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Graded buffering high-shock-resistance bending-resistance pipe-in-pipe type guide pipe and fuel assembly

A fuel assembly and anti-bending technology, applied in the direction of pipes/pipe joints/pipes, assembly of fuel elements, pipe elements, etc., can solve the problems of not fully exerting mechanical properties, affecting the bearing capacity of guide pipes, and difficult to meet seismic requirements. , to achieve the effect of facilitating high fuel consumption operation, increasing the axial equivalent stiffness and transverse bending stiffness, alleviating thermal creep and irradiating the secondary side

Active Publication Date: 2022-04-15
NUCLEAR POWER INSTITUTE OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The integrated reduced-diameter structure is simple, but the mechanical properties of the reduced-diameter section are poor, and it is difficult to meet the seismic requirements of the third-generation nuclear power plant with 0.3g limit earthquake motion, and the guide tube is difficult to manufacture; The connection at both ends, the sleeve connection of the casing structure is its mechanical weak link, and its mechanical properties have not been fully utilized; at the same time, both the pipe-in-pipe structure and the casing structure are prone to form dead water in the gap between the inner and outer pipes , it is easy to cause crevice corrosion, which in turn affects the bearing capacity of the guide tube

Method used

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  • Graded buffering high-shock-resistance bending-resistance pipe-in-pipe type guide pipe and fuel assembly
  • Graded buffering high-shock-resistance bending-resistance pipe-in-pipe type guide pipe and fuel assembly
  • Graded buffering high-shock-resistance bending-resistance pipe-in-pipe type guide pipe and fuel assembly

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Experimental program
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Effect test

Embodiment 1

[0047] For existing guide tube structures (such as figure 2 As shown), there are gaps to form dead water areas, which are likely to cause crevice corrosion, and then affect the bearing capacity of the guide tube. The tube is a tube-in-tube structure with a simple manufacturing process (reduced inner diameter, increased wall thickness), which improves the equivalent stiffness of the guide tube, improves the shock resistance and bending resistance under high fuel consumption. At the same time, multi-level hydraulic buffering is realized through the opening of the inner tube, which reduces the impact load of falling rods, thereby reducing the maximum stress of the guide tube during operation, improving the bending resistance of the fuel assembly, and avoiding dead water areas to alleviate crevice corrosion, thereby improving the bearing capacity of the guide tube .

[0048] Specific as Figure 3-5 As shown, the guide tube 1 of this embodiment is composed of an outer tube 2, an ...

Embodiment 2

[0052] This embodiment further optimizes the above-mentioned embodiment 1, such as image 3 As shown, the inner tube 3 and the outer tube 2 are connected by expansion or welding, that is, as image 3 The outer tube shown is connected to the inner tube through the connection part 4, and the connection part 4 is a convex part formed by expansion or welding.

[0053] In this embodiment, the inner tube 3 is axially connected to the outer tube 2 through a plurality of connecting parts 4 . The distance between two adjacent connecting parts, that is, the connection distance between the inner pipe 3 and the outer pipe 2 is d, and the size of d should fully consider the span of the guide pipe in the fuel assembly. Evenly arranged on the span between; and the maximum value of d, Dmax, should meet the requirement that the inner tube and the outer tube do not touch when bearing the maximum axial load, realizing the effect of "bunching into a column" between the inner tube and the outer t...

Embodiment 3

[0055] This embodiment further optimizes the above-mentioned embodiment 1. In this embodiment, the upper end of the inner tube 3 is made into a slotted and opened structure 33, which can be automatically attached after being inserted into the outer tube 2, without welding or expansion joints 4, The manufacturing process is greatly simplified, while relative vibration and potential abrasion can be avoided, and structural reliability can be improved.

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Abstract

The invention belongs to the technical field of nuclear fuel assemblies of nuclear power stations, and particularly relates to a graded buffering high-shock-resistance bending-resistance pipe-in-pipe type guide pipe and a fuel assembly. The guide pipe is composed of an outer pipe, an inner pipe and an end plug, the inner pipe is sleeved with the outer pipe, the bottom end of the inner pipe and the bottom end of the outer pipe are fixedly connected with the end plug, overflow holes are formed in the outer pipe and located at the upward position of the upper end of the inner pipe, and a plurality of bypass flow holes are formed in the position, close to the bottom, of the outer pipe in the radial direction. A plurality of buffer holes are formed in the inner pipe in the radial direction; the inner pipe is connected with the outer pipe through a plurality of connecting parts in the length direction. The overflow hole is formed in the outer pipe and located at the upward position of the upper end of the inner pipe, so that water in the guide pipe rapidly overflows when rod falling begins, and rapid rod falling is achieved; a plurality of drain holes formed in the inner pipe in the radial direction are matched with drain holes in the bottom of the end plug to achieve hydraulic buffering; crevice corrosion is relieved through an outer pipe bypass flow hole; the equivalent stiffness and the bearing capacity are improved through the multiple connecting parts, and the shock resistance and the bending resistance under high fuel consumption of the fuel assembly are improved.

Description

technical field [0001] The invention belongs to the technical field of nuclear fuel assemblies of nuclear power plants, and in particular relates to a pipe-in-pipe guide pipe and a fuel assembly with graded buffering, high shock resistance and bending resistance. Background technique [0002] The nuclear fuel assembly is composed of a number of fuel rods, guide tube parts, positioning grids, upper and lower tube seats, etc. As the fuel assembly bearing structure, the guide tube part has the following basic functions: providing continuity for the fuel assembly structure; providing insertion channels for fuel-related components; providing hydraulic buffer for the falling of control rods during reactor emergency shutdown; providing cooling for fuel-related component rods agent flow. Operating experience shows that with the deepening of the fuel consumption, the guide tube bends, which leads to poor rod drop. At the same time, the improvement of nuclear safety requirements requ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): F16L55/027F16L57/02G21C3/32G21C3/33
CPCY02E30/30
Inventor 蒲曾坪焦拥军茹俊李庆朱发文陈平郑美银肖忠李云雷涛吕亮亮李垣明任全耀邱玺韩元吉
Owner NUCLEAR POWER INSTITUTE OF CHINA
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