FR3029950B1 - PARASISMIC ISOLATION DEVICE AND ASSEMBLY COMPRISING A NUCLEAR REACTOR AND THE PARASISMIC INSULATION DEVICE - Google Patents

Abstract

The earthquake-resistant isolation device (1) comprises: - a lower anchoring plate (21); - an upper anchor plate (23); - an insulator (25). The seismic isolation device (1) comprises an end plate (35) rigidly fixed to one of the lower or upper ends of the insulator (25), and a fusible link (37) connecting the end plate (35) to the lower anchor plate (21) or to the upper anchor plate (23).

Description

The invention relates generally to seismic isolation systems for interposed between the foundations and a structure such as a building or a jet reactor.

More specifically, the invention relates in a first aspect to a seismic isolation device intended to be interposed between foundations and a structure (5), comprising: - a lower anchor plate, intended to be rigidly fixed to the foundations; - An upper anchor plate, intended to be fixed to the structure; an isolator vertically interposed between the lower and upper anchor plates, the lower and upper anchor plates being respectively connected to the lower and upper ends of the insulator, the insulator being sized to carry a first predetermined voltage according to the vertical direction.

A device of this type is known for example from JP 2009 024 753. It makes it possible to considerably reduce the forces transmitted to the structure in the event of an earthquake. This spositif comprises in particular an isolator having great flexibility and a deformation capacity in a horizontal plane, while being relatively rigid ins vertical direction.

In addition to its seismic isolation function, this device generally supports the entire weight of the structure, so that a failure of this spositive would cause the fall of the structure, including for facilities holding nuclear materials, unacceptable consequences. It is therefore necessary to design the seismic isolation devices so that they operate in the expected manner in the situations considered for the normal size of this device, but also in order to avoid a lack of support of the vertical load. in the event of extreme earthquakes of levels higher than those considered for the normal dimensioning. In the following, these jism will be called "extreme earthquakes".

A predominant failure mode of seismic isolation devices of the above pe is the tearing or breaking of the insulator under an imbined load of shear and tension.

In this context, the invention aims to provide a seismic isolation device omitting to limit the voltage forces that can pass through the insulator for extreme jismes. To this end, the invention relates to a seismic isolation device of the type described characterized in that the seismic isolation device comprises an end plate rigidly fixed to one of the lower or upper end of the insulator, and fusible link binding the end plate to the lower anchor plate or to the upper anchor plate, the fusible link being selected to break or soften under the effect of a second predetermined voltage in the vertical direction, the jconde voltage being greater than the first voltage but lower than the voltage expected to lead to a failure of the insulator.

The seismic isolation device of the invention operates substantially like that of JP 2009 024 753 for earthquakes of level less than or equal to the maximum level considered for the normal dimensioning of the device, that is to say for those of the first one. predetermined voltage in the insulator. For this maximum level of jism, the insulator remains bound to the foundation and the structure. This allows on the one hand to specter the sizing codes in force, especially in Japan and Europe elme EN 15129). The European standard imposes in particular a criterion of stability in ulement that the device of the invention makes it possible to respect. It should be noted that such a route would not be respected with a seismic isolation device having supports jn rigidly related to the structure, and allowing a detachment of the structure in case of significant vertical response.

Furthermore, the device of the invention allows to resume a moment of isting the structure, that is to say a rotational movement about a horizontal axis. Finally, the device of the invention makes it possible to ensure the absence of icollement of the structure for the maximum level of earthquake considered for the dimensioning, and thus to guarantee the absence of shock. Such shocks occur when the structure returns to position following a detachment.

On the other hand, in case of extreme earthquake, the fusible link will break or plasticize, so that a separation is authorized between the structure and the foundations. Thus, the solator is not destroyed or torn and is protected by the liaison, which plays the role of sible. When the structure returns to position, it is supported by the seismic isolation device adequately, since the seismic isolation device is still able to resume compressive forces.

The seismic isolation device may also have one or more of the following characteristics, considered individually or according to all technically possible combinations: the fusible link comprises at least one fusible member chosen from the delivering group: a screw, a rod, a plate, a cylinder, a toad; the fusible member is made of metal or of another material exhibiting the required fracture or plasticizing characteristics; the seismic isolation device comprises an additional connection of the end cap to the lower or upper anchor plate, adapted to transmit a horizontal shear force between the end plate and the lower or upper anchor plate when the fusible link is intact and when the link is broken or plasticized; the additional connection comprises a lateral surface integral with or formed in the lower or upper anchoring plate and a complementary surface secured to the end plate, the lateral surface and the complementary surface contacting the one against the other and extending parallel to the vertical direction; the lateral surface and the complementary surface extend in a substantially closed contour around the insulator; the lower or upper anchoring plate comprises a concave zone limited by a bottom and a peripheral edge, the end plate being engaged in the concave me, the peripheral edge defining the lateral surface; the end plate bears against the bottom and is connected to the bottom by the link when the fuse link is intact; the height of the lateral surface in the vertical direction is chosen so that the end plate does not disengage from the concave zone when there is detachment of the end plate and the lower anchor plate or plate; better anchorage at the occurrence of an extreme earthquake; - the peripheral edge is attached against the bottom; at least one of the lateral surface and the complementary surface is coated with an anti-seizing coating.

According to a second aspect, the invention relates to an assembly comprising: - foundations anchored in the ground; a nuclear reactor provided with a raft; at least one seismic isolation device as described above, the lower anchoring plate being rigidly fixed to the foundations, the upper anchoring plate rigidly fixed to the base. The assembly may also have at least one stop limiting the jerzontal movement of the nuclear reactor. Other characteristics and advantages of the invention will emerge from the detailed description given below, by way of indication and in no way limiting, with reference to the appended figures, in which: FIG. 1 is a diagrammatic representation of a nuclear reactor resting ir foundations through insulation devices according to the invention; FIG. 2 is a simplified schematic representation of one of the seismic isolation devices of FIG. 1, at rest; FIG. 3 is a view similar to that of FIG. 2, and shows the operation of the seismic isolation device in the event of an extreme earthquake; - Figures 4 to 6 show different variants of fusible members; and - Figures 7 and 8 show alternative embodiments of the invention.

As shown in FIG. 1, the earthquake isolation device 1 is intended to be interposed between foundations 3 and a structure 5. The device 1 is intended, in the event of an earthquake, to reduce the forces transmitted by the ground to the structure .

In the example shown, the foundations 3 are disposed in an excavation dug in the ground 9. More particularly, the foundations 3 comprise a slab 11 resting on the bottom of the excavation 7 and a plurality of pillars 13 projecting from The pillars are arranged at a distance from each other.

The foundations 3 further comprise retaining walls 15, disposed in the walls of the excavation 7.

The structure 5 comprises in its lower part a raft 17.

In the example shown, a seismic isolation device 1 is interposed interposed between the upper surface of each of the pillars 13 and the raft 17.

Thus, the structure 5 rests exclusively on the pillars 13, the seismic isolation devices 1 taking together the entire weight of the structure.

Moreover, it clearly appears in Figure 1 stops 19, limiting the horizontal reduction of the structure 5.

In the example shown, the stops 19 are carried by the walls of îutènement 15. They are arranged vertically at the level of the raft 17.

Structure 5, in the example shown, is a nuclear reactor. Alternatively, structure 5 is another building, for example a building housing turbines, a sine, or a tower, or any other type of building.

It should be noted that the foundations 3 as a variant have a structure different from that shown in FIG. 1. In particular, the raft 17 may rest not on the pillars 13 but on one or more solid masses, or even directly on the slab 11.

The earthquake isolation device 1 is shown in greater detail in FIG. 2. It comprises: a bottom anchor plate 21, intended to be rigidly fixed to the elements 3; - An upper anchor plate 23, intended to be fixed to the structure 5; an insulator 25, interposed vertically between the lower and the upper anchoring plates 21, 23, the lower and upper anchor plates 21, 23 being specifically connected to the lower and upper ends of the insulator 25.

Lower anchor plate 21 is typically a metal plate to bond.

It is, in the example shown, rigidly fixed to the foundations 3 by mechanical ganes 27, such as pins, anchor rods, tie rods or any other body adapted.

Similarly, the upper anchoring plate 23 is typically a steel plate, rigidly fixed to the structure 5 by mechanical members 29, temple dowels, anchor rods, tie rods or any other suitable member. Insulator 25 is, in the example shown, a fretted elastomeric member. This gate comprises, for example, a plurality of layers 31 made of elastomer, and a plurality of metal plates 33 interposed between the elastomer layers 31. The layers I and the plates 33 are of horizontal orientation, are stacked one on top of the other are typically joined by a vulcanization process. Thus, the insulator 25 exhibits great flexibility and great capacity for deformation under the effect of illicitness in a horizontal plane. These solicitations will be called sonoring efforts in the description that follows.

On the other hand, the insulator 25 is relatively rigid in the vertical direction. The vertical rection is substantially perpendicular to the layers 31, plates 33, and anchor plates 21 and 23. The insulator, as a variant, has any other constitution adapted to impart the large capacity of deformation under the effect of a shear force and, in vanche, a relative rigidity in the vertical direction.

According to the invention, the seismic isolation device 1 comprises an end plate 35 rigidly fixed to an upper end of the insulator 25, and a sible connection 37 connecting the end plate 35 to the upper anchoring plate 23.

It should be noted that, under tension stress, the end plate 35 and the upper anchor plate 23 are rigidly secured to each other in the axial direction only through the fusible link. In the absence of a fuse link, the plate 35 is jsceptible debatable relative to the upper anchor plate 23 according to the vertical rection.

Typically, the end plate 35 is a metal plate, of iris horizontal orientation. It is typically attached by adhesion to the insulator 25. More precisely, it is rigidly attached to the layer 31 or the uppermost plate 33 constituting the insulator 25.

In this case, the lower anchoring plate 21 is rigidly fixed to a lower itrémité of the insulator 25. It is for example fixed by adhesion, / piiquement, it is fixed to the layer 31 or plate 33 located the most The insulator 25 is dimensioned to present margins with respect to the maximum seismic level considered for sizing. This earthquake results in a predetermined shear strength to be transmitted from the lower anchoring plate 21 to the upper anchoring plate 23 and to the structure 5, through the insulator 25. This earthquake caliber is also translated by a first predetermined voltage according to the vertical rection, to be transmitted from the lower anchor plate 21 to the upper anchor 23, through the insulator 25. This first determined voltage corresponds to a vertical tensile force. The isolator 25 is adapted to dormant transmit this first predetermined voltage, without degradation. The isolator 25 is designed with a safety margin with respect to the first predetermined connection, so that it can transmit greater forces than the first predetermined voltage, without degradation, as will be seen later. The first predetermined voltage therefore does not correspond to the maximum vertical voltage isceptible to be transmitted by the insulator 25 before rupture or major degradation.

The fuse link 37 is chosen so as to break, or to laminate, under the effect of a second predetermined voltage in the vertical direction, the second voltage ant greater than the first voltage, so as to largely guarantee the absence of puncture of the fuse device for the maximum dimensioning earthquake level.

More specifically, the second predetermined voltage is between the first predetermined voltage and the maximum voltage in the vertical direction isceptible to be transmitted by the insulator 25 without degradation thereof.

Thus, the fuse link plays a protective role vis-à-vis the insulator 25 under an extreme earthquake calf. As soon as the vertical voltage applied to the isolator exceeds the caliber for which the insulator is sized, that is to say the first voltage determined plus a margin, the fuse link will break or plasticize, so that I End plate 35 becomes free with respect to the upper anchor plate 23 in the vertical direction.

This rupture, or this plasticization, occurs in any event before a calf of vertical tension causing the breakage or damage of the insulator is jpliqué it.

The connections between the lower anchor plate 21 and the insulator 25, between the lower anchor plate 21 and the foundations 3, between the end plate 35 and the solator 25, and between the upper anchor plate 23 and structure 5, are all more distant at a vertical voltage than the fuse link 37.

In the example shown in Figure 2, the fuse link 37 comprises at least 1 fuse 39, preferably a plurality of fusible members. Each sible 39 links the end plate 35 to the upper anchor plate 23, and is thereby chosen to break or plasticize under the effect of a predetermined vertical tension. Together, the fusible members 39 constitute the fuse link 37.

Here it is meant to break the fact that the fusible member 39 splits into at least two pieces completely independent of one another, without any further physical connection between the pieces.

Plasticization means that the fusible member is deformed by long, without breaking the physical organ into two independent pieces one of lutre. The elongation of the fusible member or members allows a vertical displacement of the end cap 35 relative to the upper anchor plate 23, including icollement. Elongation is a plastic deformation.

In the example shown in Figure 2, each fuse member 39 is a screw.

In this case, the end plate 35 comprises for each fuse 39 a through ifice 41, passing through the plate 35 throughout its thickness. The screw comprises the head 43, and a rod 45 of section smaller than the section of the orifice 41. The head 43 has a horizontal section greater than that of the orifice 41, and bears against the large lower face 47 of the end plate 35.

It should be noted that, in a horizontal plane, the cross section of the plate 35 is larger than the cross section of the insulator 25, so that the plate 35 has the annular portion protruding transversely beyond the isolator 25. The orifices I are formed in said annular portion.

One end 49 of the rod 45 is engaged in an orifice 51 of the upper anchoring plate 23. It is rigidly fixed in the orifice 51. For example, the end 49 is threaded and the orifice 51 carries an internal thread cooperating with the floor external end 49.

The screw further comprises a zone of weakness 53, which is formed here in a Dnçon of the rod 45 engaged in the orifice 41. The zone of weakness 53 is for example 1 section of reduced diameter of the rod 45.

Thus, when the second predetermined voltage is applied to the fuse link, each of the fusible members 39 will break or laminate at the area of impurity 53, thereby permitting peeling of the end plate 35 from the aque d. upper anchorage 23.

Alternatively, the fuse member is not a screw, but is a rod 55 (Figure 4), Aque 57 (Figure 5), a cylinder or a toad 59 (Figure 6). The fuse member could still be any other suitable mechanical member.

The rod 55 has one end rigidly attached to the upper anchoring plate 23, another end rigidly fixed to the end plate 35, the impurity zone 53 being made between the two ends. The stem can have all sorts of horizontal throws: circular, square, rectangular, etc.

In FIG. 5, the plate 57 is arranged substantially like the rod 55 of the jure 4. An upper part of the plate 57 is rigidly fixed to the upper anchoring plate 23, and a lower part of the plate 57 is rigidly fixed. at the end plate 35. The zone of weakness 53 is formed between the upper and lower parts.

The toe 59 illustrated in FIG. 6 is of the type used for fastening rails to the railway sleeper. It comprises a folded iron 60, a first end portion 61 of which is rigidly fixed to the upper anchoring plate 23. It comprises a second end portion 63 rigidly fixed to the end plate, and more accurately pressed against the face lower part 47 of the end plate 35, and jidement attached to this large lower face 47. The zone of weakness 53 is formed ins iron between the first and second end portions 61 and 63. The fuse member is metal , steel, lead or other material or an elastic material having the required breaking or plasticizing characteristics.

The earthquake isolation device 1 further comprises an additional connection 65 from the endplate 35 to the upper endplate 23. The additional ply 65 is adapted to transmit a horizontal shear force to the end plate 35 and The anchor plate 23. More specifically, it is designed and adapted to transmit said shear force at a time when the link 37 is intact and when the fuse link 37 is broken or plasticized.

In the embodiment shown in FIG. 2, the additional link j comprises a lateral surface 67 formed on the upper anchoring plate 23, and the complementary surface 69 formed on the end plate 35, the lateral surface 7 and the complementary surface 69 being in contact with each other and extending irallocally to the vertical direction.

Typically, the side surface 67 and the complementary surface 69 extend a substantially closed contour around the insulator 25. The contour is typically closed, or alternatively, has interruptions.

In the example shown in Figure 2, the upper anchor plate 23 impresses a concave zone 71. The concave zone 71 is hollowed in a large face j the upper anchor plate 23 facing downwards. It is delimited by a bottom 3 and a peripheral edge 74 projecting downwards relative to the bottom 73. It is upwardly downward. Concave zone is here understood to mean a hollow zone. It is capable of presenting any sort of shape delimited by planar or curved faces, for example parallelepipedic.

The surface of the peripheral edge 74 facing the interior of the concave zone if in it the lateral surface 67.

The end plate 35 is engaged in the concave zone 71.

It is supported by a large upper surface against the bottom 73, and is bound to the bottom 73 by the fuse link 37.

Typically, considered perpendicular to the vertical direction, the section j the end plate 35 is complementary to that of the concave zone 71.

In the example shown, the complementary surface 69 corresponds to the wafer j the end plate 35.

The additional connection could be arranged differently, as shown in FIG. 7. For example, the peripheral edge 74 is defined by a ring j attached to the bottom 73 of the upper anchoring plate 23. For example, the ganes of fixing 29 are integral with the ring, and pass through the edge 73 of the upper anchoring plate 23 passing through holes 76. Thus, the bottom of the upper anchor plate 23 is pressed against the structure 5 by the ring 75. From Preferably the ord 73 and the ring 75 are integrated in a reservation 78 dug in the structure 5. i reservation 78, perpendicular to the vertical direction, has a complementary dull section of the outer section of the bottom 73 and the ring 75.

In order to facilitate the movement of the end plate 35 relative to the upper anchor plate 23, at least one of the side surface 67 and the surface 69 may be coated with an anti-seizing coating. Preferably, the jux surfaces are coated with an anti-seizing coating. This coating is temple PTFE, or is a galvanized coating, or is an anti-seizing coating pecially used in bolts.

FIG. 3 illustrates the situation of the seismic isolation device, when it is loaded by stress and shear stresses, resulting from an earthquake itself. In particular, this earthquake is such that the seismic isolation device 1 is connected to a voltage greater than the first voltage plus the margin of measurement, which has the effect of causing the rupture of the fuse link 37, imme illustrated.

It can be seen that due to the shearing force, the structure 5, with the upper anchor plate 23 and the end plate 35, is horizontally offset by pport to the lower anchor plate 21. In FIG. upper anchor plate 3 and the end plate 35 are shifted to the right.

This movement is accompanied by a distortion of the layers 31, the isolator loptant oblique shape.

On the other hand, because the fusible link 37 is broken, the upper anchor plate 23 has a degree of freedom in the vertical direction relative to the end plate 35. The upper anchor plate 23 can in fact dislodge from the end plate 35 during a locally vertical movement of the structure 5 per pillar to the foundation 3. It thus creates a gap 77 between the bottom 73 of the anchor plate and the end plate 35.

In such a way that the additional connection 65 continues to ensure the shear forces are imparted when the fuse link 37 is broken or tanned and a detachment takes place, the height of the lateral surface 67 is chosen so that end 35 does not disengage from the concave zone 71 under illiquidity by an extreme level earthquake.

In other words, the height of the lateral surface 67 is chosen so that the detachment of the upper anchoring plate 23 is never sufficient, in the event of an extreme earthquake, for the end plate 35 to leave la) concave 71.

It should be noted that the shear force to which the seismic isolation device 1 is subjected can be limited by the establishment of the stops 19. In fact, the stops 19 limit the displacement of the structure 5 in a horizontal plane, and limit inc moving the top anchor plate 23 and the end plate 35 irre- horizontally relative to the lower anchor plate 21.

Thus, even in the event of an extreme earthquake, the seismic isolation device 1 is connected to a limited voltage, because of the existence of the fuse link 37, and to a limited sonishing force, because of the existence of the stops 19.

Of course, the fuse link 37 can be implemented even if the seismic isolation device does not have the additional link 65.

An alternative embodiment of the seismic isolation device 1 will now be described with reference to Figure 8. Only the points by which this variant is staple from that of Figures 1 to 3 will be detailed below. The identical elements j ensuring the same function will be designated by the same references as in the embodiment of Figures 1 to 3.

In the variant embodiment of FIG. 8, the fuse link 37 provides the function of the additional connection 65, namely to transmit the shear force between the end cap 35 and the upper anchor plate 23, at the same time when the link sible 37 is intact and when the fuse link 37 is broken or plasticized.

In the variant embodiment of FIGS. 1 to 3, the additional link 65 is isolated by elements distinct from those providing the fuse link 37.

In the embodiment of FIG. 8, the fusible link 37 has an urality of fusible members 79 similar to the screws shown in FIG. 2, but which are however slightly different.

Each member 79 comprises, as previously described, a head 81 and a head 83. The head 81 is pressed under and against the large lower face 47 of the end plate 35. The rod 83 has an end portion 85 located at opposite the head I, which is rigidly fixed to the upper anchoring plate 23. The rod further comprises 1 intermediate section 87, connecting the end portion 85 to the head 81, engaged in the bore 41 of the plate end. The outer surface of the intermediate section 87 is; se, and therefore does not have external thread. Intermediate section 87 has a complementary external action of the inner section of orifice 41, considered irpendicular to the vertical direction. In other words, the outer surface of the intermediate Dnce 87 is pressed against the inner surface of the orifice 41. The member 79 has a zone of weakness 89, at the junction between the rod 83 and te 81.

Furthermore, the upper anchoring plate 23 does not have the concave area I. The end plate 35 thus rests against a flat area of the large upper face of the upper anchor plate. Thus, the lateral surface 67 in the example 3 of FIG. 8 corresponds to all the internal surfaces of the orifices 41, and the implementation surface 69 corresponds to all of the external surfaces of the intermediate portions 87.

When the fusible link 37 is intact, the shear force is transmitted between the upper anchoring plate 23 and the end plate 35 through the fusible members 1, and more specifically by the internal surfaces of the orifices 41 which are in contact with each other. contact with external surfaces of intermediate sections 87.

The rupture or the plasticization of the fusible link 37 is caused by the formation or rupture of the zone of weakness 89, for the members 79. Typically, head 81 is detached from the rod 83. The rod 83 remains attached to the plate anchoring upper 3, and remains engaged by its intermediate portion 87 in the orifice 41. The end plate 35 can slide along the rod 83, in a vertical direction, because I head is separated from the rod, or since the zone of weakness 89 has been deformed, on the other hand, because the rods 83 are not disengaged from the orifices 41, the shear forces continue to be transmitted between the end plate 35 and the upper anchor plate 23 The height of the end plate 35 is chosen sufficiently large so that the rods 83 are never disengaged in the event of an earthquake.

In the description which has been given of the invention, it has been mentioned that the end cap 35 is rigidly fixed to the upper end of the insulator 25, and that the fusible link 37 links the end plate 35 to the upper anchor plate 23 of the spositive. According to an alternative not shown, the end plate 35 is fixed to a lower itrémité of the insulator 25, and the fuse link 37 links the end plate 35 lower anchor plate 21. Similarly, the additional link 65 connects the end plate 35 to the lower anchor plate 21, and is adapted to transmit the shear force between the end plate 35 and the lower anchor plate 21.

On the other hand, the fuse link and the additional link are of the same type as written above, including all the variants envisaged.

Claims (4)

1A seismic isolation device (1) intended to be interposed between ideas (3) and a structure (5), the device (1) comprising: - a lower anchoring plate (21) intended to be rigidly fixed to the ideas (3); an upper anchoring plate (23) intended to be fixed to the structure (5); an insulator (25) interposed vertically between the upper lower anchor plates (21, 23), the lower and upper anchor plates (21, 23) being specifically bound to the lower and upper ends of the insulator ( 25), the insulator (25) int sized to support a first predetermined voltage in the direction of the direction; characterized in that the seismic isolation device (1) comprises an end plate (35) rigidly attached to one of the lower or upper ends of the olator (25), and a fusible link (37) connecting the end (35) to the lower plate (21) or to the upper anchor plate (23), the fuse link (37) is selected so as to break or laminate under the effect of a second voltage determined according to the vertical direction, the second voltage being greater than the first voltage but lower than the voltage which can lead to an olator failure (25). 2, - Device according to claim 1, characterized in that the fuse link (37) mprend at least one fuse member (39) selected from the following group: a screw, a, a plate, a cylinder, a toad. 3, - Device according to claim 2, characterized in that the fuse member (39) t metal or other material having the required breaking characteristics or istification. 4, - Device according to any one of the preceding claims, characterized in that the seismic isolation device (1) comprises an additional connection>) of the end plate (35) to the lower or upper anchor plate ( 21, 23), adapted to transmit a horizontal shear force between the end plate 5) and the lower or upper anchor plate (21, 23) when the fusible link (37) is intact and when the fusible link ( 37) is broken or plasticized. 5, - Device according to claim 4, characterized in that the complementary connection (65) comprises a lateral surface (67) secured to or provided on the lower or upper anchoring plate (21, 23) and a surface complément à lfë '( 69) of or formed on the end plate (35), the side surface (67) and the complementary surface (69) being in contact with one another and extending parallel to the vertical direction. 6. - Device according to claim 5, characterized in that the lateral surface (67) the complementary surface (69) extend in a substantially closed contour around the insulator (25). 7. - Device according to claim 5 or 6, characterized in that the lower or upper plate (21, 23) comprises a concave zone (71) delimited r a bottom (73) and a peripheral edge (75), the plate end portion (35) being engaged in the concave region (71), the peripheral edge (75) defining the lateral surface (67). 8. - Device according to claim 7, characterized in that the end plate 5) bears against the bottom (73) and is connected to the bottom (73) by the fuse link (37) sque the fuse link (37) ) is intact. 9. - Device according to any one of claims 7 or 8, characterized in that the height of the lateral surface (67) in the vertical direction is chosen so that the end plate (35) does not disengage from the zone concave (71) when there is a bond between the end plate (35) and the lower anchor plate (21) or the upper anchor (23) during the occurrence of an extreme earthquake . 10. - Device according to any one of claims 7 to 9, characterized in that the peripheral edge (75) is attached against the bottom (73). 11. - Device according to any one of claims 5 to 10, characterized in that at least one of the side surface (67) and the complementary surface (69) is an anti-seizing coating. 12. - Device according to any one of the preceding claims, characterized in that the voltages considered are tensile forces. 13. An assembly comprising: the foundations (3) anchored in the ground (9); a nuclear reactor (5) provided with a slab (17); at least one seismic isolation device (1) according to any one of the preceding indications, the lower anchor plate (21) being rigidly fixed to the formations (3), the upper anchoring plate (23) being rigidly fixed at the base (17). 14. - assembly according to claim 13, characterized in that the assembly mprend at least one abutment (19) limiting the horizontal clearance of the key reactor (5). -------------- --------------------- ------. ..... ---------------------------- - ---------------- ---- - -----------------