Nuclear fuel assembly with reinforcement means

Abstract

The assembly comprises fuel rods (4) extending along a longitudinal axis (L) and a skeleton support member (6) configured to support the fuel rods (4), the skeleton support member (6) comprising two end pieces (8, 10), a plurality of ducts (12) connecting the end pieces (8, 10) to each other, a spacer grid (14) attached to the ducts (12), each spacer grid (14) supporting a fuel rod (4), the nuclear fuel assembly further comprising at least one stiffening device (20) comprising at least one stiffening plate (22) in contact with at least two ducts (12) and attached to one or more ducts (12) at attachment points (21), each stiffening plate (22) having at least two attachment points (21) offset relative to each other along the longitudinal axis (L).

Description

Technical Field

[0001] This invention relates to the field of nuclear fuel assemblies, particularly for pressurized water reactors (or PWRs). Background Technology

[0002] Nuclear fuel assemblies for pressurized water nuclear reactors typically include a bundle of nuclear fuel rods extending along a longitudinal axis and a support frame configured to support the nuclear fuel rods. The support frame specifically includes two longitudinally spaced end members, a plurality of conduits extending along the longitudinal axis by connecting the end members to each other, and spacer grids distributed along and attached to the conduits, each spacer grid being configured to support the nuclear fuel rods.

[0003] Each spacer grid has a rod cell through which nuclear fuel rods pass, wherein each rod cell is traversed by a corresponding nuclear fuel rod, and springs and / or bosses are provided on the inner surface of the rod cell to hold the nuclear fuel rod passing through the rod cell in the proper position in the lateral and longitudinal directions.

[0004] During operation, nuclear fuel assemblies are arranged vertically within the reactor core. In this location, the nuclear fuel assemblies may have a tendency to bend along their longitudinal axis, exhibiting a C-shaped, S-shaped, or W-shaped form.

[0005] Such deformation may cause operational problems, such as inserting control clusters inside the conduit, and / or maintenance problems, such as inserting and / or removing nuclear fuel assemblies in the reactor core.

[0006] FR2860334A1 and FR2860335A1 disclose nuclear fuel assemblies equipped with reinforcing devices attached to the conduits of the nuclear fuel assembly to strengthen the supporting framework and thus limit lateral deformation of the nuclear fuel assembly. These reinforcing devices include substantially planar plates, plates with angular cross-sections, or multiple sets of intersecting plates attached to the conduits in a manner that connects the conduits. These reinforcing devices are provided in addition to spacer grids. Summary of the Invention

[0007] One object of the present invention is to provide a nuclear fuel assembly whose stiffness can be improved, while also limiting the weight of the nuclear fuel assembly and / or the flow resistance of the fluid flowing through the nuclear fuel assembly.

[0008] To this end, the present invention provides a nuclear fuel assembly comprising nuclear fuel rods extending along a longitudinal axis and a support frame configured to support the nuclear fuel rods. The support frame includes two end members spaced apart along the longitudinal axis, a plurality of conduits extending along the longitudinal axis and connecting the end members to each other, and spacer grids distributed between the two end members and attached to the conduits. Each spacer grid supports the nuclear fuel rods. The nuclear fuel assembly also includes at least one reinforcing device, each reinforcing device including at least one reinforcing plate. Each reinforcing plate contacts at least two conduits and is attached to one or more conduits at attachment points. Each reinforcing plate has at least two attachment points offset relative to each other along the longitudinal axis.

[0009] By providing a reinforcing device with at least one reinforcing plate attached to the conduit at an attachment point offset along the conduit, the stiffness can be increased due to the offset of the attachment point, while also limiting the material of the reinforcing plate, and thus its cost and the effect of the reinforcing device on the neutron performance of the nuclear fuel assembly and / or on the flow resistance of the fluid flowing through the nuclear fuel assembly.

[0010] Other features of the components according to the invention, considered individually or in any technically conceivable combination:

[0011] - At least one of the reinforcing plates is attached to the conduit at two attachment points spaced apart along the conduit;

[0012] - At least one reinforcing plate is attached to each conduit in contact with the reinforcing plate;

[0013] - At least one reinforcing plate is attached only to a portion of the conduit in contact with the reinforcing plate;

[0014] - At least one reinforcing plate has at least two different and separate branches connected together, each of the at least two branches contacting at least one conduit at contact points spaced apart from each other along the longitudinal axis;

[0015] - Each branch of the reinforcing plate has two ends, each end of which is attached to a corresponding conduit;

[0016] - The two branches of the reinforcing plate are connected by at least one link extending between the two branches;

[0017] - The two branches of the reinforcing plate extend parallel to each other;

[0018] - The two branches of the reinforcing plate extend perpendicularly to the longitudinal axis;

[0019] - The component includes at least one reinforcing plate having two branches joined at a joint, each branch extending away from the joint from the other branch;

[0020] - The two branches of the reinforcing plate join at one end and are spaced apart at the other end;

[0021] - One or each of the two branches of the reinforcing plate extends at an angle relative to the longitudinal axis;

[0022] - The reinforcing device includes at least one pair of reinforcing plates, which are arranged on both sides of the conduit assembly in contact with the two reinforcing plates;

[0023] - The reinforcing device includes multiple intersecting reinforcing plates;

[0024] - The reinforcing device includes multiple pairs of intersecting reinforcing plates;

[0025] - At least one reinforcing plate has at least one hybrid fin and / or at least one deflector and / or at least one motion limiter;

[0026] - Each attachment between the reinforcing plate and the conduit is produced by plastic deformation, particularly by compression or expansion, by welding and / or by brazing. Attached Figure Description

[0027] The invention and its advantages will be better understood after reading the following description, which is given only by way of non-limiting example and with reference to the accompanying drawings, in which:

[0028] Figure 1 This is a schematic front view of a nuclear fuel assembly;

[0029] Figure 2 yes Figure 2 The nuclear fuel assembly shown is along Figure 1 Sectional view of section II-II;

[0030] Figure 3 It is shown Figure 1 Side view of the conduits and reinforcement devices of the nuclear fuel assembly;

[0031] Figure 4 yes Figure 3 Top view of the conduit and reinforcing device;

[0032] Figure 5 yes Figure 3 and Figure 4 A three-dimensional view of the reinforcing device;

[0033] Figure 6 It is a top view based on the modified duct and reinforcing device;

[0034] Figure 7 It shows the variant. Figure 1 Side view of the conduits and reinforcement devices of the nuclear fuel assembly;

[0035] Figure 8 yes Figure 7 Top view of the conduit and reinforcing device;

[0036] Figure 9 yes Figure 7 and Figure 8 Three-dimensional diagrams of some conduits and reinforcing devices;

[0037] Figures 10 to 12 It shows a side view of each conduit and reinforcing device according to some variations; and

[0038] Figure 13 This is a top view showing the modified conduit and reinforcing device. Detailed Implementation

[0039] Figure 1 The nuclear fuel assembly 2 shown includes a bundle of nuclear fuel rods 4 and a support frame 6 configured to support the nuclear fuel rods 4.

[0040] The nuclear fuel rods 4 extend parallel to each other and parallel to the longitudinal axis L. When the nuclear fuel assembly 2 is placed in the reactor core, the longitudinal axis L extends vertically. During operation, coolant fluid flows as... Figure 1 The middle arrow F indicates that the nuclear fuel assembly 2 passes vertically from bottom to top.

[0041] In the remainder of this specification, the terms “vertical,” “horizontal,” “top,” “bottom,” “longitudinal,” “lateral,” “upper,” and “lower” will be understood with reference to the position of nuclear fuel assembly 2 in the core of the nuclear reactor, where the longitudinal axis L is substantially vertical.

[0042] The support frame 6 includes a lower end member 8, an upper end member 10, a plurality of conduits 12, and a plurality of spacer grids 14. It may optionally include an instrument pipe 13, typically arranged to replace the central conduit 12, such as... Figure 2 As shown.

[0043] The lower end piece 8 and the upper end piece 10 are spaced apart along the longitudinal axis L.

[0044] The conduit 12 is, for example, made of metal.

[0045] The conduit 12 extends along the longitudinal axis L and connects the lower end member 8 and the upper end member 10 to each other while maintaining the spacing between the lower end member 8 and the upper end member 10. The nuclear fuel rod 4 is housed between the lower end member 8 and the upper end member 10.

[0046] Each conduit 12 has an opening at its upper end to allow a control rod (not shown) to be inserted through the upper end piece 10 into the interior of the conduit 12. Such a control rod provides the ability to control the reactivity of the nuclear reactor core in which the nuclear fuel assemblies 2 are inserted.

[0047] Spacer grids 14 are distributed along the conduit 12 and spaced apart from each other along the longitudinal axis L. Each spacer grid 14 is rigidly attached to the conduit 12, through which the conduit 12 extends.

[0048] Each spacer grid 14 is configured to support the nuclear fuel rods 4 by holding them spaced apart from each other in the lateral direction. The nuclear fuel rods 4 are preferably held at nodes of a generally regular imaginary network.

[0049] Each spacer grid 14 includes, for example, a plurality of rod cells, each rod cell designed to receive a corresponding nuclear fuel rod 4, the walls of the rod cell being provided with support elements that contact the outer surface of the nuclear fuel rod 4 to hold it in its proper position in the longitudinal and transverse directions.

[0050] The support elements for each fuel rod cell include, for example, at least one elastic spring and / or at least one rigid boss, each spring being configured, for example, to push the nuclear fuel rod 4 against one or more bosses.

[0051] The nuclear fuel assembly 2 also includes at least one reinforcing device 20 configured to reinforce the supporting frame 6.

[0052] Each reinforcing device 20 is, for example, made of metal.

[0053] Each reinforcing device 20 is separate from and distinct from the spacer grid 14. Each reinforcing device 20 is provided in addition to the spacer grid 14.

[0054] Each reinforcing device 20 is disposed between two consecutive spacer grids 14, between the lower end member 8 and a spacer grid 14, or between a spacer grid 14 and an upper end member 10. Figure 1 In the middle, each reinforcing device 20 is located between two consecutive spaced grids 14.

[0055] like Figure 2 As shown, each reinforcing device 20 is in contact with a plurality of conduits 12, and is also attached to one or more conduits 12 in contact with it.

[0056] This allows additional linkages to be created between the conduits 12 with the reinforcing plates 22 attached, thereby giving the support frame 6 rigidity, particularly imparting bending stiffness along the longitudinal axis L.

[0057] Each reinforcement device 20 is not attached to the nuclear fuel rod 4. Each reinforcement device 20 does not include any attachment points on the nuclear fuel rod 4.

[0058] Each reinforcement device 20 is configured to allow nuclear fuel rods 4 to pass through.

[0059] Each reinforcing device 20 optionally includes a motion limiter 36 configured to restrict the movement of the nuclear fuel rods 4 toward the reinforcing device 20, for example in the form of a rigid boss. Such a motion limiter 36 can... Figure 3 I saw it in the middle.

[0060] Preferably, each reinforcing device 20 is disposed inside the bundle of nuclear fuel rods 4.

[0061] Specifically, each reinforcing device 20 does not extend between the outer periphery of the nuclear fuel rod 4 and the adjacent layers of the nuclear fuel rod 4.

[0062] In other words, such as Figure 2 As shown, each reinforcing device 20 does not extend between the two outermost layers of nuclear fuel rods 4 located in the nuclear fuel rod bundle 4.

[0063] exist Figure 3 and Figure 5 As can be seen more clearly, each reinforcing device 20 includes at least one reinforcing plate 22, each reinforcing plate 22 contacting at least two conduits 12 and rigidly attached to one or more conduits 12 at attachment point 21.

[0064] Each reinforcing plate 22 is, for example, made of metal.

[0065] Each reinforcing plate 22 has a plurality of attachment points 21 located on one or more conduits 12.

[0066] Each reinforcing plate 22 is attached to only one conduit 12 in contact with it, or to multiple conduits 12 in contact with it.

[0067] Each reinforcing plate 22 attached to a plurality of catheters 12 is attached to each catheter 12 in contact with the reinforcing plate 22, or is attached only to a portion of the catheter 12 in contact with the reinforcing plate 22, and the reinforcing plate 22 is in simple contact with at least one catheter 12 in contact with it (without rigid attachment).

[0068] The attachment between each reinforcing plate 22 and each conduit 12 to which the reinforcing plate 22 is attached is achieved by mechanical assembly at attachment point 21 to ensure that the reinforcing device 20 is integrally fixed to each conduit 12 to which the reinforcing device is attached.

[0069] Mechanical assembly can be direct. Mechanical assembly can also be indirect, using, for example, a sleeve positioned around conduit 12. The attachment point 21 is preferably permanent and has no degrees of freedom. The attachment point 21 can be created, for example, by plastic deformation (pressurization, expansion, etc.), by welding, or by brazing. Figure 3 In the diagram, attachment point 21 is schematically represented by a black dot.

[0070] Each reinforcing plate 22 has at least two attachment points 21 that are offset relative to each other along the longitudinal axis L.

[0071] Two attachment points 21 offset along the longitudinal axis L are, for example, two attachment points 21 located on the same given conduit 12 and spaced apart from each other along the conduit 12, or two attachment points 21 located on two separate conduits 121.

[0072] The reinforcing plate 22 may include one or more branches 24. Each branch 24 preferably contacts at least two conduits 12. Each branch is in the form of an elongated strip extending laterally relative to the longitudinal axis L.

[0073] In one exemplary implementation, such as Figure 3 and Figure 5 As shown, each reinforcing plate 22 has at least one branch 24 that contacts at least two conduits 12 and is attached to at least one conduit 12 that is in contact with the branch 24.

[0074] Each attachment point 21 for attaching branch 24 to conduit 12 constitutes an attachment point 21 for attaching reinforcing plate 22 to conduit 12.

[0075] Preferably, the reinforcing plate 22 includes at least one branch 24 configured to ensure contact with at least one conduit 12.

[0076] In one exemplary embodiment, the reinforcing plate 22 has at least two distinct branches 24 connected together, each branch 24 contacting at least two conduits 12.

[0077] At least one branch 24 is attached to a conduit 12 in contact with it, and at least one attachment point 21 of the reinforcing plate 22 is located on the branch 24.

[0078] In one exemplary embodiment, each branch 24 is attached to at least one conduit 12 to which the reinforcing plate 22 is attached. Each branch 24 is therefore provided with at least one attachment point 21.

[0079] In one variation, at least one branch 24 of the reinforcing plate 22 is not attached to any conduit 12 to which the reinforcing plate 22 is attached. Thus, such a branch 24 loses its attachment point 21.

[0080] In this case, preferably, the mechanical clearance between at least one catheter 12 and the branch 24 is negative, thereby ensuring permanent frictional contact between the at least one catheter 12 and the branch 24.

[0081] In one exemplary implementation, such as Figures 3 to 5As shown, each reinforcing plate 22 has two branches 24 that are parallel to each other and spaced apart from each other along the longitudinal axis L.

[0082] Two parallel branches 24 extend, for example, perpendicular to the conduit 12, that is, perpendicular to the longitudinal axis L.

[0083] In one variation, the reinforcing plate 22 includes two branches 24 that extend parallel to each other but at an angle relative to the longitudinal axis L, i.e., neither parallel to nor perpendicular to the longitudinal axis L.

[0084] The reinforcing plate 22 includes at least one link 26 that extends between the two branches 24 and connects the two branches 24 to each other.

[0085] The reinforcing plate 22 preferably includes a plurality of links 26 distributed along the branch 24 and spaced apart from each other along the branch 24.

[0086] exist Figure 3 and Figure 5 In the example shown, link 26 extends longitudinally, i.e., parallel to the longitudinal axis L. In a particular embodiment, each link 26 is located at a distance from the end of at least one of the two branches 24, or even at a distance from the end of each of the two branches 24, such as... Figure 3 and Figure 5 As shown in the example.

[0087] Preferably, at least one or each link 26 is configured to extend along a conduit 12 that contacts the reinforcing plate 22 along the branch 24. In the example shown, each link 26 extends along a conduit 12 that contacts the reinforcing plate 22.

[0088] exist Figure 3 and Figure 5 In the example shown, each reinforcing plate 22 includes two links 26 spaced apart from each other and spaced apart from the ends of the two branches 24, each link 26 extending along a conduit 12 in contact with the reinforcing plate 22.

[0089] In one conceivable variation, the reinforcing plate 22 includes a corresponding link 26 along each conduit 12 in contact with the reinforcing plate 22.

[0090] Each reinforcing plate 22 is attached, for example, to an assembly 28 comprising a plurality of conduits 12, wherein the plurality of conduits 12 are aligned in an alignment direction perpendicular to the extension direction of the conduits 12 (that is, perpendicular to the longitudinal axis L).

[0091] exist Figure 3 In the example shown, the reinforcing plate 22 is attached to the assembly 28, which includes five conduits 12, and includes two links 26 extending along the second and fourth conduits 12 of the assembly 28.

[0092] Optionally, each reinforcing plate 22 includes an additional link 26 extending along a first conduit 12 of assembly 28, an additional link 26 extending along a third conduit 12 of assembly 28, and / or an additional link 26 extending along a fifth conduit 12 of assembly 28. These optional additional links 26 in Figure 3 It is shown in the middle with a dotted line.

[0093] The reinforcing device 20 includes, for example, intersecting reinforcing plates 22.

[0094] At least one reinforcing plate 22 extends along a first direction T1 and is attached to a first component 28, the conduit 12 of the first component 28 being aligned along the first direction T1, and at least one other reinforcing plate 22 extends along a second direction T2 forming a non-zero angle with the first direction T1 and is attached to a second component 28, the conduit 12 of the second component 28 being aligned along the second direction T2. ​​The second direction T2 is, for example, perpendicular to the first direction T1.

[0095] The reinforcing device 20 is formed, for example, by two sets of intersecting reinforcing plates 22, in particular, the first set of reinforcing plates 22 extending along the first direction T1 intersects with the second set of reinforcing plates 22 extending along the second direction T2.

[0096] In one exemplary embodiment, the reinforcing plates 22 intersect each other at a distance from the ends of their branches 24. Each branch 24 of each reinforcing plate 22 has an end portion extending beyond the intersection of the reinforcing plate 22 with each other, which is attached to the conduit 12.

[0097] Preferably and as Figures 2 to 4 As shown, each end portion of branch 24 does not extend beyond its attachment area on the corresponding conduit 12.

[0098] In one variant, at least one branch 24 of the reinforcing plate 22 extends beyond the outer periphery of the nuclear fuel rod 4 and is attached to each other by peripheral plates arranged around the nuclear fuel rod bundle 4.

[0099] In one exemplary embodiment, each reinforcing plate 22 intersecting with another reinforcing plate 22 is attached to a conduit 12 adjacent to the intersection, and the other reinforcing plate 22 is also attached to the conduit 12.

[0100] The reinforcing plates 22 are arranged, for example, in pairs 23, with each pair of reinforcing plates 22 located on both sides of the aligned conduit 12 assembly 28, such that the two reinforcing plates 22 are in contact with the opposite two surfaces of the conduit 12 of the assembly 28. The conduit 12 of the assembly 28 is sandwiched between the two reinforcing plates 22 of the pair 23.

[0101] The reinforcing device 20 includes, for example, at least one pair of reinforcing plates 22 extending along a first direction T1 and intersecting with at least one pair of reinforcing plates 22 extending along a second direction T2, with the two reinforcing plates 22 of each pair of 23 located on both sides of the assembly 28 of the conduit 12 to which they are attached.

[0102] Here, the reinforcing device 20 includes two pairs of reinforcing plates 22 extending along the first direction T1 and intersecting with two pairs of reinforcing plates 22 extending along the second direction T2.

[0103] The reinforcing plates 22 of each pair 23 extending along the first direction T1 intersect with the reinforcing plates 22 of each pair 23 extending along the second direction T2 to form a cell containing a conduit 12 to which each reinforcing plate 22 of the two pairs 23 is attached.

[0104] Multiple different and separate conduits 12 are housed within such defined cells. These conduits 12 are... Figure 4 There are four.

[0105] Each pair of reinforcing plates 22 intersecting with another pair of reinforcing plates 22 extends beyond the intersection by contacting, and in particular attaching to, a conduit 12 located outside the intersection.

[0106] One or more branches 24 of each pair of reinforcing plates 22 extend beyond their intersection with the reinforcing plate 22 of each other pair of reinforcing plates 22.

[0107] The end portions of one or more branches 24 of each pair of reinforcing plates 22, extending beyond the intersection with the reinforcing plates 22 of each other pair of reinforcing plates 22, are preferably attached to the conduit 12.

[0108] Optionally, the end portion of the branch 24 or at least one branch 24 of the first reinforcing plate 22 is attached to the end portion of one or more branches 24 of the second reinforcing plate 22 in a pair of 23 via a transverse link 27. This transverse link 27 can... Figure 7 I saw it in the middle.

[0109] Optionally, the transverse link 27 contacts the conduit 12 and is preferably attached to the conduit 12 facing the end portion of the associated branch 24. When these attachments are present, they constitute attachment points 21 of the reinforcing plate 22 on the conduit 12 as described above, and thereby constitute attachment points 21 of the reinforcing device 20 on the conduit 12.

[0110] The number of pairs 23 of intersecting reinforcing plates 22 can vary. For example... Figure 6 As shown, the reinforcing device 20 may include, for example, three pairs 23 of reinforcing plates 22 extending along a first direction T1 and / or three pairs 23 of reinforcing plates 22 extending along a second direction T2.

[0111] exist Figure 6 In the example shown, the reinforcing device 20 includes three pairs 23 of reinforcing plates 22 extending along a first direction T1 and intersecting with three pairs 23 of reinforcing plates 22 extending along a second direction T2.

[0112] The number of pairs 23 of the reinforcing plate 22 extending along the first direction T1 and the number of pairs 23 of the reinforcing plate 22 extending along the second direction T2 can be different.

[0113] In a variant not shown, the reinforcing device 20 includes three pairs 23 of reinforcing plates 22 extending along a first direction T1 and intersecting with two pairs 23 of reinforcing plates 22 extending along a second direction T2.

[0114] Preferably, the reinforcing plates 22 of the reinforcing device 20 are assembled to each other at their intersection points.

[0115] The reinforcing device 20 is, for example, composed of plates having cuts, for example, obtained by stamping, and interlocked between them, these plates in particular forming branches 24.

[0116] Preferably, the plates are attached to each other at their joints, for example by spot welding, cross-joining, or star-joining (attached collars) at the upper and / or lower edges of the plates, without any degree of freedom (firm fixation), and / or by bead welding over all or part of the height of the joint.

[0117] As a variation, all or part of the reinforcing device 20 can be produced by additive manufacturing.

[0118] Preferably, all or part of the reinforcing device 20 is configured to limit the pressure drop of the reinforcing device 20, for example by using a plate with a rounded or chamfered lower edge.

[0119] Optionally, each reinforcing plate 22 has at least one attachment tab 30 projecting from one edge, and each attachment tab 30 is attached to the conduit 12. Each attachment tab 30 thus carries an attachment point 21.

[0120] Preferably, each reinforcing plate 22 is provided with at least one attachment tab 30 associated with each conduit 12 to which the reinforcing plate 22 is attached.

[0121] When the reinforcing plate 22 has multiple branches 24, each attachment tab 30 is disposed on the edge of one branch 24. One or more branches 24 of the reinforcing plate 22 may each be provided with one or more attachment tabs 30.

[0122] exist Figure 3 In the example shown, each attachment tab 30 protrudes upward from the upper edge of the upper branch 24 of each reinforcing plate 22.

[0123] Optionally, at least one reinforcing plate 22, preferably each reinforcing plate 22, is provided with a mixing device, such as a mixing fin 32 and / or a deflector 34, configured to mix the cooling fluid flowing between the nuclear fuel rods 4 during nuclear reactor operation.

[0124] For example, the reinforcing plate 22 includes a hybrid fin 32 located at the edge of the reinforcing plate 22, preferably at the upper edge of the reinforcing plate 22.

[0125] When the reinforcing plate 22 has multiple branches 24, the mixing fins 32 are located, for example, on the edge of the branch 24 of the reinforcing plate 22, preferably on the upper edge of the upper branch 24 of the reinforcing plate 22.

[0126] The mixing fin 32 is configured to promote the mixing of cooling fluid flowing between the nuclear fuel rods 4 during nuclear reactor operation.

[0127] Each hybrid fin 32 is preferably inclined relative to the reinforcing plate 22 in an upward direction relative to the longitudinal axis L.

[0128] The reinforcing plate 22 may be provided with a deflector 34 arranged on one edge of the reinforcing plate 22.

[0129] When the reinforcing plate 22 includes multiple branches 24, the deflector 34 is located, for example, on the edge (preferably the upper edge) of the branch 24 (preferably the lower branch 24) of the reinforcing plate 22.

[0130] Each deflector 34 is, for example, formed as a rectangular protrusion projecting outward from the edge, the rectangular protrusion having at least one curved corner at its free end. As a variation, the deflector 34 is formed by cutting one edge of the reinforcing plate 22 and bending it at at least one corner located at the free end of the cut.

[0131] Deflector 34 is configured to deflect the coolant fluid flowing between the nuclear fuel rods 4 during nuclear reactor operation.

[0132] Optionally, at least one reinforcing plate 22, preferably each reinforcing plate 22, is provided with a motion limiter 36, which is configured to restrict the movement of the nuclear fuel rod 4 adjacent to the reinforcing plate 22 and prevent any further contact between the nuclear fuel rod 4 and the reinforcing device 20, especially to prevent any contact with the mixing device.

[0133] Each motion limiter 36 is, for example, in the form of a rigid protrusion forming a support for the nuclear fuel rod 4.

[0134] Each reinforcing plate 22 includes, for example, a motion limiter 36 that protrudes outward on one or each of its two opposing surfaces.

[0135] When the reinforcing plate 22 has multiple branches 24, the motion limiter 36 is preferably arranged on at least one branch 24 of each reinforcing plate 22.

[0136] Figures 7 to 9 The implementation methods shown are the same as Figures 3 to 6 The difference in the embodiment shown is that the reinforcing device 20 includes at least one reinforcing plate 22 having at least two branches 24 that engage at the joint 25 and extend away from each other from the joint 25.

[0137] The joint 25 is located, for example, at one end of each branch 24. Thus, these branches 24 join at one end and then extend toward their opposite ends, away from each other.

[0138] exist Figure 7 In the example shown, each reinforcing plate 22 has a V-shaped form consisting of two branches 24, where each branch 24 defines a corresponding branch of the V-shape.

[0139] The reinforcing plate 22 contacts the conduit 12 by attaching it to the conduit 12 at at least two attachment points 21 offset along the longitudinal axis L.

[0140] In one exemplary embodiment, the reinforcing plate 22 is attached to at least one conduit 12 at two attachment points 21 spaced apart along the conduit 12, each of the two attachment points 21 being located on a corresponding branch 24.

[0141] In one exemplary embodiment, at least one branch 24 is attached to two conduits 12 at two attachment points 21 that are offset from each other along the longitudinal axis L.

[0142] In one exemplary embodiment, the reinforcing plate 22 is attached to the conduit 12, and each branch 24 is preferably attached to at least one conduit 12 at an attachment point 21 spaced apart along the conduit 12.

[0143] Preferably, the reinforcing plate 22 is attached to the conduit 12 at the joint 25 between the branches 24. The attachment point 21 of the reinforcing plate 22 is located at the joint 25 between the branches 24.

[0144] Here, the reinforcing plate 22 is attached to the conduit 12 at the junction 25 between the branches 24, which are attached to the other conduits 12 in a manner that they are spaced apart along the longitudinal axis L of each of the plurality of other conduits 12.

[0145] The opposite ends of the junction 25 extend across the branch 24, which is attached to a plurality of catheters 12 and gradually moves away from each other. Preferably, the spacing between the branches 24 increases along each catheter 12 and between each subsequent catheter.

[0146] Alternatively, each reinforcing plate 22 can be in a manner similar to that already referenced. Figures 2 to 5 The described method involves providing one or more attachment tabs 30, hybrid fins 32, deflectors 34, and / or motion limiters 36 on one or more branches 24 of the reinforcing plate 22.

[0147] Preferably, each reinforcing device 20 is formed by a pair of reinforcing plates 22 23 in contact with the opposing surfaces of the conduits 12, and the conduits 12 are thus accommodated between the two reinforcing plates 22 of the pair 23.

[0148] Preferably, the two reinforcing plates 22 of the pair 23 are also attached to each other at least at one end and preferably at each end by a transverse link 27 perpendicular to the longitudinal axis L.

[0149] like Figure 7 As shown, the two reinforcing plates 22 of a pair 23 are similar in shape and form, and are stacked on top of each other in a view perpendicular to the longitudinal axis L.

[0150] Each branch 24 of one of the two reinforcing plates 22 in the pair 23 extends along the associated branch 24 of the other reinforcing plate 22 in the pair 23 to together form a branch of the reinforcing device 20.

[0151] Therefore, in the example shown, just like the two reinforcing plates 22 that make up the reinforcing device 20, the reinforcing device 20 has a generally V-shaped shape, and each branch is formed by two corresponding branches 24 of the two reinforcing plates 22 of the reinforcing device 20.

[0152] Multiple reinforcing devices 20 of this type can be attached at the same level along the conduit 12, and the reinforcing devices 20 can be mixed with each other.

[0153] For example, a first reinforcing device 20 is attached to a first component 28 of a conduit 12 aligned along a first direction T1, and a second reinforcing device 20 is attached to a second component 28 of a conduit 12 aligned along a second direction T2 forming a non-zero angle with the first direction T1, wherein a conduit 12 is shared by the first component 28 and the second component 28 of the conduit 12, and two branches 24 of each reinforcing plate 22 of the first reinforcing device 20 are attached to the shared conduit 12 at attachment points 21 located between the attachment points 21 of the two branches 24 of each reinforcing plate 22 of the second reinforcing device 20.

[0154] Two branches 24 of each reinforcing plate 22 of the first reinforcing device 20 are attached, for example, to attachment points 21 of the conduit 12 that are spaced apart from each other and are common to the first component 28 and the second component 28 of the conduit 12.

[0155] The nuclear fuel assembly 2 includes, for example, a pair of first reinforcing devices 20 extending along a first direction T1 and a pair of second reinforcing devices 20 extending along a second direction T2. ​​The reinforcing devices 20 are arranged such that a branch 24 of each reinforcing plate 22 of each first reinforcing device 20 passes between the branches 24 of each reinforcing plate 22 of one second reinforcing device 20 and on both sides of the branches 24 of each reinforcing plate 22 of the other second reinforcing device 20.

[0156] The two reinforcing devices 20 of each pair of reinforcing devices 20 are preferably arranged end to end: the branches 24 of each reinforcing plate 22 of one device are moved apart in one direction (first direction T1 or second direction T2) along the extension direction of the two reinforcing devices 20, and the branches 24 of each reinforcing plate 22 are moved away from each other in the other direction along the extension direction of the two reinforcing devices 20.

[0157] exist Figures 2 to 5 as well as Figure 7 and Figure 9 In the embodiment shown, each reinforcing plate 22 includes a plurality of branches 24, particularly two parallel branches 24 connected by a link 26 or two non-parallel branches 24 joined at a joint 25.

[0158] Other implementation methods are conceivable.

[0159] exist Figure 10 In one exemplary embodiment shown, the reinforcing device 20 includes a reinforcing plate 22 in the form of a single strip or single branch 24 that contacts a plurality of conduits 12.

[0160] The reinforcing plate 22 is attached to these conduits 12 at attachment points 21, which include at least two attachment points 21 offset along the longitudinal axis L.

[0161] like Figure 10 As shown, the reinforcing plate 22 includes, for example, two attachment tabs 30, one located on the upper edge of the reinforcing plate 22 and the other located on the lower edge of the reinforcing plate 22. This serves as a means to ensure longitudinal offset of the attachment point 21 carried by these attachment tabs 30.

[0162] Two attachment tabs 30 are located at both ends of the reinforcing plate 22, with each attachment tab 30 located at a corresponding end of the reinforcing plate 22. In one variation, one or both attachment tabs 30 are located at a distance from the end of the reinforcing plate 22. In a particular variation, one attachment tab 30 is located at one end of the reinforcing plate 22, while the other attachment tab 30 is closer to the other end of the reinforcing plate 22, while also at a distance from the former end.

[0163] In the illustrated example, each of the two attachment tabs 30 is used to attach the reinforcing plate 22 to a corresponding conduit 12 located at one end of the assembly 28 of the aligned conduit 12 that contacts the reinforcing plate 22. In a variation, one or both of the two attachment tabs 30 are used to attach to an intermediate conduit 12 of the aligned row of conduits 12 that contacts the reinforcing plate 22. In a particular variation, one of the two attachment tabs 30 is used to attach to an end conduit 12, while the other attachment tab 30 is used to attach to an intermediate conduit 12.

[0164] In some variations, the reinforcing plate 22 may include additional attachment tabs 30.

[0165] like Figure 10 As shown, in one exemplary embodiment, the reinforcing plate 22 is inclined such that it extends obliquely relative to the longitudinal axis L. Therefore, the reinforcing plate 22 contacts the conduit 12 in a contact area offset from each other along the longitudinal axis L.

[0166] This ensures that the attachment points 21 of the reinforcing plate 22 on the various conduits 12 are longitudinally offset.

[0167] This tilt increases the longitudinal offset between the two attachment tabs 30 located at intervals along the upper and lower edges of the reinforcing plate 22.

[0168] This tilt is used to achieve longitudinal offset between two attachment points on two different and separate conduits 12, including when the attachment points are located on the reinforcing plate 22, between the upper and lower edges of the reinforcing plate 22, or on the attachment tab 30 located on the same edge (e.g., the upper edge) of the reinforcing plate 22.

[0169] Therefore, in a variant, such as Figure 10 As shown by the dashed line, the reinforcing plate 22 is inclined to extend obliquely relative to the longitudinal axis L and is attached to two different and separate conduits 12 at two longitudinally offset attachment points 21, which are located between the upper and lower edges of the reinforcing plate 22, or on the attachment tab 30 located on the same edge, preferably the upper edge, of the reinforcing plate 22.

[0170] These considerations can also be applied to at least one branch 24 of a reinforcing plate 22 that includes multiple branches 24.

[0171] Therefore, as Figure 11 As shown, the reinforcing plate 22 includes two branches 24, each including at least one branch 24 (here, the upper branch 24) that is tilted relative to the longitudinal axis L, which is attached to the conduit 12 at an attachment point 21 that is longitudinally offset due to the tilt of the branch 24.

[0172] These attachment points 21 are arranged on the attachment tabs 30 located on the upper edge of the branch 24, and can be modified to be located between the upper and lower edges of the branch 24; or the attachment tabs 30 can be arranged wholly or partially on the lower edge of the branch 24.

[0173] In addition, Figures 3 to 5 and Figures 7 to 9 In the example shown, the reinforcing plate 22 includes parallel branches 24 connected by a link 26 or branches 24 joined at a joint 25.

[0174] like Figure 11 As shown, in one exemplary embodiment, the reinforcing plate 22 includes non-parallel branches 24 that are longitudinally spaced from each other and connected by at least one link 26.

[0175] In addition, Figures 3 to 5 and Figures 7 to 9 In the example shown, the reinforcing plate 22 includes two branches 24, each branch 24 being attached to one or more conduits 12.

[0176] like Figure 11 As shown, in one exemplary embodiment, the reinforcing plate 22 includes two distinct and separate branches 24 that contact the conduit 12, wherein only one of the branches 24 has an attachment point 21 on one or more conduits 12, and the other branch 24 does not have an attachment point 21. This other branch 24 only contacts the conduit 12.

[0177] exist Figure 11 In the middle, the upper branch 24 has an attachment point 21, while the other lower branch 24 does not have an attachment point 21.

[0178] exist Figures 3 to 5 In the embodiment shown, the reinforcing plate 22 includes two spaced-apart branches 24 connected by a link 26.

[0179] In one exemplary implementation, such as Figure 12As shown, the reinforcing plate 22 includes an upper branch 24 and a lower branch 24 connected to each other via an intermediate branch 24. The intermediate branch 24 contacts a plurality of conduits 12. The intermediate branch 24 is provided, for example, with longitudinally offset attachment points.

[0180] In the example shown, the upper branch 24 and the lower branch 24 are parallel, and the middle branch 24 extends obliquely between the upper branch 24 and the lower branch 24.

[0181] The upper branch 24 and the lower branch 24 extend perpendicularly to the longitudinal axis L, while the middle branch 24 extends obliquely.

[0182] In some variations, the inclination of branches 24 between them and the inclination relative to the longitudinal axis L can be different.

[0183] The upper branch 24 is provided with an attachment point 21 on the attachment tab 30 arranged on the upper edge of the upper branch 24, and the middle branch 24 and the lower branch 24 are provided with attachment points 21 located between the lower edge and the upper edge of each of them.

[0184] In some variations of the aforementioned embodiments, the attachment point 21 is provided only on one branch 24 or only on a portion of the branch 24, and on each branch 24 where the attachment point 21 is provided, the attachment point 21 may be arranged differently on the attachment tab 30 and / or the branch 24, and the aforementioned considerations regarding the position of the attachment point 21 apply to each branch 24.

[0185] Optionally, Figures 10 to 12 Each reinforcing plate 22 shown can be in a manner similar to that already referenced. Figures 2 to 5 The manner described is provided with one or more attachment tabs 30, hybrid fins 32, deflectors 34 and / or motion limiters 36 on one or more of its branches 24.

[0186] In addition, it has been referred to Figures 10 to 12 Each of the descriptions refers to a single reinforcing plate 22; however, the reinforcing device 20 may very clearly include one or more pairs 23 of similar reinforcing plates 22 that clamp the conduit 12 in the middle and / or other reinforcing plates 22 that intersect with the reinforcing plates 22.

[0187] In addition, Figure 2 In the example shown, the reinforcement device 20 includes a reinforcement plate 22 that contacts the assembly 28 of the conduit 12 aligned in a direction perpendicular to the side surface of the nuclear fuel assembly 2, the side surface of which is formed by rows of nuclear fuel rods 4 on the outer periphery of the nuclear fuel assembly 2.

[0188] In one variant, the reinforcing device 20 includes at least one reinforcing plate 22 in contact with an assembly 28 of a conduit 12 aligned in an inclined alignment direction relative to each side surface of the nuclear fuel assembly 2.

[0189] For example, the side surface of nuclear fuel assembly 2 is graphically represented by dashed lines. Figure 13 As shown, in one exemplary embodiment, the reinforcing device 20 includes at least one reinforcing plate 22 in contact with an assembly 28 of a conduit 12 aligned along a first direction T1 inclined relative to each side surface of the nuclear fuel assembly 2, and at least one reinforcing plate 22 in contact with an assembly 28 of a conduit 12 aligned along a second direction T2 inclined relative to each side surface of the nuclear fuel assembly 2, the first direction T1 and the second direction T2 forming a non-zero angle, the first direction T1 and the second direction T2 being particularly perpendicular to each other.

[0190] Furthermore, and as Figure 13 As shown, in one exemplary embodiment, the reinforcing device 20, which includes intersecting reinforcing plates 22, comprises reinforcing plates 22 that intersect each other to define individual cells through which the instrument tube 13 passes, particularly four reinforcing plates 22. One or more attachment points 21 of the one or more reinforcing plates 22 defining the individual cells are located, for example, on the instrument tube 13.

[0191] As is the case with the present invention, each reinforcing device 20 includes at least one reinforcing plate 22, which contacts the plurality of conduits 12 and is attached to at least one conduit 12 at an attachment point 21 offset along the longitudinal axis L, such that the conduits 12 can be connected with satisfactory stiffness due to the offset of the attachment point 21.

[0192] Therefore, the reinforcement device can be manufactured using reinforcement plates with a small amount of material, which can reduce its cost and limit the effect of the reinforcement device on the neutron performance of the fuel assembly and / or the flow resistance of the coolant fluid flowing through the nuclear fuel assembly.

[0193] A reinforcement device has been described with reference to a nuclear fuel assembly of a pressurized water reactor with a square cross-section. The conduits of this assembly are arranged in a generally straight line in the transverse direction, and the reinforcement plates extend perpendicularly to the conduits in a generally straight line.

[0194] The implementation of reinforcement devices on the nuclear fuel assemblies of pressurized water nuclear reactors with hexagonal cross-sections, in which the ducts are not arranged in a straight line in the lateral direction, can be achieved in a similar manner using reinforcement plates with a geometry suitable for ensuring contact between the reinforcement plate and the duct assembly.

Claims

1. A nuclear fuel assembly comprising: Nuclear fuel rods (4) extending along the longitudinal axis (L); A support frame (6) configured to support the nuclear fuel rods (4) includes: Two end pieces (8, 10) spaced apart along the longitudinal axis (L); A plurality of conduits (12) extending along the longitudinal axis (L) and connecting the end pieces (8, 10) to each other. Spacer grids (14) are distributed between the two end pieces (8, 10) and attached to the conduit (12), each spacer grid (14) supporting the nuclear fuel rod (4). The nuclear fuel assembly further includes at least one reinforcing device (20), each reinforcing device (20) comprising a first reinforcing plate and a second reinforcing plate extending parallel to the first reinforcing plate, the first reinforcing plate and the second reinforcing plate contacting at least two of the conduits (12), the first reinforcing plate being attached to one or more of the conduits (12) at attachment points (21), the attachment points (21) comprising at least a first attachment point and a second attachment point offset from each other along the longitudinal axis (L), the first attachment point and the second attachment point being attached to a first conduit of one or more conduits and spaced apart along the longitudinal axis (L) along the first conduit. The first reinforcing plate includes a first branch and a second branch that are vertically spaced apart from each other along the longitudinal axis (L), the first branch and the second branch extending parallel to each other, and the two branches being connected by at least one connecting rod (26) extending between the first branch and the second branch. The first branch contacts the first conduit at a first attachment point, and the second branch contacts the first conduit at a second attachment point. The first branch and the second branch of the first reinforcing plate extend perpendicularly to the longitudinal axis (L). The first reinforcing plate and the second reinforcing plate are arranged on both sides of the assembly (28) of the conduit (12) that is in contact with the first reinforcing plate and the second reinforcing plate.

2. The nuclear fuel assembly according to claim 1, wherein, The first reinforcing plate is attached to each conduit (12) in contact with the first reinforcing plate.

3. The nuclear fuel assembly according to claim 1, wherein, The first reinforcing plate is attached only to a portion of the conduit (12) that is in contact with the first reinforcing plate.

4. The nuclear fuel assembly according to claim 1, wherein, Each of the first and second branches of the first reinforcing plate has two ends, each end being attached to a corresponding conduit (12).

5. The nuclear fuel assembly according to claim 1, wherein, The first reinforcing plate includes a plurality of links (26) distributed along a first branch and a second branch of the first reinforcing plate, and the links are spaced apart from each other along the first branch and the second branch.

6. The nuclear fuel assembly according to claim 1, characterized in that, Each link (26) is connected at a certain distance from the end of at least one of the first and second branches or at a certain distance from the end of each of the first and second branches.

7. The nuclear fuel assembly according to claim 1, characterized in that, At least one or each link (26) of the first reinforcing plate is disposed along the first branch and the second branch so as to extend along the conduit in the conduit (12) in contact with the first reinforcing plate.

8. The nuclear fuel assembly according to claim 1, wherein, The reinforcing device (20) includes a plurality of intersecting reinforcing plates (22).

9. The nuclear fuel assembly according to claim 1, wherein, The reinforcing device (20) includes at least one pair of reinforcing plates (22) extending in a first direction (T1) that intersect with at least one pair of reinforcing plates (22) extending in a second direction (T2).

10. The nuclear fuel assembly according to claim 1 or 2, wherein, At least one reinforcing plate (22) has at least one hybrid fin (32) and / or at least one deflector (34) and / or at least one motion limiter (36).

11. The nuclear fuel assembly according to claim 1 or 2, wherein, Each attachment between the reinforcing plate (22) and the conduit (12) is created by plastic deformation or by welding.

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