CN112820434A

CN112820434A - Casting type hollow cylindrical radiation shielding device

Info

Publication number: CN112820434A
Application number: CN201911128231.XA
Authority: CN
Inventors: 倪伟; 张强; 曾进忠; 李厚文; 陈法国; 韩毅; 何俊男; 陈琛祥; 黄刚; 王瑞军; 湛昆; 湛丽; 平萍; 朱昌荣
Original assignee: CNNC Nuclear Power Operation Management Co Ltd; Nuclear Power Qinshan Joint Venture Co Ltd
Current assignee: CNNC Nuclear Power Operation Management Co Ltd; Nuclear Power Qinshan Joint Venture Co Ltd
Priority date: 2019-11-18
Filing date: 2019-11-18
Publication date: 2021-05-18

Abstract

The invention relates to the technical field of radiation protection of nuclear facilities, in particular to a casting hollow cylindrical radiation shielding device. In order to effectively solve the problem of hot spot shielding at the vertical radioactive plugs and blind plates of nuclear power plants and better apply radiation shielding measures, starting from the needs of optimal management of radiation protection in power plants, it is necessary to design and manufacture a set of shielding performance. A special radiation shielding device that meets the requirements of radiation protection, has strong safety and convenience, and can significantly reduce the radiation dose of shielding operators. In this device, the left shielding module and the right shielding module are both semi-cylindrical, and they are connected by front and rear locks to form a sleeve; the left shielding module and the right shielding module have the same height, and the left shielding modules of different heights are The right shielding module is composed of a short sleeve assembly, a long sleeve assembly and a bottom sleeve assembly respectively.

Description

Casting type hollow cylindrical radiation shielding device

Technical Field

The invention relates to the technical field of radiation protection of nuclear facilities, in particular to a casting type hollow cylindrical radiation shielding device.

Background

Almost all the radioactivity of the pressurized water reactor nuclear power plant comes from an active area of a reactor loaded with fuel assemblies, and along with the operation of the nuclear power plant, corrosion activation products are continuously deposited on the inner walls of equipment, valves and pipelines of a main system and an auxiliary system thereof to form points or local positions with strong radioactivity, which are often called as radioactive hot spots (hot spots for short). The radiation level of the hot spots is high and not easy to eliminate, the formed strong penetrating radiation is the main reason of the increase of the radiation level of partial buildings or areas of the nuclear power plant, high radiation dose can be caused to maintainers near the hot spots, small dose accumulation can be caused to other workers passing by the hot spots, and therefore the integral collective dose of the power plant is increased.

In order to reduce the influence of the radioactive heat points on the radiation dose of personnel and ensure the radiation safety of field workers, temporary shielding is a common optimization measure in the radiation protection management of a nuclear power plant. However, in the operation practice of nuclear power plants, it is found that some radioactive pipeline bottom plugs, blind plates and other positions are easy to form high-dose-rate radioactive hot spots, and a lot of difficulties exist in implementing temporary radiation shielding, which mainly include the following aspects:

the hot spot dose rate level is high, the shielding performance of the soft lead screen material commonly used in the power plant is limited, and the ideal shielding effect is difficult to achieve;

the lack of effective shielding devices, the difficulty of forming a fixed shield by directly covering the hot spot with shielding materials, and the safety impact on the load on the pipeline due to the heavy shielding materials, which affects the safety of the process system equipment of the nuclear power plant;

the method of setting up scaffolds as supports and then suspending shielding materials is adopted, the operation time is long, the radiation dose to operators is large, the occupied space is large, and the temporary dismantling and the reinstallation are very inconvenient if the radiation dose is large.

Therefore, in order to effectively solve the problem of hot spot shielding at vertical radioactive plugs and blind plates of a nuclear power plant and better apply radiation shielding measures, a special radiation shielding device which not only meets the radiation shielding requirement on shielding performance, but also has stronger safety and convenience and can obviously reduce the radiation dose of shielding operators needs to be designed and manufactured from the requirement of optimal management of radiation protection of the power plant.

Disclosure of Invention

1. The purpose is as follows:

the invention aims to develop a set of radiation shielding device, mainly solves the problem of shielding hot spots at radioactive plugs and blind plates with certain structural sizes of a nuclear power plant, and has better comprehensive performance in the aspects of shielding performance, safety, convenience and the like, thereby reducing the radiation dose of shielding construction personnel and other working personnel of the power plant.

The main functions of the device are as follows: firstly, according to the dose rate level of the hot spot, the thickness of the shielding material is conservatively determined by calculation, and a stainless steel module structure with the same thickness of the lead material poured inside is adopted to achieve sufficient shielding performance; secondly, the shielding device can be quickly assembled and disassembled by adopting a modular structure design through building block type assembling combination, so that good convenience performance is achieved, and the irradiated dose of operators is reduced; thirdly, a hollow cylindrical design is adopted, so that the shielding device is prevented from being in direct contact with the hot spot equipment, and the shielding device is prevented from causing safety influence on the hot spot equipment; fourthly, the shielding device can be properly combined and adjusted according to the diameter size, the length and the space height of the hot spot pipeline, has certain general performance, and is also suitable for other hot spots with similar pipe diameter structures.

2. The technical scheme is as follows:

the invention is realized by the following technical scheme:

a cast hollow cylindrical radiation shield comprising: a left side shielding module; a right side shielding module; a handle; locking; a short sleeve assembly; a long sleeve assembly; a bottom end sleeve assembly; and (7) anchor bolts. The left shielding module and the right shielding module are both semi-cylinders and are connected through front and rear lock catches to form a sleeve; the left side shielding module is the same with the right side shielding module height, and short sleeve subassembly, long sleeve subassembly and bottom sleeve subassembly are constituteed respectively to the left side shielding module of co-altitude and right side shielding module.

Handles are fixed on the side surfaces of the left shielding module and the right shielding module.

The bottom end sleeve assembly is fixedly connected with the bottom of the foundation bolt.

The short sleeve assembly, the long sleeve assembly and the bottom sleeve assembly are connected in a concave-convex nested manner from top to bottom.

The short sleeve assembly, the long sleeve assembly and the bottom end sleeve assembly are all hollow structures.

The weight of the left shielding module and the right shielding module is less than or equal to 6 kg.

The outer surfaces of the left shielding module and the right shielding module adopt 304 stainless steel as an external structure module, and lead materials are poured in the stainless steel.

The thickness of the lead material is 24mm, and the purity is more than 99.9%.

3. The effect is as follows:

the related components of the cast hollow cylindrical radiation shielding device can be combined and used at will, the shielding requirements of vertical pipe hot spots with different heights can be met, and the system function is not influenced. Meanwhile, compared with a shielding erection mode adopting a scaffold as a support, the working load and the operation time are both obviously reduced, and the radiation dose received by an operator can be reduced. The comparison of the application effects of the cast hollow cylindrical radiation shielding device is shown in table 2.

TABLE 2 comparative analysis table for application effect of casting type hollow cylindrical radiation shielding device

Drawings

Left and right shielding module in figure 1

FIG. 2 top plan view of a single sleeve assembly

FIG. 3 is a single sleeve front view

FIG. 4 side view of a single sleeve

FIG. 5 is a view showing the assembly and installation of a plurality of sleeve assemblies

FIG. 6 bottom socket assembly section and anchor bolt installation

FIG. 7 is a combined mounting view of a foundation bolt with a view

FIG. 8 is a view of the assembly of the bottom support device

In the figure: 1. a left side shielding module; 2. a right side shielding module; 3. a handle; 4. locking; 5. a short sleeve assembly; 6. a long sleeve assembly; 7. a bottom end sleeve assembly; 8. and (7) anchor bolts.

Detailed Description

A set of casting type hollow cylinder type radiation shielding device comprises a short sleeve component, a long sleeve component and a bottom sleeve component, wherein the standard specification and the size of each component are shown in table 1 (the size of each component and the thickness of a shielding material can be adjusted according to actual requirements if needed).

TABLE 1 Standard Specifications for the respective Sleeve assemblies

The short sleeve assembly, the long sleeve assembly and the bottom sleeve assembly are all composed of two hollow semi-cylindrical modules, and the two semi-cylindrical modules of the same type are connected in a left-right mode through the hasps to form a hollow cylindrical assembly. The below of bottom sleeve subassembly is closed structure, and the bottom is equipped with two M8 screw holes, is equipped with two rag bolts and can finely tune the whole device height.

The short sleeve assembly and the long sleeve assembly can be combined with a plurality of modules up and down at will, and the upper part of the bottom sleeve assembly can be combined with the short sleeve assembly or the long sleeve assembly up and down at will.

(1) Design in radiation shielding performance

The cast hollow cylindrical radiation shielding device adopts 304 stainless steel as an external structural module, and a lead material with proper thickness is cast in the stainless steel. The thickness of the lead material can be determined by using a half-value layer approximate estimation method (firstly, the weakening multiple K is calculated, secondly, the number of half-value layers of the shielding material is calculated, and finally, the thickness of the shielding material is determined according to empirical data of the half-value layers). the device adopts the lead material with the thickness of 24mm (the purity is more than 99.9 percent), the thickness of the lead material is equivalent to the thickness of 2 half-value layers of the typical nuclide CO-60 of a nuclear power plant, and the theoretical weakening multiple of the lead with the thickness of 24mm relative to the CO-60 rays is about 4 times. In order to further verify the shielding performance of the material, a standard radiation field test platform of a CO-60 source is also established, the shielding effect of the shielding body on the gamma rays of the CO-60 source is tested, and the test result is consistent with the theoretical calculation result.

In order to avoid reducing the shielding performance due to the clearance generated when the shielding device is combined, two semi-cylindrical modules of each sleeve assembly are connected in a stepped left-right mode; the upper and lower connections between the sleeve assemblies are connected in a concave-convex nested manner, so that no ray leakage gap is formed at the upper, lower, left and right connection parts of the device.

(2) Design of safety aspects

The casting type hollow cylindrical radiation shielding device is of a hollow structure, is not in direct contact with equipment to be shielded, and cannot cause load influence on the equipment even if the casting type hollow cylindrical radiation shielding device is arranged for a long time, so that the operation safety of the equipment is guaranteed.

The lead material is enclosed by a stainless steel outer package, so that the safety influence of the heavy metal toxicity of the lead material on operators is avoided.

The weight of the single semi-cylindrical shielding module is not more than 6Kg, and the operation safety of the shielding device during transportation and installation can be improved.

(3) Design in convenience

The integral parts of the casting type hollow cylindrical radiation shielding device are fewer, the short sleeve assembly, the long sleeve assembly and the sleeve bottom assembly are all configured by standard components and can be combined and used at will, the implementation difficulty of shielding measures is lower, operators can be trained simply and skillfully, the operation time is short, the required manpower is less, and the irradiation dose of the operators can be obviously reduced.

The whole weight of each sleeve component is lighter, and the convenient handle of outside all design is convenient for transport and installation operation.

Two semi-cylindrical modules of each sleeve component are connected and fixed left and right by adopting a hasp, and the hasp and the component shell are of an integrated structure, so that movable parts are reduced, and the operation is convenient. Each subassembly adopts unsmooth nested formula to connect from top to bottom, relies on self gravity to realize better stability, has also reduced the application of accessory.

(4) Design in versatility

The sleeve components are of standard structures and can be combined randomly according to requirements, and therefore the implementation range of shielding is enlarged.

And a threaded hole is formed below the bottom sleeve component, and after the bottom sleeve component is connected with a foundation bolt, the height can be finely adjusted within the range of 6 cm.

For the plug pipeline positioned in the air, the threaded hole below the bottom sleeve component can be fixedly connected with the related supporting device, so that the shielding application of the vertical pipeline in the air is realized.

The specific installation process is described below with reference to the accompanying drawings:

(1) radiation shielding scheme determination

According to the spatial position and the structural size of the radioactive hot spot, the types and the number of different components of the cast hollow cylindrical radiation shielding device are determined, and whether a bottom support device is required to be used or not is determined.

(2) Radiation shield support device installation implementation

And for the vertical plugs or blind plates close to the ground, sleeve assemblies are sequentially installed from the ground position upwards. As shown in fig. 1, firstly, two cylindrical shielding modules of a single sleeve assembly are sleeved on two sides of a hot spot plug from the bottom; as shown in fig. 2, the two cylindrical modules are fixed by the lock catches; and finally, sequentially installing other sleeve assemblies above the installed sleeve assembly as shown in fig. 3, so that the installation can be completed quickly. When in dismounting, the hasps are sequentially loosened from the upper part, and the cylindrical modules can be quickly dismounted by removing.

For hot spot line lengths slightly greater than the mating dimensions of the sleeve assemblies, fine tuning may be achieved using anchor bolts below the bottom sleeve assembly, as shown in fig. 4. Firstly, adjusting two foundation bolts with the same height below a bottom sleeve assembly according to a hot spot structure size measurement result, and pre-installing the bottom sleeve assembly; as shown in fig. 5, the installation can be completed quickly by installing the short sleeve assembly or the long sleeve assembly above the bottom sleeve assembly in sequence.

Referring to fig. 7, for a vertical plug or a blind plate located in the air, a cast hollow cylindrical radiation shielding device can be applied in cooperation with a ground support structure, the support structure needs to be additionally configured, the support structure has an adjusting function, and the upper surface of the support structure can be fixed with a screw hole of a bottom sleeve assembly through a bolt. As shown in fig. 8, the bottom sleeve assembly and the supporting device are firstly fixed by bolts when being installed; secondly, integrally moving the supporting device and the bottom sleeve assembly to the position below the hot point; as shown in fig. 6, finally, the short sleeve assembly or the long sleeve assembly is installed above the bottom sleeve assembly in sequence, so that the installation can be completed quickly.

Claims

1. Casting hollow cylindrical radiation shielding device, comprising: left shielding module (1), right shielding module (2), characterized in that: the left shielding module (1) and the right shielding module (2) are both The half cylinder is connected by the front and rear locks (4) to form a sleeve; the left shielding module (1) and the right shielding module (2) have the same height, and the left shielding module (1) and the right shielding module with different heights The shielding module (2) is respectively composed of a short sleeve assembly (5), a long sleeve assembly (6) and a bottom sleeve assembly (7).

2 . The casting hollow cylindrical radiation shielding device according to claim 1 , wherein the left shielding module ( 1 ) and the right shielding module ( 2 ) are both fixed with handles ( 3 ). 3 .

3 . The casting hollow cylindrical radiation shielding device according to claim 1 , wherein the bottom of the bottom sleeve assembly ( 7 ) is fixedly connected with the anchor bolts ( 8 ). 4 .

4. The casting hollow cylindrical radiation shielding device according to claim 1, characterized in that: the short sleeve assembly (5), the long sleeve assembly (6) and the bottom sleeve assembly (7), A concave-convex nested connection is used between the three.

5. The cast-type hollow cylindrical radiation shielding device according to claim 4, wherein the short sleeve assembly (5), the long sleeve assembly (6) and the bottom sleeve assembly (7) are inside All are hollow structures.

6 . The casting hollow cylindrical radiation shielding device according to claim 1 , wherein the weight of the left shielding module ( 1 ) and the right shielding module ( 2 ) is less than or equal to 6 kg. 7 .

7. The casting hollow cylindrical radiation shielding device according to claim 2, characterized in that: the outer surfaces of the left shielding module (1) and the right shielding module (2) are made of 304 stainless steel as the external structural module, Stainless steel internally poured lead material.

8 . The casting hollow cylindrical radiation shielding device according to claim 7 , wherein the lead material has a thickness of 24 mm and a purity of >99.9%. 9 .