Buried nuclear facility with vertical arrangement

Abstract

The invention relates to a buried nuclear facility (10) comprising: - a vertical well (12) comprising, at a lower end, a bottom (12c) and, at an upper end, an opening (12b); - at least one reactor building (26) accommodated in the well; - and which contains at least one nuclear reactor containment building (30) enclosed inside the at least one reactor building (26); - at least one protective slab (20) for protection against external threats that completely seals the opening (12b) of the well, extending, in particular, above the at least one reactor building; - one or more items of equipment or buildings (b1-b4) arranged on the at least one protective slab (20).

Description

Description Title of the invention: BURIED NUCLEAR INSTALLATION WITH VERTICAL ARRANGEMENT Technical Field

[0001] The present invention relates to the field of buried nuclear installations. Prior art

[0002] We know, in particular from document WO 2018 / 204081, a nuclear installation in which a boiling water nuclear reactor containment vessel is housed in a silo built into the ground and rests on the bottom of the silo. The silo is closed at its upper part by a concrete cover to protect the nuclear reactor against external impacts and explosions.

[0003] In view of the above, there is a need to realize a new architecture of buried nuclear installation with high compactness. Statement of the invention

[0004] The invention thus relates to a buried nuclear installation comprising: - a vertical shaft comprising, at a lower end, a bottom and, at an upper end, an opening, - at least one reactor building housed in the shaft, - at least one nuclear reactor enclosure enclosed inside said at least one reactor building, - at least one slab providing protection against external attacks which completely closes the opening of the shaft, extending in particular above said at least one reactor building, - one or more pieces of equipment or buildings placed on said at least one protective slab.

[0005] The aforementioned installation makes it possible, by arranging on said at least one protective slab one or more pieces of equipment or buildings, in particular of an auxiliary type in relation to the reactor building (main building) located under the protective slab, to limit the footprint of the installation and thus to increase its compactness. Said at least one reactor building is also housed entirely in the shaft without extending above the opening in order to be arranged under the protective slab and so that the entire installation is thus buried. The equipment or buildings, for their part, rest solely on the protective slab without extending over the edges of the shaft opening.

[0006] According to other possible characteristics: -the buried nuclear installation includes at least one nuclear fuel storage pool housed in the well; - the equipment or buildings arranged on said at least one protective slab are configured to provide support functions for the operation of the nuclear reactor and the entire nuclear installation; - the equipment or buildings arranged on said at least one protective slab comprise at least one of the following elements: a nuclear installation control room, a building providing ventilation functions, a building providing cooling functions, a room containing control and command cabinets for operating support and electricity production functions, an instrumentation room, a high-current electrical distribution room, a low-current electrical distribution room and batteries / inverters, a valve and exchanger room, a first-aid diesel engine room;other equipment or buildings may be arranged on said at least one slab for protection against external attacks in addition to or instead of some of the aforementioned equipment or buildings; this additional equipment or buildings may perform functions different from those identified above; it should be noted that depending on the nuclear technologies envisaged, suitable redundancies may be required; - said at least one reactor building comprises a roof which covers said at least one nuclear reactor enclosure, said at least one protective slab extending in particular above the roof and at a distance from it so as to provide between them a technical gallery which constitutes an intermediate space; - the roof covers said at least one nuclear reactor enclosure and said at least one nuclear fuel storage pool; - said at least one reactor building and the technical gallery are arranged under said at least one protective slab and the equipment or buildings are arranged on said at least one protective slab, which gives rise to an architecture having a vertical arrangement with improved compactness divided into three parts, namely a lower part housed in the shaft, an upper part located on the protective slab and an intermediate part (technical gallery) housed in the shaft between the upper and lower parts and which serves to connect these two parts together, and in particular the prefabricated networks thereof; -the installation comprises one or more vertical walls bordering the interior of the well, said at least one protective slab being supported vertically: directly on an embankment arranged at the outer periphery of the well, a bellows device being arranged vertically between said at least one protective slab and the vertical wall or walls bordering the interior of the well, or directly on the vertical wall or walls bordering the interior of the well, or indirectly on the vertical wall or walls bordering the interior of the well by means of a damping joint device and / or directly on one or more supports arranged externally relative to the vertical wall or walls bordering the interior of the well; -said at least one reactor building comprises one or more vertical walls which are spaced horizontally from the vertical wall or walls bordering the interior of the well or attached to the vertical wall or walls bordering the interior of the well; - said at least one nuclear reactor enclosure is supported by at least one support slab resting on the bottom of the well; - said at least one nuclear fuel storage pool is supported by at least one support slab resting on the bottom of the well; - said at least one support slab is either connected to or separated from the wall(s) of the reactor building by one or more peripheral isolation joints or by a space between said at least one support slab and the wall(s) of the reactor building; - the installation comprises, adjacent to a zone of the shaft in which said at least one reactor building is housed, at least one other zone of the shaft which forms in particular a vertical handling zone capable of being placed in communication with the zone of said at least one reactor building; -said at least one protective slab comprises a hopper which is located in an area of ​​said at least one protective slab located above said at least one other area of ​​the well; - said at least one nuclear fuel storage pool is arranged adjacent to said at least one reactor building, and is, for example, arranged in the vertical handling shaft or in another space adjacent to said at least one reactor building; - said at least one protective slab is formed of one slab or two half-slabs which are fixed to each other; the use of two or more half-slabs makes it possible to reduce the weight of the load to be shifted from a half-slab construction area located near the shaft to the shaft and therefore to size the slab movement system accordingly, which simplifies the construction of the installation and the shifting operations, as well as the energy consumption of the shifting operations; this is particularly advantageous when one or more equipment or buildings are built on the half-slabs and therefore increase the weight of the load to be shifted; - said at least one protective slab is configured to be able to be removed subsequently in the event of modification or dismantling of the nuclear installation; - the vertical well has a general rectangular or circular shape according to a view taken in a horizontal plane. Brief description of the drawings

[0007] Other characteristics and advantages will appear during the description which follows, given solely as a non-limiting example and made with reference to the appended drawings, in which:

[0008] [Fig. 1] Figure 1 is a schematic view of a possible example of the installation of a buried nuclear installation according to one embodiment of the invention;

[0009] [Fig. 2] Figure 2 is an enlarged simplified schematic view of the buried nuclear installation of Figure 1, in a vertical section, according to a possible embodiment of the invention;

[0010] [Fig. 3] Figure 3 is a view of the buried nuclear facility of Figure 2 in a vertical section plane parallel to that of Figure 2;

[0011] [Fig. 3A] Figure 3A is a partial schematic view in vertical cross-section showing the through openings of a slab and also a representation of a technical gallery;

[0012] [Fig. 4A] Figure 4A is an enlarged partial schematic view of an area of ​​the buried nuclear installation of Figure 1 located between the protective slab and the walls bordering the shaft, showing a flexible joint provided between these two elements, according to a possible embodiment of the invention;

[0013] [Fig. 4B] Figure 4B is a partial schematic view illustrating a support of the protective slab according to an alternative embodiment;

[0014] [Fig. 4C] Figure 4C is a partial schematic view illustrating a support of the protective slab according to another variant embodiment;

[0015] [Fig. 4D] Figure 4D is a partial schematic view illustrating a support of the protective slab according to another variant embodiment;

[0016] [Fig. 4E] Figure 4E is a partial schematic view illustrating a support of the protective slab according to another variant embodiment;

[0017] [Fig. 5] Figure 5 illustrates, in a vertical sectional view, another possible embodiment of a buried nuclear installation;

[0018] [Fig. 5A] Figure 5A is a partial schematic perspective view from above of two half-slabs for protection against external attacks spaced longitudinally from each other;

[0019] [Fig. 5B] Figure 5B is an enlarged partial schematic view of a connection zone between two half-slabs for protection against external attacks according to a possible example of embodiment;

[0020] [Fig. 5C] Figure 5C is a schematic perspective view from above of two half-slabs for protection against external aggression joined together;

[0021] [Fig. 6] Figure 6 illustrates, in a vertical sectional view, another possible embodiment of a buried nuclear installation;

[0022] [Fig. 7] Figure 7 illustrates, in a horizontal sectional view, another possible embodiment of a buried nuclear installation;

[0023] [Fig. 8] Figure 8 illustrates, in top view, a possible embodiment of a circular underground nuclear installation under construction;

[0024] [Fig. 9] Figure 9 illustrates, in a vertical sectional view, the installation of figure 8 after the sliding of the protection slab against external aggression. Description of the embodiments

[0025] The invention which is described below with reference to the attached drawings concerns different possible embodiments of a new buried nuclear installation architecture.

[0026] As shown schematically in Figure 1, a buried nuclear installation 10 comprises a vertical shaft 12 dug into a ground 14 to a predetermined depth, for example of the order of 30-35 m using conventional excavation techniques and equipment.

[0027] This well 12 comprises, at a lower end, a bottom 12a, and, at an upper end, an opening 12b of dimensions substantially equal to those of the bottom. In this embodiment, the earth which is removed to form the well is, for example, used to form one or more embankments 16 arranged around the opening 12b of the well, thus forming an elevation relative to the surface of the ground 14. This arrangement can serve as a barrier against flooding. However, the presence of embankment is not obligatory.

[0028] The height or depth of the shaft 12 is defined between the opening 12b and the bottom 12a of the shaft and is chosen in order to be able to house entirely inside the shaft all of the elements making up the buried part of the nuclear installation 10 and which will be described later (reactor building, technical gallery, possible nuclear fuel storage pool, etc.), taking into account the height of the base that will be formed at the bottom of the shaft. The shaft 12 can have any general shape following a horizontal section (perpendicular to the plane of Figure 1) and, for example, can adopt a generally rectangular, square, circular section, etc. In general, the components of the buried part of the nuclear installation are located at a height which is lower than that of the ground surface and / or that of the lower surface of the embankment.

[0029] These walls serve to absorb the pressure of the earth surrounding the well and to ensure a seal (barrier) of the interior of the well, in particular against water likely to infiltrate into the surrounding earth. This sealing barrier can be supplemented by another barrier comprising a waterproofing membrane. Depending on the geometry of the well, a single wall (well with a circular section) or several vertical walls (well with a square, rectangular section, etc.), for example molded, can be considered. In a well with a rectangular section, for example, four walls are provided to delimit the useful interior space of the well.

[0030] As shown in Figure 1, the buried nuclear installation 10 comprises at least one protective slab 20 against external attacks on the well, such as falling objects (e.g., airplanes) or external explosions. For the simplification of the following description, said at least one protective slab 20 is considered here as being a single protective slab 20. However, everything relating to the buried nuclear installation which is the subject of the invention also applies to a protective slab which is formed of several slabs, and for example of two half-slabs as will be seen later in another embodiment. This protective slab 20 is arranged above the well 12 and extends horizontally so as to completely close the opening 12b of the well in which all the components of the buried part of the nuclear installation are housed.The general shape of the slab 20 is adapted to the shape of the horizontal section of the opening 12b of the well and, in the present embodiment, the general shape of the slab 20 is rectangular (however, the general shape is likely to adopt other shapes depending on the shape of the opening of the well and, for example, a circular shape). The protective slab 20 is generally made of reinforced concrete. Alternatively, the slab can be constructed of prestressed concrete or made according to a mixed construction with a lower facing consisting of a stiffened steel sheet on which flexible connectors are welded.

[0031] In the embodiment illustrated in Figure 1, the protective slab 20 is arranged in vertical support directly on the embankment 16 located at the outer periphery of the well, so that the weight of the slab does not rest directly on the upper edges, also called heads, of the walls 18a, 18b (the protective slab is a separate element from the embankment(s) 16 on which the slab rests, in particular by its peripheral edges). Thus, the protective slab 20 is mechanically independent of the buried structure and in particular of the walls 18a, 18b, which means that in the event of vibration of the slab (for example under the impact of an object external to the installation), the vibrations generated at the level of the slab will be transmitted to the embankment and damped by the earth and will therefore not be transmitted to the buried structure via the walls 18a, 18b.The protective slab 20 is preferably configured to be able to be removed later in the event of a major modification or dismantling of the installation 10. The configuration of the slab which allows it to be removed later (i.e. after installation to seal the well) is linked to the fact that it is either a single homogeneous slab which can therefore be shifted outside the area occupied by the well to clear the opening of the well (the shifting takes place in an axial direction which is parallel to the large dimension of the rectangular slab), or a slab resulting from the assembly of two half-slabs or more than two half-slabs and which thus becomes a single slab formed from a single piece which can also be shifted outside the well in the aforementioned axial direction, in order to clear the opening of the well.It should be noted that this movement / sliding of the slab follows the opposite path to that linked to the installation of the slab during the construction of the installation.

[0032] It should be noted, however, that the mechanical independence mentioned above does not mean that the slab 20 and the walls 18a, 18b cannot be in indirect mechanical contact with each other, as described later with reference to FIG. 4A, or in direct mechanical contact with each other, as is the case in FIGS. 4C and 4E also described later. In the configurations of FIGS. 4A-4E, an embankment 16 is present. However, the protective slab does not rest on it but is arranged adjacent to the embankment, against it, while being distinct from it. In the figures, the slab extends in height substantially at the same height as the embankment so as to form a upper surface flush with that of the embankment. However, the slab may be higher or lower than the embankment depending on the configurations envisaged.

[0033] Figures 2 and 3 are enlarged views of a buried nuclear installation similar to that of Figure 1 but remain schematic for the purposes of the presentation. However, the support of the protective slab 20 differs from that of Figure 1 since the slab 20 is here in vertical support directly on the vertical wall(s) 18a, 18b bordering the shaft, by means of a skirt or peripheral edge 20b which extends downwards from the lower face 20a of the slab. The skirt 20b rests directly on the heads of the walls (only the walls 18a, 18b are shown in this section) which each have a peripheral edge forming an external shoulder, such as that 18a2 of the wall 18a. It will be noted that the following description applies to all embodiments and variants and, in general, is not limited to the method of vertical support of the protective slab or to the presence of backfill 16.

[0034] As shown in Figure 2, the well 12 comprises, at its lower end, a raft 12c constituting the bottom of the well on which the various elements / components of the buried installation will be installed. This raft was put in place in a known manner after the excavation of the well (an injected bottom may prove necessary to limit water inflows from the bottom if the ground is permeable).

[0035] The buried nuclear installation 10 here comprises a reactor building 26 housed entirely in the shaft 12 (under the protective slab 20 which completely closes the opening 12b of the shaft) and resting on the foundation 12c. It will be noted that several reactor buildings can be installed in the shaft 12, as will be seen later during the description of other embodiments.

[0036] In the present embodiment, the buried reactor building 26 comprises one or more vertical walls (depending on the geometry of the building). If the building has a rectangular or square horizontal section, it will necessarily have several walls (which is the case here with the rectangular shape), whereas it may have only one wall if it has a circular horizontal section (cylindrical-shaped shaft). The reactor building 26 also comprises a roof 28 which rests on the head of the wall(s) (depending on the configuration) to cover the building, in order to define a closed space internal to the latter. In the example described, the reactor building 26 has a rectangular horizontal section and comprises four vertical walls, of which only two 26a, 26b facing each other are shown in Figure 2, the other two adjacent vertical walls being perpendicular and not visible here. The walls of the reactor building 26 rest on the raft 12c. The roof 28 is here a reinforced concrete slab of simple structure, which means that it has a sufficient thickness of reinforced concrete to ensure its resistance under all the stresses to which it may be subjected. This slab can alternatively be a mixed steel-concrete slab.

[0037] The walls of the reactor building 26 (wall 26a and the two other adjacent perpendicular walls not visible in Figure 2) are arranged opposite the vertical walls bordering the shaft (wall 18a and the two other adjacent perpendicular walls 18c and 18d, not visible in Figure 2 but visible in Figures 4B-4E described later), close to each other, leaving as little space as possible between them (this space is however not visible in Figures 2 and 3), without however being mechanically linked together, so as not to create a mechanical connection through which mechanical forces / vibrations would be likely to pass.

[0038] As shown in Figures 2 and 3, the protective slab 20 is arranged above the roof 28 of the reactor building 26 which it covers entirely, at a distance (vertically) from the latter so as to provide between them a vertical space which has a function of technical gallery G of which the roof 28 forms the floor, allowing in particular, depending on the length of the gallery, the circulation of people and the routing of cables, conduits and other equipment or any other component serving as a connection between, on the one hand, the buildings which are outside the buried part of the installation, in particular those mounted on the protective slab 20 and, on the other hand, the interior of the reactor building and, in fact, up to the reactor enclosure contained in the building.In other words, technical gallery G forms an intermediate space between the reactor building and slab 20 and, more particularly, between the reactor building and the space which is located on slab 20 and which is occupied by buildings and / or equipment. auxiliaries which will be described later. Access to technical gallery G can be gained via the stairs (visible in Figure 2) which are located in the shaft area which is adjacent to the area housing the reactor building.

[0039] The horizontal dimensions of the slab (in the length which appears in Figure 2 but also in a horizontal direction perpendicular to the plane of this figure) are greater than those of the roof 28 which stops at the level of the upper edges or heads of the walls 26a, 26b of the reactor building 26. The slab extends horizontally in particular above a space or zone of the shaft which is adjacent to the zone of the shaft in which the reactor building is housed and which will be described later.

[0040] The reactor building 26 contains, in the closed space which is delimited by its vertical walls 26a, 26b (and the two adjacent perpendicular vertical walls not visible in FIG. 3) and its horizontal roof 28, at least one nuclear reactor enclosure. In the present embodiment, a single nuclear reactor enclosure 30 is housed in the reactor building 26. The enclosure here has a rounded shape at its upper part in order to withstand internal pressure.

[0041] In the present embodiment, the nuclear reactor is of the PWR type, that is to say that it uses pressurized water technology. Such a reactor may comprise mainly inside the sealed enclosure 30, in a known manner, a primary circuit which comprises: - a reactor vessel containing in particular the fuel elements and the control rods, - one or more steam generators, - primary pumps ensuring a loop circulation of the primary fluid which travels through the fuel elements of the reactor vessel by recovering the thermal energy released by the nuclear reaction and circulates in the primary part of the steam generators, where a heat exchange takes place between the primary fluid and the secondary part of the steam generators in order to produce steam at the top of said steam generators. The steam thus produced is evacuated from the steam generators through the steam pipes of a secondary circuit which passes through the walls of the enclosure 30 and conveys it to one or more turbines outside the shaft to turn it or them and thus produce, at the alternator output, electric current distributed on a high voltage electrical network.

[0042] The primary circuit also includes a pressurizer which has a primary circuit regulation function.

[0043] It will be noted that the walls bordering the well, the walls of the building and the roof 28 have much lighter structures than that of the wall of the enclosure 30, which makes it possible not to affect the integrity of the enclosure in the event that one of the preceding elements is projected against the enclosure 30.

[0044] Furthermore, independently of the previous preferred embodiment, the buried nuclear installation according to the invention can be applied to any other nuclear technology such as one of the following technologies: BWR, HTR, with powers adapted to the SM R model ("Small Modular Reactor" in English terminology). For example, the powers can range from 50MWe to N x 50MWe, with N greater than 1 and, for example, N can take values ​​between 1 and 8, or even greater than 8. According to another example, the powers can range from 100MWe to N x 100MWe, with N greater than 1 and, for example, N can take values ​​between 1 and 8, or even greater than 8.

[0045] The raft 12c has been arranged so as to include a support slab 32 on which the nuclear reactor containment 30 rests. The support slab 32 may have, in its central part located under the reactor vessel, a recess or cut-out 32a (footprint of a volume) which extends downwards. The raft 12c may be excavated to possibly install a device there to deal with any accident occurring around, on or in the vessel. It will be noted that the raft 12c and the support slab 32 may constitute a single reinforced concrete structural element. It will also be noted that the enclosure 30 is only supported by the support slab 32 but is not suspended from an upper part of the reactor building 26 such as the roof 28. The reactor building itself is also not suspended from an area located at the top of the shaft. The above applies to all the modes and variants described in this description.

[0046] As shown in Figures 2 and 3, the reactor building 26 may also include a horizontal intermediate slab 34 which is integral with the vertical walls of the building (26a and 26b in Figures 2 and 3 and the two other adjacent vertical walls perpendicular). The intermediate slab 34 extends horizontally from these walls so as to radially surround the nuclear reactor enclosure 30, without however coming into contact with it, as shown in Figure 2. This slab 34 is arranged at a level or a level along the vertical of the building which represents an intermediate position between the support slab 32 and the roof 28. This intermediate slab 34 is arranged parallel to the support slab 32 and the roof 28, and at a distance from them.

[0047] Figure 2 also illustrates on the right part of the buried installation 10 a zone Z1 adjacent to the zone containing the reactor building 26, which is housed inside the shaft but separately from this building. This zone Z1 is delimited between the wall 26b of the building and a wall of the installation, opposite noted P1, which is arranged opposite the wall 18b bordering the shaft. The zone Z1 forms an internal compartment in the shaft in which a staircase 36 can be arranged allowing personnel to circulate between the lower part of the shaft and its upper part (including to access the level of the protective slab).

[0048] In Figure 3 (section plane parallel to that of Figure 2), another zone Z2, adjacent to the zone containing the reactor building 26, is arranged between the wall 26b of the building and the opposite wall P1 which is arranged opposite the wall 18b bordering the shaft. The zone Z2 forms a vertical handling shaft which provides access in particular to the support slab 32 arranged in the lower part of the shaft. The protective slab 20 extends above the reactor building and the adjacent zones Z1 and Z2. As shown in this figure, an opening O (called a buffer) which is permanently closed during operation of the reactor (by means of a sliding or pivoting door not shown) and opened only to evacuate or bring in equipment, is arranged in the vertical wall 26b of the reactor building to connect the handling shaft Z2 and the interior of the reactor building.Opposite this opening O another opening O' (called a buffer) is arranged in the enclosure 30 which is permanently closed. operation of the reactor (via a sliding or pivoting door not shown).

[0049] A hopper 40 is for example arranged in the protective slab 20 directly above at least one of the two zones Z1 and Z2 adjacent to the zone of the reactor building 26. This hopper 40 permanently occupies a closed position but can open when it is necessary to access the space located below and, in particular, to carry out maintenance operations via the handling shaft Z2, such as, for example, for maintenance operations, to evacuate, and re-enter by the same route, (components) or elements of the nuclear reactor enclosure. The reactor enclosure 30 has an opening (not shown), called a buffer, which must be placed (ideally) opposite the sliding door 01 closing the opening (of the reactor building).

[0050] As shown in Figures 2 and 3, one or more pieces of equipment and / or buildings are arranged on the protective slab 20 without, however, encroaching on the edges of the opening of the well. The protective slab 20 alone supports the piece of equipment or building.

[0051] This or these pieces of equipment and / or buildings are configured to provide support functions for the operation of the nuclear reactor and the entire nuclear facility and, as such, they are called 'auxiliary' equipment or buildings as opposed to so-called 'main' equipment or buildings which provide nuclear safety functions and which are positioned buried inside the shaft. In other words, they are pieces of equipment or buildings located above the slab providing protection against external attacks and which may be subject to external attacks to the extent that the functions necessary for the safety of the reactor that they perform, in the event of degraded or accidental situations, are redundant with the reactor safety functions of the equipment or buildings located below the slab.

[0052] This or these equipment or buildings are constructed solely on the protective slab and may include at least one of the following elements: a nuclear installation control room, a building providing ventilation functions, a building providing cooling functions, a room containing control and command cabinets for operating support and electricity production functions, an instrumentation room, a high-current electrical distribution room, a low-current electrical distribution room and batteries / inverters, a valve and exchanger room, a first-aid diesel engine room.

[0053] In the embodiment of Figures 2 and 3, the slab 20 supports an auxiliary building b1 forming a control room for the installation and, in the background, three auxiliary buildings b2, b3 and b4 which are respectively an auxiliary building providing cooling functions, an auxiliary building providing ventilation functions and an auxiliary diesel engine room. It will be noted that the slab can of course support other equipment or auxiliary buildings, in addition to or replacing at least some of those already described.

[0054] It should be noted that through openings (not shown in the figures) can be provided at different locations in the slab, in its thickness, to the right of which the auxiliary buildings mentioned above are built. Each of these openings is used for the passage of cables, pipes, etc. (various connections) between the auxiliary building located above the slab and the reactor building located under the slab via the technical gallery located between the slab and the reactor building and through openings (not shown in the figures) provided in the roof of the reactor building for the passage of these various connections.

[0055] Figure 3A is a schematic vertical sectional view of a slab Di for protection against external attacks (along its smallest dimension) showing for example two through openings Di 1 and Di2 (a greater number of openings can be envisaged in a variant if the number of buildings increases) arranged respectively in line with future buildings constructed on the slab and an opening Ti, arranged on one side of the slab, acting as a hopper and which is for example closed by a hatch ti shown in the two positions in Figure 3A. After having selectively put in place the various connections through each opening Di 1 (e.g.: pipes), Di2 (e.g.: cables), the latter is sealed in a manner known to those skilled in the art, in particular to ensure sealing and protection fire break (at least 2 hours). Note that the above also applies to a half-slab in the case where the protective slab is formed of two half-slabs. Figure 3A illustrates a possible configuration of the technical gallery G between the upper slab (or half-slab) Di (the auxiliary building(s) are not shown for the sake of simplicity for the purposes of the presentation) and the lower roof T of the corresponding reactor building.In this figure, the openings Di 1 and Di2 arranged in the thickness of the slab (or half-slab) Di are used for the selective passage of pipes (Di1) and electrical cables (Di2) and other connecting elements not shown (for example through other through openings not shown) between the auxiliary building(s) built on the slab (or half-slab) Di and the technical gallery G, then between the latter and the reactor building below through corresponding openings Oi 1, Oi2 arranged in the roof T of the building. It will be noted for example that the electrical cables passing through the opening Di2 are connected to a collector equipment UT (processing unit) and that other electrical cables leave this equipment to pass through the opening Oi2 of the roof for connection to equipment in the reactor building.Generally speaking, the connections are made in a sectorised manner by making separately (and for example staggered in time) the connections between the area located above the slab (or half-slab) and the technical gallery, on the one hand, and the connections between the area located under the slab (or half-slab) and the technical gallery, on the other hand, unlike the simultaneous making of the connections to connect the area above to the area below after completion of these areas.

[0056] In the event of a modification to be made, the advantage of having a segmentation into three parts (technical gallery, part above the technical gallery and part below the technical gallery) is to avoid having to redo the entire circuit (piping, cables, etc.) since only the part of the circuit concerned by the modification can be modified (e.g. the part of the electrical wiring circuit between the top of the slab and the technical gallery).

[0057] The new architecture described above provides high compactness and a limited footprint by arranging the nuclear facility on several vertically superimposed levels, by placing, on said at least one slab of protection, one or more auxiliary equipment or buildings and, at least one buried reactor building (in the shaft), under said at least one protective slab which completely closes the opening of the shaft. Preferably, the technical gallery is arranged in the shaft, above said at least one reactor building and below said at least one protective slab in order to complete this arrangement and further improve the compactness of the installation.

[0058] Figure 4A is a partial enlarged view of the area between the slab 20 and the head 18a1 of the wall 18a of Figure 1 and shows the presence, between these two elements, of a bellows device 22 with a thick rubber wave of known type, arranged substantially vertically. This device 22 rests on the entire perimeter of the wall heads 18a, 18b. This perimeter here takes a rectangular shape but it can take a square, circular shape, etc., depending on the geometry of the (horizontal) cross-section of the well. The device 22 is for example connected to the wall heads, as well as to the lower surface 20a of the slab 20 (on an area which is in geometric correspondence with the wall heads 18a, 18b, directly above them) by respective fixing members 24a, 24b.In this embodiment, the edges of the bellows device 22 are, all around, fixed, for example, by stainless steel slats which compress them, these stainless steel slats themselves being fixed in the concrete by spaced anchor studs. The bellows device 22 makes it possible to ensure sealing between the two spaces E1 and E2 which it separates: space E1 corresponds to the useful space inside the well and in which the various elements / components of the buried installation are arranged and space E2 corresponds to the space adjacent to the backfill 16 (not visible in FIG. 4A).

[0059] It should be noted that with such an arrangement the intermediate space formed by the technical gallery G described above with reference to figures 2 and 3 can be isolated in terms of building ventilation thanks to this rubber wall 22. A slight depression (-5 or -10mm CE) can thus be created thanks to this specific ventilation function.

[0060] According to an alternative embodiment shown in Figure 4B, the protective slab 20' is connected to the vertical walls 18c, 18d bordering the well (these two walls are adjacent and perpendicular to the two walls 18a, 18b of Figure 1) by means of a flexible joint device 22'. In this alternative, the protective slab 20' rests vertically directly on one or more supports 23 arranged externally relative to the vertical walls 18a, 18b bordering the interior of the well. More particularly, the slab 20' comprises one or more peripheral edges 20b' jointly forming a skirt which extends vertically from the external periphery of the lower surface 20a' away from the latter. As shown in Figure 4B, the skirt 20b' rests on one or more supports 23 such as stringers which are supported by piles or sole plates 25 anchored vertically in the ground at a distance from the vertical walls 18a, 18b bordering the interior of the well.

[0061] According to another variant embodiment shown in Figure 4C, the protective slab 20” rests vertically directly on the vertical wall(s) 18c, 18d bordering the well, by means of a skirt 20b” similar to the skirt in Figure 4B.

[0062] As illustrated in Figures 4B and 4C described above, the respective walls facing the reactor building 26 and the well may be joined or joined.

[0063] According to an alternative embodiment of the installations of figures 4B and 4C, the walls of the reactor building 26 are spaced horizontally from the vertical walls bordering the shaft so as to provide a space between the respective facing walls. These facing walls spaced from one another are not mechanically connected to each other so as not to create a mechanical connection through which mechanical forces / vibrations would be likely to pass. The space thus provided can be a useful technical space to allow inspection by maintenance personnel, or even by cameras. In practice, this space can have a width of approximately 1.5 to 2 m.

[0064] Figures 4D and 4E illustrate such arrangements in which respectively the respective walls of the reactor building 26' (the wall 26a' and the two other adjacent perpendicular walls not visible in Figures 4D and 4E) and the walls facing the well (the wall 18d and the two other adjacent perpendicular walls 18a and 18b, not visible in Figures 4D and 4E) are spaced horizontally from each other as explained above. The vertical supports of the protective slab in Figures 4D and 4E correspond respectively to the supports in Figures 4B and 4C.

[0065] It will be noted that the arrangements described above between the respective walls facing the reactor building 26, 26' and the shaft also apply to the method described above concerning the vertical support of the protective slab 20 on the embankment 16 (fig. 1).

[0066] Figure 5 shows a view along a vertical section of a new configuration of buried nuclear installation 10' according to another embodiment in which two reactor buildings 26.1 and 26.2 are housed in the shaft 12', adjacent to each other and separated from each other by an internal transverse wall 26.12. Each reactor building is for example identical to the other, as well as to the reactor building 26 already described.

[0067] As shown in Figure 5, the walls bordering the shaft (only the parallel walls 18a' and 18b' are visible) surround the two buildings 26.1 and 26.2. The walls (not visible) which are perpendicular to the walls 18a' and 18b' are elongated relative to the corresponding walls of Figures 2 and 3 in order to accommodate side by side two reactor buildings 26.1 and 26.2 containing two nuclear reactor enclosures 30.1 and 30.2. As for the mode of figures 2 and 3, each nuclear reactor enclosure rests on a support slab 32', which is common to both enclosures and similar to the support slab 32 of figure 2. The support slab 32' thus has in each of the parts located under a reactor vessel 30.1, 30.2, a recess or cut-out 32a.1, 32a.2 (footprint of a volume) which extends downwards, in a manner identical to the recess 32a of figures 2 and 3.

[0068] As in Figures 2 and 3, zones (not visible in Figure 5) which are analogous to zones Z1 and Z2 of Figures 2 and 3 are arranged adjacent to each of the zones of the shaft containing one of the two reactor buildings 26.1 and 26.2.

[0069] In Figure 5, the protective slab 20.2 is here formed of two protective half-slabs 20.2a and 20.2b which are fixed to each other at their junction 20.2c located substantially in line with the internal wall 26.12 separating the two reactor buildings. The fixing can be carried out by known techniques and, for example, the two protective half-slabs 20.2a and 20.2b can be keyed to each other or joined to each other by overlapping reinforced concrete reinforcements or by reinforced concrete reinforcements connected by sleeves (couplers) in reserved areas which are concreted in the second phase, after completion of the reinforcement junction.

[0070] Figure 5A shows, in a perspective view from above, the two protective half-slabs 20.2a and 20.2b (without the other elements of Figure 5 for the sake of clarity) spaced apart from each other in a longitudinal direction X, for example in a position where each half-slab is on its construction area or zone near the well (not shown here). The half-slabs are thus constructed at a distance from each other and each have a free end face fa1, fa2 facing each other. These two faces fa1, fa2 are intended to be mechanically joined / assembled with each other to form a single slab as explained further on with reference to Figure 5B. As shown in Figure 5A, a peripheral edge R1, R2 is arranged respectively on the lower face of each half-slab 20.2a, 20.2b and extends vertically downwards in the manner of a skirt or a dropped edge.

[0071] Each half-slab 20.2a, 20.2b may have openings which are made through its thickness in order to allow the passage of cables, pipes, equipment and people depending on the opening(s) concerned. In Figure 5A an opening T1, T2 offset laterally with respect to the longitudinal median axis (parallel to the X axis) of each half-slab is present. This opening is for example intended to form a hopper which will be used later for maintenance or handling and which will be arranged above the well or handling area located along the reactor building. Other through openings (not shown here) may be arranged at separate locations in each half-slab on which auxiliary buildings are built. Each of these openings is used for the passage of cables, pipes, etc.(various connections) between the equipment or building located above the half-slab and the reactor building located under the half-slab via the technical gallery located between the half-slab and the reactor building and through openings (not shown in the figures). fitted in the roof of the reactor building for the passage of these different connections.

[0072] Furthermore, each half-slab 20.2a, 20.2b may include imprints r1.1, r1.2, r2.1, r2.2 (figs. 5A and 5C) of the rails of an overhead crane which will be used subsequently to move various equipment on the slab and in particular for maintenance above the handling hoppers T1, T2.

[0073] In the position of Figure 5 (the half-slabs are positioned above the opening 12b' of the well), the half-slab 20.2a is arranged against the half-slab 20.2b and the two half-slabs are mechanically joined / assembled with each other, for example by keying, in order to mechanically form a single protective slab while ensuring continuity of the mechanical resistance of the slab at the junction or connection zone 20.2c between the half-slabs. To do this, the reinforcement or reinforcement must be continuous at this zone.

[0074] Figure 5B illustrates a possible example of mechanical connection between the half-slabs 20.2a and 20.2b. This figure is an enlarged partial view of a mechanical connection zone between the two half-slabs. The connection between the two half-slabs 20.2a and 20.2b can be achieved by providing a keying zone Zcl between these half-slabs. The half-slabs are installed by providing a keying width greater than the overlap length of the longitudinal reinforcements which are located in the lower layer a1 i and a2i and in the upper layer aï s and a2s of the half-slabs. The longitudinal reinforcements of each slab element (half-slab) overlap with the longitudinal reinforcements of the other slab element.Several layers of upper and lower reinforcement are required for each slab element, but only one layer of upper reinforcement and one layer of lower reinforcement are shown for each slab element in the schematic diagram of Figure 5A to facilitate understanding. The longitudinal reinforcement in the other direction and the shear reinforcement are also installed (see schematically the perpendicular reinforcements a3i and a3s in the figure). In addition, temporary formwork Cfp can be fixed under the slab elements and concreting of the keying zone is then carried out in order to mechanically connect the two elements together. slab. The temporary CFP formwork, which, for example, rests on the reactor roof (previously installed), is removed and removed, for example a few days after concreting the keying area. It should be noted that other solutions can be considered to ensure the continuity of the longitudinal reinforcement: couplers, welding of bars, etc.

[0075] Figure 5C illustrates the slab 20.2 obtained after assembling the two half-slabs 20.2a, 20.2b, for example as explained in the embodiment example described above, but which can, alternatively, be obtained in a different manner not described in detail here. The slab 20.2 of Figure 5 is for example that shown in Figure 5C without the auxiliary buildings b1 '-b4' for the sake of clarity. Certain details of the construction may vary between the slab of Figure 5C and that of Figure 5, in particular the position and the number of the through openings of each half-slab for the maintenance hoppers and for the auxiliary building(s), the presence or absence of the rails r1 .1 -r2.2 and their position ...

[0076] The 20.2 slab obtained after assembly of the two half-slabs 20.2a, 20.2b is a protective slab against external attacks on the shaft and thus protects the components of the installation which are housed in the 12' shaft, under this slab.

[0077] Generally, each half-slab is placed above the shaft after the roof slab of the reactor building has been completed and in such a way that the complete slab (e.g. slab in Figure 5C) can be removed in one piece, later in the event of dismantling of the installation (at the end of its life) or even in the event of modification of the latter, for example to carry out major maintenance work on the safety and operation of the installation. For example, the replacement of one or more steam generators may justify such an operation.The configuration of the slab which allows it to be removed later (i.e. after installation to seal the well) in a single block is linked to the fact that it is here a slab resulting from the assembly of two half-slabs (or even more than two half-slabs in a variant not shown) and which thus becomes a single slab formed from a single piece which can be slid out of the well in an axial / longitudinal direction X in order to clear the opening of the well. It should be noted. that this axial / longitudinal (horizontal) displacement / sliding of the slab follows the opposite slip path to that linked to the installation of the slab during the construction of the facility. The same applies to a single slab that is homogeneous in its construction.

[0078] Furthermore, each reactor building is closed at its upper part by a roof 28.1, 28.2 (fig. 5) and the protective slab 20.2 defines with each of the facing roofs that it covers a technical gallery G' of larger dimensions than the technical gallery G of figures 3 and 4. More particularly, each half-slab 20.2a, 20.2b located above the roof 28.1, 28.2 of the corresponding reactor building, provides with the latter a part of the technical gallery G', along its length. An intermediate slab 34.1, 34.2 can be arranged in each of the reactor buildings 26.1, 26.2, in a manner similar to the intermediate slab 34 of figures 2 and 3.

[0079] In this embodiment, each half-slab 20.2a, 20.2b supports one or more auxiliary equipment or buildings as explained above with reference to Figures 2 and 3.

[0080] More particularly, in Figure 5, the half-slab 20.2a supports an auxiliary building b1' forming a control room for the installation and an auxiliary diesel engine room b2', while the half-slab 20.2b supports two auxiliary buildings b3' and b4' which are respectively an auxiliary building providing ventilation and cooling functions and an auxiliary building providing cooling functions. It will be noted that each half-slab can of course support other equipment or auxiliary buildings, in addition to or in replacement of at least some of those already described.

[0081] Everything described above also applies in this embodiment where two reactor buildings are housed entirely in the shaft and will therefore not be repeated.

[0082] Figure 6 illustrates, in a vertical section, another embodiment of a buried nuclear installation 100 which differs mainly from the embodiment of Figures 2 and 3 by the presence of a nuclear fuel storage pool, identified in the figure by the acronym PECN, located in a zone Z2” of the shaft adjacent to the zone where the reactor building 126 is located. elements corresponding to the mode of figures 2 and 3 and which are repeated here are preceded by the number “1 and, in principle,” will not be described again. The PECN pool rests on the same support slab 132 as the nuclear reactor containment 130. A roof 128 extends here above the reactor building 126 and the adjacent zone Z2”. It will be noted that the arrangement of the roof above zone Z2” may be only local by extending above the PECN pool, but without however extending over the entire zone Z2”.

[0083] As shown in Figure 6, an opening O' (called a buffer) which is permanently closed during operation of the reactor (by means of a sliding or pivoting door not shown), is arranged in the vertical wall 126b of the reactor building 126 which separates the interior of the building from the adjacent zone Z2”. The opening O' is opened only to access the interior of the reactor building when the evacuation of material(s) and / or the introduction of new material(s) are necessary. The protective slab 120 extends above the reactor building 126 and the zone Z2” adjacent to the latter, and therefore the PECN pool. As for the mode of Figures 2 and 3, a similar technical gallery G” is arranged between the roof 128 and the protective slab 120.

[0084] Furthermore, one or more auxiliary equipment or buildings are arranged on the protective slab 120 as explained above with reference to figures 2 and 3.

[0085] In the embodiment of Figure 6, the slab 120 supports an auxiliary building b1” forming a control room for the installation and, in the background, three auxiliary buildings b2”, b3” and b4” which are respectively an auxiliary building providing cooling functions, an auxiliary building providing ventilation functions and an auxiliary diesel engine room. It will be noted that the slab 120 can of course support other equipment or auxiliary buildings, in addition to or replacing at least some of those already described.

[0086] It should be noted that through openings are provided at distinct locations in the slab, in its thickness, to the right of which the auxiliary buildings mentioned above are constructed. Each of these openings are used for the passage of cables, pipes, etc. (various connections) between the auxiliary building located above the slab and the reactor building located under the slab via the technical gallery G" located between slab 120 and the reactor building 126 and through openings (not shown in the figures) fitted in the roof of the reactor building for the passage of these various connections.

[0087] Everything described above also applies in this embodiment and will not be repeated.

[0088] Figure 7 illustrates, in a horizontal sectional view (top view), another embodiment of a buried nuclear installation 200 similar to the buried nuclear installation 10' of Figure 5. The difference between these two embodiments lies in the presence of a nuclear fuel storage pool PECN' in an area of ​​the shaft 12" which is adjacent to the area of ​​the shaft in which the two reactor buildings 26.1 and 26.2 are housed. This pool is located in the extension of the wall 126.12 which separates the two reactor buildings and is adjacent to each of the two buildings, because it extends on either side of this wall. This intermediate position between the two buildings makes it possible to store, in this pool, fuel elements from one or other of the reactors of the enclosures 130.1 and 130.2.Furthermore, in a variant not shown, two pools can alternatively be provided, each in an area adjacent to a reactor building and dedicated to the latter.

[0089] Analogously to the arrangement of the zones in Figure 5, the facility 200 comprises zones Z1” and Z2” (vertical handling shafts) which are located adjacent to the shaft area containing the reactor building 126.1. Similarly, the facility 200 comprises other zones Z1'” and Z2'” (vertical handling shafts) which are located adjacent to the shaft area containing the reactor building 126.2. The zones Z1” and Z2” and the zones Z1'” and Z2'” are arranged symmetrically with respect to the intermediate position of the PECN' pool located between them. Each of the zones has, for example, the same functions as the corresponding zone in the previous figures.

[0090] As with the arrangement of Figure 5, the installation 200 comprises a slab (not shown) formed of two half-slabs on each of which auxiliary equipment and / or buildings are constructed.

[0091] Everything described above also applies in this embodiment and will not be repeated.

[0092] Figures 8 and 9 illustrate a buried nuclear installation 300 according to another embodiment.

[0093] The right part of Figure 8 is a plan view of the installation following a horizontal section of the shaft 312. The section shows the elements located under the protective slab whose contours appear transparently above the shaft. The shaft 312 (of general cylindrical shape) has a circular section with a wall, for example cast, 318 of annular section which borders the interior of the shaft. The reactor building 326 also has a circular shape and contains a nuclear reactor enclosure 330 as described above. These circular and annular shapes have the advantage of better resisting thrusts coming from the outside (the earth in the case of the shaft) and overpressures (internally, coming from the enclosure or the reactor building). In particular, the annular-shaped diaphragm wall 318 (in section) works like a ring compressed by the earth thrust which is directed radially relative to the diaphragm wall.The diaphragm wall 318 is self-stable and the number of anchors of the wall in the ground is thus reduced, which in particular simplifies the design and construction. It will be noted that the wall 318 more generally has a cylindrical crown shape according to a three-dimensional view and the internal space of the well which is bordered by the wall 318 occupies a cylindrical shaped space.

[0094] In this embodiment, a PECN nuclear fuel storage pool can be arranged inside the reactor building 326 but off-center relative to the enclosure 330, as illustrated in FIG. 8. The installation 300 can also comprise a zone Z3 forming a handling shaft and which is also off-center relative to the enclosure 330, as well as a zone Z4, off-center, in which a staircase 336 is arranged. Tl allowing the different levels of the well 312 to be connected together, from the base 312c to the protective slab 320 visible only in figure 9.

[0095] Figure 9 is a vertical sectional view along section plane AA of Figure 8 and shows an arrangement similar to that of Figure 6. The entire reactor building 326 and containment 330 is supported by the same support slab 332 and the PECN nuclear fuel storage pool is also supported by the same support slab 332. It should be noted that in a circular configuration, it is simpler to provide only one circular support slab. Providing two separate (independent) support slabs, one to support the reactor building 326 and the other to support the PECN pool, as positioned in Figure 8, would lead to removing part of the circular slab to accommodate the slab supporting the pool, which would affect the integrity of the support slab of the reactor building 326 and risk weakening this support slab.

[0096] On the contrary, when the well has a generally rectangular (in section) or even square shape, and accommodates at least one reactor building and an adjacent pool, it may be more suitable, and in particular more economical, to have two independent support slabs.

[0097] In general, figures 8 and 9 include most of the common elements described with reference to the preceding figures and which will not be described again here, namely in particular the raft 312c, the recess 312c1 (optional), the support slab 332, the intermediate slab 334 (optional), the roof 328, the technical gallery G'” between the roof 328 and the slab 320. In the present embodiment, the gallery occupies a circular space in top view and not a rectangular one as in the previous embodiments.

[0098] According to an alternative embodiment not shown, the reactor building can adopt a general shape of square (horizontal) cross-section fitting inside the internal space of circular (horizontal) cross-section of the well (bordered by the circular wall 318).

[0099] According to another variant embodiment not shown, the well retains a circular (horizontal) cross-section which is here divided into two distinct compartments each forming a surface occupying a semicircle and a reactor building with a circular, square or rectangular (horizontal) section occupies each of the two semicircles. This variant can be adapted to low-power technologies, for example of the order of 50 or 100 MWe each, to avoid a diameter which would be too large for the upper protection slab if the reactors were of larger dimensions).

[0100] In the present embodiment, the protective slab is shown bearing directly on the wall 318 and the wall 318 is spaced from the wall 326a of the reactor building 326. However, the different arrangements described with reference to FIGS. 4A to 4E are also applicable here.

[0101] It will be noted that the protective slab (and each half-slab) of the various installations described above with one or more reactor buildings can be supported in different ways, as described above with reference to Figures 4A to 4E, whether or not there is one or more embankments 16.

[0102] Generally, buried nuclear installations according to certain embodiments of the invention may comprise two or more reactor buildings, as in Figures 5 and 7, thus making it possible to have smaller reactor cores providing less power (e.g. 50 or 100 MWe) than that of a larger installation with greater power (e.g. 800 MWe, or even higher powers). For example, to provide a power of 800 MWe, a buried nuclear installation according to the invention may be configured according to four shafts of 200 MWe each, each shaft being able to produce 2x100 MWe or 1x200 MWe.

[0103] The power modularity offered by these smaller installations also comes with a simplification of the installations and a reduced implementation cost compared to a larger power installation which can however benefit from the effect of standardization and repetition.

[0104] The left part of Figure 8 illustrates in top view (horizontal section) a possible general shape for the protective slab 320 which must completely close the upper opening 312b of the well 312 (Figures 8 and 9). As shown in Figure 8, the slab 320 has a generally circular shape with dimensions corresponding to those of the opening 312b to be covered. The slab 320 comprises, at two diametrically opposite zones of its circumference, two external radial extensions 320a and 320b, here symmetrical with respect to each other, which each start from two diametrically opposite portions 320c, 320d of the circular circumference of the slab to each end with a flat face (cut or beveled) 320a.1 and 320b.1. The two flat faces 320a.1 and 320b.1 are parallel to each other and are used to convey the protection slab 320 to a position located above the opening of the well 312 by sliding, from a zone Zed shown on the left part of figure 8 and which is located outside the well but close to it.

[0105] The two flat faces 320a.1 and 320b.1 each form a dropped lateral peripheral edge, one of which is visible on the left part of figure 9.

[0106] In the embodiment of figures 8 and 9, the protective slab 320 is for example constructed on the Zed area or zone, with, on this slab, auxiliary equipment / buildings such as those described above (at least partially constructed on the slab before its shifting), while the reactor building 326 is being constructed in the shaft 312.

[0107] On the left part of Figure 8 (top view), several equipment / buildings b3.1, b3.2, b3.3 were built on the slab 320 during the construction of the reactor building in the shaft. For example, buildings b3.1, b3.2, b3.3 are respectively an auxiliary building providing cooling functions, an auxiliary building providing ventilation functions and a control room for the installation. Other equipment / buildings can of course be built on the slab in place of at least some of these buildings or in addition to them. An opening T can also be arranged in the thickness of the slab 320 to serve in particular as a hopper at the level of the handling zone Z3 of the shaft 312 (right part in Figures 8 and 9), when the slab will be put in place above the shaft.

[0108] The protective slab 320 thus constructed can be slid from its construction zone Zed to a position located above the opening 312b of the well using for example two parallel guide beams L1, L2 (fig. 8) each intended to cooperate with a lateral peripheral edge falling from one of the two flat faces 320a.1 and 320b.1 of the slab.

[0109] A system for moving the slab 320 by translation comprises, for example, two jacks V1, two blocks M1 on which the jacks can be fixed and to which two traction cables Ca1 are attached, the cables passing through the external radial extensions 320a and 320b of the slab in their length and being fixed to the faces of these extensions which are opposite the shaft (anchor A1). Alternatively, the operation of shifting the half-slabs can be carried out on an air cushion using for example so-called APS modules of the Freyssinet system which are air-cushion sliding supports arranged under each half-slab. More particularly, the air-cushion sliding supports can be arranged between the lower faces of the two longitudinal edges or skirts of the slab or of each half-slab and the upper face of the two shifting stringers (the coefficient of friction is very low, of the order of 1%).

[0110] The right part of Figure 9 illustrates the slab 320 with its auxiliary equipment / buildings, after sliding, in the position of closing the opening 312b of the shaft, above the roof 325 of the reactor building 326. As for the previous modes, the installation thus configured has a compact vertical arrangement with the reactor building(s) in the shaft and under the protective slab (half-slab) and the auxiliary equipment / buildings which are above the slab and rest only on it. The compactness is further improved with the technical gallery located between the protective slab (half-slab) (above) and the reactor building(s) (below).

[0111] It should be noted that the shifting of the 320 slab which has just been described can be applied to the other slabs or half-slabs described above with reference to the preceding figures even if the shape of the latter is different. The shifting principle remains the same.

[0112] It should be noted that the equipment or buildings arranged on the half-slabs, or on the slab if it is a single slab, may take other forms and perform other functions than those described above depending on the nuclear technology envisaged.

Claims

Claims

1. Buried nuclear installation (10; 10'; 100; 200; 300), comprising: - a vertical shaft (12) comprising, at a lower end, a bottom (12c) and, at an upper end, an opening (12b), - at least one reactor building (26) housed in the shaft, - at least one nuclear reactor enclosure (30) enclosed inside said at least one reactor building (26), -at least one protective slab (20; 20'; 20"; 120; 320) against external attacks which completely closes the opening (12b) of the well by extending in particular above said at least one reactor building, -one or more pieces of equipment or buildings (bl-b4) arranged on said at least one protective slab (20; 20'; 20"; 120; 320).

2. Buried nuclear installation according to the preceding claim, characterized in that it comprises at least one nuclear fuel storage pool (PECN; PECN'; PECN") housed in the well.

3. Buried nuclear installation according to claim 1 or 2, characterized in that the equipment or buildings (bl-b4) arranged on said at least one protective slab (20; 20'; 20"; 120; 320) are configured to provide support functions for the operation of the nuclear reactor and the entire nuclear installation.

4. Buried nuclear installation according to one of claims 1 to 3, characterized in that the equipment or buildings (bl-b4) arranged on said at least one protective slab (20; 20'; 20"; 120; 320) comprise at least one of the following elements: a control room for the nuclear installation, a building providing ventilation functions, a building providing cooling functions, a room containing control and monitoring cabinets control for operating support and power generation functions, an instrumentation room, a high-current power distribution room, a low-current power distribution and battery / inverter room, a valve and exchanger room, a first-aid diesel engine room.

5. Buried nuclear installation according to one of the preceding claims, characterized in that said at least one reactor building (26) comprises a roof (28) which covers said at least one nuclear reactor enclosure (30), said at least one protective slab (20; 20'; 20"; 120; 320) extending in particular above the roof and at a distance from it so as to provide between them a technical gallery (G; G'; G"; G'").

6. Buried nuclear installation according to claims 2 and 5, characterized in that the roof (28) covers said at least one nuclear reactor enclosure (30) and said at least one nuclear fuel storage pool (PECN; PECN'; PECN").

7. Buried nuclear installation according to one of the preceding claims, characterized in that it comprises one or more vertical walls (18a-d) bordering the interior of the well, said at least one protective slab (20; 20'; 20") being in vertical support: - directly on an embankment (16) arranged at the outer periphery of the well, a bellows device (22) being arranged vertically between said at least one protective slab and the vertical wall(s) (18a-d) bordering the interior of the well, or - directly on the vertical wall(s) (18a-d) bordering the interior of the well, or - indirectly on the vertical wall(s) (18a-d) bordering the interior of the well by means of a damping joint device (229 and / or - directly on one or more supports (23, 25) arranged externally relative to the vertical wall(s) (18a-d) bordering the interior of the well.

8. Buried nuclear installation according to the preceding claim, characterized in that said at least one reactor building (26) comprises one or more vertical walls (26a, 26b) which are horizontally spaced from the vertical wall(s) (18a-d) bordering the interior of the well or attached to the vertical wall(s) bordering the interior of the well.

9. Buried nuclear installation according to one of the preceding claims, characterized in that said at least one nuclear reactor enclosure (30) is supported by at least one support slab (32) resting on the bottom of the well.

10. Buried nuclear installation according to claims 2 and 9, characterized in that said at least one nuclear fuel storage pool (PECN; PECN'; PECN") is supported by at least one support slab (32) resting on the bottom of the well.

11. Buried nuclear installation according to claim 8 and according to claim 9 or 10, characterized in that said at least one support slab (32) is either connected to or separated from the wall(s) of the reactor building by one or more peripheral isolation joints or by a space between said at least one support slab and the wall(s) of the reactor building.

12. Buried nuclear installation according to one of the preceding claims, characterized in that it comprises, adjacent to a zone of the shaft in which said at least one reactor building (26) is housed, at least one other zone of the shaft which forms in particular a vertical handling zone capable of being placed in communication with the zone of said at least one reactor building.

13. Buried nuclear installation according to the preceding claim, characterized in that said at least one protective slab (20; 20'; 20"; 120; 320) comprises a hopper (40) which is located in an area of ​​said at least one protective slab located above said at least one other area of ​​the well.

14. Buried nuclear installation according to one of claims 2, 6 and 10, characterized in that said at least one pool nuclear fuel storage facility (PECN; PECN'; PECN") is arranged adjacent to said at least one reactor building (26).

15. Buried nuclear installation according to one of the preceding claims, characterized in that said at least one protective slab is formed of a slab (20; 20'; 20"; 120; 320) or two half-slabs (20.2a, 20.2b) which are fixed to each other.

16. Buried nuclear installation according to one of the preceding claims, characterized in that said at least one protective slab (20; 20'; 20"; 120; 320) is configured to be able to be removed subsequently in the event of modification or dismantling of the nuclear installation.

17. Buried nuclear installation according to one of the preceding claims, characterized in that the vertical well (12; 12'; 12"; 312) has a generally rectangular or circular shape according to a view taken in a horizontal plane.

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