Reactor fuel device suitable for high fuel consumption limit value

Abstract

The utility model provides a reactor fuel device suitable for a high fuel consumption limit value, and relates to the technical field of pressurized water nuclear reactors, the reactor fuel device comprises an upper reactor core plate, a lower reactor core plate, a fuel assembly, a pressing piece and at least two irradiation growth supporting pieces, a reactor cavity is formed between the upper reactor core plate and the lower reactor core plate, the fuel assembly is vertically arranged in the reactor cavity, and the pressing piece is arranged in the reactor cavity. The pressing piece is clamped between the fuel assembly and the upper reactor core plate, and a gap is formed between the top end face of the fuel assembly and the bottom end face of the upper reactor core plate; and the supporting pieces are uniformly distributed at the periphery of the fuel assembly and are fixedly connected between the upper reactor core plate and the lower reactor core plate. According to the device, the supporting piece capable of growing by irradiation is arranged between the upper reactor core plate and the lower reactor core plate, so that the gap between the upper reactor core plate and the fuel assembly can be correspondingly increased along with the irradiation growth of the supporting piece, and the fuel assembly is prevented from being in rigid contact with the upper reactor core plate and being closed due to overgrowth.

Description

Technical Field

[0001] This application relates to the technical field of pressurized water nuclear reactors, and particularly relates to a reactor fuel device suitable for high burnup limits. Background Art

[0002] In recent years, there have been huge changes in the form of nuclear power grid connection. The power generation demands of each nuclear power plant have generally decreased and changed violently, resulting in a large deviation between the nuclear fuel management plan and the pre-designed one. As a result, problems such as the difficulty in realizing the refueling design plan, early reactor shutdown and waste of fuel, poor fuel economy, and reduction of the core safety margin have emerged. There is an urgent need to increase the fuel limit of the reactor fuel assembly to further improve the flexibility and economy of fuel management. However, at the same time, increasing the burnup limit will lead to an increase in the irradiation growth of the fuel assembly. During the operation of the reactor, it is easy to have abnormal situations where the upper end of the fuel assembly makes hard contact with the upper core plate and closes due to excessive irradiation growth of the fuel assembly and insufficient clearance reserved between the assembly and the upper core plate.

[0003] To address this problem, traditional methods generally modify the structure of the fuel assembly to adapt to the height of the reactor cavity. This requires a large modification to the fuel assembly design and additional out-of-pile tests are needed before installation to verify effectiveness and safety, which will incur additional costs and is relatively expensive. Utility Model Content

[0004] This application provides a reactor fuel device suitable for high burnup limits, which is used to solve the problem that the fuel assembly of the existing device is prone to hard contact with and close to the upper core plate due to excessive irradiation growth under high burnup limits. The reactor fuel device suitable for high burnup limits provided by this application is provided with a support member that can undergo irradiation growth between the upper and lower core plates without changing the structural design of the fuel assembly, so that the clearance between the upper core plate and the fuel assembly can increase correspondingly with the irradiation growth of the support member, avoiding the problem that the fuel assembly makes hard contact with and closes to the upper core plate due to excessive growth.

[0005] This application provides a reactor fuel device suitable for high burnup limits, which includes an upper core plate, a lower core plate, a fuel assembly, a pressing member, and at least two support members that can undergo irradiation growth. The upper core plate and the lower core plate are parallel and opposite to each other, and a reactor cavity is formed therebetween; the fuel assembly is vertically arranged in the reactor cavity; the pressing member is clamped between the fuel assembly and the upper core plate, and a clearance is formed between the top end face of the fuel assembly and the bottom end face of the upper core plate.

[0006] The support members are vertically and uniformly distributed around the fuel assembly and are fixedly connected between the upper core plate and the lower core plate to undergo irradiation growth and support the upper core plate during the operation of the reactor, increasing the height of the reactor cavity.

[0007] In some embodiments, the support member includes a zirconium alloy support column, and the zirconium alloy support column is detachably connected to the upper core plate and the lower core plate.

[0008] In some embodiments, the fuel assembly includes an upper nozzle, a lower nozzle, a guide tube unit, a fuel unit, and a grid unit. The upper nozzle and the lower nozzle are disposed opposite to each other. A plurality of the guide tube units are vertically connected between the upper nozzle and the lower nozzle. A plurality of the fuel units are vertically and spaced apart by a plurality of the grid units and arranged in a matrix on the guide tube units.

[0009] In some embodiments, the lower nozzle is seated on the lower core plate and fixedly connected to the lower core plate by a plurality of connecting pins.

[0010] In some embodiments, the gap is formed between the top end face of the upper nozzle and the bottom end face of the upper core plate.

[0011] In some embodiments, the upper nozzle is provided with a concave receiving groove on the top facing the upper core plate. At least a part of the pressing member is limited in the receiving groove, at least a part of the pressing member extends out of the upper nozzle and elastically abuts against the upper core plate, so as to elastically compress and deform when the upper core plate and the upper nozzle approach each other relatively.

[0012] In some embodiments, a limiting portion vertically extends downward from the part of the pressing member that elastically abuts against the upper core plate, and the height of the limiting portion is greater than the depth of the receiving groove, so that when the bottom end of the limiting portion abuts against the bottom surface of the receiving groove, the distance between the top end face of the upper nozzle and the bottom end face of the upper core plate is greater than zero.

[0013] For the reactor fuel device suitable for high burnup limits provided by the present application, a reactor cavity is formed between the upper core plate and the lower core plate. The fuel assembly is vertically arranged in the reactor cavity. The pressing member is clamped between the fuel assembly and the upper core plate, and a gap is formed between the fuel assembly and the upper core plate. Without changing the structural design of the fuel assembly, the present application device is provided with a support member that can undergo irradiation growth between the upper and lower core plates, so as to grow under irradiation and push up the upper core plate upward during the operation of the reactor, increase the height of the reactor cavity, realize the adaptive adjustment of the height of the reactor cavity, and further increase the gap height between the fuel assembly and the upper core plate, effectively avoiding the problem that the fuel assembly is in hard contact and closed with the upper core plate due to excessive growth, and without involving changes in the structural design of the fuel assembly, with lower cost. Description of the Drawings

[0014] To more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings, where:

[0015] Figure 1 Structural schematic of one embodiment of the present application after hiding the support member Figure 1 ;

[0016] Figure 2 Structural schematic of one embodiment of the present application after hiding the support member Figure 2 ;

[0017] Figure 3 Overall structural schematic of one embodiment of the present application.

[0018] Wherein: 1 - upper core plate, 2 - pressing member, 21 - limiting portion, 3 - fuel assembly, 31 - upper nozzle, 311 - accommodating groove, 32 - conduit unit, 33 - fuel unit, 34 - grid unit, 35 - lower nozzle, 4 - lower core plate, 5 - reactor cavity, 6 - gap, 7 - support member. Specific embodiments

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present application in conjunction with the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. According to the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application. In addition, the features, operations or characteristics described in the specification can be combined in any appropriate manner to form various embodiments.

[0020] Please refer to Figures 1 to 3 , the present application provides a reactor fuel device suitable for high burnup limits. The device includes an upper core plate 1, a lower core plate 4, a fuel assembly 3, a pressing member 2, and at least two support members 7 with irradiation growth. Among them, the upper core plate 1 and the lower core plate 4 are parallel and opposite to each other, and a reactor cavity 5 is formed between the two. The fuel assembly 3 is vertically arranged in the reactor cavity 5. The pressing member 2 is clamped between the fuel assembly 3 and the upper core plate 1, and a gap 6 is formed between the top end face of the fuel assembly 3 and the bottom end face of the upper core plate 1.

[0021] The support members 7 are vertically and uniformly distributed around the fuel assembly 3 and are fixedly connected between the upper core plate 1 and the lower core plate 4 to irradiate and grow during the operation of the reactor and push up the upper core plate 1 upward to increase the height of the reactor cavity 5.

[0022] Understandably, all the support members 7 that can axially elongate under irradiation conditions can support the upper core plate 1 upward during the operation of the reactor, thereby realizing the adaptive adjustment of the height of the reactor cavity 5.

[0023] For the reactor fuel device suitable for high burnup limits provided by the present application, a reactor cavity 5 is formed between the upper core plate 1 and the lower core plate 4. The fuel assembly 3 is vertically arranged in the reactor cavity 5. The pressing member 2 is clamped between the fuel assembly 3 and the upper core plate 1, and a gap 6 is formed between the fuel assembly 3 and the upper core plate 1. Without changing the structural design of the fuel assembly 3, the present application device is provided with a support member 7 that can grow under irradiation between the upper and lower core plates to grow under irradiation and support the upper core plate 1 upward during the operation of the reactor, increase the height of the reactor cavity 5, realize the adaptive adjustment of the reactor cavity height, and thereby increase the gap height between the fuel assembly 3 and the upper core plate 1, effectively avoiding the problem that the fuel assembly 3 makes hard contact and closes with the upper core plate 1 due to excessive growth, and without involving changes in the structural design of the fuel assembly 3, the cost is lower.

[0024] Preferably, the support member 7 includes a zirconium alloy support column, and the zirconium alloy support column is detachably connected to the upper core plate 1 and the lower core plate 4. Under irradiation conditions, two-dimensional triangular vacancy-type defects with special crystallographic plane characteristics (the edge columnar surface of a triangle) in zirconium alloy can directly collapse into basal plane vacancy-type dislocation loops after reaching a certain critical size. During the formation process of the basal plane two-dimensional triangular vacancy-type defects, trace elements in zirconium alloy, such as a very small amount of hydrogen atoms, can greatly reduce the basal plane surface energy of zirconium, thereby promoting the nucleation and growth of two-dimensional triangular defects, and then transforming into <c>The type of dislocation loop causes the irradiation growth of the zirconium alloy support column in the axial direction, thereby pushing up the upper core plate 1 upward to realize the adaptive adjustment of the height of the reactor cavity 5.

[0025] The upper and lower ends of the zirconium alloy support column can be detachably connected to the corresponding core plates by means of threaded connections, which is convenient for the combined assembly of the reactor fuel device and is also conducive to later replacement and maintenance.

[0026] Please refer to Figures 1 to 2 , in some embodiments, the fuel assembly 3 includes an upper nozzle 31, a lower nozzle 35, a guide tube unit 32, a fuel unit 33 and a grid unit 34. Among them, the upper nozzle 31 and the lower nozzle 35 are arranged opposite to each other, and a plurality of guide tube units 32 are vertically connected between the upper nozzle 31 and the lower nozzle 35. A plurality of fuel units 33 are vertically and fixedly connected to the guide tube units 32 at intervals through a plurality of grid units 34 and are arranged in a matrix. On the one hand, the guide tube unit 32 serves as a support and fixing structure to connect the upper and lower nozzles and the fuel unit 33 and the grid unit 34. On the other hand, it also serves as a channel for the reactor coolant to enter and exit in the reactor cavity 5. The fuel unit 33, such as a long-columnar fuel rod, is fixedly connected to the guide tube unit 32 through the grid unit 34, and gaps are left between the fuel rods for the coolant to flow through and realize heat exchange.

[0027] The lower nozzle 35 is located on the lower core plate 4 and is fixedly connected to the lower core plate 4 through a number of connecting pins (not shown in the figure), playing a role in supporting and fixing the fuel assembly 3 and ensuring that the fuel assembly 3 can be stably arranged in the reactor cavity 5.

[0028] A gap 6 as described above is formed between the top end face of the upper nozzle 31 and the bottom end face of the upper core plate 1.

[0029] The upper nozzle 31 is provided with a concave receiving groove 311 facing the top of the upper core plate 1. At least part of the pressing member 2 is limited in the receiving groove 311, at least part of it extends out of the upper nozzle 31 and elastically abuts against the upper core plate 1, so as to elastically compress and deform when the upper core plate 1 and the upper nozzle 31 approach each other.

[0030] The pressing member 2 realizes the elastic pressing of the upper core plate 1 on the fuel assembly 3 as an intermediate medium, ensuring the reliable and stable assembly of the fuel assembly 3 inside the reactor pressure vessel. The pressing member 2 is actually elastically clamped between the upper nozzle 31 and the upper core plate 1. When the fuel assembly 3 becomes higher due to irradiation growth during the operation of the reactor, the gap 6 reserved between the upper nozzle 31 and the upper core plate 1 is compressed, causing the pressing member 2 to elastically compress and deform. The device of the present application allows for sufficient redundancy when calculating the height of the fuel assembly 3, so it can adapt to the irradiation growth amount of the fuel assembly 3 under high burnup limit conditions and can avoid the problem that the fuel assembly 3 hard contacts and closes with the upper core plate 1 due to excessive growth.

[0031] The pressing member 2 elastically abuts against a part of the upper core plate 1 that extends vertically downward, and a limiting portion 21 is provided at the lower end of the pressing member 2. The height of the limiting portion 21 is greater than the depth of the accommodating groove 311. When the bottom end of the limiting portion 21 abuts against the bottom surface of the accommodating groove 311, the distance between the top end surface of the upper nozzle 31 and the bottom end surface of the upper core plate 1 is greater than zero. When the pressing member 2 of the device in this application is compressed to the limit, the bottom end of the limiting portion 21 abuts against the bottom surface of the accommodating groove 311. Since the height of the limiting portion 21 is greater than the depth of the accommodating groove 311, at least a part of the upper portion of the pressing member 2 still protrudes from the upper nozzle 31, so that there will still be a certain gap 6 between the top end surface of the upper nozzle 31 and the bottom end surface of the upper core plate 1, ensuring that the upper nozzle 31 of the fuel assembly 3 will not rigidly abut against the upper core plate 1 and close.

[0032] The above is only the preferred embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied to other related technical fields, shall be equally included in the patent protection scope of the present application.< / c>

Claims

1. A reactor fuel assembly suitable for high burnup limits, characterized in that: The invention comprises an upper core plate (1), a lower core plate (4), a fuel assembly (3), a pressing piece (2) and at least two irradiation-grown supporting pieces (7); the upper core plate (1) and the lower core plate (4) are parallel to each other and a core cavity (5) is formed between the two; the fuel assembly (3) is vertically arranged in the core cavity (5); the pressing piece (2) is clamped between the fuel assembly (3) and the upper core plate (1) so that a gap (6) is formed between the top end surface of the fuel assembly (3) and the bottom end surface of the upper core plate (1); The support members (7) are evenly distributed vertically on the periphery of the fuel assembly (3) and are fixedly connected between the upper core plate (1) and the lower core plate (4) so ​​as to grow by irradiation during the operation of the reactor and support the upper core plate (1) to increase the height of the reactor cavity (5).

2. The reactor fuel assembly suitable for high burnup limit according to claim 1, characterized in that: The support member (7) comprises a zirconium alloy support column, and the zirconium alloy support column is detachably connected to the upper core plate (1) and the lower core plate (4).

3. The reactor fuel assembly suitable for high burnup limit according to claim 1, characterized in that: The fuel assembly (3) comprises an upper tube seat (31), a lower tube seat (35), a guide tube unit (32), a fuel unit (33) and a grid unit (34); the upper tube seat (31) and the lower tube seat (35) are arranged opposite to each other; a plurality of guide tube units (32) are vertically connected between the upper tube seat (31) and the lower tube seat (35); a plurality of fuel units (33) are vertically spaced and fixed to the guide tube unit (32) via a plurality of grid units (34) and are arranged in a matrix.

4. The reactor fuel assembly suitable for high burnup limit according to claim 3, characterized in that: The lower pipe seat (35) is seated on the lower core plate (4) and is fixedly connected to the lower core plate (4) via a plurality of connecting pins.

5. The reactor fuel assembly suitable for high burnup limit according to claim 3, characterized in that: The gap (6) is formed between the top end surface of the upper tube seat (31) and the bottom end surface of the upper core plate (1).

6. The reactor fuel assembly suitable for high burnup limit according to claim 3, characterized in that: The upper tube seat (31) is provided with a concave receiving groove (311) toward the top of the upper core plate (1); the pressing member (2) is at least partially confined in the receiving groove (311), at least partially extends out of the upper tube seat (31) and elastically presses against the upper core plate (1), so as to elastically compress and deform when the upper core plate (1) and the upper tube seat (31) are relatively close to each other.

7. The reactor fuel assembly suitable for high burnup limit according to claim 6, characterized in that: The clamping member (2) elastically abuts against the portion of the upper core plate (1) to form a limiting portion (21) extending vertically downward, wherein the height of the limiting portion (21) is greater than the depth of the accommodating groove (311), so that when the bottom end of the limiting portion (21) abuts against the bottom surface of the accommodating groove (311), the distance between the top end surface of the upper tube seat (31) and the bottom end surface of the upper core plate (1) is greater than zero.

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