Handling plug for spent fuel storage

Abstract

The present disclosure belongs to the technical field of nuclear power and particularly relates to a loading and unloading plug for spent fuel storage. The loading and unloading plug provided by the present disclosure adopts a split structure of a loading and unloading ring combined with an inner plug, the outer surface of the inner plug is continuously curved and gradually decreases in diameter from top to bottom, can form shielding for rays in multiple directions, and is beneficial to centering and guiding during hoisting of the inner plug, effectively reducing problems such as bumping; the stepped portion of the loading and unloading ring side wall protruding part pressing against the discharge port can not only play a supporting role for the loading and unloading ring, but also form effective radiation shielding for the gap between the loading and unloading ring and the discharge port, and the side wall of the loading and unloading ring combined with the first flange of the inner plug and the shielding ring can further form multidirectional radiation shielding for the gap between the loading and unloading ring and the discharge port and the gap between the inner plug and the loading and unloading ring, so as to control the radiation dose outside the loading and unloading plug within a safe range.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of nuclear power, and particularly relates to a loading and unloading plug for spent fuel storage. BACKGROUND

[0002] In the process of loading spent fuel of a heavy water reactor, if the fuel basket inside the storage cylinder is not filled, a suitable device is needed to replace the shielding plug of the storage cylinder to play a role of radiation shielding, and the smooth development of loading and unloading operation needs to be ensured. Due to the high radioactivity of spent fuel, the loading thereof needs to be performed remotely. During the lifting performed by a loading and unloading personnel operating a device such as a gantry crane, the personnel's line of sight is blocked or feedback is delayed, so that the related components cannot be completely in place, and the deviation of the centering will cause the plug body to collide with the storage cylinder, resulting in damage and further affecting the shielding effect of the storage cylinder. Therefore, how to ensure the safety of spent fuel loading and unloading and improve the efficiency of spent fuel loading and unloading has become a problem to be solved. SUMMARY

[0003] In order to overcome the problems in the related art, a loading and unloading plug for spent fuel storage is provided, which comprises a loading and unloading ring, an inner plug and a shielding ring.

[0004] The loading and unloading ring is a tubular structure, and the inner wall of the side wall of the loading and unloading ring has a first cavity. The first cavity is filled with shielding material to form a first ring body that fully covers the side wall of the loading and unloading ring. The inner wall of the discharge port of the top plate of the spent fuel storage module has a step portion extending radially inward in the circumferential direction. The outer side wall of the loading and unloading ring has a protruding portion extending radially outward at the upper end in the circumferential direction. The protruding portion is adapted to be clamped into the step portion and fully fit the surface of the step portion. The lower end of the side wall of the loading and unloading ring is pressed against the opening edge of the spent fuel storage cylinder.

[0005] The outer surface of the inner plug has a continuous curvature transition, and the diameter gradually decreases from top to bottom. The upper surface of the inner plug has a first flange extending radially outward in the circumferential direction at the intersection with the side wall. The shielding ring is an annular structure and is fixedly connected to the upper surface of the inner plug and fully covers the first flange. The materials of the inner plug and the shielding ring have the function of shielding radiation.

[0006] In the case of needing to store spent fuel, the inner plug is inserted into the loading and unloading ring, and the shielding ring, the first flange and the upper end of the loading and unloading ring are fixedly installed by a plurality of bolts. The outer wall of the inner plug and the inner wall of the loading and unloading ring form a gap therebetween, and the first flange and the shielding ring fully cover the upper end of the gap and the surface of the upper end of the loading and unloading ring. In the case of needing to load and unload spent fuel, the plurality of bolts fixedly installed at the upper end of the loading and unloading ring and the shielding ring are removed, the inner plug is lifted out, and the spent fuel unloading operation is performed.

[0007] In a possible implementation, the inner plug is divided into a first segment and a second segment, the first segment is a cylinder, and the second segment is an inverted circular truncated cone.

[0008] In a possible implementation, the outer diameter of the handling ring gradually decreases below the first flange.

[0009] In a possible implementation, the inner plug comprises a shell made of stainless steel, a plurality of welding studs are fixed to the inner wall of the shell, after the mesh steel bars are bound, the shell is filled with concrete, and a lifting ring is fixed to the top of the inner plug through a pre-embedded part, for lifting the inner plug.

[0010] In a possible implementation, a plurality of sub-shielding rings are fixed and stacked on the upper surface of the shielding ring in a direction from bottom to top, and the position of the gap between the inner plug and the handling plug is opposite to the middle line between the inner ring and the outer ring of the shielding ring.

[0011] In a possible implementation, the side wall of the protruding part of the handling ring has a second cavity, and the second cavity is filled with shielding material to form a second ring body covering the side wall of the protruding part.

[0012] In a possible implementation, the upper surface of the handling ring has a second flange extending in an oblique upward direction in a circumferential direction of the edge of the upper surface, and the second flange covers the upper part of the protruding part.

[0013] In a possible implementation, the gap is opposite to the middle line between the inner ring and the outer ring of the shielding ring.

[0014] In a possible implementation, the material of the shell of the inner plug is Q345R, the material of the shielding ring is carbon steel, and the materials of the first ring body and the second ring body are lead.

[0015] In a possible implementation, a plurality of through holes are formed in the upper end and the lower end of the side wall of the shielding ring and lead into the first cavity, lead is poured into the cavity from the through holes of the lower end until the cavity is filled, and each through hole is sealed after the lead solidifies.

[0016] The handling plug provided by the present disclosure has the following beneficial effects: the handling plug adopts the split structure of the handling ring and the inner plug, the outer surface of the inner plug has a continuous curvature transition, and the diameter gradually decreases from top to bottom, which can shield the rays in multiple directions and facilitate the centering and guiding of the inner plug during hoisting, thereby effectively reducing the problems such as bumping; the protruding part of the side wall of the handling ring is pressed against the stepped part of the discharge port, which can support the handling ring and effectively shield the gap between the handling ring and the discharge port; the side wall of the handling ring, in combination with the first flange of the inner plug and the shielding ring, can further shield the gap between the handling ring and the discharge port, the gap between the inner plug and the handling ring, and the rays in multiple directions, so that the radiation dose outside the handling plug is controlled within a safe range. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a sectional view of a detachable plug according to an embodiment of the present disclosure.

[0018] Figure 2 is a sectional view of a detachable ring according to an embodiment of the present disclosure.

[0019] Figure 3 is a sectional view of an inner plug according to an embodiment of the present disclosure.

[0020] Figure 4 is a sectional view of a shield ring according to an embodiment of the present disclosure.

[0021] Figure 5 is a partial sectional view of a shield ring according to an embodiment of the present disclosure.

[0022] In the drawings:

[0023] 1, shield ring; 2, inner plug; 3, detachable ring; 11, sub-shield ring; 21, lifting ring;

[0024] 22, first flange; 23, housing; 31, protruding portion; 32, first ring body; 33, second ring body;

[0025] 34, second flange. DETAILED DESCRIPTION

[0026] The present disclosure will be further described by way of example with reference to the accompanying drawings.

[0027] Unless otherwise defined, technical and scientific terms used in the present disclosure have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used in the disclosure herein was chosen to best describe the particular embodiment, and is not intended to limit the disclosure. The use of the terms "include," "includes" or "including" in this disclosure are meant to be non-limiting and thus should be interpreted as "comprising," "comprises" or "comprising."

[0028] Reference throughout this disclosure to "embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the disclosure. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive or alternative embodiments. It is expressly understood that the embodiments described herein are merely examples from a multitude of embodiments that are of the present disclosure. Numerous variations and modifications will occur to those in the art.

[0029] Figure 1 is a sectional view of a loading and unloading plug according to an embodiment of the present disclosure, as shown in Figure 1 The loading and unloading plug comprises a loading and unloading ring 3, an inner plug 2, and a shielding ring 1.

[0030] Figure 2 is a sectional view of a loading and unloading ring according to an embodiment of the present disclosure, as shown in Figure 1 and Figure 2 The loading and unloading ring 3 is a tubular structure; the inner side wall of the loading and unloading ring 3 has a first cavity, which is filled with shielding material to form a first ring body 32 that can fully cover the side wall of the loading and unloading ring 3; the inner wall of the discharge port of the top plate of the spent fuel storage module has a step portion extending radially inward in the circumferential direction; the outer side wall of the loading and unloading ring 3 has a protruding portion 31 extending radially outward in the circumferential direction at the upper end, which can be fitted into the step portion and fully fit the surface of the step portion; and the lower end of the side wall of the loading and unloading ring 3 is pressed against the opening edge of the spent fuel storage cylinder, so that when the loading and unloading ring is hoisted into the discharge port, the step portion can effectively support the shielding ring.

[0031] Figure 3 is a sectional view of an inner plug according to an embodiment of the present disclosure, as shown in Figure 3 The outer surface of the inner plug 2 has a continuous curvature transition, and the diameter gradually decreases from top to bottom; and the upper surface of the inner plug 2 has a first flange 22 extending radially outward in the circumferential direction at the intersection with the side wall.

[0032] Figure 4 is a sectional view of a shielding ring according to an embodiment of the present disclosure, as shown in Figure 1 and Figure 4 The shielding ring 1 is a ring structure, and is fixedly connected to the upper surface of the inner plug 2 to fully cover the first flange 22. For example, the position of the shielding ring 1 close to the inner ring is fixedly connected to the upper surface of the inner plug 2 by a plurality of expansion bolts, forming an integral whole with the inner plug 2. For example, the gap between the outer wall of the inner plug 2 and the inner wall of the loading and unloading ring 3 can be aligned with the center line between the inner ring and the outer ring of the shielding ring 1, so that the shielding ring 1 can more fully shield the gap.

[0033] In the case of need to store spent fuel, the inner plug 2 is inserted into the inside of the handling ring 3, the shielding ring 1, the first flange 22 and the upper end of the handling ring 3 are fixedly installed by a plurality of bolts (for example, the shielding ring 1, the first flange 22 and the upper end of the handling ring 3 are provided with a plurality of bolt holes which are opposite to each other, and each bolt is fixedly installed in a group of bolt holes, so as to fixedly install the shielding ring 1, the inner plug 2 and the handling ring 3); a gap is formed between the outer wall of the inner plug 2 and the inner wall of the handling ring 3 (for example, the length of the inner plug 2 is 1200mm, the gap is between 13mm and 114mm, and gradually increases from bottom to top); the first flange 22 and the shielding ring 1 fully cover the upper end of the gap and the surface of the upper end of the handling ring 3, and the materials of the inner plug 2 and the shielding ring 1 have the function of shielding radiation; thus, the gap between the inner plug 2 and the handling ring 3 is shielded.

[0034] In the case of need to handle spent fuel, the plurality of bolts installed on the shielding ring 1, the first flange 22 and the upper end of the handling ring 3 are removed, the inner plug 2 is lifted out, and the spent fuel handling operation is performed.

[0035] The handling plug provided by the present disclosure adopts the split structure of the handling ring combined with the inner plug, the outer surface of the inner plug is continuously and smoothly transitioned, and the diameter gradually decreases from top to bottom, which can shield the rays in multiple directions, and is beneficial to the centering and guiding of the inner plug during hoisting, and effectively reduces the problems such as bumping; the stepped portion of the discharge port is pressed against the protruding portion of the side wall of the handling ring, which can not only support the handling ring, but also effectively shield the radiation between the handling ring and the discharge port; the side wall of the handling ring, in combination with the first flange and the shielding ring of the inner plug, can further shield the radiation in multiple directions between the handling ring and the discharge port, and between the inner plug and the handling ring, so as to control the radiation dose outside the handling plug within a safe range.

[0036] In a possible implementation manner, as shown in Figure 3 The inner plug 2 includes a shell 23 made of stainless steel, a plurality of welding pins are fixedly installed on the inner wall of the shell 23, after the net-shaped steel bars are bound, the shell 23 is filled with concrete, and the top of the inner plug 2 is fixedly connected with a lifting ring 21 through a pre-embedded part, which is used for lifting the inner plug 2.

[0037] In a possible implementation manner, the inner plug 2 can be divided into a first segment and a second segment, the first segment is a cylinder, and the second segment is an inverted circular truncated cone. The outer diameter of the handling ring 3 gradually decreases below the first flange 22. In this way, the handling ring and the discharge port are centered and guided, and the handling ring is hoisted conveniently; in addition, the curvature change of the outer wall of the inner plug and the outer wall of the handling ring can shield the rays in multiple directions, and the protection effect is enhanced.

[0038] Figure 5is a partial sectional view of a shielding ring according to an embodiment of the present disclosure, see Figure 1 and Figure 5 The position of the upper surface of the shielding ring 1 facing the gap between the inner plug 2 and the removable plug is fixed from bottom to top by stacking multiple sub-shielding rings 11, thereby further strengthening the shielding of the gap between the inner plug 2 and the removable plug, wherein the multiple sub-shielding rings and the shielding ring can be fixedly connected by bolts. The detachable design of the shielding ring and the sub-shielding ring can increase or decrease the number of sub-shielding rings according to the actual radiation protection needs, thereby flexibly adapting to different radiation dose application scenarios.

[0039] In a possible implementation, as shown in Figure 2 The side wall of the protruding part 31 of the removable ring 3 has a second cavity, which is filled with shielding material to form a second ring body 33 covering the side wall of the protruding part 31. Thereby further enhancing the protection of the radiation of the gap between the discharge port step.

[0040] In a possible implementation, the upper surface of the removable ring 3 has a second flange 34 extending obliquely upward along the circumference of the edge, which covers the upper part of the protruding part 31, thereby further shielding the radiation escaping from the protruding part 31.

[0041] In a possible implementation, the material of the shell 23 of the inner plug 2 is Q345R, the material of the shielding ring 1 is carbon steel, and the materials of the first ring body 32 and the second ring body 33 are lead.

[0042] In a possible implementation, the upper end and the lower end of the side wall of the shielding ring 1 are respectively provided with multiple through holes leading into the first cavity, lead is poured into the cavity from the through holes of the lower end until the cavity is filled, the through holes of the upper end can function as exhaust, and after the lead solidifies, a sealing plate is used to plug each through hole, thereby effectively preventing the occurrence of pores and the like during the pouring of lead.

[0043] The above has described the embodiments of the present disclosure, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The choice of terms used herein is intended to best explain the principles, practical applications, or improvements to the technology in the market of the embodiments, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein.

Claims

1. A blind for spent fuel storage, characterized in that, The loading and unloading plug comprises a loading and unloading ring, an inner plug and a shielding ring. The loading and unloading ring is in a tubular structure; the inner wall of the side wall of the loading and unloading ring has a first cavity, the first cavity is filled with shielding material to form a first ring body covering the side wall of the loading and unloading ring; the inner wall of the top plate discharge port of the spent fuel storage module has a step portion extending radially inward in the circumferential direction, the outer side wall of the loading and unloading ring has a convex portion extending radially outward in the circumferential direction at the upper end, the convex portion is adapted to be clamped into the step portion and fully matched with the surface of the step portion, and the lower end of the side wall of the loading and unloading ring is pressed against the opening edge of the spent fuel storage cylinder. The outer surface of the inner plug is in a continuous curvature transition, and the diameter gradually decreases from top to bottom; the upper surface of the inner plug has a first flange extending radially outward in the circumferential direction at the junction with the side wall; the shielding ring is in a ring structure and is fixedly connected to the upper surface of the inner plug and fully covers the first flange; the materials of the inner plug and the shielding ring have the function of shielding radiation. In the case of needing to store spent fuel, the inner plug is inserted into the loading and unloading ring, the shielding ring, the first flange and the upper end of the loading and unloading ring are fixedly installed by a plurality of bolts; a gap is formed between the outer wall of the inner plug and the inner wall of the loading and unloading ring, the first flange and the shielding ring fully cover the upper end of the gap and the surface of the upper end of the loading and unloading ring; in the case of needing to load and unload spent fuel, the plurality of bolts for fixing the shielding ring, the first flange and the upper end of the loading and unloading ring are removed, the inner plug is hoisted out, and the spent fuel unloading operation is performed.

2. The access cap of claim 1, wherein The inner plug is divided into a first segment and a second segment, the first segment is a cylinder, and the second segment is an inverted circular truncated cone.

3. The access cap of claim 1, wherein, The outer diameter of the loading and unloading ring gradually decreases below the first flange.

4. The access cap of claim 1, wherein The inner plug comprises a shell made of stainless steel, a plurality of welding studs are fixedly arranged on the inner wall of the shell, after the net-shaped steel bars are bound, the shell is filled with concrete, and a lifting ring is fixedly connected to the top of the inner plug by a pre-embedded part for hoisting the inner plug.

5. The access cap of claim 1, wherein, A plurality of sub-shielding rings are fixedly stacked from bottom to top on the upper surface of the shielding ring opposite to the gap between the inner plug and the loading and unloading plug.

6. The access cap of claim 1, wherein, The convex portion of the loading and unloading ring has a second cavity in the side wall, the second cavity is filled with shielding material to form a second ring body covering the side wall of the convex portion.

7. The access cap of claim 1, wherein, The upper surface edge of the loading and unloading ring has a second flange extending in an obliquely upward direction in the circumferential direction, and the second flange covers the upper portion of the convex portion.

8. The access cap of claim 1, wherein, The gap is opposite to the center line between the inner ring and the outer ring of the shielding ring.

9. The access cap of claim 1, wherein, The material of the shell of the inner plug is Q345R, the material of the shielding ring is carbon steel, and the materials of the first ring body and the second ring body are lead.

10. The access cap of claim 1, wherein, A plurality of through holes are formed in the upper end and the lower end of the side wall of the shielding ring and lead into the first cavity, lead is poured into the cavity from the through holes in the lower end until the cavity is filled, and each through hole is sealed by a sealing plate after the lead solidifies.

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