A large hatch cover for a spent fuel transport ship

Abstract

The present invention provides a large hatch cover for a spent fuel transport ship, and the present invention belongs to the technical field of ships. The large hatch cover of the spent fuel transport ship of the present invention has each compartment divided into at least two split hatch covers. Two radiation shielding layers are provided inside and at the bottom of each split hatch cover. In addition to achieving the conventional weathertightness at the connection of every two split hatch covers, two radiation shielding layers also need to be provided. Compared with the prior art, the beneficial effects of the present invention are as follows: Since a radiation shielding layer is provided on the large hatch cover, on the premise of not reducing the weathertightness of the hatch cover, the hatch cover also has good shielding performance to prevent the radiation generated by the radioactive substances in the compartment from penetrating the hatch cover and threatening the external crew, which is safer and more reliable. Moreover, the structure is simple, and the manufacturing and installation are convenient, effectively achieving the purpose of the present invention.

Description

Technical Field

[0001] The present invention relates to a shielding structure of a spent fuel transport ship, and particularly to a large hatch cover of a spent fuel transport ship. The present invention belongs to the technical field of ships. Background Art

[0002] A spent fuel transport ship refers to a transport ship dedicated to transporting spent fuel. Spent fuel is a by-product of nuclear energy utilization, which refers to nuclear fuel that has been burned in a reactor and cannot be used in the same reactor continuously. Spent fuel belongs to highly radioactive substances, containing a large number of radioactive nuclides, including unirradiated fertile materials, fission nuclides generated by irradiation, and transuranic nuclides. It has characteristics such as strong radiation, large calorific value, high toxicity, long half-life of nuclides, and the existence of nuclear criticality risks, bringing complex problems such as containment, shielding, heat dissipation, and prevention of nuclear criticality during its transportation. Therefore, its safety must be ensured during transportation to avoid harm to the environment and humans.

[0003] Due to the reduction of traditional energy sources, clean energy will gradually replace traditional energy sources, and the application of nuclear energy will also become more and more extensive. Generally, the fuel storage pool capacity of a nuclear power plant is limited, usually only able to meet the storage requirements of the spent fuel unloaded within more than a decade, while the design life of a nuclear power plant is 40 - 60 years. Currently, many nuclear power plants in China are facing the problem of insufficient in-plant storage capacity. In the future, the amount of spent fuel produced in China will still increase year by year. Therefore, safely transporting spent fuel to a reprocessing plant is important and urgent for the development of nuclear energy in China.

[0004] According to the provisions of the International Maritime Dangerous Goods Code (IMDG Code), Class VII is radioactive substances. Compared with other dangerous goods, radioactive substances have the uniqueness of nuclear and radiation safety. Especially for goods such as spent fuel with the characteristics of long-life and high radioactivity, its radiation safety is more prominent. Therefore, ensuring its irradiation safety during the transportation of spent fuel and avoiding harm to workers, the environment, and the public are important design and evaluation contents during its transportation.

[0005] The spent fuel is loaded in the cargo hold, and a large number of radioactive particles such as neutrons and γ-rays released by the spent fuel penetrate the packaging and reach the cargo hold. Therefore, when transporting radioactive substances on a ship, its irradiation safety is mainly achieved through the radiation shielding measures of the spent fuel transport ship, that is, shielding measures are set in the key areas of the spent fuel transport ship to reduce the radiation levels in each area of the ship.

[0006] Since the large cargo hatch cover can form a deck after being closed and water tightness is also required, the existing large cargo hatch cover does not have the function of shielding radiation. As a result, the local shielding of the large cargo hatch cover is weakened, leading to radioactive particles such as neutrons and gamma rays in the cargo hold passing through the penetration area of the large cargo hatch cover to form radiation leakage beams, reaching outside the cargo hold, and further reaching the upper deck area through the cargo hold passage, resulting in radiation hotspots in local areas, thus restricting the access of workers and area management.

[0007] Therefore, there is a particular need for a shielding structure for the large cargo hatch cover of a spent fuel transport ship to solve the above existing problems. Summary of the Invention

[0008] To solve the above technical problems, the present invention provides a large cargo hatch cover for a spent fuel transport ship, which can effectively reduce the radiation leakage beam dose caused by the large cargo hatch cover.

[0009] The technical solution of the present invention is as follows: A large cargo hatch cover for a spent fuel transport ship provided by the present invention, each hatch cover is divided into at least two split hatch covers. Two shielding layers for radiation protection are provided inside and at the bottom of each split hatch cover, and two shielding layers for radiation protection are provided at the connection of every two split hatch covers. The first shielding layer and the second shielding layer partially overlap.

[0010] Furthermore, the two shielding layers on the split hatch cover are divided into a first shielding layer and a second shielding layer. The first shielding layer is a polyethylene layer, placed inside the split hatch cover and arranged according to the entire area of the hatch cover; the second shielding layer is a concrete layer, placed at the bottom of the split hatch cover and arranged according to the entire area of the hatch cover, and there is a gap between the concrete layer and the polyethylene layer.

[0011] Furthermore, the two shielding layers at the connection of the split hatch covers are divided into a third shielding layer and a fourth shielding layer. The third shielding layer is a polyethylene layer, and the fourth shielding layer is a concrete layer.

[0012] Furthermore, at least one of the first shielding layer and the second shielding layer partially overlaps with at least one of the third shielding layer and the fourth shielding layer.

[0013] Furthermore, the two shielding layers inside the hatch cover are fixed in the split hatch cover by a support frame. The support frame is divided into a horizontal plate and a vertical plate. Steel plates for protecting and fixing the concrete layer are provided on the upper and lower surfaces of the concrete layer of the second shielding layer. A steel plate for protecting the polyethylene layer is provided above the polyethylene layer. The polyethylene layer of the third shielding layer is fixed on the upper surface of the horizontal plate, and its position is higher than the position of the polyethylene layer of the first shielding layer.

[0014] Furthermore, the concrete layer of the fourth shielding layer is located in the middle and lower part of the connection of the two split hatch covers, and the concrete layers of the two split hatch covers are arranged overlappingly.

[0015] Furthermore, the concrete layer of one of the split hatch covers at the connection of the two split hatch covers is of an L-shaped structure, the L-shaped bent part is placed above the concrete layer of the other split hatch cover, and the two partially overlap. A rubber sealing strip is provided in the direction of the extension of the L-shaped bent part, and the rubber sealing strip is pressed on the concrete layer of the other split hatch cover.

[0016] Furthermore, rubber sealing strips are respectively provided on the concrete layers of the two split hatch covers on both sides of the hatch cover to cooperate with the main body of the hatch cover.

[0017] Furthermore, the polyethylene layer is at least composed of two sections, and a fifth shielding layer is provided at the connection of the two sections. The fifth shielding layer is a polyethylene layer, and the polyethylene layer of the fifth shielding layer is located below the polyethylene layer of the first shielding layer and partially overlaps with the polyethylene layer of the first shielding layer.

[0018] Furthermore, a fifth shielding layer is provided in the two split hatch covers on both sides of the hatch cover. The fifth shielding layer is a polyethylene layer, and the fifth polyethylene layer is fixed on the side of the hatch cover and is located below the polyethylene layer of the first shielding layer, and the two partially overlap.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: Since the first shielding layer and the second shielding layer for radiation protection are provided inside and at the bottom of each split hatch cover, in addition to achieving the conventional wind and rain tightness at the connection of every two split hatch covers, two shielding layers also need to be provided in the same way. On the premise of not reducing the wind and rain tightness of the hatch cover, the hatch cover also has good shielding performance to prevent the radiation generated by the radioactive substances in the cabin from penetrating the hatch cover and threatening the external crew. It is convenient for the crew to move inside the cabin, reduces the time exposed to the radiation area, is safer and more reliable, and has a simple structure, is easy to manufacture and install, and effectively realizes the purpose of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 It is a schematic cross-sectional structure diagram of the shielding layer on the spent fuel transport ship of the present invention;

[0022] Figure 2 It is a schematic overall structure diagram of the shielding layer on the spent fuel transport ship of the present invention.

[0023] Description of the reference numerals in the figure:

[0024] P1-1 The first split hatch cover; P1-2 The second split hatch cover; P1-3 The third split hatch cover; 10 - The first shielding layer; 11 - Polyethylene layer; 20 - The second shielding layer; 21 - Concrete layer; 30 - The third shielding layer; 31 - Polyethylene layer; 40 - The fourth shielding layer; 41 - Concrete layer; 50 - The fifth shielding layer; 51 - Polyethylene layer; 23 - Steel plate; 24 - Installation part; 25 - Bolt; 411 - L-shaped concrete layer; 412 - Thickened concrete layer; 33 - Rubber sealing strip; 60 - Support frame; 61 - Horizontal plate; 62 - Vertical plate; 63 - Support plate. Detailed implementation manners

[0025] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0026] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present invention and the above accompanying drawings are used to distinguish similar objects and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such used data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily need to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0027] Figure 1 and Figure 2 is a schematic structural diagram of the shielding layer in the large hatch cover of the spent fuel transport ship of the present invention. A large hatch cover of a spent fuel transport ship of the present invention is divided into at least two split hatch covers to Figure 1Take three split hatch covers as an example. Of course, it can also be other numbers of split hatch covers. The large hatch cover 1 in the present invention is respectively the first split hatch cover P1-1, the second split hatch cover P1-2 and the third split hatch cover P1-3. Inside the first split hatch cover P1-1, the second split hatch cover P1-2 and the third split hatch cover P1-3, there are two radiation shielding layers, namely the first shielding layer 10 and the second shielding layer 20. The first shielding layer 10 is a polyethylene layer 11, which is placed inside the split hatch cover and is arranged according to the entire area of the hatch cover; the second shielding layer 20 is a concrete layer 21, which is placed at the bottom of the split hatch cover and is arranged according to the entire area of the hatch cover. There is a gap between the concrete layer 21 and the polyethylene layer 11.

[0028] The two shielding layers at the connection of the two split hatch covers are divided into a third shielding layer 30 and a fourth shielding layer 40. The third shielding layer 30 is a polyethylene layer 31, and the fourth shielding layer 40 is a concrete layer 41.

[0029] Specifically, at the connection between the first split hatch cover P1-1 and the second split hatch cover P1-2 and at the connection between the second split hatch cover P1-2 and the third split hatch cover P1-3, there are the second shielding layer 20 and the third shielding layer 30. The first shielding layer 10 and the second shielding layer 20 partially overlap with the third shielding layer 30 and the fourth shielding layer 40.

[0030] The first shielding layer 10 on each split hatch cover is fixed to each split hatch cover through a support frame 60.

[0031] The support frame 60 is composed of a horizontal plate 61 and a vertical plate 62, and a support plate 63 is also provided therein.

[0032] The concrete layer 21 of the second shielding layer 20 is placed at the bottom of the hatch cover, and steel plates 23 are provided on the upper and lower surfaces of the concrete layer 21. The steel plates 23 are connected to the support frame 60 to protect and fix the concrete layer 21. Specifically, installation parts 24 are provided at both ends of the concrete layer 21. The installation parts 24 can be double-layer steel plates. At the double-layer steel plates, the steel plates 23 are connected to the concrete layer 21 through bolts 25 to protect the concrete layer 21 from welding damage.

[0033] A polyethylene layer 11 is provided above the concrete layer 21. The polyethylene layer 11 can effectively prevent radiation. There is a gap between the concrete layer 21 and the polyethylene layer 11. A steel plate 23 is provided above the polyethylene layer 11. The steel plate 23 is connected to the support plate 63, that is, the steel plate 23 is connected to the support frame 60 through the support plate 63. There is a gap between the polyethylene layer 11 and the horizontal plate on the support frame 60.

[0034] The polyethylene layer 21 is composed of multiple layers, which are connected into a whole by bolts.

[0035] The first shielding layer 10 in each split hatch cover is divided into two sections. Of course, according to the use environment, it can also be integral or multiple sections. At the connection of the two sections of the first shielding layer 10, there is also a vertical plate 62 of the support frame 60. Below the polyethylene layer 11, there is also a fifth shielding layer 50. The fifth shielding layer 50 is a polyethylene layer 51. There are two polyethylene layers 51, which are respectively placed on both sides of the vertical plate 62 and are horizontally connected to the vertical plate 62 by bolts. The polyethylene layer 51 partially overlaps with the polyethylene layer 11.

[0036] At both ends of the concrete layer 21 at the connection of the two sections of the first shielding layer 20, there are also installation parts 24. The installation parts 24 can be double-layer steel plates. At the double-layer steel plates, the steel plates 24 are connected to the concrete layer 21 by bolts.

[0037] The third shielding layer 30 is a polyethylene layer 31. The second polyethylene layer 31 is divided into two parts, separated by the vertical plate 62. The two parts of the polyethylene layer 31 are directly fixed on the horizontal plate 61 of the support frame 60. That is, its position is higher than the position of the polyethylene layer 11 in the first shielding layer 10, so that it also has good shielding performance at the connection.

[0038] In the middle and lower part of the connection of the two split hatch covers is the concrete layer 41, and the concrete layers of the two split hatch covers are arranged overlapping.

[0039] Specifically, the concrete layer 41 is divided into two parts, which are respectively an L-shaped concrete layer 411 and a thickened concrete layer 412. The thickness of the concrete layer 41 is greater than the thickness of the concrete layer 21. The L-shaped concrete layer 411 is an L-shaped structure. The L-shaped bending part is placed above the thickened concrete layer 412, and there is partial overlap between the two. And at the extension part of the L-shaped bending part, there is a rubber sealing strip 33, and the rubber sealing strip 33 is pressed on the thickened concrete layer 412.

[0040] On both sides of the large hatch cover 1, rubber sealing strips 33 are respectively provided at the positions where the concrete layer 21 is close to the cabin body, and cooperate with the main body of the large hatch cover 1.

[0041] Below the edge of the polyethylene layer 11, there is also a fifth shielding layer 50. The fifth shielding layer 50 is a polyethylene layer 51. The polyethylene layer 51 is fixed on the vertical plate 62 and partially overlaps with the polyethylene layer 11.

[0042] Since there are two radiation shielding layers provided on the large hatch cover, and two radiation shielding layers are also provided at the connection of the split hatch covers; on the premise of not reducing the watertightness of the hatch cover, the hatch cover also has good shielding performance, which facilitates the activities of the crew in the cabin, reduces the time of exposure in the radiation area, and is safer and more reliable.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A large hatch cover for a spent fuel transport ship, each hatch cover is divided into at least two split hatch covers, and is characterized in that: Each of the split hatch covers is provided with two radiation shielding layers inside and at the bottom, and two radiation shielding layers are provided at the connection of every two split hatch covers; the two radiation shielding layers on the split hatch covers are divided into a first shielding layer and a second shielding layer, and the first shielding layer and the second shielding layer partially overlap; the first shielding layer is a polyethylene layer, which is placed inside the split hatch cover and is arranged according to the entire area of the hatch cover; The second shielding layer is a concrete layer, which is placed at the bottom of the split hatch cover and is arranged according to the entire area of the hatch cover, and there is a gap between the concrete layer and the polyethylene layer; The two radiation shielding layers at the connection of the split hatch covers are divided into a third shielding layer and a fourth shielding layer, the third shielding layer is a polyethylene layer, and the fourth shielding layer is a concrete layer; The concrete layer of the fourth shielding layer is located in the middle and lower part of the connection of the two split hatch covers, and the concrete layers of the two split hatch covers overlap; The concrete layer of one of the split hatch covers at the connection of the two split hatch covers is an L-shaped structure, the L-shaped bending part is placed above the concrete layer of the other split hatch cover, and the two partially overlap, and a rubber sealing strip is provided in the direction of the extension of the L-shaped bending part, and the rubber sealing strip is pressed on the concrete layer of the other split hatch cover.

2. The large hatch cover for a spent fuel transport ship according to claim 1, characterized in that: At least one of the first shielding layer and the second shielding layer partially overlaps with at least one of the third shielding layer and the fourth shielding layer.

3. The large hatch cover for a spent fuel transport ship according to claim 1, characterized in that: The two shielding layers in the hatch cover are fixed in the split hatch cover by a support frame. The support frame is divided into a horizontal plate and a vertical plate. Steel plates for protecting and fixing the concrete layer are provided on the upper and lower surfaces of the concrete layer of the second shielding layer. A steel plate for protecting the polyethylene layer is provided above the polyethylene layer. The polyethylene layer of the third shielding layer is fixed on the upper surface of the horizontal plate, and its position is higher than the position of the polyethylene layer of the first shielding layer.

4. The large hatch cover for a spent fuel transport ship according to claim 1, characterized in that: Rubber sealing strips are respectively provided on the concrete layers of the two split hatch covers located outside the hatch cover and cooperate with the hatch cover body.

5. The large hatch cover for a spent fuel transport ship according to claim 1, characterized in that: The polyethylene layer is at least composed of two sections, and a fifth shielding layer is provided at the connection of the two sections. The fifth shielding layer is a polyethylene layer, which is located below the polyethylene layer of the first shielding layer and partially overlaps with the polyethylene layer of the first shielding layer.

6. The large hatch cover for a spent fuel transport ship according to claim 1, characterized in that: A fifth shielding layer is provided in the two split hatch covers located outside the hatch cover. The fifth shielding layer is a polyethylene layer, which is fixed on the side of the hatch cover and is located below the polyethylene layer of the first shielding layer, and the two partially overlap.

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