A method for preparing an integrated insulating protective sheath for an external cable of a nuclear power plant

Abstract

The present invention discloses a method for preparing an integrated insulating protective sleeve for an external cable of a nuclear power plant, comprising: arranging glass fiber wires in a mesh structure on a mold to form a tubular fiber inner layer, mixing and kneading phenyl silicone rubber, bismuth oxide, white carbon black, KH560, and an irradiation cross-linking sensitizer to obtain a silica gel matrix; coating the silica gel matrix on the fiber inner layer to obtain a prefabricated insulating protective sleeve; irradiating the prefabricated insulating protective sleeve to obtain the insulating protective sleeve of the present invention. The inner layer of the present invention is a tubular structure in which large tow fibers are arranged in a mesh structure, the silica gel matrix is ​​the outer layer, and the introduction of the fiber inner layer forms a composite structure, so that the insulating protective sleeve of the present invention has good bending resistance in addition to high temperature resistance and radiation resistance. The mesh structure in the fiber memory will not affect the expansion and contraction of the rubber, and relative to the rubber surface, the fiber inner layer is more convenient for cable insertion.

Description

Technical Field

[0001] The invention relates to the technical field of cables, and in particular to a method for preparing an integrated insulating protective sheath of an external cable of a nuclear power plant. Background Art

[0002] The development of nuclear power plants is closely linked to the application of cables. As a key component of power transmission and signal control, cables play an indispensable role in the operation of nuclear power plants. However, the internal environment of nuclear power plants is extremely harsh, including multiple factors such as high temperature, strong nuclear radiation and chemical corrosion. Under the combined effect of these factors, special cables for nuclear power plants face severe challenges. Specifically, these harsh conditions greatly shorten the service life of cables and increase the risk of cable failure during use, such as leakage, short circuit and other problems. These problems not only affect the normal operation of nuclear power plants, but may also cause major safety accidents, posing a serious threat to personnel safety and the environment.

[0003] Traditional or conventional insulating materials are unable to cope with the special environment of nuclear power plants. They often cannot meet the multiple requirements of nuclear power plant cables, such as high temperature resistance, strong radiation resistance, and good mechanical properties (such as bending resistance). The working environment of nuclear power plant cables is complex and changeable. Cables undergo frequent and irregular bending during use. This requires that the insulating materials not only have excellent physical and chemical stability, but also be able to achieve good integration with the cable body to ensure stable performance in various complex layout scenarios, without cracks, peeling or performance degradation due to bending, thereby effectively avoiding potential electrical failures and safety hazards.

[0004] Therefore, in view of the special requirements of nuclear power plant cables, how to solve the deficiencies of the above-mentioned prior art has become a topic to be studied and solved by the present invention. Summary of the invention

[0005] The purpose of the invention is to provide a method for preparing an integrated insulating protective sheath for an external cable of a nuclear power plant.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for preparing an integrated insulating protective sheath for an external cable of a nuclear power plant, comprising:

[0008] Step 1: Prepare the fiber inner layer and the rubber compound

[0009] Arranging glass fiber wires on a mold in a mesh structure to form a tubular fiber inner layer, wherein the winding direction of the glass fiber wires in the fiber inner layer has an angle with the axial direction of the tube, and the degree of the angle is 30 to 88 degrees; the diameter of the glass fiber wires is 2 to 3 mm, and they are woven from 0.1 to 0.14 mm glass fiber yarns; during preparation, the pulling speed of the tubular glass fiber inner layer is 0.5 to 1.5 m / min;

[0010] The mixing temperature was set to 125±5℃ and the speed was set to 30±3r / min. 100 parts of phenyl silicone rubber were added and mixed for 2 minutes. Then, 5-10 parts of bismuth oxide, 50 parts of white carbon black, 2-5 parts of KH560 and 2-5 parts of radiation cross-linking sensitizer were added in sequence and mixed for 5 minutes to obtain a mixed rubber.

[0011] Step 2, coating the rubber mixture onto the inner layer of the fiber, applying a pressure of 0.02-0.06 MPa after coating and maintaining it for 0.5-1 hour to obtain a prefabricated insulating protective sleeve;

[0012] Step three: irradiating the prefabricated insulating protective sleeve to obtain an integrated insulating protective sleeve for an external cable of a nuclear power plant.

[0013] In the above scheme, the axial direction of the tube is the axial direction of the cable when the cable is sheathed.

[0014] According to a further technical solution, in step 1, the radiation cross-linking sensitizer is selected from a combination of one or more of triallyl isocyanurate (TAIC), trimethylolpropane triacrylate (TMPTA) and trimethylolpropane trimethacrylate (TMPTMA).

[0015] According to a further technical solution, in step 2, the thickness of the silica gel matrix coated on the fiber inner layer is 6 to 8 mm.

[0016] A further technical solution is that before step three, the prefabricated insulating protective sleeve is first placed flat on a conveyor belt; then the electron accelerator is started to make the electron beam energy and beam current meet the irradiation processing requirements; then the conveyor belt is started, maintaining a speed of 3 to 5 cm / s, an irradiation dose of 50 to 300 kGy, and the energy of the electron accelerator is 1 to 12 MeV; and then step three is performed.

[0017] A further technical solution is that in step three, after the irradiation is completed, the irradiated prefabricated insulating protective sleeve is first removed, and after grinding, polishing and trimming, an integrated insulating protective sleeve for the external cable of a nuclear power plant is obtained.

[0018] The terms “include,” “including,” “have,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0019] The terms used herein generally have the ordinary meanings of each term used in the art, in the context of the present invention, and in the specific context, unless otherwise noted. Certain terms used to describe the present invention will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art regarding the description of the present invention.

[0020] The working principle and advantages of the present invention are as follows:

[0021] The present invention provides an integrated insulating protective sleeve for cables outside the nuclear power plant, wherein the inner layer is a tubular structure in which large tow fibers are arranged in a mesh structure, and then a silicone matrix is ​​coated on the outside of the fiber inner layer and irradiated and cross-linked to obtain the insulating protective sleeve body. The fiber inner layer can have a certain elasticity as the silicone matrix is ​​stretched, and can wrap the cable well. After post-processing, an insulating protective sleeve is obtained that is resistant to high temperature and radiation, can be stably wrapped on the surface of the cable, and will not fall off due to long-term operation. The insulating protective sleeve of the present invention can prevent the cable from being directly exposed outside the nuclear power plant, thereby increasing the service life of the cable and avoiding the safety hazards caused by leakage short circuits. At the same time, the insulating protective sleeve of the present invention has longitudinal elasticity, which is convenient for installing cables. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Attached Figure 1 This is a reference diagram of the use state of the insulating protective sleeve of the embodiment of the present invention when it is sleeved on the cable;

[0023] Attached Figure 2 Schematic diagram of the winding direction of the glass fiber line when preparing the fiber inner layer in an embodiment of the present invention.

[0024] In the above figures: 1. Fiber inner layer; 2. Silicone matrix; 3. Cable; D. Winding direction; L. Axial direction. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0026] Embodiment: The present invention will be clearly described below with diagrams and detailed descriptions. After understanding the embodiments of the present invention, any person skilled in the art can make changes and modifications based on the techniques taught by the present invention without departing from the spirit and scope of the present invention.

[0027] The terms used herein are only for describing specific embodiments and are not intended to be limiting of the present invention. Singular forms such as "a", "this", "here", "this" and "the" as used herein also include plural forms.

[0028] A method for preparing an integrated insulating protective sheath for an external cable of a nuclear power plant, comprising:

[0029] Arrange the large tow glass fibers in a mesh structure on the mold to form a tubular fiber inner layer. Set the mixing temperature to 125°C and the rotation speed to 30 r / min. Add 100 parts of phenyl silicone rubber and mix them for 2 minutes. Then add 6 parts of bismuth oxide, 50 parts of white carbon black and 4 parts of KH560 in sequence, add 4 parts of radiation cross-linking sensitizer, and mix them for 5 minutes to obtain a silica gel matrix.

[0030] The prepared silica gel matrix is ​​coated on the inner layer of the fiber with a coating thickness of 8 mm. After coating, a pressure of 0.03 MPa is applied and maintained for 0.5 h before shaping to obtain a prefabricated insulating protective cover.

[0031] The material is irradiated and cross-linked under the beam of an electron accelerator on a conveyor belt to obtain an insulating protective sleeve. The conveyor belt speed is 3 cm / s, the irradiation dose is 120 kGy, and the electron accelerator energy is 2.8 MeV.

[0032] The insulating protective cover of this embodiment was tested, and the test results are shown in Table 1.

[0033] Table 1

[0034]

[0035]

[0036] The life span at different temperatures was tested, see Table 2.

[0037] Table 2

[0038] Operating temperature / K 363 373 393 Service life / year 85.3 35.42 7.09

[0039] It can be seen from the test results of Table 1 and Table 2 that the insulating protective sleeve prepared in the present invention is evaluated by the Arrhenius formula accelerated thermal aging test, and its life at an aging temperature of 120°C exceeds 7 years, and it can pass the 3000kGy gamma ray radiation test, meeting the use requirements.

[0040] like Figure 1 As shown, the fiber inner layer 1 can have a certain degree of elasticity as the silicone matrix 2 is stretched, and can wrap the cable 3 well. After post-processing, an insulating protective sleeve is obtained that is resistant to high temperature and radiation, can be stably wrapped on the surface of the cable 3, and will not fall off due to long-term operation.

[0041] like Figure 2As shown, the winding direction D of the glass fiber line in the fiber inner layer 1 has an angle α with the axial direction L of the tube, and the degree of the angle α is 30-88°. The diameter of the glass fiber line is 2-3 mm, and it is woven from 0.1-0.14 mm glass fiber filaments. The present invention utilizes the good rigidity of glass fiber and adopts an angled winding process to form a mesh structure in order to match the elasticity of the silicone matrix. When the silicone is stretched, the angled mesh structure can be stretched with the silicone, thereby increasing the folding resistance and improving the wear resistance.

[0042] During preparation, the pulling speed of the tubular glass fiber inner layer 1 is 0.5-1.5 m / min. The specific pulling speed can ensure that the glass fiber mesh can be evenly spread and conveniently inserted into the vulcanization mold.

[0043] The insulating protective sleeve of the present invention can prevent the cable from being directly exposed outside the nuclear power plant, thereby increasing the service life of the cable and avoiding the potential safety hazard caused by leakage short circuit. At the same time, the insulating protective sleeve of the present invention has longitudinal retractability, which is convenient for installing the cable.

[0044] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an integrated insulating protective sheath for an external cable of a nuclear power plant, characterized in that: include: Step 1: Prepare the fiber inner layer and the silica gel matrix Arranging glass fiber wires on a mold in a mesh structure to form a tubular fiber inner layer, wherein the winding direction of the glass fiber wires in the fiber inner layer has an angle with the axial direction of the tube, and the degree of the angle is 30-88°; the diameter of the glass fiber wires is 2-3 mm, and they are woven from 0.1-0.14 mm glass fiber yarns; during preparation, the pulling speed of the tubular glass fiber inner layer is 0.5-1.5 m / min; The mixing temperature was set to 125±5℃ and the speed was set to 30±3r / min. 100 parts of phenyl silicone rubber were added and mixed for 2 minutes. Then, 5-10 parts of bismuth oxide, 50 parts of white carbon black, 2-5 parts of KH560 and 2-5 parts of radiation cross-linking sensitizer were added in sequence and mixed for 5 minutes to obtain a silica gel matrix. Step 2: coating the silica gel matrix onto the fiber inner layer, applying a pressure of 0.02-0.06 MPa after coating and maintaining it for 0.5-1 hour to obtain a prefabricated insulating protective sleeve; Step three: irradiating the prefabricated insulating protective sleeve to obtain an integrated insulating protective sleeve for an external cable of a nuclear power plant.

2. The method for preparing an integrated insulating protective sheath for an external cable of a nuclear power plant according to claim 1, characterized in that: Before step three, the prefabricated insulating protective sleeve is first placed flat on the conveyor belt; then the electron accelerator is started to make the electron beam energy and beam current meet the irradiation processing requirements; then the conveyor belt is started, maintaining a speed of 3-5 cm / s, an irradiation dose of 50-300 kGy, and the energy of the electron accelerator is 1-12 MeV; and then step three is performed.

3. The method for preparing an integrated insulating protective sheath for an external cable of a nuclear power plant according to claim 1, characterized in that: In step three, after the irradiation is completed, the irradiated prefabricated insulating protective sleeve is first removed, and after grinding, polishing and trimming, an integrated insulating protective sleeve for the external cable of a nuclear power plant is obtained.

4. The method for preparing an integrated insulating protective sheath for an external cable of a nuclear power plant according to claim 1, characterized in that: In step 1, the radiation cross-linking sensitizer is selected from a combination of one or more of triallyl isocyanurate, trimethylolpropane triacrylate and trimethylolpropane trimethacrylate.

5. The method for preparing an integrated insulating protective sheath for an external cable of a nuclear power plant according to claim 1, characterized in that: In step 2, the thickness of the silica gel matrix coated on the fiber inner layer is 6-8 mm.

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