Method for calculating aging index of XLPE material of cable, and system and method for monitoring aging state of nuclear power plant cable using same

Abstract

A system for monitoring an aging state of a nuclear power plant cable according to one embodiment of the present invention comprises: an aging index calculation unit for calculating an aging index by substituting, as a variable, a spectrum analysis result value representing a molecular structure into an aging index evaluation formula, the spectrum analysis result value being provided by a spectrum analysis unit of an FTIR device that analyzes an infrared absorption spectrum detected after irradiating infrared rays onto a suspected area of a nuclear power plant cable suspected of aging made of XLPE material and detecting infrared rays for measurement passed through the nuclear power plant cable suspected of aging; and an aging state determination unit for evaluating aging of the nuclear power plant cable suspected of aging by comparing the aging index of the suspected area of the nuclear power plant cable suspected of aging calculated by the aging index calculation unit with the aging index of a normal area of the nuclear power plant cable suspected of aging.

Description

Method for calculating the aging index of XLPE cable material, nuclear power plant cable aging state monitoring system and method using the same

[0001] The present invention relates to a method for calculating an aging index of XLPE cable material, a nuclear power plant cable aging state monitoring system and method using the same, and more specifically, to a method for calculating an aging index of XLPE cable material that evaluates cable aging by indexing the molecular structure that increases and the molecular structure concentration that decreases when an XLPE cable deteriorates, and a nuclear power plant cable aging state monitoring system and method using the same.

[0002] As industry develops today, electricity consumption is gradually increasing. Furthermore, facilities are becoming larger in scale and requiring high reliability. Therefore, the stabilization of electrical facilities is a very important task.

[0003] In particular, nuclear power plants using high voltage must also perform cable condition monitoring to assess the degree of cable aging in accordance with government regulations.

[0004] However, there are currently no reliable measurement means or standards to monitor the condition of high-voltage cables in nuclear power plants.

[0005] High-voltage cables used in nuclear power plants consist of a conductor and an insulating material covering the conductor; however, if the insulating material is exposed to moisture and electric fields simultaneously for a long period, deterioration or aging occurs that affects the insulation characteristics of the cable.

[0006] In nuclear power plants, a method is used to evaluate the degradation of specific locations of cables that have been degraded by localized high heat / high radiation, by calculating and analyzing the 'Oxidation Index' using Fourier Transform-Infrared Spectrometry (FTIR) analysis technique. However, there was a problem in that this method was not effective for all materials, especially for XLPE (Cross Linking Polyethylene) material used as insulation for high-voltage cables.

[0007] The present invention was devised to solve these problems, and the objective of the present invention is to provide a method for calculating a cable XLPE material aging index that can evaluate the aging of a cable by indexing the molecular structure that increases and the molecular structure concentration that decreases when an XLPE material cable deteriorates as variables, and a nuclear power plant cable aging state monitoring system using the same.

[0008] A nuclear power plant cable aging state monitoring system according to one embodiment of the present invention comprises: an irradiation device that irradiates infrared rays onto a suspected area of ​​a nuclear power plant cable suspected of aging made of XLPE material; a detection device that detects the measured infrared rays that pass through the nuclear power plant cable suspected of aging made of XLPE material, which are irradiated by the irradiation device; a spectrum analysis unit that analyzes the infrared absorption spectrum output from the detection device; an aging index calculation unit that calculates an aging index by substituting a spectrum analysis result value representing a molecular structure into an aging index evaluation formula as a variable by the spectrum analysis unit; and an aging state determination unit that evaluates the aging of the nuclear power plant cable suspected of aging by comparing the aging index of the suspected area of ​​the nuclear power plant cable suspected of aging calculated by the aging index calculation unit with the aging index of the normal area of ​​the nuclear power plant cable suspected of aging.

[0009] A method for deriving an aging assessment formula for a nuclear power plant cable according to one embodiment of the present invention comprises the steps of: irradiating infrared rays onto an insulating material of XPLE material of a cable suspected of aging in a nuclear power plant used in a nuclear power plant and detecting the FTIR of the infrared rays that have passed through the XPLE material of the cable suspected of aging in the nuclear power plant; analyzing the infrared absorption spectrum; selecting a molecular structure effective for the aging assessment of the cable suspected of aging in the nuclear power plant; and deriving an aging assessment formula for the cable using the selected molecular structure as a variable.

[0010] The above spectrum analysis results represent the absorption rates of specific regions of the increased molecular structure and the decreased molecular structure when the XLPE material of the suspected nuclear power plant aging cable deteriorates, and

[0011] The above aging index evaluation formula is Equation 1, and

[0012] Equation 1)

[0013] Here, A1, A2, and A3 are the absorption rates of specific regions of the increased molecular structure, and B1, B2, and B3 are the absorption rates of specific regions of the decreased molecular structure.

[0014] A method for monitoring the aging state of a nuclear power plant cable according to one embodiment of the present invention comprises the steps of: irradiating infrared rays onto an insulating material of XPLE material of a nuclear power plant cable suspected of aging used in a nuclear power plant and detecting the FTIR of the infrared rays that have passed through the suspected area of ​​the XPLE material of the nuclear power plant cable suspected of aging; analyzing the infrared absorption spectrum; selecting a molecular structure effective for evaluating the aging of the nuclear power plant cable suspected of aging; calculating an aging index by substituting the spectrum analysis result of the selected effective molecular structure as a variable into an aging index evaluation formula; comparing the aging index calculated for the suspected area of ​​the nuclear power plant cable suspected of aging with the aging index calculated for another normal area of ​​the nuclear power plant cable suspected of aging; and, if the difference between the aging index of the suspected area of ​​the nuclear power plant cable suspected of aging and the aging index calculated for another normal area of ​​the nuclear power plant cable suspected of aging is smaller than a predetermined value, periodically measuring the aging index for the same suspected area of ​​the nuclear power plant cable suspected of aging to confirm the trend of change in the aging index.

[0015] The above aging index evaluation formula is Equation 1, and

[0016] Equation 1)

[0017] Here, A1, A2, and A3 are the absorption rates of specific regions of the increased molecular structure, and B1, B2, and B3 may be the absorption rates of specific regions of the decreased molecular structure.

[0018] According to one embodiment of the present invention, a method for calculating a cable XLPE material aging index that can evaluate the aging of a cable by indexing the molecular structure that increases and the molecular structure concentration that decreases when an LPE material cable deteriorates as variables, and a nuclear power plant cable aging state monitoring system using the same are provided, thereby enabling monitoring of the condition of a nuclear power plant cable installed at a nuclear power plant site.

[0019] FIG. 1 is a configuration diagram of a nuclear power plant cable aging condition monitoring system according to one embodiment of the present invention,

[0020] Figure 2 is a graph showing the FTIR measurement waveform results for a nuclear power plant cable,

[0021] FIG. 3 is a flowchart illustrating a method for deriving a nuclear power plant cable aging evaluation formula according to an embodiment of the present invention,

[0022] FIG. 4 is a flowchart illustrating a method for monitoring the aging state of a nuclear power plant cable according to an embodiment of the present invention. and

[0023] FIG. 5 is a nuclear power plant cable aging evaluation formula according to one embodiment of the present invention.

[0024] Hereinafter, a method for evaluating the lifespan of an ultra-high voltage power cable according to the present invention will be described with reference to the attached drawings. In this process, the thickness of lines or the size of components depicted in the drawings may be exaggerated for the sake of clarity and convenience of explanation. Furthermore, the terms described below are defined considering their functions in the present invention, and these may vary depending on the intentions or conventions of the user or operator. Therefore, the definitions of these terms should be based on the content throughout this specification.

[0025] FIG. 1 is a configuration diagram of a nuclear power plant cable aging condition monitoring system according to one embodiment of the present invention.

[0026] As illustrated in FIG. 1, a nuclear power plant cable aging state monitoring system (100) according to one embodiment of the present invention comprises: an infrared absorption spectrometer (101) which is a device that uses a Fourier transform type to measure infrared absorption by irradiating infrared rays of a measurement frequency onto a suspected nuclear power plant aging cable used in a nuclear power plant and suspected of aging; an irradiation device (110) that irradiates infrared rays onto an insulating material of XPLE material of a suspected nuclear power plant aging cable used in a nuclear power plant; a detection device (130) that detects infrared rays that have passed through the XPLE material of the suspected nuclear power plant aging cable through the irradiation device (110); a spectrum analysis unit (150) that performs a Fourier transform on a signal input from the detection device (130) to output an infrared absorption spectrum and analyzes the output infrared absorption spectrum; an aging index calculation unit (170) that calculates an aging index using an aging index evaluation formula that evaluates the aging of the suspected nuclear power plant aging cable using the spectrum analysis result value of the spectrum analysis unit (150) as a variable; and the aging index It includes an aging state determination unit (190) that evaluates the aging of the suspected aging cable by comparing the aging index calculated through the calculation unit (170) with the aging index calculated using the aging index evaluation formula for the normal region of the suspected aging cable.

[0027] FIG. 2 shows the result of analyzing the result of irradiating infrared rays onto a suspected aging nuclear power cable using the irradiation device (110) in a nuclear power cable aging condition monitoring system (100) according to one embodiment of the present invention through the spectrum analysis unit (150).

[0028] As shown in Figure 2 and [Table 1], it was found that when the XLPE material of the suspected nuclear power plant aging cable deteriorates, the absorption rate (740 cm-1, 1395 cm-1, 1771 cm-1) in specific areas of A1, A2, and A3 increases, and the absorption rate (1239 cm-1, 1466 cm-1, 1738 cm-1) in specific areas of B1, B2, and B3 decreases.

[0029]

[0030] This indicates that when XLPE material undergoes thermal or high-radiation degradation, there are molecular structures that absorb specific infrared rays and, as a result of FTIR spectrum analysis, increase and decrease.

[0031] Accordingly, the method for calculating the aging index of a cable XLPE material according to one embodiment of the present invention selects molecular structures effective for cable aging evaluation (molecular structures that increase when deteriorated and molecular structures that decrease) from the FTIR measurement results of the XLPE material of the nuclear power plant aged cable, and calculates the cable aging evaluation equation for cable aging evaluation by configuring the selected structures as variables as shown in Equation 1 and Fig. 5.

[0032] Equation 1)

[0033] Now, with reference to FIG. 3, a method for calculating the aging index of a cable XLPE material according to one embodiment of the present invention will be explained in more detail.

[0034] FIG. 3 is a flowchart illustrating a method for deriving a nuclear power plant cable aging evaluation formula according to one embodiment of the present invention.

[0035] As illustrated in FIG. 3, a method for deriving an aging evaluation formula for a nuclear power plant cable according to one embodiment of the present invention may include the steps of: irradiating infrared rays onto an insulating material of XPLE material of a nuclear power plant cable suspected of aging used in a nuclear power plant and detecting the FTIR of the infrared rays that have passed through the XPLE material of the nuclear power plant cable suspected of aging (S310); analyzing the infrared absorption spectrum (S320); selecting a molecular structure effective for the aging evaluation of the nuclear power plant cable suspected of aging (S330); and deriving an aging evaluation formula for the cable using the selected molecular structure as a variable (S340).

[0036] The step (S330) of selecting molecular structures effective for the aging evaluation of the above-mentioned suspected nuclear power plant aging cable may include the step of selecting molecular structures in which the peak value of the infrared absorption spectrum increases and molecular structures in which it decreases.

[0037] More specifically, as shown in FIG. 2, the absorption rates of specific regions of A1, A2, and A3 in the measured waveform of the infrared absorption spectrum (740 cm-1, 1395 cm-1, 1771 cm-1) can be increased and the absorption rates of specific regions of B1, B2, and B3 (1239 cm-1, 1466 cm-1, 1738 cm-1) can be decreased and the molecular structures can be selected.

[0038] The step (S340) of deriving an aging evaluation formula for a cable using selected molecular structures as variables is

[0039] The aging evaluation formula of Equation 1 can be derived using the Y-axis values ​​corresponding to the red (A1, A2, A3) and blue (B1, B2, B3) bars in the measurement waveform of Fig. 2, that is, the absorption rate, which is the peak value of the infrared absorption spectrum.

[0040] Now, with reference to FIGS. 4 and 5, a method for monitoring the aging state of a nuclear power plant cable using a cable XLPE material aging index according to one embodiment of the present invention will be described in detail.

[0041] FIG. 4 is a flowchart illustrating a method for monitoring the aging state of a nuclear power plant cable according to an embodiment of the present invention. FIG. 5 is a formula for evaluating the aging of a nuclear power plant cable according to an embodiment of the present invention.

[0042] As illustrated in FIG. 4, a method for monitoring the aging state of a nuclear power plant cable according to an embodiment of the present invention comprises the steps of: irradiating infrared rays onto an insulating material of XPLE material of a nuclear power plant cable suspected of aging used in a nuclear power plant using an irradiation device (100), detecting the FTIR that has passed through the XPLE material of the nuclear power plant cable suspected of aging using a detection device (130), and analyzing the output infrared absorption spectrum using a spectrum analysis unit (150) (S410); selecting a valid molecular structure from the output infrared absorption spectrum (S420); calculating an aging index by substituting the spectrum analysis result value selected through the spectrum analysis unit (150) into the aging index evaluation formula through an aging index calculation unit (170) using the value as a variable (S430); comparing and analyzing the aging index calculated through the aging index calculation unit (170) with the aging index calculated using the aging index evaluation formula for the normal region of the cable suspected of aging (S440); and the aging index A step (S450) of comparing and analyzing the aging index calculated through the calculation unit (170) with the aging index calculated using the aging index evaluation formula for the normal area of ​​the cable suspected of aging, and if the difference in aging index is smaller than a predetermined value, periodically measuring the aging index for the same location of the same cable suspected of aging to check the trend of change in the aging index;

[0043] The method may include a step (S460) of determining the cable suspected of aging as an aged cable if, as a result of comparing and analyzing the aging index calculated through the aging index calculation unit (170) with the aging index calculated using the aging index evaluation formula for the normal region of the cable suspected of aging, the difference in aging index is greater than a predetermined value.

[0044] The step (S420) of selecting valid molecular structures from the above-mentioned infrared absorption spectrum can be performed by utilizing cases where the absorption rate of a specific region increases or the absorption rate of a specific region decreases.

[0045] This indicates that when XLPE material undergoes thermal or high-radiation degradation, there are molecular structures that absorb specific infrared rays and, as a result of FTIR spectrum analysis, increase and decrease.

[0046] In the step (S430) of calculating the aging index by substituting into the above aging index evaluation formula, the cable aging evaluation formula is as follows, and it can be seen that the Y-axis values ​​corresponding to the red (A1, A2, A3) and blue (B1, B2, B3) bars in the measurement waveform, i.e., the absorption rate which is the peak value of the infrared absorption spectrum, are substituted as variables.

[0047] Equation 1)

[0048]

[0049] According to one embodiment of the present invention, a method for calculating a cable XLPE material aging index that can evaluate the aging of a cable by indexing the molecular structure that increases and the molecular structure concentration that decreases when an LPE material cable deteriorates as variables, and a nuclear power plant cable aging state monitoring system using the same are provided, thereby enabling monitoring of the condition of a nuclear power plant cable installed at a nuclear power plant site.

Claims

1. An irradiation device that irradiates infrared rays onto a suspected area of ​​an XLPE cable suspected of nuclear aging; A detection device that detects the measured infrared radiation irradiated by the above-mentioned irradiation device and passes through the above-mentioned XLPE material cable suspected of nuclear aging; A spectrum analysis unit that analyzes the infrared absorption spectrum output from the above detection device; An aging index calculation unit that calculates an aging index by substituting a spectrum analysis result value representing a molecular structure, obtained by the spectrum analysis unit above, into an aging index evaluation formula as a variable; and A nuclear power plant cable aging state monitoring system comprising an aging state determination unit that evaluates the aging of a nuclear power plant cable suspected of aging by comparing the aging index of the suspected region of the nuclear power plant cable suspected of aging, calculated by the aging index calculation unit, with the aging index of the normal region of the nuclear power plant cable suspected of aging.

2. In Paragraph 1, The above spectrum analysis result is a nuclear power plant cable aging state monitoring system, which is the absorption rate of a specific region of the increased molecular structure and the absorption rate of a specific region of the decreased molecular structure when the XLPE material of the suspected nuclear power plant aging cable deteriorates.

3. In Paragraph 1, The above aging index evaluation formula is Equation 1, and Equation 1) Here, A1, A2, and A3 are absorption rates of specific regions of increased molecular structures, and B1, B2, and B3 are absorption rates of specific regions of decreased molecular structures, in a nuclear power plant cable aging condition monitoring system.

4. A step of irradiating infrared rays onto an insulating material made of XPLE material of a suspected aging cable used in a nuclear power plant, and detecting the FTIR of the infrared rays that have passed through the XPLE material of the suspected aging cable; Step of analyzing the infrared absorption spectrum; A step of selecting a molecular structure effective for the aging evaluation of the above-mentioned cable suspected of nuclear power plant aging; A method for deriving an aging evaluation formula for nuclear power plant cables, comprising the step of deriving an aging evaluation formula for cables using the selected molecular structure as a variable.

5. In Paragraph 4, The above spectrum analysis result is a method for deriving a nuclear power plant cable aging evaluation formula, which is the absorption rate of a specific region of the increased molecular structure and the absorption rate of a specific region of the decreased molecular structure when the XLPE material of the nuclear power plant cable suspected of aging deteriorates.

6. In Paragraph 5, The above aging index evaluation formula is Equation 1, and Equation 1) A method for deriving a nuclear power plant cable aging evaluation formula, wherein A1, A2, and A3 are absorption rates of specific regions of increased molecular structures, and B1, B2, and B3 are absorption rates of specific regions of decreased molecular structures.

7. A step of irradiating infrared rays onto an XPLE insulating material of a suspected aging cable used in a nuclear power plant, and detecting the FTIR of the infrared rays that have passed through the suspected XPLE material of the suspected aging cable; Step of analyzing the infrared absorption spectrum; Step of selecting molecular structures effective for the aging assessment of the above-mentioned nuclear power plant cable suspected of aging A step of calculating an aging index by substituting the spectrum analysis result of the selected valid molecular structure above into an aging index evaluation formula as a variable; A step of comparing an aging index calculated for a suspected region of the above-mentioned cable suspected of nuclear power plant aging with an aging index calculated for another normal region of the above-mentioned cable suspected of nuclear power plant aging; and A method for monitoring the aging state of a nuclear power plant cable, comprising the step of periodically measuring the aging index for the same suspected area of ​​the nuclear power plant cable to check the trend of change in the aging index, if the difference between the aging index of the suspected area of ​​the nuclear power plant cable suspected of aging and the aging index calculated for another normal area of ​​the nuclear power plant cable suspected of aging is smaller than a predetermined value.

8. In Paragraph 7, The above aging index evaluation formula is Equation 1, and Equation 1) A method for monitoring the aging state of nuclear power plant cables, wherein A1, A2, and A3 are absorption rates of specific regions of increased molecular structures, and B1, B2, and B3 are absorption rates of specific regions of decreased molecular structures.

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