A foldable radiation shielding device

Abstract

The present invention belongs to the field of nuclear radiation, and specifically relates to a foldable radiation shielding device. The shielding materials of the prior art are heavy and occupy a large space. The square joints of the two single-headed ratchet arms of the device are inserted into the square slots in the L-shaped joint of the end connecting arm component, and the two ends of the connecting cross bar are connected to the L-shaped joint side of the two single-headed ratchet arms by screws B; the square joints of the ratchets at one end of the two double-headed ratchet arms are respectively inserted into the square grooves in the L-shaped joint of the end connecting arm component, and then the square joints of the ratchets at the other end of the two double-headed ratchet arms are respectively inserted into the square grooves in the L-shaped joint above the side component of the single-headed ratchet arm. The device has strong advantages in safety performance, stability performance, convenience performance and personnel radiation dose control.

Description

Technical Field

[0001] The invention belongs to the field of nuclear radiation, and in particular relates to a foldable radiation shielding device. Background Art

[0002] Radioactivity in pressurized water reactor nuclear power plants comes almost entirely from the active areas of the reactor fuel assemblies. As the nuclear power plant operates, corrosion activation products are continuously deposited on the equipment, valves, and inner walls of pipes in the main system and its auxiliary systems, forming some points or local locations with strong radioactivity, often referred to as radioactive hot spots (hot spots for short). These hot spots have high radiation levels and are difficult to eliminate. The strong penetrating radiation formed is the main reason for the increase in radiation levels in some buildings or areas of the nuclear power plant. It will also cause high radiation doses to maintenance personnel near the hot spots, and cause small doses to accumulate for other workers passing by the hot spots, thereby increasing the overall collective dose of the power plant.

[0003] In order to reduce the impact of these radioactive hot spots on the radiation dose of personnel, ensure the radiation safety of on-site workers, and improve the radiation safety management level of power plants, temporary shielding is a commonly used optimization measure in the radiation protection management of nuclear power plants. However, in actual applications, it is found that power plants have many radioactive hot spot pipelines or equipment close to the ground and close to the wall. It is difficult to effectively implement radiation shielding measures for these hot spots. The main reason is that there are currently no effective and applicable radiation shielding devices at home and abroad. The current shielding methods have many limitations and it is difficult to take into account the safety impact on system equipment, operational convenience, and reducing the radiation dose of operators. The main manifestations are as follows:

[0004] - The shielding method of directly covering the hot spot with shielding materials is more convenient to operate and the radiation dose to the operator is less. However, since the shielding materials are usually heavy and difficult to fix, they may cause damage to the hot spot equipment and affect the safety of the nuclear power plant process system. It is currently being gradually replaced;

[0005] – Using scaffolding as support and then hanging shielding materials can avoid adding weight to equipment pipelines, but it takes up a large space, requires a large workload, takes a long time to operate, and exposes operators to a large radiation dose. At the same time, other departments are required to build scaffolding in advance, which is less effective and is extremely inconvenient if temporary dismantling and reinstallation is required.

[0006] Therefore, in order to effectively solve the shielding problem of such radioactive hotspots and better apply radiation shielding measures, based on the needs of optimal management of radiation protection in power plants, it is necessary to design and manufacture a set of radiation shielding devices that not only meet the radiation protection requirements in terms of shielding performance, but also have strong safety and stability, and can significantly reduce the radiation dose of shielding operators. Summary of the invention

[0007] 1. Purpose:

[0008] The purpose of the present invention is to develop a set of foldable radiation shielding devices, which have four main functions: first, to achieve physical isolation between the shielding material and the hotspot equipment to be shielded, so as to avoid damage to the hotspot equipment due to the weight of the shielding material, and at the same time, the device has strong stability and firm stability within the rated load range; second, it can match the shielding materials (soft lead screens) commonly used in nuclear power plants, save resource costs, and can achieve different shielding performance requirements by hanging different amounts of shielding materials according to the level of radiation source dose rate; third, it has strong convenience and meets the operational requirements of rapid installation and removal, and the main part can be installed in a low-radiation area to reduce the workload near the radioactive hotspot and reduce the radiation dose of the operator; fourth, it has strong versatility. Through different changes in the structure, it can be applied to the shielding requirements of hotspots in various locations and of different types, and multiple devices can be combined and applied to expand the scope of use.

[0009] 2. Technical solution:

[0010] The purpose of the present invention is to provide a foldable radiation shielding support device to solve the application problem of radiation shielding of radioactive hotspots close to the ground, especially close to the wall or equipment in nuclear power plants. At the same time, the shielding device has strong advantages in safety performance, stability performance, convenience performance and personnel radiation dose control.

[0011] A foldable radiation shielding device, wherein two ends of a connecting crossbar are respectively screwed into threaded holes of two L-shaped joints of two end connecting arms; the bottoms of the two end connecting arms are respectively fixed to the two ends of the connecting rod of the bracket end by screws A and nuts; the square joints of the two single-head ratchet arms are inserted into the square slots in the L-shaped joints of the end connecting arms, and the two ends of the connecting crossbar are connected to the L-shaped joints of the two single-head ratchet arms by screws B; the square joints of the ratchets at one end of the two double-head ratchet arms are respectively inserted into the square grooves in the L-shaped joints of the end connecting arms, and then the square joints of the ratchets at the other ends of the two double-head ratchet arms are respectively inserted into the square grooves in the L-shaped joints above the side parts of the single-head ratchet arms.

[0012] Both ends of the double-headed ratchet support arm are square joints, and columnar protrusions are arranged on the square joints.

[0013] One end of the single-head ratchet arm is a ratchet joint, and the other end is an L-shaped joint; a columnar protrusion is provided on the ratchet joint; a square slot is provided on one side of the L-shaped joint, and two threaded holes are provided on the other side.

[0014] One end of the terminal connecting arm is an L-shaped joint, the left side of the L-shaped joint is a square slot, and the right side is a threaded hole; a groove is opened at the center of the bottom of the terminal connecting arm, and through holes are respectively provided on both sides of the groove.

[0015] The two ends of the connecting cross bar are threaded joints.

[0016] Both ends of the connecting rod at the end of the bracket are narrow joints, and the middle part and both ends are provided with screw holes, and each screw hole is perpendicular to the cross section of the narrow joint.

[0017] One of the threaded holes of the single-head ratchet support arm is used for fixing, and the other is connected to the arc-shaped hook.

[0018] 3. Effect:

[0019] The foldable radiation shielding device described in the present invention can be used alone or in combination, achieving the shielding requirements of ground pipelines or equipment of different lengths, heights and positions without affecting the system function; when the foldable radiation shielding device described in the present invention is erected, compared with the shielding erection method of the same scale using scaffolding as support, the workload and operation time are greatly reduced (at least 1 times or more), and the workload near the hotspot is small, which can greatly reduce the radiation dose of the shielding operator; the foldable radiation shielding device described in the present invention has a strong load-bearing capacity and can achieve a higher shielding performance, thereby reducing the accumulation of small doses of people passing near the hotspot and reducing the overall collective dose of the nuclear power plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Double ratchet arm

[0021] Figure 2 Single head ratchet arm

[0022] Figure 3 End connection arm

[0023] Figure 4 Connecting crossbar

[0024] Figure 5 Bracket end link

[0025] Figure 6 Installation diagram of end connection arm

[0026] Figure 7 Single-head ratchet arm side component installation diagram

[0027] Figure 8 Installation drawing of double-ended ratchet arm side parts

[0028] Fig. 9 Folding radiation shielding device assembly drawing

[0029] Fig.10 Radiation shielding device folded

[0030] Fig.11 Example of using L-type shielding device

[0031] Figure 12-1 Example of using the shielding device type Λ

[0032] Figure 12-2 Another example of using the shielding device in the Λ-type

[0033] Fig.13 Examples of other uses of shielding devices

[0034] In the figure: 1. double-headed ratchet arm, 2. single-headed ratchet arm, 3. end connecting arm, 4. screw A, 5. nut, 6. connecting rod at the end of the bracket, 7. connecting cross bar, 8. arc hook, 9. screw B. DETAILED DESCRIPTION

[0035] 1. The present invention is achieved through the following technical solutions:

[0036] The foldable radiation shielding device is composed of 2 double-headed ratchet arms, 2 single-headed ratchet arms, 4 end connecting arms, 3 connecting cross bars, 2 bracket end connecting rods, 16 arc hooks, and 6 sets of bolts and nuts. The double-headed ratchet arms, single-headed ratchet arms, end connecting arms, connecting cross bars, and bracket end connecting rods can be assembled into an integral device (no need to disassemble when using), and the arc hook is a standard accessory and is pre-installed as needed when using (installed by threaded connection).

[0037] The size parameters of each component are as follows:

[0038] – The total length of the double-ended ratchet arm is 465mm, with 1-inch ratchet joints at both ends, and a connecting rod is used in the middle to weld the two ratchet joints together. The connecting rod is made of SUS304 stainless steel, 200mm long and 36mm in diameter.

[0039] – The total length of the single-head ratchet arm is 432mm, with a 1-inch ratchet joint at one end and an L-shaped joint at the other end. The two joints are welded together using a connecting rod in the middle. The overall length, width and height of the L-shaped joint are 132mm×74mm×65mm. The thickness of the narrow side is 32cm and there is an M8 screw hole (for installing the arc hook). There are two M8 threaded holes on the top side (one for fixing and one for installing the arc hook). There is a 25.5mm×25.4mm×17mm square hole on the wide side, with an effective depth of 17mm, and an M18 threaded hole with an effective depth of 15mm on the other side that runs through the entire side. The connecting rod is made of SUS304 stainless steel, 170mm long and 36mm in diameter.

[0040] – The total length of the end connecting arm is 450mm, including an L-shaped joint (same as above), which is completed by CNC machining and made of 6065 aluminum alloy. There is a 12mm wide and 40mm deep groove in the center of the bottom of the connecting rod, and there are through holes with a diameter of 9mm on both sides of the groove (the center of the hole is 18mm from the bottom edge).

[0041] – The total length of the connecting rod at the end of the bracket is 472mm, the diameter is 36mm, the connecting rod is made of 6065 aluminum alloy, and both ends are narrow joints with a length of 40mm, a width of 36mm, and a thickness of 12mm. There is a through hole with a diameter of Φ9mm in the middle of the two joints (the center distance between the two holes is 428mm); there is an M8 screw hole in the middle and at both ends of the connecting rod at the end of the bracket (the center distance between the screw holes at both ends is 336mm), and each screw hole is perpendicular to the cross section of the narrow joint.

[0042] – The total length of the connecting crossbar is 346mm, the diameter is 36mm, the crossbar is made of 6065 aluminum alloy, and both ends of the crossbar are M18 threaded connectors (effective thread length 15mm).

[0043] – The total length of the arc hook is 77mm, the arc radius of the hook is 20mm, the thickness is 8mm, and the other end of the hook is M8 thread with a thread length of 24mm.

[0044] – After the foldable radiation shielding device is assembled as a whole, the size of a single side wall is 836mm long and 472mm wide.

[0045] (1) Design of radiation shielding performance

[0046] The shielding performance of the foldable radiation shielding device mainly depends on the thickness of the installed shielding material, which is directly related to the weight of the shielding material that the device can bear. The commonly used shielding material in nuclear power plants is soft lead screen, with a lead equivalent of 5mmPb, including two common specifications of 40cm×40cm (about 12.5kg) and 40cm×80cm (about 25kg). After comprehensive consideration of various factors, it is determined that the maximum load weight of a single foldable radiation shielding device is 200kg.

[0047] – For the “Λ” type setting, the two arms can bear a maximum load of 100kg each (4 layers of soft lead screen,

[0048] 20mm lead equivalent), which is approximately 3 times the half-value layer protection thickness of Cs-137 gamma rays (0.662Mev), and approximately 1.7 times the half-value layer protection thickness of Co-60 gamma rays (1.25Mev).

[0049] – For the “∠” type setting, the upper arm can bear a maximum load of 200kg (8 layers of soft lead screen, 40mm lead equivalent), which is approximately 6.7 times the half-value layer thickness of Co-60 gamma rays (1.25Mev).

[0050] In practical applications, the amount of shielding material can be increased or decreased as needed to achieve different shielding performance requirements.

[0051] (2) Security design

[0052] The foldable radiation shielding device is an integrated structure with fewer scattered parts, which facilitates foreign body protection and control at the work site.

[0053] The foldable radiation shielding device adopts a bridge-type installation method to avoid direct contact between the shielding material and the hot spot equipment, and will not cause any load-bearing safety impact on the system equipment.

[0054] The foldable radiation shielding device provides an indicator of the maximum load-bearing capacity, and the weight of the shielding material can be controlled through quantitative standards to ensure the safety of the device.

[0055] The on-site construction of the foldable radiation shielding device requires less work and shorter operation time, which can significantly reduce the radiation dose of operators.

[0056] (3) Design for convenience

[0057] The foldable radiation shielding device can be used as a whole after assembly. No additional installation operation is required except for the arc hooks (the arc hooks are standard accessories and are installed as needed during use). When used on site, only the device structure needs to be adjusted and the arc hooks need to be installed. The operation is very convenient.

[0058] The foldable radiation shielding device is easy to operate. Operators can master the use requirements after simple training. It does not require the cooperation of other departments, and the implementation of radiation shielding work is highly effective.

[0059] The total weight of a set of foldable radiation shielding device is about 10Kg. One person can easily complete the transportation and disassembly operations. The arms on both sides of the device can be folded, occupying less space, which is convenient for on-site storage and management.

[0060] (4) Design in terms of economy and versatility

[0061] The foldable radiation shielding device can be directly used with the shielding materials (soft lead screens) commonly used in nuclear power plants. It can be used with two commonly used specifications of soft lead screens of 40cm*40cm and 40cm*80cm (other specifications can also be used when the hanging hole spacing is about 336mm). There is no need to purchase additional shielding materials, which can save resource costs.

[0062] The foldable radiation shielding device can be used in a variety of ways according to different hot spot characteristics. It has strong versatility. Commonly used methods are:

[0063] – When radioactive hotspot pipelines or equipment are located in an open area, the radiation shielding device can be adjusted to

[0064] For "Λ" type (the height of the outer diameter of the shielding equipment does not exceed 70cm) or "П" type (the height of the outer diameter of the shielding equipment does not exceed 35cm);

[0065] – When radioactive hotspot pipelines or equipment are located near walls or other equipment, the radiation shielding device can be adjusted to a “∠” shape (the angle between the two arms is adjustable) and can shield pipelines with an outer diameter up to 110 cm in height;

[0066] – The arms on both sides of the device can be folded from the middle, and the arms on both sides can be adjusted according to the hot spot height and other conditions to achieve more usage methods.

[0067] When the hot spot pipeline that needs to be shielded is long, multiple sets of devices can be used in combination. The shielding devices can be placed one by one along the direction of the pipeline in advance, and then the shielding materials can be hung in sequence to complete the operation. The larger the shielding range, the higher the cost performance.

[0068] 2. The installation steps of this device are as follows:

[0069] (1) Installation of foldable radiation shielding device

[0070] Step 1: Select two end connection arms 3 ( Figure 3 )、1 connecting cross bar 7( Figure 4 ) and 1 bracket end link 6 ( Figure 5 ). Screw the two ends of the connecting crossbar 7 into the threaded holes of the L-shaped joints of the two end connecting arms 3 until they are tightened; tighten the bottom of the two end connecting arms 3 and the two ends of the bracket end connecting rod 6 with bolts and nuts respectively, and the complete installation of one end connecting arm 3 component is completed ( Figure 6 ).

[0071] Step 2: Repeat step 1 again to complete the installation of the other end connecting arm 3 parts.

[0072] Step 3: Select two single-head ratchet arms 2 ( Figure 2 )、1 connecting cross bar 7( Figure 4 ) and 1 assembled end connection arm 3 parts ( Figure 6 ). Insert the square joints of the two single-head ratchet arms 2 into the square slots in the L-shaped joints of the end connecting arm 3, and screw the two ends of the connecting crossbar 7 into the threaded holes of the L-shaped joints of the two single-head ratchet arms 2 until they are tightened. Tighten and fix the tops of the L-shaped joints of the two single-head ratchet arms 2 with M8 bolts. Complete the installation of the side parts of the single-head ratchet arm 2 ( Figure 7 ).

[0073] Step 4: Select two double-ended ratchet arms 1 ( Figure 1 ), 1 assembled end connecting arm 3 parts ( Figure 6 )、1 assembled single-head ratchet arm 2 side parts ( Figure 7 Insert the square joints of the ratchets at one end of the two double-ended ratchet arms 1 into the square grooves in the L-shaped joints of the end connecting arms ( Figure 8 ), and then insert the square joints of the ratchets at the other end of the two double-headed ratchet arms 1 into the square grooves in the L-shaped joints above the side parts of the single-headed ratchet arm 2. Finally, tighten and fix the four ratchet square joints and the four square joint slots with M8 bolts. Complete the installation of the whole device ( Fig. 9 ).

[0074] A set of foldable radiation shielding device can be used and stored as a whole after assembly without separate disassembly. The whole set of device can be folded for storage or transportation, which can reduce the storage space ( Fig.10 The arc-shaped hook 8 can be installed as needed when in use and can be stored separately at other times.

[0075] (2) Use of foldable radiation shielding device

[0076] 1) Radiation shielding scheme determination

[0077] Determine the scope of shielding measures and the number of radiation shielding devices required based on the spatial location of the radioactive hotspot and the affected area.

[0078] Based on the dose rate level of the hot spot to be shielded, the expected dose rate level, the load-bearing capacity of the shielding device, and the shielding performance data of the shielding material, determine the amount of shielding material (soft lead screen) required and prepare sufficient shielding material.

[0079] 2) How to use the device

[0080] According to the structural characteristics of the hotspot, the installation method of the shielding device is adjusted in the low-radiation area on site, and the arc hook is installed at the position where the soft lead screen needs to be hung on the shielding device.

[0081] The shielding device can be used in a variety of ways according to the hot spot conditions on site. The specific methods are roughly the same: first, set the shielding device above or on the side of the hot spot, and then hang a certain amount of soft lead screen on the arc hook to complete the installation. For longer hot spot pipelines or equipment, multiple sets of radiation shielding devices can be set according to the length and direction of the pipeline, and finally the soft lead screens are hung in sequence. It should be noted that the soft lead screens hung by adjacent shielding devices should overlap as much as possible to avoid gaps that affect the shielding performance. When dismantling, first remove the soft lead screen, and then retrieve the shielding devices in sequence.

[0082] Several common usage methods are as follows:

[0083] a) “∠” type usage, mainly used for radioactive hot spots close to walls or other equipment.

[0084] – The angle of the two arms of the “∠” type usage is adjustable, and both arms can be folded from the middle. The structure can be adjusted according to the height of the pipeline and the distance between the pipeline and the wall to achieve a variety of uses (such as Fig.11 ).

[0085] b) “Λ-type” usage, mainly used for radioactive hotspots at a certain height and in open areas.

[0086] – When the hot spot is at a higher position (outer diameter height does not exceed 70cm), the shielding device can be Figure 12-1 Place it directly over the hot spot and hang a soft lead screen;

[0087] – When the hot spot is at a low position (outer diameter height does not exceed 35cm), the shielding device can be folded ( Figure 12-2 ), then place the shielding device above the hot spot, hang the soft lead screen, and finally press the soft lead screen with the folded end connecting arms on both sides.

[0088] c) Other uses

[0089] – The shielding device can also be adjusted in various ways according to the hot spot characteristics and usage requirements to achieve different usage methods, such as adjusting the shielding device to a "П" type structure ( Fig.13 )wait.

Claims

1. A foldable radiation shielding device, characterized in that: The two ends of the connecting cross bar (7) are respectively screwed into the threaded holes of the L-shaped joints of the two end connecting arms (3); the bottoms of the two end connecting arms (3) are respectively fixed to the two ends of the bracket end connecting rod (6) by screws A (4) and nuts (5); the square joints of the two single-head ratchet arms (2) are inserted into the square slots in the L-shaped joints of the end connecting arms (3), and the two ends of the connecting cross bar (7) are connected to the L-shaped joints of the two single-head ratchet arms (2) by screws B (9); the square joints of the ratchets at one end of the two double-head ratchet arms (1) are respectively inserted into the square grooves in the L-shaped joints of the end connecting arms (3), and then the square joints of the ratchets at the other ends of the two double-head ratchet arms (1) are respectively inserted into the square grooves in the L-shaped joints on the upper side parts of the single-head ratchet arms (2).

2. A foldable radiation shielding device according to claim 1, characterized in that: Both ends of the double-headed ratchet support arm (1) are square joints, and columnar protrusions are provided on the square joints.

3. A foldable radiation shielding device according to claim 1, characterized in that: The single-head ratchet support arm (2) has a ratchet joint at one end and an L-shaped joint at the other end; the ratchet joint has a columnar protrusion; one side of the L-shaped joint has a square slot and the other side has two threaded holes.

4. A foldable radiation shielding device according to claim 1, characterized in that: One end of the terminal connecting arm (3) is an L-shaped joint, the left side of the L-shaped joint is a square slot, and the right side is a threaded hole; a groove is opened at the center of the bottom of the terminal connecting arm (3), and through holes are respectively provided on both sides of the groove.

5. A foldable radiation shielding device according to claim 1, characterized in that: Both ends of the connecting cross bar (7) are threaded joints.

6. A foldable radiation shielding device according to claim 1, characterized in that: Both ends of the bracket end connecting rod (6) are narrow joints, and the middle part and both ends are provided with screw holes, and each screw hole is perpendicular to the cross section of the narrow joint.

7. A foldable radiation shielding device according to claim 1, characterized in that: One of the threaded holes of the single-head ratchet support arm (2) is used for fixing, and the other is connected to the arc-shaped hook (8).

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