A core guide column with switchable length

Abstract

The present invention provides a core guide column with switchable length, comprising: a guide column lower section with a connecting portion at its upper end; a short guide column detachable head section with a guide section and a guide positioning spring seat connected to each other; a guide positioning spring seat with a load-bearing connecting screw, a spring pressure plate, and a return spring provided therein; the load-bearing connecting screw is used to connect the connecting section; the return spring elastically pushes the spring pressure plate upward to move the load-bearing connecting screw upward; and a long guide column detachable head section with the guide section and the guide positioning spring seat, with a middle extension rod provided between the guide section and the guide positioning spring seat. The core guide column with switchable length provided by the present invention can optimize the mainline construction period, reduce the lifting work when the core is exposed, and reduce the radiation dose to personnel.

Description

Technical Field

[0001] The present invention relates to the technical field of core guide columns, and in particular to a core guide column with switchable length. Background Art

[0002] The core of a pressurized water reactor (PWR) nuclear reactor consists of the pressure vessel body and upper and lower internals. During refueling overhauls, the reactor pressure vessel head and internals must be hoisted. Three guide posts are used to guide and position the core components during hoisting. These posts, serving as guidance tools, are non-permanent components of the core. When not in use, they are stored on a rack within the refueling pool. When in use, they are hoisted using a ring crane and installed in corresponding bolt holes on the pressure vessel flange. The core guide posts are responsible for guiding and positioning the core components during hoisting.

[0003] Currently, the core is equipped with two types of guide columns, each suitable for lifting different components and operating conditions. The short guide column is 5.5 meters long and weighs 390 kg. It is used to lift the top cover, upper reactor internals, and sealing surface protection rings. The long guide column is 9.4 meters long and weighs 650 kg. It is used to lift lower reactor internals.

[0004] During the unit's ten-year overhaul, the lower reactor internals needed to be lifted out after unloading. This required installing a dedicated mainline window after the main cover was opened, replacing the short guide posts with long ones. The entire guide post replacement process took 6.5 hours of the mainline overhaul. Summary of the Invention

[0005] The present invention aims to provide a core guide column with switchable lengths, solving the problem of switching between long and short guide columns over long distances. This invention optimizes the mainline overhaul schedule and process flow, reduces lifting work during core exposure, and reduces radiation dose to personnel. Switching between short and long guide columns does not occupy the mainline window, allowing it to be performed simultaneously with other tasks without requiring separate mainline time allocation.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A core guide column with switchable length, comprising:

[0008] The lower section of the guide column has a connecting portion at its upper end; the short guide column has a detachable head, which has a guide section and a guide positioning spring seat connected up and down. The guide positioning spring seat is provided with a load-bearing connecting screw, a spring pressure plate and a return spring. The load-bearing connecting screw is used to connect the connecting portion, and the return spring elastically pushes the spring pressure plate upward to move the load-bearing connecting screw upward.

[0009] The long guide column has a detachable head, which is provided with the guide section and the guide positioning spring seat, and a middle extension rod is provided between the guide section and the guide positioning spring seat.

[0010] As an implementable manner, the connecting portion is a fastening bolt hole, and the fastening bolt hole is cooperatively connected with the lower end of the load-bearing connecting screw.

[0011] As an implementable manner, the upper end of the lower section of the guide post has a tapered guide hole, and the tapered guide hole is adapted to the lower end tapered head of the detachable head of the short guide post or the detachable head of the long guide post.

[0012] As an implementable manner, a positioning groove is provided at the upper end of the lower section of the guide post, and the positioning groove is adapted to the circumferential positioning block protruding from the lower end of the detachable head of the short guide post or the detachable head of the long guide post.

[0013] As an practicable manner, the number of the positioning grooves is 2, which are arranged at 180°.

[0014] As an practicable manner, a cone head lifting lug is provided on the guide section.

[0015] As an practicable manner, the guide segment and the guide positioning spring seat are fixedly connected by connecting bolts.

[0016] As an practicable manner, the number of the connecting bolts is 4.

[0017] As an implementable manner, a positioning plate is provided on the load-bearing connecting screw, and the positioning plate is provided above the spring pressure plate. The spring pressure plate pushes the positioning plate upward to enable the load-bearing connecting screw to move upward.

[0018] As an practicable manner, the lower end of the load-bearing connecting screw has an external thread.

[0019] Compared with the prior art, the core guide column with switchable length provided by the present invention has the following beneficial effects:

[0020] The present invention enables rapid switching between short and long guide posts, eliminating the need for dedicated mainline windows to replace short guide posts with long ones. Switching from short to long guide posts takes only 0.5 hours, and can be completed during the core water filling process, eliminating the need for separate mainline time. This represents a significant advantage over the previous 6.5-hour timeframe, optimizing existing operating procedures and methods. The present invention optimizes mainline construction timelines, reduces lifting operations during core exposure, and reduces radiation dose to personnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 A schematic diagram of the short guide column structure provided by an embodiment of the present invention;

[0023] Figure 2 A schematic diagram of the lower section structure of a guide post provided in an embodiment of the present invention;

[0024] Figure 3 A schematic diagram of the installation of a detachable head portion of a short guide post provided in an embodiment of the present invention;

[0025] Figure 4 A schematic diagram of the detachable head structure of a short guide post provided in an embodiment of the present invention;

[0026] Figure 5 A schematic diagram of the structure of a long guide column provided in an embodiment of the present invention;

[0027] Figure 6 This is a schematic diagram of the detachable head structure of a long guide column provided by an embodiment of the present invention.

[0028] Description of reference numerals:

[0029] 1. Lower section of guide column; 21. Conical head lifting lug; 22. Guide section; 23. Load-bearing connecting screw; 24. Connecting bolt; 25. Guide positioning spring seat; 26. Spring pressure plate; 27. Return spring; 3. Removable head of long guide column; 31. Middle extension rod. DETAILED DESCRIPTION

[0030] The following is further explained in detail through specific implementation methods.

[0031] like Figures 1 to 6 As shown, the present invention provides a core guide post with switchable length, comprising a guide post lower section 1, a short guide post detachable head 2, and a long guide post detachable head 3.

[0032] The lower end of the guide post lower section 1 is mounted in the reactor pressure vessel bolt hole, and the upper end has a tapered guide hole 11, a positioning groove 12, and a fastening bolt hole 13. The tapered guide hole 11 mates with the tapered head at the lower end of the short guide post's detachable head 2, the positioning groove 12 mates with the raised circumferential positioning block at the lower end of the short guide post's detachable head 2, and the fastening bolt hole 13 mates with the load-bearing connecting screw 23 of the short guide post's detachable head 2.

[0033] The short guide column detachable head 2 and the long guide column detachable head 3 have the same structure but different lengths. The internal hollow conical head ear 21 is threadedly connected to the guide section 22, and then the guide section 22 and the guide positioning spring seat 25 are connected together by four connecting bolts 24. A return spring 27, a spring guide rod, and a spring pressure plate 26 are installed inside the guide positioning spring seat 25. The spring pressure plate 26 presses on the return spring 27 and is installed inside the guide positioning spring seat 25. The load-bearing connecting screw 23 is installed in the hollow interior of the guide section 22 and the guide positioning spring seat 25, wherein the positioning plate on the load-bearing connecting screw 23 is installed above the spring pressure plate 26. The load-bearing connecting screw 23 can perform reciprocating motion in the hollow axial direction to compress the return spring 27.

[0034] When the long guide column detachable head 3 or the short guide column detachable head 2 is not installed on the guide column lower section 1, the return spring 27 lifts the spring pressure plate 26, causing the load-bearing connecting screw 23 to move upward and retract the bolt into the guide positioning spring seat 25.

[0035] The structure of the detachable head portion 3 of the long guide post is basically the same as that of the detachable head portion 2 of the short guide post, except that it has an additional middle extension rod 31 which is a hollow tube structure and is used to extend the length of the guide post.

[0036] To install the detachable head 2 of the short guide post, use a dedicated operating tool to hoist the detachable head 2 onto the top of the guide post lower section 1. Ensure that the boss on the detachable head 2 fits correctly with the groove (i.e., the positioning groove 12) of the guide post lower section 1. Use another dedicated rotating operating tool to insert the square head above the load-bearing connecting screw 23 in the detachable head 2 of the short guide post. Press down to overcome the spring force of the return spring 27 and rotate the tool to screw the thread below the load-bearing connecting screw 23 into the threaded hole of the guide post lower section 1. Once the thread is fully rotated, the detachable head 2 of the short guide post and the guide post lower section 1 form a short guide post.

[0037] Similarly, the long guide column is installed in the same way as the short guide column.

[0038] When switching between short and long guide columns, first use a special operating tool to connect the detachable head 2 of the short guide column. After tightening the sling, use another special rotating operating tool to insert it into the square head above the load-bearing connecting screw 23 in the detachable head 2 of the short guide column, rotate and loosen the load-bearing connecting screw 23 to release the threaded connection with the lower section 1 of the guide column. After the load-bearing connecting screw 23 is released, the upward force of the reset spring 27 and the spring pressure plate 26 causes the thread below the load-bearing connecting screw 23 to retract back into the guide positioning spring seat 25. Then use a special operating tool to lift the detachable head 2 of the short guide column from the lower section 1 of the guide column. Then use another special operating tool to connect it to the detachable head 3 of the long guide column, lift it above the lower section 1 of the guide column, and make sure that the boss below the detachable head 3 of the long guide column and the groove above the lower section 1 of the guide column are in place. The installation method of the detachable head 3 of the long guide column is the same as that of the detachable head 2 of the short guide column, so it will not be described in detail here.

[0039] This invention utilizes an integrated, "switchy" core guide post. This eliminates the need for dedicated mainline windows to switch from short to long guide posts. Switching from a short guide post to a long one takes only 0.5 hours, and can be completed during the core water filling process, eliminating the need for separate mainline time. The guide post itself does not need to be disassembled. Operators simply use specialized tools on the auxiliary bridge above the water tank to replace the guide post's removable joint. Switching from the short joint to the long joint completes the short-to-long switch.

[0040] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention are intended to be covered by the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope of protection of the claims.

Claims

1. A core guide column with switchable length, characterized in that: include: The lower section (1) of the guide column has a tapered guide hole (11), a positioning groove (12), and a fastening bolt hole (13) at its upper end, wherein the fastening bolt hole (13) serves as a connecting portion; A short guide column detachable head (2) has a guide section (22) and a guide positioning spring seat (25) connected to each other, wherein a load-bearing connecting screw (23), a spring pressure plate (26) and a return spring (27) are provided in the guide positioning spring seat (25), wherein the load-bearing connecting screw (23) is used to connect the connecting portion, and the return spring (27) elastically pushes the spring pressure plate (26) upward to move the load-bearing connecting screw (23) upward; A long guide column detachable head (3) has the guide section (22) and the guide positioning spring seat (25), and a middle extension rod (31) is provided between the guide section (22) and the guide positioning spring seat (25); The conical guide hole (11) cooperates with the lower end cone head of the short guide column detachable head (2) or the long guide column detachable head (3), the fastening bolt hole (13) cooperates with the load-bearing connecting screw (23), and the positioning groove (12) is adapted to the circumferential positioning block protruding from the lower end of the short guide column detachable head (2) or the long guide column detachable head (3).

2. The core guide column with switchable length according to claim 1, characterized in that: The number of the positioning grooves (12) is 2, and they are arranged at 180 degrees.

3. The core guide column with switchable length according to claim 1, characterized in that: The guide section (22) is provided with a cone head lifting lug (21).

4. The core guide column with switchable length according to claim 1, characterized in that: The guide section (22) and the guide positioning spring seat (25) are fixedly connected via a connecting bolt (24).

5. The core guide column with switchable length according to claim 4, characterized in that: The number of the connecting bolts (24) is 4.

6. The core guide column with switchable length according to claim 1, characterized in that: A positioning plate is provided on the load-bearing connecting screw (23), and the positioning plate is provided above the spring pressure plate (26). The return spring (27) lifts the spring pressure plate (26) to move the load-bearing connecting screw (23) upward.

7. The core guide column with switchable length according to claim 1, characterized in that: The lower end of the load-bearing connecting screw (23) has an external thread.

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