice 20.

A fourth step 204 consists of securing the outer end of the insulating sheath 113 of the electric cable 110 to the screwing element 122. In the first embodiment illustrated in FIG. 1, this fourth step is carried out by: a first sub-step of deforming the outer end of the insulating sheath 112 by means of a die and a punch (not shown) so as to bring the insulating sheath 112 closer to the screw element 122; in the exemplary embodiment illustrated in FIG. 1, the female die is for example a conical die in half-shell (for the hot side) and the punch is a conical punch (for the cold side); a second substep of soldering the portion of the insulating sheath 113 embossed on the screw element 122.

According to an alternative embodiment, illustrated in Figure 5, it is possible to overcome the first substep deformation of the insulating sheath or outer casing of the cable by providing for example an annular flange 523 so as to facilitate the realization of a good quality welding between the insulating sheath and the screwing element 522 of the penetration assembly 500.

A fifth step 205 consists in securing the screwing element 122 on the reactor vessel, and more specifically on an annular lip 15 formed on the outer wall of the vessel 10 around the orifice 20.

A sixth step 206 consists in adding an insulator 114 at the outer portion of the electrical cable 110 so as to isolate the conductors 111 and to replace the mineral insulation 112 of the cable 110 which could have been removed or damaged around the wires. electrical conductors 111 during the step of securing between the sheath 113 and the screw element 122. This step is for example carried out by adding a preformed refractory material.

Figure 3 illustrates a second embodiment of a penetration assembly 300 according to the invention. This second embodiment is identical to the first embodiment described above with the exception of what will be described below.

In this second embodiment, the conical element 323 of the radial clamping device 320 is formed by a biconical olive extending on either side of the axis of revolution of the orifice 20. Indeed, the screwing element 322 comprises a conical bore 324 formed at its upstream end adapted to cooperate with the conical element 323.

FIG. 4 illustrates a third embodiment of a penetration assembly 400 according to the invention. This third embodiment is identical to the second embodiment described above with the exception of what will be described below.

In this third embodiment, the screw member 422 of the radial clamping device 420 has at its outer end an annular flange 423 in the form of a tulip. Thus, in this embodiment, the fourth step 204 of securing the outer end of the insulating sheath 113 of the electrical cable 110 to the screwing element 122 comprises a sub-step of deformation of the outer end of the sheath. 113 carried out based on the annular flange 423.

This third embodiment has been shown by way of example with a conical element 323 forming a biconical olive as shown in FIG. 3. However, this third embodiment can also be realized with a conical element 123 such that shown in Figure 1.

The invention has been particularly described with an electric cable as a through body; however, the described mounting method is identical for a penetration assembly of a thermowell having an outer shell.

The penetration assembly according to the invention makes it possible to propose a more compact solution than the known traverses of the state of the art. The mounting / dismounting solution of the electric cable, the thermowell or another body passing through the interior of the tank makes it possible to minimize the diameter of the orifice of the bushing while allowing power to be supplied to an electrical device. inside the tank having a greater bulk than the orifice of the bushing.

Thus, the dimensioning of the through hole reduced to the diameter of the electric cable or the through body reduces leakage rates in case of gaps and simplify development constraints in the case of the implementation of a large number of bushings, for example on integrated type reactors.

The penetration assembly according to the invention has been particularly described for the passage of an electric cable for the supply of sensors or actuators. More generally, the penetration assembly can be applied to any electromechanical electrical or inductive devices implanted in a tank of a nuclear reactor, for example: inductive assemblies for a heating block in the pressurizer; electromagnetic actuators: mechanisms, hydraulic shut-off valves; inductive sensors, in-core neutron counting chains.

Claims (16)

1. A penetration assembly (100, 300, 400, 500) of tank (10) of a nuclear reactor suitable for being installed in a vessel orifice (20) (10) of a nuclear reactor, said penetration assembly comprising - a through body (110) passing through said vessel orifice (20), said through body (110) having a first end adapted to be positioned inside the vessel (10) and a second end adapted to be positioned at the outside of the tank (10); - a radial clamping device (120, 320, 420, 520) radially clamping said through body (110) and forming a sealing barrier of the bushing; said penetration assembly (100) being characterized in that the radial clamping device (120, 320, 420, 520) is formed by: - a conical element (123, 323) having an apex and a base, said apex being oriented inwardly of the vessel (10) of the reactor; a screwing element (122, 322, 422, 522) exerting a compressive force on said conical element (123, 323) to ensure the radial clamping of said through body (110) and the sealing of the penetration. 2. A reactor penetration assembly (100) of a nuclear reactor according to claim 1 characterized in that the through body has an outer casing (113) acting as a second confinement barrier of the primary fluid. 3. assembly penetration (100) tank of a nuclear reactor according to claim 2 characterized in that said outer casing (113) is secured by welding on Γ screw element (122, 322, 422, 522). 4. A reactor penetration assembly (100) of a nuclear reactor according to one of claims 1 to 3 characterized in that said screw element (122, 322, 422, 522) comprises a ferrule adapted to be secured to the tank (10). 5. Tank penetration assembly (100) of a nuclear reactor according to one of claims 2 to 4 characterized in that the body through is an electric cable (110) surrounded by a sheath (113) forming said outer envelope . 6. tank penetration assembly (100) of a nuclear reactor according to one of claims 2 to 4 characterized in that the through body is a thermowell having an outer wall, said outer wall of the thermowell forming said outer envelope. 7. Vessel (10) of a nuclear reactor comprising: - an orifice (20) for the passage of a through body (110), said orifice (20) having: a first part (21) of cylindrical shape presenting a end opening out of the tank; - a second portion (22) of cylindrical shape having an end opening into the vessel and having a diameter smaller than the first portion (21); - a third conically shaped portion (23) connecting the first portion (21) to the second portion (22); - A penetration assembly (100) according to one of claims 1 to 6 comprising: - a through body (110) passing through said vessel orifice (20); - a radial clamping device (120, 320, 420, 520) radially clamping said one of said through body (110) and forming a barrier to penetration. 8. Tank (10) of a nuclear reactor according to claim 7, characterized in that said first portion (21) of cylindrical shape of said orifice (20) comprises a thread and that the periphery of said screw element (122, 322, 422, 522) has a thread complementary to said thread formed inside the first portion (21) of cylindrical shape of said orifice (20). 9. Nuclear reactor characterized in that it comprises a tank (10) according to one of claims 7 to 8. 10. Nuclear reactor according to claim 9 characterized in that said nuclear reactor is an integrated reactor or a small modular reactor. 11. A method of mounting a penetration assembly (100) according to one of claims 1 to 6 in an orifice (20) of a tank (10) of a nuclear reactor, said penetration assembly (100) comprising a through body (110) passing through said vessel orifice (20) (10) and a radial clamping device (120, 320, 420, 520), said method being characterized in that it comprises: - a step (201 ) introducing said through body (110) through said orifice (20) from the interior to the outside of the vessel (10); a step (202) of positioning in said orifice (20) of said radial clamping device (120) formed by a conical element (123, 323) and by a screwing element (122, 322, 422, 522), the positioning being made from outside the vessel (10); a step (203) of clamping said radial clamping device (120, 320, 420, 520) by the outside of the tank (10) so as to mechanically real estate said through body (110), said clamping being able to withstand at the pressure of the primary fluid. 12. A method of mounting a penetration assembly (100) according to claim 11 characterized in that said clamping step is performed by rotation of said screw member (122, 322, 422, 522) towards the inside of the orifice (20), said rotation generating a translation of the radial clamping device (120, 320, 420, 520) to the generation of a compression force of said screw member (122, 322, 422, 522) on said conical element (123, 323), said compressive force being able to deform said conical element (123, 323) so that said conical element (123, 323) provides a radial clamping of said through body (110). 13. A method of mounting a penetration assembly (100) according to one of claims 11 to 12, said traversing body (110) having an outer casing (113), said method being characterized in that it comprises a step (204) for securing the outer casing (113) of the through body (110) on said screw element (122, 322, 422, 522) at the end of said through body (110) positioned on the outside of the tank (10). 14. A method of mounting a penetration assembly (100) according to claim 13 characterized in that prior to said step of securing the outer casing (113) of the body through (110) on said screw element (122, 322, 422, 522), the method comprises a step of deforming said outer casing (113) of the through body (110) at the end positioned outside the vessel. 15. A method of mounting a penetration assembly (100) according to claim 14 characterized in that said step of deforming said outer casing (113) of the body (110) is made by stamping in situ of said outer casing ( 113) by means of a punch and a die. 16. A method of mounting a penetration assembly (100) according to one of claims 11 to 15 characterized in that said method comprises a step (205) for securing said screw member (122) on said bowl (10). .