Heavy water reactor spent fuel transport basket

Abstract

This invention relates to a heavy water reactor spent fuel transport basket, and more specifically, to a heavy water reactor spent fuel transport basket for transporting a predetermined amount of spent fuel required only for integrity testing, which minimizes the containment space and maximizes the thickness, thereby reducing the burden on test personnel in handling spent fuel. To this end, the invention provides a heavy water reactor spent fuel transport basket, characterized by comprising: a basket body forming a containment space and having an internal support dividing the containment space; a fuel bag disposed on one side of each containment space divided by the internal support, configured to rotate to the other side of the containment space, and forming an upward-opening disassembly groove to allow the fuel box containing spent fuel to be disassembled; and a cover for opening and closing the containment space of the basket body and being threadedly connected to the basket body.

Description

Technical Field

[0001] This invention relates to a spent fuel transport basket for heavy water reactors, and more specifically, to a spent fuel transport basket for heavy water reactors that can safely handle small amounts of spent fuel in an experimental facility for soundness evaluation. Background Technology

[0002] Generally, spent fuel refers to nuclear fuel material used as fuel in nuclear reactors or nuclear fuel material that has undergone nuclear fission through other methods. Compared to low- and intermediate-level radioactive waste generated from items such as gloves and clothing worn by nuclear power plant workers, it is considered high-level radioactive waste. Although this type of spent fuel appears identical to the nuclear fuel before use, it becomes highly radioactive due to the fission products produced during the nuclear fission reaction in the reactor. Therefore, it continues to generate heat even after the fission reaction ends. Thus, direct contact with humans is strictly prohibited during handling or storage of this type of spent fuel; it must be handled outside of radiation-shielding structures. Before being disposed of in an underground landfill, this spent fuel is stored in specially designed storage containers. First, the spent fuel is stored in a wet storage facility (SFB: Spent Fuel Bay) inside a building and cooled for an extended period. Only spent fuel cooled in the wet storage facility for more than six years and exhibiting minimal decay heat is transported and stored in a dry storage facility (SFDSF: Spent Fuel Dry Storage Facility) outside the building. At this point, if... Figure 1a As shown, spent fuel is transferred to stainless steel storage baskets (FBs) via a water-based process within the wet storage facility. Each FB, containing 60 bundles of spent fuel (FA), is then transferred to a shielded work station (SWS) located above the wet storage facility for hot air drying. After drying, the FB lids are closed and sealed remotely. The sealed FBs are then inserted into fuel transport baskets (FBTFs) and transported to the dry storage facility for storage.

[0003] In addition, in order to conduct a soundness assessment of continuous storage, spent fuel stored in the dry storage facility of the nuclear power plant as described above is placed into... Figure 1bThe transport container (CV) shown is transported to experimental facilities such as the Korea Atomic Energy Research Institute (KAERI) for integrity testing. Afterwards, operators extract storage baskets (FBs) from the transport container (CV) at the experimental facilities. The sealed welded storage baskets (FBs) are cut to extract one or two spent fuel bundles (FAs) for integrity evaluation, which are then transported to external research institutions. Specifically, operators transport the storage baskets (FBs) stored in dry storage facilities to wet storage facilities. After cutting the storage baskets in the storage tanks of the wet storage facilities, spent fuel bundles (FAs) are extracted from the cut baskets, or spent fuel (FAs) are individually removed from the extracted spent fuel bundles. The extracted spent fuel bundles or individual spent fuel rods are then transported as follows: Figure 1a The contents were transferred to an empty storage basket, which was then sealed and welded shut. Afterwards, the operator... Figure 1a The storage basket (FB) shown is filled with Figure 1b The equipment was transported to the experimental facility in the transport container (CV) shown.

[0004] However, transporting spent fuel stored in the aforementioned storage baskets to the experimental facility presents a series of complex and time-consuming processes, resulting in low efficiency. In particular, because the storage baskets (FB) need to accommodate 60 spent fuel bundles, they are made of thin metal sheets to ensure sufficient space, while the transport container (CV) is made of thick metal sheets to compensate for the thickness of the storage baskets. This makes it difficult for experimental facility operators to handle the storage baskets (FB) retrieved from the transport container (CV). In other words, during the process of cutting conventional storage baskets (FB) to extract spent fuel (FA), the experimental facility's processing facilities are less sophisticated than those of a nuclear power plant, making operations such as cutting the storage baskets difficult. Furthermore, because experimental facility operators must be in direct contact with the storage baskets (FB), they are concerned about radiation exposure from the thin-sheet construction of the baskets.

[0005] [Existing technical documents]

[0006] [Patent Document] Korean Patent No. 10-1169612

[0007] Disclosed technical issues

[0008] This invention addresses the aforementioned problems. The objective of this invention is to provide a spent fuel transport basket for heavy water reactors that minimizes the space required to contain the spent fuel, thereby maximizing the thickness of the basket body and the cover. This also reduces the manpower burden on experimental facilities, and the basket body and cover are threaded together to improve the operability of spent fuel extraction operations.

[0009] To achieve the above objectives, the present invention provides a spent fuel transport basket for heavy water reactors, comprising: a basket body forming a receiving space and having an internal support that divides the receiving space; a fuel bag disposed on one side of each receiving space divided by the internal support and configured to rotate to the other side of the receiving space, and having an upwardly opening disassembly groove to allow the fuel box containing spent fuel to be disassembled; and a cover that opens and closes the receiving space of the basket body and is threadedly connected to the basket body.

[0010] At this time, a central through hole is formed on the cover, and a hollow central column is provided on the internal support, which is exposed to the outside of the cover through the central through hole. The central column opens inward through the central through hole, and an exhaust hole is formed around the central column to allow the receiving space and the interior of the central column to communicate.

[0011] Multiple threaded grooves are formed on the upper edge of the basket body, and fastening holes for fastening to the threaded grooves are formed on the cover body. The fastening holes are arc-shaped elongated holes formed along the circumferential direction of the cover body.

[0012] In addition, a support is provided in the containing space to tilt and support the fuel bag in the direction of rotation of the fuel bag.

[0013] Additionally, it includes a shielding adapter having a mounting groove and a base, wherein the mounting groove has an inner diameter corresponding to the outer diameter of the basket body, the base allows the mounting groove to be separated from the ground, and the cover and the shielding adapter can be threaded together.

[0014] Additionally, the fuel cartridge includes a guide that forms a partitioned space divided into multiple spaces for the storage of spent fuel, and the fuel cartridge is configured to accommodate rod-shaped spent fuel.

[0015] Additionally, the internal support is formed in a stepped shape downwards along the depth direction of the accommodating space. The cover includes a fastener that is threadedly connected to the edge of the basket body; and a close-fitting protrusion that is set corresponding to the inner diameter of the accommodating space of the basket body, protruding downwards from the center of the cover and closely fitting the internal support, and forming the central through hole so that the central post can be inserted into the central through hole.

[0016] Beneficial effects

[0017] The heavy water reactor spent fuel transport basket according to the present invention has the following effects.

[0018] First, the heavy water reactor spent fuel transport basket has a reduced space to minimize the amount of spent fuel required for integrity testing, thus maximizing the thickness of the basket body and cover. In other words, since integrity testing only requires a predetermined amount of spent fuel, the storage space for transporting the basket body to the experimental facility is rationally achieved. Therefore, according to the present invention, due to the reduced storage space, the basket body and cover can be correspondingly maximized, thereby minimizing radiation risk and reducing the burden on test personnel in handling spent fuel, even in experimental facilities with less sophisticated processing facilities compared to power plants.

[0019] Secondly, the present invention can maximize the thickness of the basket body and the cover, thereby providing a screw-fastening structure instead of a welded seal, thus having the effect of making it easy to remove spent fuel from the basket body.

[0020] Third, the present invention provides a screw fastening structure between the cover and the basket body, but by setting the fastening hole formed on the cover as an elongated hole, it has the effect of increasing the convenience of adjusting the screw fastening position.

[0021] Fourth, in this invention, the central column disposed in the center of the basket body is made of a hollow tube, and an exhaust hole communicating with the accommodating space of the basket body is formed on the central column, thereby achieving the effect of drying the accommodating space outside the basket body even when the accommodating space of the basket body is not open.

[0022] Fifth, the present invention provides a guide that divides the fuel box into multiple partitioned spaces to store individual spent nuclear fuel rods, thereby enabling not only the storage of a batch of spent fuel rods, but also the efficient storage of individual spent fuel rods in a non-flowing manner. Attached Figure Description

[0023] Figure 1a This is a schematic diagram of a storage basket filled with spent fuel bundles, showing a partial cross-sectional view of the storage basket in the state of being filled with spent fuel bundles to be tested.

[0024] Figure 1b This is a schematic diagram of a transport container used to transport storage baskets filled with spent fuel bundles.

[0025] Figure 2 This is an exploded perspective view of a spent fuel transport basket of a heavy water reactor according to a preferred embodiment of the present invention.

[0026] Figure 3 This is a perspective view of a spent fuel transport basket for a heavy water reactor according to a preferred embodiment of the present invention.

[0027] Figure 4 This is a cross-sectional view of a spent fuel transport basket for a heavy water reactor according to a preferred embodiment of the present invention.

[0028] Figure 5 This is a perspective view of the basket body of a spent fuel transport basket for a heavy water reactor according to a preferred embodiment of the present invention.

[0029] Figure 6 This is a plan view of the basket body of a spent fuel transport basket for a heavy water reactor according to a preferred embodiment of the present invention.

[0030] Figure 7 It is along Figure 6 The cross-sectional view shown by line II.

[0031] Figure 8 This is a side view of the fuel box being inserted into the fuel bag of the heavy water reactor spent fuel transport basket according to a preferred embodiment of the present invention and supported by a bracket.

[0032] Figure 9 This is a side view of the fuel bag of a spent fuel transport basket for a heavy water reactor according to a preferred embodiment of the present invention, showing the bag vertically upright relative to the support under the influence of gravity.

[0033] Figure 10 This is a perspective view of the bracket connecting the spent fuel transport basket of a heavy water reactor to its axis, according to a preferred embodiment of the present invention.

[0034] Figure 11 This is a plan view showing the cover of a spent fuel transport basket for a heavy water reactor according to a preferred embodiment of the present invention.

[0035] Figure 12 This is a cross-sectional view showing the cover of a spent fuel transport basket for a heavy water reactor according to a preferred embodiment of the present invention.

[0036] Figure 13 This is a perspective view showing the shielding adapter of a spent fuel transport basket for a heavy water reactor according to a preferred embodiment of the present invention.

[0037] Figure 14 This is a cross-sectional view showing the shielding adapter of the spent fuel transport basket of a heavy water reactor according to a preferred embodiment of the present invention.

[0038] Figure 15 This is a perspective view showing the guide of a spent fuel transport basket for a heavy water reactor according to a preferred embodiment of the present invention.

[0039] Figure 16 This is a perspective view showing the state in which the guide of the spent fuel transport basket of a heavy water reactor is inserted into the fuel box according to a preferred embodiment of the present invention.

[0040] Figure 17This is a cross-sectional view showing the state in which the heavy water reactor spent fuel transport basket is housed in a transport container according to a preferred embodiment of the present invention. Detailed Implementation

[0041] The terms or words used in this specification and claims are not limited to their usual or dictionary meanings. Based on the principle that inventors may appropriately define terms and concepts to best express their inventive ideas, these terms should be interpreted as meanings and concepts consistent with the inventive ideas.

[0042] Below, please refer to the appendix. Figures 2 to 17 The present invention will describe a heavy water reactor spent fuel transport basket (hereinafter referred to as "transport basket") according to a preferred embodiment of the present invention.

[0043] As a device for transporting spent fuel to the test facility, the transport basket has its capacity reduced to only hold the predetermined amount of spent fuel required for the integrity test due to the characteristics of the test facility. However, as the capacity is reduced, the thickness is maximized, which reduces the burden of handling spent fuel even if the test facility does not have the same specialized handling equipment as the power plant.

[0044] like Figures 2 to 5 As shown, the transport basket includes a basket body 100, a fuel bag 200, a cover 300, and a shielding adapter 400.

[0045] The basket body 100 is configured to accommodate a fuel cartridge 500 and forms a receiving space 110 for accommodating the fuel cartridge 500, wherein the fuel cartridge 500 contains spent fuel (FA) intended for integrity evaluation. The basket body 100 is preferably circular, and as shown... Figure 2As shown, multiple threaded grooves 120 are formed at the upper edge. The threaded grooves 120 are configured to thread into the cover 300, which will be described later. The basket body 100 is configured to minimize the size of the receiving space 110 while maximizing the thickness of the basket body 100. That is, the receiving space 110 of the basket body 100 is only necessary to accommodate the predetermined spent fuel FA as the object of the integrity test, so the size of the receiving space 110 does not need to be too large, thereby maximizing the thickness of the basket body 100 by reducing the size of the receiving space 110. At this time, the receiving space 110 is preferably divided by an internal support 130. The receiving space 110 is divided into two sides based on the internal support 130, and each of the divided receiving spaces 110 accommodates one fuel box 500. The internal support 130 is preferably formed in a stepped position from the upper edge of the basket body 100 downwards. An internal support frame 130 is fitted with a central column 140, which is configured to connect to the lifting equipment of a power plant and, in this invention, is also configured to supply hot air to the storage space 110 of the basket body 100 for drying. The central column 140 is located at the center of the internal support frame 130, as... Figure 4 As shown, it has the form of a hollow tube that opens upwards. Multiple vent holes 141 are formed on the central column 140. With the configuration described above, hot air can flow in through the upper part of the central column 140 and be discharged to the receiving space 110 through the vent holes 141, thus allowing the receiving space 110 to be dried even when it is shielded by the cover 300. Additionally, a drain hole 150 is formed at the bottom of the basket body 100.

[0046] Fuel bag 200 is an intermediate device for housing fuel box 500 in housing space 110, such as Figure 5 and 6 As shown, the fuel bag 200 is provided on both sides of the receiving space 110 relative to the internal support 130. The fuel bag 200 is provided with a removal slot 210 for removing the fuel box 500, and the removal slot 210 opens towards the upper side of the fuel bag 200. (See attached image) Figure 4 , Figures 8 to 10 As shown, the fuel bag 200 is hinged to allow rotation within the receiving space 110. As described above, only a predetermined amount of spent fuel FA is stored in the basket body 100, allowing the overall thickness of the basket body 100 to be increased accordingly. Therefore, the size of the receiving space 110 is reduced, and the efficiency of the receiving space 110 is improved because the fuel box 500 is tilted into the receiving space 110. Figure 8 and Figure 9As shown, the fuel bag 200 is axially connected to the bracket 220, and a weight 230 can be placed on one side of the bottom of the fuel bag 200. The weight 230 is positioned biased towards one side of the fuel bag 200 so that the fuel bag 200 can always be upright relative to the bracket 220. Because of the weight 230, the fuel bag 200 is always upright, and therefore the disassembly slot is always facing upwards. Therefore, the operator can easily insert the fuel box 500 into the fuel bag 200. At this time, as... Figure 10 As shown, a stop 221 can be installed on the bracket 220. The stop 221 is configured to limit excessive rotation of the fuel bag 200 during the process of the fuel bag 200 being erected by the weight 230, thereby maintaining the vertical angle of the fuel bag 200. That is, during the vertical rotation of the fuel bag 200, as... Figure 9 As shown, due to the interference between the weight and the stop 221, the fuel bag 200 can always remain vertical. On the other hand, as described above, the fuel bag 200 houses the fuel box 500, and when the fuel box 500 is housed in the disassembly slot 210, as... Figure 8 As shown, the fuel bag 200 rotates automatically due to the weight of the fuel box 500. At this time, a support S is provided on one side of the fuel bag 200 to support the fuel box 500 housed within it. The support S has a support groove with a curvature corresponding to the curvature of the fuel box 500. Additionally, as... Figure 5 and Figure 6 As shown, preferably, each fuel bag 200 is configured to rotate in opposite directions to each other on one side and the other side of the receiving space 110, but each fuel bag 200 may also be configured to rotate in the same direction to each other.

[0047] like Figure 3 and Figure 4 As shown, the cover 300 is used to open and close the receiving space 110 of the basket body 100 and is detachable from the shielding adapter 400. Figure 11 As shown, the cover 300 is circular, and its diameter corresponds to the diameter of the shielding adapter 400. The cover 300 includes a flange 310 fastened to the basket body 100 and the shielding adapter 400, and as shown... Figure 12 The closely spaced protrusion 320 shown protrudes downward from the center of the flange 310. For example... Figure 11As shown, flange 310 forms fastening holes 311 and a central through hole 312. Fastening holes 311 are for fastening bolts to pass through and be screwed into threaded grooves formed on the basket body 100 and the shielding adapter 400 (described later), including a first fastening hole 311a corresponding to the threaded groove 120 of the basket body 100 and a second fastening hole 311b corresponding to the threaded groove of the shielding adapter 400. Fastening holes 311 are made of elongated holes and are formed in an arc shape with curvature in the circumferential direction of the cover 300. Therefore, when fastening the cover 300, the fastening holes 311 can easily correspond to the positions of the threaded grooves formed on the basket body 100 and the shielding adapter 400, respectively, thereby improving the operator's ease of use. Additionally, as... Figure 12 As shown, a central through-hole 312 is formed through the closely spaced protrusion 320. The central through-hole 312 corresponds to the aforementioned central post 140 and allows the central post 140 to be inserted. That is, the internal conduit of the central post 140 can be exposed to the outside of the basket body 100 through the central through-hole 312. In addition, the flange 310 is formed with a plurality of lifting bolt holes 313.

[0048] The shielding adapter 400 is provided with a mounting slot 400a, which is used to receive the basket body 100 and is accommodated within it. Figure 2 The spent fuel (FA) is transported to the experimental facility in the transport container (CV) shown. The shielding adapter 400, together with the basket body 100, can shield the spent fuel (FA) from radiation and heat emitted, thus allowing for safe transport of the spent fuel (FA) and minimizing the burden on personnel handling the spent fuel, even in experimental facilities with inadequate processing equipment. Preferably, the shielding adapter 400 is configured such that the thickness of the shielding adapter 400 plus the thickness of the basket body 100 corresponds to the thickness of the transport container (CV). Figure 13 As shown, the shielding adapter 400 has multiple threaded grooves 410 formed along its upper edge, the threaded grooves 410 corresponding to the second fastening hole 311b. The shielding adapter 400 has lifting bolt holes 420 formed around its perimeter for hoisting, and also has... Figure 14 The drain hole 430 is shown. (As shown) Figure 4 As shown, the drain hole 430 is used to drain water discharged from the drain hole 430 of the basket body 100 to the outside of the shield adapter 400. Additionally, the shield adapter 400 is transported to the experimental facility via a transport container (CV) as described above, and is manufactured to match the internal space of a standard-sized transport container (CV). For this purpose, the shield adapter 400 is provided with a downwardly extending base 440 and a circumferentially extending extension piece 450.

[0049] Additionally, the fuel cartridge 500 may further include a guide 510, configured to receive the spent fuel (FA) to be tested, such as... Figure 15As shown, the guide member 510 has multiple partitioned spaces 511. By forming the partitioned spaces 511, the guide member 510 can accommodate rod-shaped spent fuel (FA) within the fuel cartridge 500. That is, as... Figure 16 As shown, the guide 510 is detachably connected to the fuel cartridge 500 and can accommodate a single spent fuel (FA) rod. The partition space 511 can be configured in a grid shape, but its shape is not limited. Additionally, a drain hole 512 is formed at the bottom of the fuel cartridge 500.

[0050] The process of using the transport basket constructed with the above structure to hold spent fuel, which is the subject of a soundness test evaluation, is described below.

[0051] Power plant operators retrieve storage baskets (FB) from the dry storage facility, cut them in the spent fuel tank of the wet storage facility, and then remove spent fuel (FA) from the storage baskets (FB). Subsequently, as... Figure 2 and Figure 5 As shown, the operator collects the spent fuel into the fuel box 500 and installs the fuel box 500 containing the spent fuel into the fuel bag 200. Figure 9 As shown, the fuel bag 200 is initially positioned vertically in the storage space 110 by a weight 230. The operator inserts the fuel cartridge 500 into the disassembly slot 210 of the fuel bag 200. Because the fuel cartridge 500 is heavier than the weight 230, the fuel bag 200 loses its center of gravity on the bracket 220. Figure 4 , Figure 6 , Figure 8 As shown, the container is rotated and tilted from one side of the storage space 110 to the other. At this time, the fuel box 500 is supported by the bracket (S). Then, the operator aligns the first fastening hole 311a of the cover 300 with the threaded groove 120 of the basket body 100 and uses fastening bolts to thread the cover 300 onto the basket body 100. At this time, the central post 140 is exposed on the outside of the cover 300 through the central through hole 312. Next, the operator installs the basket body 100 with the cover 300 attached onto the mounting groove 400a of the shielding adapter 400. At this time, as... Figure 4 As shown, the second fastening hole 311b of the cover 300 corresponds to the threaded groove 410 of the shielding adapter 400, and the close-fitting protrusion 320 of the cover 300 is in close contact with the internal support 130. Thereafter, the operator uses fastening bolts to thread the cover 300 onto the shielding adapter 400, thereby completing the process as shown. Figure 3 The image shows the storage of spent fuel (FA) in a transport basket.

[0052] Afterwards, the operator connects the lifting equipment to the lifting ring connected to the cover 300, lifts the transport basket from the spent fuel tank, and raises it to the work area. At this time, the water inside the transport basket is drained through the drain holes 150 and 512, and the operator injects hot air through the central column 140 to dry the inside of the transport basket.

[0053] After that, as Figure 17 As shown, the operator places the transport basket into the transport container (CV) and seals the transport container (CV) with a lid. Subsequently, assuming the personnel transport the transport container (CV) to the experimental facility, the experimenters remove the spent fuel from the transport container (CV) and perform a soundness assessment. At this point, because the spent fuel (FA) is shielded by the basket body 100, the shielding adapter 400, and the transport container (CV), the handling burden on the test personnel due to concerns about radiation exposure is reduced.

[0054] As described above, the heavy water reactor spent fuel transport basket according to the present invention is configured to transport only a predetermined amount of spent fuel for spent fuel integrity assessment. By minimizing storage space and maximizing thickness, the burden on test facility personnel to handle spent fuel can be minimized even in test facilities without specialized handling equipment.

[0055] Although the invention has been described in detail with reference to the described embodiments, it will be apparent to those skilled in the art that various changes and modifications are permissible within the scope of the technical concept of the invention, and such changes and modifications should fall within the scope of the claims.

Claims

1. A heavy water reactor spent fuel transport basket, characterized in that, include: The basket body forms an accommodating space and is provided with an internal support that divides the accommodating space; The fuel bag is disposed on one side of each receiving space divided by the internal support, and is configured to rotate to the other side of the receiving space, and has an upward-opening disassembly groove to make the fuel box containing spent fuel removable. as well as The cover opens and closes the receiving space of the basket body and is threadedly connected to the basket body; A central through hole is formed on the cover. The internal support is provided with a hollow central column that is exposed to the outside of the cover through the central through hole. The central column opens inward through the central through hole and has vent holes around its periphery to allow the receiving space to communicate with the interior of the central column.

2. The heavy water reactor spent fuel transport basket as described in claim 1, characterized in that, Multiple threaded grooves are formed on the upper edge of the basket body, and fastening holes for fastening to the threaded grooves are formed on the cover body. The fastening holes are arc-shaped elongated holes formed along the circumferential direction of the cover body.

3. The heavy water reactor spent fuel transport basket as described in claim 1, characterized in that, A support is provided in the receiving space to tilt and support the fuel bag in the direction of rotation of the fuel bag.

4. The heavy water reactor spent fuel transport basket as described in claim 1, characterized in that, It also includes a shielding adapter having a mounting groove and a base, wherein the mounting groove has an inner diameter corresponding to the outer diameter of the basket body, and the base enables the mounting groove to be separated from the ground, wherein the cover and the shielding adapter can be threaded together.

5. The heavy water reactor spent fuel transport basket as described in claim 1, characterized in that, The fuel cartridge includes a guide that forms a partitioned space divided into multiple spaces for the storage of spent fuel, and the fuel cartridge is configured to accommodate rod-shaped spent fuel.

6. The heavy water reactor spent fuel transport basket as described in claim 1, characterized in that, The internal support is formed in a stepped shape downward along the depth direction of the receiving space. The cover includes: a fastener that is threadedly connected to the edge of the basket body; and a close-fitting protrusion that is set corresponding to the inner diameter of the receiving space of the basket body, protruding downward from the center of the cover and closely fitting the internal support, and forming the central through hole so that the central post can be inserted into the central through hole.

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