Vibration-inhibiting bar for a steam generator tube bundle

Abstract

A vibration-inhibiting bar is provided that is interposed between bends of the tubes of two adjacent banks of tubes of a U tube bundle of a steam generator and includes at least one internal element, referred to as a damping element, designed to mechanically damp the vibrations of the tubes; and at least one external element, referred to as percussion element, in contact with the damping element, the percussion element being designed to be in contact with the bends of the tubes of the bundle.

Claims

1. An anti-vibration bar able to be interposed between bends of tubes of two adjacent banks of tubes of a U-shaped tube bundle of a steam generator, the anti-vibration bar comprising: a plurality of internal elements, referred to as a plurality of damping elements, adapted to mechanically dampen the vibrations of the tubes of the two adjacent banks of tubes; two external elements, referred to as percussion elements, at least one of the two external elements being adjacent to a first damping element of said plurality of damping elements, said percussion elements being configured to be in contact with the bends of the tubes, said percussion elements extending on either side of the plurality of damping elements; a first damping clearance between said first damping element and one of said percussion elements; and a second damping clearance between a second damping element of said plurality of damping elements, and said first damping element, or between said second damping element and a third damping element of the plurality of damping elements, said first damping clearance including a first portion of a fluid trapped in said first damping clearance, said first portion of the fluid performing a viscous damping between said first damping element and said one of said percussion elements, and said second damping clearance including a second portion of the fluid trapped in said second damping clearance, said second portion of the fluid performing a viscous damping between said first damping element and said second damping element or between said second damping element and said third damping element wherein the first damping element, the second damping element, and the third damping element are parallel to each other.

2. The anti-vibration bar according to claim 1, wherein at least one of said plurality of damping elements is in the shape of a plate.

3. The anti-vibration bar according to claim 1, further comprising: an element presenting an I-shaped profile and having a core; said plurality of damping elements each extending on either side of the core.

4. The anti-vibration bar according to claim 1, wherein the percussion elements are plates.

5. The anti-vibration bar according to claim 1, wherein the first portion of the fluid trapped in said first damping clearance and the second portion of the fluid trapped in the second damping clearance are the same.

6. The anti-vibration bar according to claim 1, wherein each percussion element of the percussion elements includes a surface treatment able to improve its hardness.

7. The anti-vibration bar according to claim 1, wherein the percussion elements are held together by at least a weld bead.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The figures are presented by way of indicating and in no way limiting purpose of the invention.

(2) FIG. 1 shows a cross-section view of a steam generator of a pressurized water nuclear reactor.

(3) FIG. 2 shows a cross-section view of an anti-vibration bar according to a first embodiment of the invention.

(4) FIG. 3 shows a cross-section view of an anti-vibration bar according to a second embodiment of the invention.

(5) FIG. 4 shows a cross-section view of an anti-vibration bar according to a third embodiment of the invention.

(6) FIG. 5a shows a cross-section view of an anti-vibration bar according to a fourth embodiment of the invention.

(7) FIG. 5b shows a cross-section view of an anti-vibration bar according to an alternative fourth embodiment of the invention.

(8) FIG. 6 shows a cross-section view of an anti-vibration bar according to a fifth embodiment of the invention.

DETAILED DESCRIPTION

(9) Unless otherwise specified, a same element appearing in different figures bears a single reference numeral.

(10) The invention relates to an anti-vibration bar 20 of a steam generator such as the steam generator 10 of the pressurized water nuclear reactor described in FIG. 1. The anti-vibration bar 20 according to a first embodiment of the invention is able to replace the anti-vibration bar 18 of the steam generator 10 of FIG. 1.

(11) Previously described FIG. 1 shows a cross-section view, according to the first plane P1, of the steam generator 10 of the pressurized water nuclear reactor.

(12) FIG. 2 shows a cross-section view, according to a second plane P2 having a centre O and orthogonal axes x and y, said second plane P2 being perpendicular to the first plane P1, of the anti-vibration bar 20 according to the first embodiment of the invention.

(13) The anti-vibration bar 20 includes: a plurality of damping plates 22; a first percussion plate 23-1 and a second percussion plate 23-2 extending on either side of the plurality of damping plates 22.

(14) The damping plates 22 are advantageously made of a stainless material with a suitable roughness, able to provide a significant viscous damping. The first and second percussion plates 23-1 and 23-2 can undergo a surface treatment, such as a nitriding, in order to improve their hardness.

(15) The damping plates 22 preferably have, along a direction Ox, a same width L1. Alternatively, the damping plates 22 can have, along the direction Ox, different widths. The damping plates 22 have, along a direction Oy, a same height H. Advantageously, two consecutive damping plates 22 have a clearance 25 between them. A fluid, for example air or liquid- and/or vapour-phase water, is trapped in the clearance 25, which enables a viscous damping to be created which is added to the mechanical damping of the damping plates 22.

(16) In the example represented in FIG. 2, the percussion elements 23-1 and 23-2 are percussion plates, of a height H along the direction Oy. The first and second percussion elements 23-1 and 23-2 preferably have, along the direction Ox, a same width L2. Alternatively, the first and second percussion elements 23-1 and 23-2 can have, along the direction Ox, different widths. The damping plates 22 as well as the first and second percussion elements 23-1 and 23-2 are held together by a first weld bead 24-1 and by a second weld bead 24-2.

(17) FIG. 3 shows a cross-section view, along the second plane P2 having a centre O and orthogonal axes x and y, of an anti-vibration bar 30 according to a second embodiment of the invention.

(18) The anti-vibration bar 30 according to the second embodiment of the invention includes: an I-shaped profile 31 forming an element for rigidifying the anti-vibration bar 30; a plurality of damping plates 32; a first percussion plate 33-1 and a second percussion plate 33-2.

(19) The I-shaped profile 31 has a first end 31-1 and a second end 31-2 connected by a core 31-3. The damping plates 32 extend between the first and second ends 31-1 and 31-2 of the profile 31 on either side of the core 31-3 of the profile 31. Similarly to the damping plates 22 according to the first embodiment, the damping plates 32 according to the second embodiment are advantageously made of a material able to provide a significant mechanical damping and two consecutive damping plates 32 advantageously have a clearance 35 between them. A fluid is trapped in the clearance 35, which enables a viscous damping to be created which is added to the mechanical damping of the damping plates 32.

(20) The first and second damping plates 33-1 and 33-2 extend between the first and second ends 31-1 and 31-2 of the profile 31 and on either side of the damping plates 32. Similarly to the first and second percussion plates 23-1 and 23-2 according to the first embodiment, the first and second percussion plates 31-1 and 31-2 according to the second embodiment can undergo a surface treatment, such as a nitriding, in order to improve their hardness.

(21) The first and second percussion plates 33-1 and 33-2 each have a first end and a second end. The first percussion plate 33-1 is attached, at its first end, to the first end 31-1 of the profile 31 thanks to a first weld bead 34-1. The second percussion plate 33-2 is attached, at its first end, to the first end 31-1 of the profile 31 thanks to a second weld bead 34-2. The first percussion plate 33-1 is attached, at its second end, to the second end 31-2 of the profile 31 thanks to a third weld bead 34-3. The second percussion plate 33-2 is attached, at its second end, to the second end 31-2 of the profile 31 thanks to a fourth weld bead 34-4.

(22) The I-shaped profile 31 advantageously improves the stiffness of the anti-vibration bar 30.

(23) FIG. 4 shows a cross-section view, along the second plane P2 having a centre O and orthogonal axes x and y, of an anti-vibration bar 40 according to a third embodiment of the invention.

(24) The anti-vibration bar 40 according to the third embodiment of the invention includes: a first substantially parallelepiped support piece 41 having a first groove 41-1; a second substantially parallelepiped support piece 42 having a first groove 42-1; a plurality of damping plates 43, the ends of which are inserted on the one hand into a centre part of the first groove 41-1 of the first support piece 41 and on the other hand into a centre part of the second groove 42-1 of the second support piece 42; a first percussion plate 44 and a second percussion plate 45 extending on either side of the plurality of damping plates 43.

(25) Similarly to the damping plates 22 according to the first embodiment and to the damping plates 32 according to the second embodiment, the damping plates 43 according to the third embodiment are advantageously made of a material able to provide significant mechanical damping and two consecutive damping plates 43 advantageously have a clearance 46 between them. A fluid is trapped in the clearance 46, which enables a viscous damping to be created, which is added to the mechanical damping of the damping plates 43.

(26) The first percussion plate 44 has a first notch 44-1 at its first end and a second notch 44-2 at its second end. The first percussion plate 44 is embedded: into a first side part of the groove 41-1 of the first support piece 41 thanks to its first notch 44-1; into a first side part of the groove 42-1 of the second support piece 42 thanks to its second notch 44-2.

(27) The second percussion plate 45 has a first notch 45-1 at its first end and a second notch 45-2 at its second end. The second percussion plate 45 is thus embedded: into a second side part of the groove 41-1 of the first support piece 41 thanks to its first notch 45-1; into a second side part of the groove 42-1 of the second support piece 42 thanks to its second notch 45-2.

(28) Similarly to the first and second percussion plates 23-1 and 23-2 according to the first embodiment and to the first and second percussion plates 31-1 and 31-2 according to the second embodiment, the first and second percussion plates 44 and 45 according to the third embodiment can undergo a surface treatment, such as a nitriding, in order to improve their hardness.

(29) The first and second support pieces 41 and 42 thus provide a holding in position of the first and second percussion plates 44 and 45 and of the damping plates 43 at their ends, while allowing a certain displacement of the percussion plates and of the damping plates, related to the presence of the clearance 46, during an impact between the anti-vibration bar 40 and a tube.

(30) The first, second and third embodiments described until now implement a plurality of damping plates 22, 32, 43 and first 23-1, 31-1, 44 and second 23-2, 31-2, 45 percussion plates, the damping plates and the percussion plates forming pieces separated from the anti-vibration device. Nevertheless, according to an alternative of the first, second and third embodiments, the damping plates and the percussion plates could be merged. According to this alternative, the percussion plates are formed by the external surfaces of the damping plates that can have improved hardness properties.

(31) FIG. 5a shows a cross-section, along the second plane P2 having a centre O and orthogonal axes x and y, of a anti-vibration bar 50 according to a fourth embodiment of the invention.

(32) The anti-vibration bar 50 according to this fourth embodiment of the invention includes: a first substantially parallelepiped support piece 51 having a first groove 51-1; a second substantially parallelepiped support piece 52 having a second groove 52-1; a flexible damping cable 53 including a plurality of strands; a first percussion plate 54 and a second percussion plate 55.

(33) The first percussion plate 54 has a first notch 54-1 at its first end and a second notch 54-2 at its second end. The first percussion plate 54 is embedded: into a first side part of the groove 51-1 of the first support piece 51 thanks to its first notch 54-1; into a first side part of the groove 52-1 of the second support piece 52 thanks to its second notch 54-2.

(34) The second percussion plate 55 has a first notch 55-1 at its first end and a second notch 55-2 at its second end. The second percussion plate 55 is embedded: into a second side part of the groove 51-1 of the first support piece 51 thanks to its first notch 55-1; into a second side part of the groove 52-1 of the second support piece 52 thanks to its second notch 55-2.

(35) Furthermore, the first percussion plate 54 has a first semi-circular cavity 54-3, and the second percussion plate 55 has a second semi-circular cavity 55-3. The first and second semi-circular cavities 54-3 and 55-3 are thus able to form, when they are positioned facing each other, a circular cavity 56. The circular cavity 56 is able to accommodate the damping cable 53.

(36) The damping cable 53 is a flexible cable comprised of a plurality of strands able to deform and form a mechanical damping during an impact with a tube.

(37) An operational clearance advantageously exists between the first percussion plate 54, the damping cable 53 and the second percussion plate 55. This operational clearance accommodates a fluid which enables a viscous damping to be created. This viscous damping is added to the mechanical damping of the damping cable 53.

(38) Similarly to the first percussion plate 23-1, 31-1, 44 and to the second percussion plate 23-2, 31-2, 45 according to the previous embodiments, the first and second percussion plates 54 and 55 according to the first alternative of the fourth embodiment of the invention can undergo a surface treatment, such as a nitriding, in order to improve their hardness.

(39) The first and second support pieces 51 and 52 thus provide the holding in position of the first and second percussion plates 54 and 55 at their ends, while allowing a certain displacement of the percussion plates and of the damping cable 53, related to the presence of the operational clearance, during an impact between the anti-vibration bar 50 and a tube.

(40) FIG. 5b shows a cross-section view, along the second plane P2 having a centre O and orthogonal axes x and y, of an anti-vibration bar 60 according to an alternative of the previously described fourth embodiment of the invention.

(41) The anti-vibration bar 60 according to this alternative embodiment is identical to the previously described anti-vibration bar 50 except for the percussion plates.

(42) The anti-vibration bar 60 indeed includes: a first percussion plate 64 having a first trapezoid cavity 64-3; a second percussion plate 65 having a second trapezoid cavity 65-3.

(43) The first and second trapezoid cavities 64-3 and 65-3 are thus able to form, when they are positioned facing each other, a hexagonal cavity 66. The hexagonal cavity 66 is able to accommodate the damping cable 53.

(44) The advantage of this alternative is to enable a greater radial deformation of the damping cable 53 submitted to the compression, and thus a greater mechanical damping.

(45) FIG. 6 shows a cross-section view, along the second plane P2 having a centre O and orthogonal axes x and y, of an anti-vibration bar 70 according to a fifth embodiment of the invention.

(46) The anti-vibration bar 70 according to this fourth embodiment of the invention includes: a damping plate 71 forming a solid core of the anti-vibration bar 70; a damping tube 72 surrounding the damping plate 71; a percussion tube 73 surrounding the damping tube 72.

(47) The thickness of the walls of the damping tube 72 and of the percussion tube 73 is for example of 0.5 mm.

(48) The damping plate 71 and the damping tube 72 are advantageously made of a material able to provide a significant mechanical damping. The damping plate 71 and the damping tube 72 advantageously have a clearance 74 between them. Similarly, the damping tube 72 and the percussion tube 73 advantageously have a clearance 75 between them. A fluid is trapped in the clearance 74 and in the clearance 75, which enables a viscous damping to be created which is added to the mechanical damping of the damping plate 71 and the damping tube 72.