WO2018098703A1

WO2018098703A1 - Fuel assembly and tube base thereof

Info

Publication number: WO2018098703A1
Application number: PCT/CN2016/108059
Authority: WO
Inventors: 禹文池; 李伟才; 傅先刚; 周跃民; 田俊
Original assignee: 中广核研究院有限公司; 中国广核集团有限公司; 中国广核电力股份有限公司
Priority date: 2016-11-30
Filing date: 2016-11-30
Publication date: 2018-06-07

Abstract

Provided are a fuel assembly and a tube base (6) thereof. The tube base (6) comprises a hole plate (61) distributed with through holes (611) and a support mechanism (62) disposed on one side of the hole plate (61). The support mechanism (62) comprises at least one arched rib plate (623) disposed on the hole plate (61). An arched opening (6231) is disposed on one side of the arched rib plate (623) away from the hole plate (61), and an opening direction of the arched opening (6231) faces the side away from the hole plate (61). The arched rib plate (623) effectively prevents stress concentration between the hole plate (61) and a support leg (621), so that the stress of the tube base (6) is continuously distributed more evenly, thereby increasing the strength of the tube stand (6). In addition, for rib plates of the same size and thickness, an area of a flow-facing surface of the arched rib plate (623) gradually changes upward in an axial direction when coolant flows upward from a lower end, such that a sudden and large change in the flow resistance of the coolant is reduced and a flow field is improved. The integrally processed tube base (6) eliminates a billet that needs to be removed, improving material utilization.

Description

Fuel assembly and fuel assembly header

Technical field

This invention relates to nuclear power plant fuel assemblies and, more particularly, to a fuel assembly and a fuel assembly header.

Background technique

The fuel assembly structure of the prior art consists of a rigid skeleton and a fuel rod. As shown in Fig. 1, the fuel rods are arranged in parallel in the rigid skeleton and are evenly spaced. The rigid skeleton includes a mixing grid 4, an upper header 5, a lower header 6 and a guiding tube 7. The mixing frame 4 is composed of regularly arranged cells for accommodating and holding the fuel rods. The positioning grid 10 and the mixing grid 4 are spaced apart in the axial direction of the fuel rod for the fuel rod to pass through the set position. The guide tube 7 is longer than the fuel rod, which projects from the end of the fuel bundle and is fixed to the upper stem 5 and the lower stem 6. The lower header 6 is located at the lower portion of the fuel assembly and has a plurality of support legs and an orifice plate 61. The orifice plate 61 has holes for fixing the guide tubes 7 and coolant passages penetrating the orifice plates 61. The other end of the fuel assembly, i.e., the upper header 5 at the upper end of the assembly, includes a transverse orifice plate through which the orifices and flow holes for receiving and securing the guide tubes 7 are passed.

Generally, as shown in Fig. 13, the lower header is composed of a square orifice plate 61 and four support columns 625 having beam-supporting ribs 624 directly below the four corners thereof, which allows the coolant to be supplied by the holes. The holes in the plate 61 flow to the cavity of the fuel assembly. The two support posts 625 on the diagonal of the lower header 6 have locating pin holes for fitting with the locating pins on the lower core plate to ensure accurate positioning of the fuel assembly at the core.

Since the supporting rib 624 is a long strip-shaped plate structure, numerical analysis is performed by the finite element method, and there is a sharp change in the section between the lower tube 6-hole plate 61 and the supporting rib 624, as shown in Fig. 14, the beam-type lower tube The seat structure has a significant stress concentration at right angles, resulting in a high stress at which local abrupt changes occur, the stress peaks being much larger than the average stress of the component as a whole. Due to the stress concentration there, the strength of the lower header 6 of the assembly is weakened, and the load carrying capacity of the lower header 6 is lowered. In the month of 2004, a water pipe connected to the No. 3 reactor in the building of a nuclear power plant turbine in Japan suddenly burst. Although the accident did not lead to a nuclear leak, the steam explosion killed five workers and injured dozens. The cause of the accident is that the stress concentration of the thin tubes in the steam generator causes cracks in the pipes, and metal fatigue causes crack propagation. Therefore, stress concentration has serious damage to components. It is necessary to optimize the design of the lower header 6 where there is a potential hazard of stress concentration to overcome, or reduce, the stress concentration to weaken the structural strength.

In addition, the current lower header structure results in uneven axial velocity of the coolant flowing out of the core plate, and the beam ribs used in the prior art form a large opening. Although this structure is advantageous for pressure drop, it is not conducive to uniform flow field, which will result in unevenness of the coolant before the lower tube 6 orifice plate 61.

Further, as shown in FIG. 15 and FIG. 16, since the cross-section of the beam-supporting ribs 624 is changed at the same height, when the coolant flushes the cross-section of the ribs, the position of the web is abruptly changed, and the sudden change of the flow-through section causes cross-flow radical change.

technical problem

The technical problem to be solved by the present invention is to provide an improved fuel assembly and a socket for a fuel assembly. Problem solution

Technical solution

The technical solution adopted by the present invention to solve the technical problem thereof is: constructing a pipe base of a fuel assembly, comprising: an orifice plate distributed with a through hole; and a supporting mechanism disposed at one side of the orifice plate; the support The mechanism includes at least one arched rib disposed on the orifice plate; an arched opening is disposed on a side of the arched rib away from the orifice plate, and an opening direction of the arcuate opening faces away from the One side of the orifice plate.

Preferably, the arched ribs are disposed between outer edges of the orifice plates in different directions.

Preferably, the arched ribs include arched ribs disposed in the first direction and the second direction, respectively.

Preferably, the arcuate ribs in the first direction and the arcuate ribs in the second direction are disposed to intersect.

Preferably, the first direction comprises at least two arched ribs arranged side by side, and the second direction comprises at least two arched ribs arranged side by side, each of the arched ribs forming toward the orifice plate The domed structure is arched on one side.

Preferably, the support mechanism further comprises a leg supporting the orifice plate;

The arched rib includes arched ribs disposed between the legs adjacent the circumferential direction of the orifice along the edge of the orifice; and/or

The arched ribs include arched ribs disposed between two of the legs that are not adjacent in the circumferential direction of the orifice plate.

Preferably, the arched rib is a plate-like structure, and the side edges corresponding to the orifice plate and the leg are respectively connected to the orifice plate and the leg.

Preferably, the arched ribs disposed between the two legs are integral with the legs.

Preferably, the supporting mechanism and the orifice plate are integrally formed; or the supporting mechanism is welded with the orifice plate to form an integral structure.

Preferably, the bottom of at least two of the legs is provided with a keyhole.

Preferably, the arcuate ribs disposed between the two legs are symmetrical with respect to a centerline between the two corresponding legs.

Preferably, the orifice plate has a square shape, and the legs include four, respectively located at four corners of the orifice plate; or the orifice plate has a polygonal shape, and the leg includes a number corresponding to the number of sides of the orifice plate A plurality of strips are located at the corners of the orifice plate.

Preferably, the arched shape of the arched opening is formed by sequentially connecting a plurality of line segments in an arched direction.

Preferably, the arcuate profile of the arcuate opening comprises an arcuate section at both ends and a straight section connected between the arcuate sections at both ends.

Preferably, the straight section is parallel to the orifice plate.

Preferably, the arched shape of the arched opening is a circular arc or an arc.

Preferably, the cross-sectional shape of the arched opening is curved.

Preferably, at least one of the two edges corresponding to the arched opening and the opposite sides of the arched rib is provided with a chamfered structure.

The present invention also contemplates a fuel assembly including the stem.

Advantageous effects of the invention

Beneficial effect

The implementation of the fuel assembly and the fuel assembly of the present invention has the following beneficial effects: the lower tube seat of the present invention can effectively avoid the stress concentration between the lower orifice plate and the leg through the arch bridge type arch rib, so that the lower header can be The continuous distribution of stress is more uniform, thereby increasing the strength of the lower header; in addition, the coolant flows upward from the lower end. For arched ribs of the same size and thickness, the flow-through area of the arch-shaped arched rib changes gradually along the axial direction. The flow resistance is reduced when the coolant flows, and the flow field is improved. In addition, for the integrated processing of the lower header, the removed blank is reduced, and the utilization rate of the material is improved.

Brief description of the drawing

DRAWINGS

The present invention will be further described below in conjunction with the accompanying drawings and embodiments, in which:

1 is a schematic structural view of a fuel assembly in an embodiment of the present invention;

2 is a schematic perspective structural view of a lower header of a fuel assembly according to an embodiment of the present invention;

Figure 3 is a perspective view of another lower angle of the lower header of Figure 2;

Figure 4 is a schematic view showing the arched opening of the arched ribs when the plurality of segments are sequentially connected;

Figure 5 is a schematic view showing the structure when the two ends of the arched opening of the arched rib are curved;

Figure 6 is a schematic view showing the structure when the arched opening of the arched rib is curved;

Figure 7 is a schematic view of the A-A structure when the arched opening of the arched rib of Figure 6 is curved in cross section;

Figure 8 is a schematic view of the A-A structure when the arched opening of the arched rib of Figure 6 has a rounded chamfered cross section;

Figure 9 is a schematic view of the A-A structure when the cross-section of the arched opening of the arched rib of Figure 6 is provided with a beveled chamfered structure;

Figure 10 is an isometric stress line distribution of the lower header of Figure 2 when simulated by a finite element method;

Figure 11 is a schematic cross-sectional view showing a lower header of an arched arch rib according to an embodiment of the present invention;

Figure 12 is a graph showing the relationship between the upstream surface and the axial position of the lower header of Figure 11;

Figure 13 is a perspective view showing the structure of the lower header in the background art;

Figure 14 is an isometric stress line distribution of the lower header of Figure 13 when simulated by a finite element method;

Figure 15 is a schematic cross-sectional view of a lower header in the background art;

Figure 16 is a graph showing the relationship between the upstream surface and the axial position of the lower header of Figure 15.

BEST MODE FOR CARRYING OUT THE INVENTION

For a better understanding of the technical features, objects and effects of the present invention, the embodiments of the present invention are described in detail with reference to the accompanying drawings.

As shown in Figure 1, a fuel assembly in a preferred embodiment of the invention consists of a rigid frame and a fuel rod, the fuel rods being arranged in parallel in the rigid frame and evenly spaced. The rigid skeleton includes a mixing frame 4 and an upper socket 5. Lower header 6 and guide tube 7. The mixing frame 4 is composed of regularly arranged cells for accommodating and holding the fuel rods. The positioning grid 10 and the mixing grid 4 are spaced apart in the axial direction of the fuel rod for the fuel rod to pass through the set position. The guide tube 7 is longer than the fuel rod, which projects from the end of the fuel bundle and is fixed to the upper stem 5 and the lower stem 6. The upper header 5 is disposed at the upper end of the fuel assembly and includes a lateral upper orifice plate through which the plurality of orifices and flow holes for receiving and fixing the guide tubes 7 are passed. Further, the header of the fuel assembly of the present invention corresponds to the lower header 6 of the fuel assembly.

As shown in FIG. 2 and FIG. 3, the lower header 6 is located at a lower portion of the fuel assembly, and includes an orifice plate 61 and a support mechanism 62 disposed on the lower side of the orifice plate 61. The support mechanism 62 includes four supports for supporting the orifice plate 61. Leg 621. Correspondingly, the orifice plate 61 has a square shape, and the four legs 621 are respectively located at the four corners of the orifice plate 61. In other embodiments, the orifice plate 61 may also have other polygonal shapes. The number of the legs 621 may also be three or more than three other numbers, which can ensure balanced support of the orifice plate 61. Preferably, The leg 621 includes a plurality of strips corresponding to the number of sides of the orifice plate 61, and is located at a corner of the orifice plate 61, respectively.

The bottom of the two diagonal legs 621 are provided with a locking hole 622 for fitting with a locating pin on the lower core plate to ensure accurate positioning of the fuel assembly at the core. In other embodiments, the locking holes 622 may be provided on the legs 621 at other positions, or the locking holes 622 may be provided in the plurality of legs 621.

A through hole 611 is disposed in the orifice plate 61. The through hole 611 includes a passage for fixing the guide pipe 7 and a coolant flow path through which the coolant flows through the orifice plate 61. The leg 621 is located in the outer ring of the through hole 611 region, and the supporting mechanism 62 further includes an arched rib 623 disposed between the two adjacent legs 621 in the circumferential direction of the through hole 611 region, and the arched rib 623 is away from the orifice plate One side of the 61 is provided with an arched opening 6231, and the opening direction of the arcuate opening 6231 faces the side away from the orifice plate 61.

The arch bridge type arch rib 623 can effectively avoid the stress concentration between the orifice plate 61 and the leg 621, so that the stress distribution of the lower stem 6 is more uniform, thereby improving the strength of the lower stem 6. In addition, the coolant flows upward from the lower end. For the arch rib 623 of the same size and thickness, the flow-through area of the arch-shaped arch rib 623 gradually changes upward in the axial direction, and the flow resistance change and the improvement when the coolant flows are reduced. Flow field. At the same time, for the integrated processing of the lower header, the removed blank is reduced and the utilization of the material is improved.

In some embodiments, an arcuate rib 623 is disposed between any two adjacent legs 621 in the circumferential direction of the through hole 611 region, so that the strength of the circumference of the orifice plate 61 is improved, and the balance is increased. At the same time, the flow resistance change when the coolant flows is reduced, and the flow field is improved. Preferably, an arched rib 623 disposed between the two legs 621 Symmetrical with respect to the center line between the corresponding two legs 621, the stress and the flow resistance when the coolant flows are reduced, and the flow field is improved.

In other embodiments, the arched ribs include arched ribs 623 disposed between the legs 621 that are not adjacent in the circumferential direction of the orifice plate 61, such that the arcuate ribs are joined by the sides of the orifice plate in two Between the legs.

Further, each of the legs 621 and the arched ribs 623 are symmetrically disposed with respect to the orifice plate 61, and may also be symmetrically disposed with respect to the center of the orifice plate 61 to ensure a more balanced force of the lower header 6.

Preferably, the arched ribs 623 are disposed along the outer ring of the region of the through hole 611 to avoid the influence of the installation of the guide tube 7 and the circulation of the coolant. In other embodiments, the arched rib 623 may also partially overlap the through hole 611 in the axial direction, and does not affect the installation of the guide tube 7 and the circulation of the coolant.

In some embodiments, the legs 621 are integrally formed with the arched ribs 623 to increase the strength of the joint. Further, the support mechanism 62 and the orifice plate 61 are also integrated, which can increase the joint strength. In other embodiments, the legs 621 and the arched ribs 623 may also be welded joints, and the support mechanism 62 and the orifice plate 61 may also be welded to form a unitary structure.

In some embodiments, the arched ribs 623 are plate-like structures, and the side edges corresponding to the orifice plate 61 and the legs 621 are respectively connected to the orifice plate 61 and the legs 621, and the joint position is seamless, thereby avoiding the flow of the coolant. Have an impact. In other embodiments, the arcuate ribs 623 can also be arched support bar structures or arched stent structures.

Further, in some embodiments, as shown in FIG. 4, the arcuate shape of the arcuate opening 6231 is formed by sequentially connecting a plurality of line segments in an arched direction. In other embodiments, as shown in FIG. 5, the arcuate shape of the arcuate opening 6231 can also be other shapes, including an arcuate section 6232 at both ends and a straight section 6233 between the arcuate sections 6232 connected at both ends. Preferably, the straight section 6233 is parallel to the orifice plate 61, and the structure can reduce the height of the arched rib 623 when the length of the arched rib 623 is long. Of course, as shown in FIG. 6, the arched shape of the arcuate opening 6231 is circular or curved.

In some embodiments, as shown in FIG. 7, the cross-sectional profile of the arcuate opening 6231 is curved to provide a smoother flow of coolant and reduce the impact on the arched ribs 623. In other embodiments, as shown in FIG. 8 and FIG. 9 , in the two edges corresponding to the inner and outer opposite sides of the arched opening 6231 and the arched rib 623, the two edges are provided with a chamfered structure, and the chamfered structure may be Rounded or beveled. Of course, it is also possible to provide a chamfered structure only on the corresponding one of the inner and outer opposite sides of the arched rib 623.

The force analysis of the arched arched rib 623 of the present invention is a plane stress problem, and the finite element can be used. Method for numerical analysis. For the example of the present invention, in the case of the same span, uniform load and boundary conditions, the quadrilateral element is used to compare the arch type arch rib 623 with the beam structure of the lower tube seat in the background art. 10 is the equal stress line distribution of the arch type arch rib 623. As can be seen from FIG. 4, the stress distribution of the arch type arch rib 623 is more uniform, and the structural strength is superior to the structural strength of the base under the background art.

By comparative analysis, the lower header 61 with the arched arched ribs 623 avoids the stress concentration of the sudden change of the section, and the stress distribution of the lower header, compared to the lower header of the straight beam rib in the background art. More even.

Further, the lower header 61 of the present invention with the arch bridge type arch rib 623 can function to equalize the flow field, as shown in FIG. 11 as compared with the lower tube seat of the straight beam rib in the background art. The inward cross-section of the arched rib 623 of the present invention is a smooth transition in the axial direction, correspondingly, in conjunction with the relationship between the flow-through area and the axial position in FIG. 12, the arch-shaped rib of the present invention 623 can play a role in balancing the flow field.

In other embodiments, the supporting mechanism 62 may also include an arched rib 623 disposed on the orifice plate 61. The direction in which the arched ribs 623 are disposed is not limited, and may be disposed at the edge of the orifice plate 61. It may be disposed on the side of the orifice plate 61 to be connected between any two sides. Correspondingly, an arched opening 6231 is disposed on a side of the arched rib 623 away from the orifice plate 61, and an opening direction of the arched opening 6231 faces a side away from the orifice plate 61, so that the arched rib When the 623 is impacted by the coolant from the opening side of the arched opening 6231, the strength of the orifice plate 61 is increased, the balance is increased, and the flow resistance change when the coolant flows is reduced, and the flow field is improved.

When the arched ribs 623 include a plurality of, the arched ribs 623 may also be disposed between the outer edges of the orifice plates 61 in different directions, such that the arched ribs are joined by the sides of the orifice plate 61 between the edges of the different positions. . The direction in which the plurality of arched ribs 623 are disposed may be the same or different, or may be arranged in a cross.

In some embodiments, the arcuate ribs include arched ribs 623 disposed in the first direction and the second direction, respectively, and the number of arcuate ribs 623 in each direction is not limited. The arcuate ribs 623 of the first direction and the arcuate ribs 623 of the second direction are disposed to intersect, and the arched ribs 623 of the two directions may intersect in the region of the orifice 61, and the intersections may also be in the holes. The edge of the plate 61 may also be in the direction of the extension of the arched ribs 623 outward.

Further, the first direction includes two or more arched ribs 623 arranged side by side, the second direction Two or more arched ribs 623 are provided side by side, and each of the arched ribs 623 forms a dome structure that is arched toward one side of the orifice plate 61. The dome structure forms a lattice-like structure, which can increase the strength of the orifice plate 61, and can reduce the flow resistance change when the coolant flows in the entire region on the side opposite to the orifice plate 61, thereby improving the flow field.

It will be understood that each of the above technical features may be used in any combination without limitation.

The above is only the embodiment of the present invention, and is not intended to limit the scope of the invention, and the equivalent structure or equivalent process transformation of the present invention and the contents of the drawings may be directly or indirectly applied to other related technologies. The fields are all included in the scope of patent protection of the present invention.

Claims

A socket for a fuel assembly, comprising: an orifice plate (61) having a through hole (611) and a support mechanism (62) disposed on one side of the orifice plate (61); the support mechanism ( 62) comprising at least one arched rib disposed on the orifice plate (61); an arched opening (6231) is disposed on a side of the arched rib away from the orifice plate (61), and The opening direction of the arched opening (6231) faces the side away from the orifice plate (61).
A socket for a fuel assembly according to claim 1, wherein said arcuate ribs are disposed between outer edges of said orifice plates (61) in different directions.
A header for a fuel assembly according to claim 2, wherein said arcuate ribs include arcuate ribs (623) disposed in a first direction and a second direction, respectively.
A header for a fuel assembly according to claim 3, wherein said first direction of arched ribs (623) and said second direction of arcuate ribs (623) are disposed to intersect.
A header for a fuel assembly according to claim 4, wherein said first direction comprises at least two arched ribs (623) arranged side by side, said second direction comprising at least two arches arranged side by side A ribbed plate (623), each of the arched ribs (623) forming a dome structure that is arched toward one side of the orifice plate (61).
A header for a fuel assembly according to any one of claims 1 to 5, wherein the support mechanism (62) further comprises a leg (621) supporting the orifice plate (61);

The arched rib includes arched ribs (623) disposed between the legs (621) adjacent to each other in the circumferential direction of the orifice plate (61) along an edge of the orifice plate (61); /or,

The arched ribs include arched ribs (623) disposed between two of the legs (621) that are not adjacent in the circumferential direction of the orifice plate (61).
A socket for a fuel assembly according to claim 6, wherein said arched rib (623) is a plate-like structure corresponding to said orifice plate (61) and legs (621) The side edges are respectively connected to the orifice plate (61) and the legs (621).
A socket for a fuel assembly according to claim 6, wherein said arched ribs (623) disposed between said legs (621) are integral with said legs (621) .
A header for a fuel assembly according to claim 6, wherein said support mechanism (62) is integral with said orifice plate (61); or said support mechanism (62) and said orifice plate (61) Welding forms an integral structure.
A socket for a fuel assembly according to claim 6, wherein the bottom of at least two of said legs (621) is provided with a keyhole (622).
A socket for a fuel assembly according to claim 6, wherein said arched ribs (623) disposed between said two legs (621) are relatively corresponding to said two legs (621) The midline is symmetrical between.
The socket of the fuel assembly according to claim 6, wherein the orifice plate (61) has a square shape, and the legs (621) comprise four, respectively located at four corners of the orifice plate (61); Alternatively, the orifice plate (61) is polygonal, and the legs (621) include a plurality of strips corresponding to the number of sides of the orifice plate (61), and are respectively located at corners of the orifice plate (61).
A socket for a fuel assembly according to claim 6, wherein the arcuate shape of the arcuate opening (6231) is formed by sequentially connecting a plurality of line segments in an arched direction.
A header for a fuel assembly according to claim 6, wherein the arcuate profile of the arcuate opening (6231) includes an arcuate section (6232) at both ends and the arcuate section connected at both ends ( Straight section between 6232) (6233).
A header for a fuel assembly according to claim 14, wherein said straight section (6233) is parallel to said orifice plate (61).
A header for a fuel assembly according to claim 6, wherein the arcuate shape of the arcuate opening (6231) is arcuate or curved.
A header for a fuel assembly according to claim 6, wherein said arcuate opening (6231) has an arcuate cross-sectional profile.
A socket for a fuel assembly according to claim 6, wherein at least one of said two edges of said arcuate opening (6231) and said opposite sides of said arcuate rib (623) The edge is provided with a chamfered structure.
A fuel assembly characterized by comprising the stem of any one of claims 1 to 18.