Auxiliary centering device for reassembling main bolt of nuclear reactor pressure vessel

Abstract

The utility model discloses an auxiliary centering device for reassembly of a main bolt of a nuclear reactor pressure vessel, relates to the technical field of nuclear power overhaul, and is used for solving the problem that a stretcher is difficult to position during installation due to the fact that a long unthreaded hole section of a top cover and large axial displacement of the reassembled main bolt and the unthreaded hole section of the top cover are not considered in the existing reassembly overhaul process of the main bolt. The auxiliary centering device is of a hollow cylindrical boss structure and adopts stepped shaft section design, the inner diameter of the upper portion and the inner diameter of the lower portion of the auxiliary centering device are the same, the outer diameter of the upper portion is smaller than that of the lower portion of the auxiliary centering device, and a notch consistent with a boss of a top cover sealing face in radian is formed in the position, close to the boss of the top cover sealing face, of the auxiliary centering device. Holes for mounting handles are formed in the two sides of the lower part of the auxiliary centering device; the upper portion of the auxiliary centering device is installed at the bottom end of the unthreaded hole section of the top cover and fixed to the top cover through friction force. The device provides forced centering acting force for reinstallation of the main bolt, assists accurate centering of the main bolt, guarantees the reinstallation accuracy of the main bolt, and improves the working efficiency.

Description

TECHNICAL FIELD

[0001] The utility model belongs to nuclear power overhauls technical field, and specifically relates to a kind of nuclear reactor pressure vessel main bolt reinstallation auxiliary centering device. BACKGROUND

[0002] Certain nuclear reactor pressure vessel main sealing surface is arranged with several bolt holes, and top cover is arranged with several through holes.Pressure vessel and top cover are sealed by main sealing element, including main bolt, concave-convex gasket, nickel washer and the like.

[0003] Sealing work of reactor pressure vessel includes: main bolt is reinstalled to upper assembly in upper assembly inspection well, upper assembly is reinstalled, main bolt tensioner is installed on upper assembly, all main bolts are screwed in by tensioner, support leg is withdrawn after ring lifting tensioner is lifted again and then falls on upper assembly, pressure vessel main nut is screwed in and fastened to complete pressure vessel sealing work, and main bolt tensioner is lifted out.To improve work quality and efficiency, special tool main bolt tensioner is usually used for sealing, opening and closing cover operation of nuclear reactor pressure vessel.Tensioner needs to be dropped on top cover twice for the whole closing cover, so as to realize fast and accurate centering of tensioner on top cover, and the coaxiality of all main bolts and top cover light hole section must be ensured.

[0004] Existing main bolt reinstallation maintenance process does not consider axial movement of main bolt after reinstallation and light hole section of top cover, which leads to difficult positioning of tensioner during installation, greatly improves maintenance time and labor intensity of workers, delays critical path maintenance time, causes unnecessary dose irradiation and efficiency waste. UTILITY MODEL CONTENTS

[0005] The utility model aims at providing a kind of nuclear reactor pressure vessel main bolt reinstallation auxiliary centering device, to solve the problem that existing main bolt reinstallation maintenance process does not consider that light hole section of top cover is longer, and axial movement of main bolt after reinstallation and light hole section of top cover is larger, which leads to difficult positioning of tensioner during installation.

[0006] The utility model solves the technical problems by adopting the following technical scheme: a kind of nuclear reactor pressure vessel main bolt reinstallation auxiliary centering device, the auxiliary centering device is hollow cylindrical boss structure, adopts stepped shaft section design, the inner diameter of upper portion and lower portion of the device is same, the outer diameter of upper portion is less than the outer diameter of lower portion, the device has the notch consistent with the arc of top cover sealing surface boss at the position close to top cover sealing surface boss, and the hole for installing handle is designed on the two sides of lower portion of auxiliary centering device;Upper portion of auxiliary centering device is installed at the bottom end of light hole section of top cover, and is fixed on top cover by friction force.

[0007] The auxiliary centering device for the main bolt of the nuclear reactor pressure vessel is installed between the light hole section at the bottom of the upper assembly and the main bolt, and can give the main bolt a forced centering force from the radial direction when the main bolt is reinstalled, thereby assisting the accurate centering of the main bolt.

[0008] The auxiliary centering device for the main bolt of the nuclear reactor pressure vessel is installed between the light hole section at the bottom of the upper assembly and the main bolt, and can give the main bolt a forced centering force from the radial direction when the main bolt is reinstalled, thereby assisting the accurate centering of the main bolt.

[0009] The auxiliary centering device for the main bolt of the nuclear reactor pressure vessel is installed between the light hole section at the bottom of the upper assembly and the main bolt, and can give the main bolt a forced centering force from the radial direction when the main bolt is reinstalled, thereby assisting the accurate centering of the main bolt.

[0010] The auxiliary centering device for the main bolt of the nuclear reactor pressure vessel is installed between the light hole section at the bottom of the upper assembly and the main bolt, and can give the main bolt a forced centering force from the radial direction when the main bolt is reinstalled, thereby assisting the accurate centering of the main bolt.

[0011] The auxiliary centering device for the main bolt of the nuclear reactor pressure vessel is installed between the light hole section at the bottom of the upper assembly and the main bolt, and can give the main bolt a forced centering force from the radial direction when the main bolt is reinstalled, thereby assisting the accurate centering of the main bolt.

[0012] The auxiliary centering device for the main bolt of the nuclear reactor pressure vessel is installed between the light hole section at the bottom of the upper assembly and the main bolt, and can give the main bolt a forced centering force from the radial direction when the main bolt is reinstalled, thereby assisting the accurate centering of the main bolt.

[0013] Compared with the prior art, the auxiliary centering device for the main bolt of the nuclear reactor pressure vessel has the following beneficial effects: on the one hand, the device is used in the main bolt reinstallation process to assist the accurate centering of the main bolt, thereby avoiding the difficulty in positioning the main bolt stretcher when the upper assembly is reinstalled and the pressure vessel is sealed; on the other hand, the device is installed on the bolt hole of the upper assembly from the bottom of the upper assembly, thereby providing a forced centering effect for the main bolt reinstallation and ensuring the coaxiality of the main bolt and the bolt hole of the upper assembly; and the device is simple and easy to use, thereby reducing the physical consumption of the maintenance personnel and improving the work efficiency of the main bolt reinstallation. BRIEF DESCRIPTION OF DRAWINGS

[0014] Fig. 1 Fig. 1 is a front view of the auxiliary centering device for the main bolt of the nuclear reactor pressure vessel;

[0015] Fig. 2 Fig. 2 is a top view of the auxiliary centering device for the main bolt of the nuclear reactor pressure vessel;

[0016] Fig. 3 Fig. 3 is a handle of the auxiliary centering device for the main bolt of the nuclear reactor pressure vessel.

[0017] Explanation of reference numerals in the drawings: 1. auxiliary centering tool; 2. hole; 3. cutout; 4. handle. DETAILED DESCRIPTION

[0018] In order to solve the problem that the existing main bolt reinstallation maintenance process does not consider that the axial displacement of the main bolt after reinstallation is large due to the long light hole section of the top cover, and the positioning is difficult when the drawing frame is installed, the utility model provides a kind of auxiliary centering device for the main bolt reinstallation of nuclear reactor pressure vessel. As shown in the figure, the auxiliary centering device 1 is a hollow cylindrical boss structure, and a stepped shaft section is designed. The inner diameters of the upper and lower parts of the device are the same, the outer diameter of the upper part is smaller than that of the lower part, and the cutout 3 consistent with the curvature of the boss of the top cover sealing surface is provided at the position close to the boss of the top cover sealing surface of the device. The hole 2 for installing the handle 4 is designed on both sides of the lower part of the auxiliary centering device 1. The upper part of the auxiliary centering device 1 is installed at the bottom end of the light hole section of the top cover, and can be fixed on the top cover only by relying on the friction force. Figs. 1-3 The auxiliary centering device 1 is made of plastic material, and the material is preferably polytetrafluoroethylene, which has certain strength and does not damage the threads of the main bolt. The auxiliary centering device 1 is installed in the middle of the light hole section at the bottom of the top cover and the main bolt. The curvature of the cutout 3 at the position close to the boss of the top cover sealing surface is consistent with that of the boss of the top cover sealing surface, and the cutout is attached to the boss without covering the sealing surface, so it will not cause wear to the sealing surface of the top cover. By using the auxiliary centering device 1, a forced centering force can be applied to the main bolt in the radial direction during the reinstallation of the main bolt, which can assist the accurate centering of the main bolt and reduce the displacement of the main bolt in the light hole section of the top cover.

[0019] The handle 4 is installed in the hole 2 on both sides of the lower part of the auxiliary centering device 1. Before the main bolt enters the auxiliary centering device 1, the maintenance personnel only need to hold the auxiliary centering device 1 by the handle 4 to prevent it from falling. After the main bolt is completely in place, the maintenance personnel removes the auxiliary centering tool, observes from the bottom end of the top cover whether the main bolt is uniformly spaced around the light hole of the top cover, and whether the coaxiality is deviation-free. If there is no abnormality, the auxiliary centering tool is installed into the next light hole of the top cover. If there is still deviation, the main bolt is lifted out, the centering of the main bolt and the installation position of the auxiliary centering device 1 are adjusted again, and then the main bolt is lowered again until all the main bolts are reinstalled.

[0020] It should be noted that the combination mode of each technical feature in the embodiments of the utility model is not limited to the combination mode described in the embodiments of the utility model or the combination mode described in the specific embodiments. All technical features described in the utility model can be freely combined or combined in any mode, unless contradictory to each other.

[0021]

[0022] ​The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications or equivalent substitutions made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A device for auxiliary alignment of main bolts for reinstallation in a nuclear reactor pressure vessel, characterized in that, The auxiliary centering device (1) is a hollow cylindrical boss structure with a stepped shaft section design. The upper and lower inner diameters of the device are the same, and the outer diameter of the upper part is smaller than that of the lower part. The device has a cut (3) with the same curvature as the boss of the top cover sealing surface near the boss of the top cover sealing surface. Holes (2) for installing handles (4) are designed on both sides of the lower part of the auxiliary centering device (1). The upper part of the auxiliary centering device (1) is installed at the bottom end of the top cover smooth hole section and is fixed to the top cover by friction.

2. The auxiliary alignment device for reinstalling the main bolts of a nuclear reactor pressure vessel according to claim 1, characterized in that, The auxiliary centering device (1) is installed between the bottom light hole section of the top cover and the main bolt. When the main bolt is reinstalled, it provides a forced centering force to the main bolt from the radial direction to assist it in accurate centering.

3. The auxiliary alignment device for reinstalling the main bolts of a nuclear reactor pressure vessel according to claim 1, characterized in that, Before the main bolt enters the auxiliary centering device (1), the auxiliary centering device (1) is supported to prevent it from falling.

4. The auxiliary alignment device for reinstalling the main bolts of a nuclear reactor pressure vessel according to claim 3, characterized in that, The handle (4) is installed in the holes (2) on both sides of the lower part of the auxiliary centering device (1). During construction, the auxiliary centering device (1) is supported by the handle (4).

5. The auxiliary alignment device for reinstalling the main bolts of a nuclear reactor pressure vessel according to claim 1, characterized in that, Remove the auxiliary centering device (1) after the main bolt is fully in place.

6. The auxiliary alignment device for reinstalling the main bolts of a nuclear reactor pressure vessel according to claim 1, characterized in that, After the main bolt is installed using the auxiliary centering device (1), the gap between the main bolt and the top cover light hole is uniform and they are coaxial.

7. The auxiliary alignment device for reinstalling the main bolts of a nuclear reactor pressure vessel according to claim 1, characterized in that, The auxiliary centering device (1) is made of plastic.

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