CN117766162A - Multi-point supporting and compressing device and nuclear fuel assembly - Google Patents

Abstract

The invention discloses a multi-point support compressing device and a nuclear fuel assembly, wherein the multi-point support compressing device is used for the nuclear fuel assembly and comprises a plurality of compressing units: each compression unit comprises an upper plate spring and a middle plate spring which are sequentially stacked from top to bottom; the upper plate spring comprises a first connecting arm, a first inclined arm, a first contact section and a vertical arm, wherein the first contact section is arranged at one end of the first inclined arm, which is far away from the first connecting arm; the vertical arm extends downwards to penetrate out of the middle plate spring; the middle plate spring comprises a second connecting arm, a second inclined arm, a second contact section arranged at one end of the second inclined arm far away from the second connecting arm, and a first window for the vertical arm to pass through; the highest point of the second contact section is staggered with the highest point of the first contact section in the horizontal direction and is on the same horizontal plane. The upper plate spring and the middle plate spring of the multipoint support pressing device are simultaneously and independently contacted with the upper reactor core plate, so that friction among the plate springs can be reduced or eliminated, and the service life of the device is prolonged.

Description

Multi-point supporting and compressing device and nuclear fuel assembly

Technical Field

The invention relates to the technical field of nuclear reactors, in particular to a multi-point supporting and compressing device and a nuclear fuel assembly.

Background

The compression plate spring is an important component in a pressurized water reactor fuel assembly, and the fuel assembly compression system consists of four plate spring groups. The main function of the leaf spring group is to provide proper pressing force to keep the fuel assembly pressed on the upper surface of the lower core support plate during operation, so as to prevent the fuel assembly from being damaged due to the jumping-up of the assembly caused by water flow scouring. The deformation of the hold-down plate spring compensates for the differential growth of the fuel assembly height and stack cavity height during normal life. In addition, the hold down force provided by the leaf springs should not be excessive, otherwise, the fuel assembly would be caused to bend too much, thereby affecting the normal insertion of the control rod assembly and increasing the risk of hooking between adjacent fuel assembly grids during lifting.

The existing plate spring compression system has the advantages that the plate spring group and the upper reactor core plate in the reactor are supported in a single point mode, friction exists between the plate springs, surface strain can occur in severe cases, even tiny cracks occur, and then the plate spring piece can be broken.

Meanwhile, in the plate spring group formed by stacking and combining a plurality of plate springs, the difficulty of the deformation of the spring pieces is increased due to the mutual friction effect between the adjacent spring pieces in the compression process, and the integral rigidity of the spring group can be influenced, so that the integral rigidity is difficult to accurately consider in theoretical analysis. This can increase the difficulty of analysis and is detrimental to accurate analysis of the compaction force.

Disclosure of Invention

The invention aims to solve the technical problem of providing a multi-point supporting and compacting device and a nuclear fuel assembly.

The technical scheme adopted for solving the technical problems is as follows: a multi-point support hold down device for a nuclear fuel assembly comprising a plurality of hold down units: each compression unit comprises an upper plate spring and a middle plate spring which are sequentially stacked from top to bottom;

the upper plate spring comprises a first connecting arm, a first inclined arm, a first contact section and a vertical arm, wherein the first inclined arm is obliquely arranged at one end of the first connecting arm, the first contact section is arranged at one end of the first inclined arm, which is far away from the first connecting arm, and the vertical arm is arranged at one end of the first contact section, which is far away from the first inclined arm; the vertical arm extends downward out of the middle leaf spring;

the middle plate spring comprises a second connecting arm, a second inclined arm, a second contact section and a first window, wherein the second inclined arm is obliquely arranged at one end of the second connecting arm, the second contact section is arranged at one end of the second inclined arm, which is far away from the second connecting arm, and the first window is used for the vertical arm to pass through;

the highest point of the second contact section is staggered with the highest point of the first contact section in the horizontal direction and is positioned on the same horizontal plane.

Preferably, in the multi-point support pressing device according to the present invention, the second inclined arm includes a second curved section provided between both ends of the second inclined arm;

in the initial state, the second bending section is of a bending structure, and an included angle alpha formed by tangent lines at two ends of the second inclined arm is 100-170 degrees.

Preferably, in the multipoint support pressing device according to the present invention, the cross section of the second bending section is an arc, and the center of the circle of the arc is located above the second bending section.

Preferably, in the multi-point support pressing device according to the present invention, the first inclined arm includes a first curved section provided between both ends of the first inclined arm;

in the initial state, the first bending section is of a bending structure, and an included angle beta formed by tangent lines at two ends of the second inclined arm is 100-170 degrees.

Preferably, in the multipoint support pressing device according to the present invention, the cross section of the first bending section is an arc, and the center of the arc is located above the first bending section.

Preferably, in the multipoint support pressing apparatus according to the present invention, the shape of the first curved section and the shape of the second curved section are adjusted to adjust a position of a highest point of the second contact section from a highest point of the first contact section and a distance in a horizontal direction.

Preferably, in the multi-point support pressing device according to the present invention, a gap is left between the first inclined arm and the second inclined arm.

Preferably, in the multi-point support pressing device according to the present invention, the first contact section includes a first contact portion; the second contact section includes a second contact portion; the first contact section and the second contact section are respectively arc-shaped structures.

Preferably, in the multi-point support pressing device according to the present invention, the multi-point support pressing device further includes at least one lower leaf spring stacked under the middle leaf spring; the lower plate spring comprises a third connecting arm, a third inclined arm, a third contact section and a second window, wherein the third inclined arm is obliquely arranged at one end of the third connecting arm, the third contact section is arranged at one end of the third inclined arm, which is far away from the third connecting arm, and the second window is used for the vertical arm to pass through;

the third contact section is clung to the bottom of the second contact section.

The invention also constructs a nuclear fuel assembly comprising an upper tube seat, a lower tube seat arranged at intervals with the upper tube seat, a grid arranged between the upper tube seat and the lower tube seat, a guide tube arranged in the grid, and the multi-point supporting and compacting device arranged on any one of the upper tube seat;

the multiple pressing units of the multipoint support pressing device are arranged on the upper tube seat at intervals and are detachably connected with the upper tube seat.

By implementing the invention, the following beneficial effects are achieved:

the highest points of the upper plate spring and the middle plate spring of the multipoint support pressing device are positioned on the same horizontal plane, and can be simultaneously and independently contacted with the upper reactor core plate, so that friction among the plate springs is reduced or eliminated, and the service life of the multipoint support pressing device is prolonged. The upper plate spring and the middle plate spring can be simultaneously and independently kept in contact with the upper reactor core plate, so that the rigidity of the plate spring group can be calculated more accurately, and the accuracy of compression force analysis is improved.

The multi-point supporting and compacting device for the multi-point support is arranged on the nuclear fuel assembly, can reduce or eliminate friction among plate springs, prolongs the service life of the nuclear fuel assembly and prolongs the service life of the nuclear fuel assembly.

Drawings

The invention will be further described with reference to the accompanying drawings and examples, in which:

FIG. 1 is a schematic illustration of a nuclear fuel assembly top nozzle mated with a hold-down device in accordance with one embodiment of the present invention;

FIG. 2 is a side view of the top nozzle of FIG. 1 mated with a compression device in accordance with the present invention;

FIG. 3 is a schematic perspective view of a compressing unit of the multi-point support compressing apparatus of the present invention;

FIG. 4 is a side view of the compacting unit of FIG. 3 of the present invention;

FIG. 5 is a schematic view of the compression unit of FIG. 3 mated with an upper core plate in accordance with the present invention;

FIG. 6 is a schematic view of the structure of the upper leaf spring of FIG. 3 of the present invention;

FIG. 7 is a schematic view of the construction of the middle leaf spring of FIG. 3 according to the present invention;

FIG. 8 is an example of a second connecting arm of the middle leaf spring of FIG. 7 of the present invention;

fig. 9 is a schematic view of the structure of the lower leaf spring of fig. 3 according to the present invention.

Detailed Description

For a clearer understanding of technical features, objects and effects of the present invention, a detailed description of embodiments of the present invention will be made with reference to the accompanying drawings.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first", "a second", etc. may explicitly or implicitly include one or more such feature. In the description of the present invention, unless otherwise indicated, the meaning of "a plurality" is two or more.

In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or chemically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art in a specific case.

Referring to fig. 1-9, one embodiment of the present invention discloses a nuclear fuel assembly that may be placed in a pressurized water reactor to reduce or eliminate friction between leaf springs, extend the operational life of the fuel assembly, and increase the service life of the fuel assembly.

As shown in fig. 1 and 2, the nuclear fuel assembly in some embodiments includes an upper header 2, a lower header, a lattice, guide tubes, and the multi-point support compression device of the present invention. The lower tube seat is arranged at intervals with the upper tube seat 2, the upper tube seat 2 and the lower tube seat are arranged oppositely, the grid is arranged between the upper tube seat 2 and the lower tube seat and can be used for installing the guide tube, the guide tube is arranged in the grid, and the multi-point supporting and pressing device is arranged on the upper tube seat 2. The plurality of compression units 1 of the multi-point support compression device are arranged on the upper tube seat 2 at intervals and are detachably connected with the upper tube seat 2. The plurality of compressing units 1 compress the nuclear fuel assembly in the axial direction, maintain the nuclear fuel assembly in contact with the lower core plate on the lower tube seat, and compensate for the difference in thermal expansion between the nuclear fuel assembly with respect to the upper and lower core plates after the nuclear fuel assembly is irradiated and grown.

As shown in fig. 3 or 4, the multi-point support pressing device may include a plurality of pressing units 1 in some embodiments, and each pressing unit 1 may include an upper plate spring 11, a middle plate spring 12, and at least one lower plate spring 13, which are sequentially stacked from top to bottom, and a connection assembly not shown in the drawing. The upper leaf spring 11, the middle leaf spring 12 and the lower leaf spring 13 may be connected to the upper tube socket 2 by a connection assembly. Referring to fig. 5 together, the upper plate springs 11 and the middle plate springs 12 can be simultaneously and independently kept in contact with the upper core plate 3, so that the rigidity of the plate spring group formed by the upper plate springs 11 and the middle plate springs 12 can be calculated more accurately, and the accuracy of the compression force analysis can be improved. It will be appreciated that in some embodiments, each compression unit 1 may only comprise an upper leaf spring 11 and a middle leaf spring 12, which are arranged in a stack from top to bottom, so that the compression force requirements are met.

As shown in fig. 6, the upper leaf spring 11 in some embodiments includes a first connecting arm 111, a first inclined arm 112 disposed at one end of the first connecting arm 111 extending obliquely, a first contact section 113 disposed at one end of the first inclined arm 112 remote from the first connecting arm 111, and a vertical arm 114 disposed at one end of the first contact section 113 remote from the first inclined arm 112, the vertical arm 114 extending downwardly out of the middle leaf spring 12. It will be appreciated that in some embodiments, the first connecting arm 111, the first angled arm 112, the first contact section 113, and the vertical arm 114 are connected in sequence, and may be of unitary construction.

Further, the first contact section 113 in some embodiments includes a first body 1131 and a first contact 1132, the first contact 1132 being disposed above the first body 1131, the first contact 1132 being located at a highest point of the first contact section 113. Preferably, in order to prevent damage to the upper core plate 3, the first contact portion 1132 of the first contact section 113 has an arc-shaped structure, i.e., the cross section of the first contact portion 1132 of the first contact section 113 has an arc shape.

Further, the vertical arm 114 is connected to the bottom of the end of the first contact section 113, i.e., below the first body 1131 in some embodiments, and the vertical arm 114 may be disposed in a vertical direction and inserted into the upper socket 2. The specific construction of the vertical arm 114 and its associated connection to the top nozzle 2 is well established in the art and the present invention will not be described in detail herein.

Further, when the first inclined arm 112 of the upper plate spring 11 is of a straight plate structure, it is easy to contact with the upper core plate 3, and bending the first inclined arm 112 can avoid this phenomenon, and the first inclined arm 112 includes a first bending section disposed between two ends of the first inclined arm 112 in some embodiments, and in an initial state, the first bending section is of a bending structure (not shown in the figure). Preferably, the cross section of the first bending section is an arc, and the center of the arc is arranged above the first bending section. In the initial state, the included angle β formed by the tangents at the two ends of the first tilting arm 112 is 100 ° -170 °, for example, the included angle β is 120 °, 135 °, 160 °, etc. It should be noted that, in the pressure state, the shape of the first bending section may be deformed, and the larger the pressure is, the more serious the deformation is, and the included angle β formed by the tangents at the two ends of the first tilting arm 112 is also changed. When the upper leaf spring 11 is not compressed, i.e., is not subjected to an external force, the upper leaf spring 11 is considered to be in an initial state at this time; when the upper leaf spring 11 is deformed by an external force, it can be considered that the upper leaf spring 11 is in a pressurized state at this time. The initial state and the pressure state of the middle leaf spring 12 are also explained hereinafter, and will not be described in detail.

As shown in fig. 7, the middle leaf spring 12 in some embodiments includes a second connecting arm 121, a second inclined arm 122 disposed at one end of the second connecting arm 121 to extend obliquely, a second contact section 123 disposed at one end of the second inclined arm 122 remote from the second connecting arm 121, and a first window 124, with the vertical arm 114 extending through the first window 124 and downward. The highest point of the second contact section 123 is staggered in the horizontal direction and on the same horizontal plane as the highest point of the first contact section 113, so that the upper plate spring 11 and the middle plate spring 12 can simultaneously and independently keep contact with the upper core plate 3, friction between the upper plate spring 11 and the middle plate spring 12 is reduced or eliminated, and the service lives of the upper plate spring 11 and the middle plate spring 12 are prolonged. It will be appreciated that in some embodiments, the second connecting arm 121, the second inclined arm 122 and the second contact section 123 are sequentially connected, and may be an integral structure, and the first window 124 is disposed on the second contact section 123.

Further, the second contact section 123 in some embodiments includes a second body 1231 and a second contact portion 1232, the second contact portion 1232 is disposed above the second body 1231, the second contact portion 1232 is located at the highest point of the second contact section 123, and the first window 124 is disposed on the second body 1231. The second contact section 123 may have a curved structure such as an arc or a coil, in addition to the straight plate structure shown in fig. 7. Preferably, in order to prevent damage to the upper core plate 3, the second contact portion 1232 of the second contact section 123 has an arc-shaped structure, i.e., the cross section of the second contact portion 1232 is arc-shaped.

Further, in order to prevent the upper plate spring 11 from interfering with the middle plate spring 12, a gap is left between the first inclined arm 112 and the second inclined arm 122, and the upper plate spring 11 and the middle plate spring 12 may be independently pressed by the upper core plate 3, respectively.

Further, the second tilting arm 122 in some embodiments includes a second bending section disposed between two ends of the second tilting arm 122, and in an initial state, the second bending section is in a bending structure. It will be appreciated that in some embodiments, the second curved section is circular in cross-section with its centre located above the second curved section. In the initial state, the angle alpha formed by the tangents at the two ends of the second inclined arm 122 is 100-170 degrees. For example, the included angle β is 120 °, 135 °, 160 °, and the like. In the pressurized state, the shape of the second curved section may be deformed, with the larger the pressure, the more severe the deformation. The angle alpha formed by the tangents to the ends of the second angled arm 122 also varies. As shown in fig. 8, the second inclined arm 122 has an included angle α of 135 degrees, which is formed by the tangent lines at both ends of the second inclined arm. Preferably, the angle α formed by the tangents at the two ends of the second tilting arm 122 and the angle β formed by the tangents at the two ends of the first tilting arm 112 may be identical, i.e., the structures of the second tilting arm 122 and the first tilting arm 112 are identical.

The shape of the first curved section and the shape of the second curved section are adjusted to adjust the position of the highest point of the second contact section 123 and the highest point of the first contact section 113 and the distance in the horizontal direction. For example, the degree of bending of the second bending section may be adjusted, and the angle of the included angle α formed by the tangents at the two ends of the second inclined arm 122 may be adjusted, or the position of the second contact portion 1232 of the second contact section 123 and its highest point on the horizontal may be adjusted. Similarly, adjusting the bending degree of the first bending section may adjust the angle of the included angle β formed by the tangent lines at the two ends of the first tilting arm 112, and may also adjust the position of the first contact section 113 on the horizontal. That is, only the shape of the first curved section or the shape of the second curved section, or the shape of the first curved section or the shape of the second curved section is adjusted, the position of the highest point of the second contact section 123 and the highest point of the first contact section 113 and the distance in the horizontal direction can be adjusted.

As shown in fig. 9, the lower leaf spring 13 includes in some embodiments a third connecting arm 131, a third inclined arm 132 provided to extend obliquely at one end of the third connecting arm 131, a third contact section 133 provided at one end of the third inclined arm 132 remote from the third connecting arm 131, and a second window 134 through which the vertical arm 114 passes. A second window 134 is provided on the third contact section 133 and the vertical arm 114 extends downwardly through the first and second windows 124, 134 in sequence. The third contact section 133 is tightly attached to the bottom of the second contact section 123 and is pressed together with the middle plate spring 12, so that the pressing force of the single pressing unit 1 is enhanced. It will be appreciated that the lower leaf springs 13 may be provided as desired, and that one, two or more may be provided.

Further, the third angled arm 132 in some embodiments includes a third curved section disposed between the ends of the third angled arm 132, the third curved section being a curved structure. Preferably, the cross section of the third bending section is an arc, and the center of the arc is arranged above the third bending section. The angle θ formed by the tangents to the ends of the third angled arm 132 is 100 ° -170 °. For example, the included angle β is 120 °, 135 °, 160 °, and the like. It will be appreciated that the curvature of the third curved section may be different from the curvature of the second curved section, i.e., the angle θ formed by the tangents to the ends of the third angled arm 132 and the angle α formed by the tangents to the ends of the second angled arm 122 may be different.

Further, the upper leaf spring 11 in some embodiments further comprises a first through hole 115, the first through hole 115 being provided on the first connecting arm 111. The upper leaf spring 11 in some embodiments further comprises a second through hole 125, the second through hole 125 being provided on the second connecting arm 121. The lower leaf spring 13 in some embodiments further comprises a third through hole 135, the third through hole 135 being provided on the third connecting arm 131. The first, second and third connection arms 111, 121 and 131 are stacked, and the first, second and third through holes 115, 125 and 135 are disposed opposite to each other.

Each of the pressing units 1 includes a coupling assembly (not shown) passing through the first through-hole 115, the second through-hole 125, and the third through-hole 135 in order and being lockingly coupled with the upper boss. Preferably, the connection assembly is a bolt. It will be appreciated that the specific structure of the connection assembly and its associated connection arrangement with the header 2 are well known in the art and the present invention will not be described in detail herein.

By implementing the invention, the following beneficial effects are achieved:

the highest point of the upper plate spring 11 and the middle plate spring 12 of the multipoint support pressing device is positioned on the same horizontal plane, and can be simultaneously and independently contacted with the upper reactor core plate 3, so that friction among the plate springs is reduced or eliminated, and the service life of the multipoint support pressing device is prolonged. The upper plate springs 11 and the middle plate springs 12 can be simultaneously and independently kept in contact with the upper core plate 3, so that the rigidity of the plate spring group can be calculated more accurately, and the accuracy of compression force analysis is improved.

The multi-point supporting and compacting device for the multi-point support is arranged on the nuclear fuel assembly, can reduce or eliminate friction among plate springs, prolongs the service life of the nuclear fuel assembly and prolongs the service life of the nuclear fuel assembly.

It is to be understood that the above examples only represent preferred embodiments of the present invention, which are described in more detail and are not to be construed as limiting the scope of the invention; it should be noted that, for a person skilled in the art, the above embodiments or technical features may be freely combined, and several variations and modifications may be made, without departing from the spirit of the invention, which fall within the scope of the invention, i.e. the embodiments described in "some embodiments" may be freely combined with any of the above and below embodiments; therefore, all changes and modifications that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims (10)

1. A multipoint support hold-down device for nuclear fuel assemblies, characterized by comprising a plurality of hold-down units (1): each compression unit (1) comprises an upper plate spring (11) and a middle plate spring (12) which are sequentially stacked from top to bottom;

the upper plate spring (11) comprises a first connecting arm (111), a first inclined arm (112) obliquely extending at one end of the first connecting arm (111), a first contact section (113) arranged at one end of the first inclined arm (112) far away from the first connecting arm (111), and a vertical arm (114) arranged at one end of the first contact section (113) far away from the first inclined arm (112); the vertical arm (114) extends downwardly out of the middle leaf spring (12);

the middle plate spring (12) comprises a second connecting arm (121), a second inclined arm (122) obliquely extending at one end of the second connecting arm (121), a second contact section (123) arranged at one end of the second inclined arm (122) far away from the second connecting arm (121), and a first window (124) for the vertical arm (114) to pass through;

the highest point of the second contact section (123) is staggered in the horizontal direction from the highest point of the first contact section (113) and is on the same horizontal plane.

2. The multi-point support compression device of claim 1, wherein the second tilt arm (122) includes a second curved section disposed between two ends of the second tilt arm (122);

in the initial state, the second bending section is of a bending structure, and an included angle alpha formed by tangent lines at two ends of the second inclined arm (122) is 100-170 degrees.

3. The multipoint support compressing apparatus according to claim 2, wherein the second curved section has a circular arc cross section, and the center of the circle is located above the second curved section.

4. The multi-point support compression device of claim 2, wherein the first tilt arm (112) includes a first curved section disposed between two ends of the first tilt arm (112);

in an initial state, the first bending section is of a bending structure, and an included angle beta formed by tangent lines at two ends of the second inclined arm (122) is 100-170 degrees.

5. The multi-point support compressing apparatus according to claim 4, wherein the cross section of the first bending section is an arc, and the center of the arc is arranged above the first bending section.

6. The multipoint support compressing apparatus according to claim 4, wherein the shape of the first curved section and the shape of the second curved section are adjusted to adjust a position and a distance in a horizontal direction of a highest point of the second contact section (123) from a highest point of the first contact section (113).

7. The multi-point support compression device of claim 1, wherein a gap is left between the first tilt arm (112) and the second tilt arm (122).

8. The multipoint support compression device of any one of claims 1-7, wherein the first contact section (113) comprises a first contact portion (1132); the second contact section (123) comprises a second contact (1232); the first contact portion (1132) and the second contact portion (1232) are respectively arc-shaped structures.

9. The multipoint support compressing device according to any one of claims 1-7, further comprising at least one lower leaf spring (13) stacked under the middle leaf spring (12); the lower plate spring (13) comprises a third connecting arm (131), a third inclined arm (132) obliquely extending at one end of the third connecting arm (131), a third contact section (133) arranged at one end of the third inclined arm (132) far away from the third connecting arm (131), and a second window (134) for the vertical arm (114) to pass through;

the third contact section (133) is closely attached to the bottom of the second contact section (123).

10. A nuclear fuel assembly comprising an upper header (2), a lower header disposed in spaced relation to the upper header (2), a grid disposed between the upper header (2) and the lower header, guide tubes disposed in the grid, and the multi-point support compression device of any one of claims 1 to 9 disposed on the upper header (2);

the multiple pressing units (1) of the multipoint support pressing device are arranged on the upper tube seat (2) at intervals and are detachably connected with the upper tube seat (2).