CN114252169A - Temperature monitoring optical fiber sensing system of nuclear power fluctuation pipe and monitoring method thereof - Google Patents
Temperature monitoring optical fiber sensing system of nuclear power fluctuation pipe and monitoring method thereof Download PDFInfo
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- 239000013307 optical fiber Substances 0.000 title claims abstract description 112
- 238000012544 monitoring process Methods 0.000 title claims abstract description 23
- 238000000034 method Methods 0.000 title claims description 10
- 230000003287 optical effect Effects 0.000 claims abstract description 47
- 238000009529 body temperature measurement Methods 0.000 claims abstract description 31
- 238000001069 Raman spectroscopy Methods 0.000 claims abstract description 21
- 230000005855 radiation Effects 0.000 claims abstract description 16
- 239000000835 fiber Substances 0.000 claims description 31
- 230000005865 ionizing radiation Effects 0.000 claims description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 6
- 238000009413 insulation Methods 0.000 claims description 4
- 238000000149 argon plasma sintering Methods 0.000 claims description 3
- 238000005253 cladding Methods 0.000 claims description 3
- 239000011248 coating agent Substances 0.000 claims description 3
- 238000000576 coating method Methods 0.000 claims description 3
- 235000012239 silicon dioxide Nutrition 0.000 claims description 3
- 239000000377 silicon dioxide Substances 0.000 claims description 3
- 238000005259 measurement Methods 0.000 abstract description 11
- 238000013517 stratification Methods 0.000 abstract description 9
- 239000002826 coolant Substances 0.000 description 6
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 4
- 239000003381 stabilizer Substances 0.000 description 4
- 238000005452 bending Methods 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 238000000691 measurement method Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000008646 thermal stress Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000004441 surface measurement Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
- G01K11/324—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres using Raman scattering
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Abstract
The invention discloses a temperature monitoring optical fiber sensing system of a nuclear power fluctuation tube, which comprises a temperature measuring optical fiber, a demodulator and a computer which are connected in sequence; the temperature measurement optical fiber is arranged in a loop form along the surface of the surge tube, two ends of the temperature measurement optical fiber are respectively connected with two ends of an optical switch in the demodulator, the optical switch enables light to respectively enter the temperature measurement optical fiber from the clockwise direction and the anticlockwise direction through switching, and the computer performs geometric mean value calculation on the backward Raman scattering light intensity ratio of the clockwise direction and the anticlockwise direction so as to obtain the real-time temperature of the surface of the surge tube. The invention can realize real-time continuous measurement of the temperature of the fluctuation pipe by adopting the temperature measurement optical fiber, and effectively monitor the temperature stratification phenomenon of the whole fluctuation pipe. The optical fiber sensor is anti-electromagnetic interference, miniaturized, uncharged and intrinsically safe; the special optical fiber with radiation resistance and high temperature resistance is adopted, so that the reliability is higher in the application of a nuclear power plant; the temperature measurement error of the optical fiber sensor in the irradiation field is calibrated, and the measurement precision is effectively improved.
Description
Technical Field
The invention relates to the field of process parameter measurement of a reactor coolant system of a nuclear power plant, in particular to a temperature monitoring optical fiber sensing system of a nuclear power fluctuation pipe and a monitoring method thereof.
Background
In the nuclear power device, a fluctuation pipe is connected with a reactor main pipeline hot section and a voltage stabilizer and is a main transmission channel for controlling the pressure of a loop system by the voltage stabilizer. In the operation process of the reactor, the temperature difference between the pressure stabilizer and the coolant in the hot section of the main pipeline is obvious, the fluid from the hot section of the main pipeline is low in temperature and high in density and occupies the lower part of the surge pipe, and the fluid from the pressure stabilizer is high in temperature and low in density and occupies the upper part of the surge pipe. Because the wave tube is provided with a section of approximately horizontal tube section, the flowing speed of the coolant in the wave tube is low, the coolant exchanges heat only under the action of natural convection, the coolant with different temperatures is not fully mixed, and then a larger temperature difference is generated to form heat stratification, the temperature stratification of the coolant in the wave tube can cause the temperature stratification of the tube wall, and the radial direction and the axial direction of the wave tube generate total bending thermal stress and local thermal stress to threaten the structural integrity of the wave tube.
Currently, the stratification of the surge tube temperature is measured using a platinum resistance thermometer mounted on the surge tube surface. The disadvantage of this measurement method is that the thermometer can only realize single-point measurement, and the thermal stratification is distributed on the whole wave tube, so that it can not be monitored completely, if more thermometers are arranged, the complexity and cost of the system will be increased correspondingly, and the heat-insulating layer is damaged, and the heat-insulating effect of the system will also be deteriorated.
Disclosure of Invention
The invention aims to solve the technical problems that more thermometers are arranged when the whole wave tube is comprehensively monitored in the prior art, the complexity and the cost of a system are increased, a heat insulation layer is damaged, and the heat insulation performance of the system is influenced.
The invention is realized by the following technical scheme:
the first realization method is that the temperature monitoring optical fiber sensing system of the nuclear power fluctuation tube comprises a temperature measuring optical fiber, a demodulator and a computer which are connected in sequence; the temperature measurement optical fiber is arranged in a loop form along the surface of the surge tube, two ends of the temperature measurement optical fiber are respectively connected with two ends of an optical switch in the demodulator, the optical switch enables light to respectively enter the temperature measurement optical fiber from the clockwise direction and the anticlockwise direction through switching, and the computer carries out geometric mean value calculation on the backward Raman scattering light intensity ratio of the clockwise direction and the anticlockwise direction so as to obtain the real-time temperature of the surface of the surge tube.
According to the invention, the temperature measurement optical fiber is arranged on the surface of the surge tube in a loop form, and the real-time temperature of the surface of the surge tube is calculated by calculating the geometric mean value of the intensity ratio of the backward Raman scattering light in the clockwise direction and the counterclockwise direction in the temperature measurement optical fiber. The temperature measuring optical fiber adopted by the invention has the characteristics of high temperature resistance and radiation resistance, and is arranged on the surface of the surge tube, so that the surge tube is not damaged, the temperature of the whole surge tube can be monitored in real time, and the real-time monitoring of the surge tube is realized with a simple structure and low cost. The optical loop directions comprise clockwise and anticlockwise loop directions, so that the influence of different loss coefficients of anti-Stokes light and Stokes light in an irradiation environment on temperature measurement precision is fully eliminated, and the measured surface temperature of the wave tube is more accurate and closer to the actual dynamic temperature of the wave tube.
Further, the optical switch is a 1 × 2 optical switch, and the 1 × 2 optical switch makes light enter the temperature measuring optical fiber in the clockwise direction and the counterclockwise direction respectively under the control of the computer.
Furthermore, the optical switch switches according to a time sequence, so that light enters the temperature measuring optical fiber from the clockwise direction and the anticlockwise direction respectively.
Furthermore, the number of the temperature measuring optical fibers is two, and the optical switch simultaneously enables light to enter one temperature measuring optical fiber from the clockwise direction and enter the other temperature measuring optical fiber from the anticlockwise direction.
Furthermore, the temperature measuring optical fiber adopts a special radiation-resistant high-temperature-resistant multimode optical fiber.
Furthermore, the fiber core of the multimode fiber is pure silica, and the cladding is fluorine-doped silica.
Furthermore, the coating of the multimode optical fiber is made of metal.
Furthermore, the temperature measuring optical fiber is arranged on the inner surface of the heat-insulating layer of the surge tube, the temperature measuring optical fiber is positioned in the ionizing radiation field, the demodulator is positioned between the primary instruments, and the computer is positioned in the control room. The temperature measuring optical fiber is arranged on the surface of the fluctuation tube, namely the temperature measuring optical fiber is positioned in a nuclear power reactor factory building, namely an ionizing radiation field, the demodulator connected with the temperature measuring optical fiber is positioned between primary instruments with weaker irradiation intensity, and the computer in communication connection with the demodulator is positioned in a human movable control room. The irradiation intensity of the control room, the primary instrument room and the fluctuation pipe is sequentially enhanced.
In a second implementation manner of the invention, a temperature measuring optical fiber is arranged along the surface of a fluctuation tube, two ends of the temperature measuring optical fiber are respectively connected with two ends of an optical switch in a demodulator, the optical switch enables light to respectively enter the temperature measuring optical fiber from clockwise and anticlockwise directions through switching, a computer performs geometric mean calculation on the ratio of the intensity of backward Raman scattered light in the clockwise direction and the anticlockwise direction, and the real-time temperature of the surface of the fluctuation tube is obtained by combining the temperature of a reference optical fiber in the demodulator.
Furthermore, two ends of the optical switch are respectively provided with a first end point and a second end point, the light pulse 1 emitted by the light source enters the temperature measuring optical fiber from the first end point along the clockwise direction, and the anti-stokes light-to-stokes light intensity ratio at the position with the distance L from the first end point is obtained, namely the backward Raman scattering light intensity ratio R in the clockwise direction1(T)；
Kas，KsAnti-stokes light and stokes light scattering cross section coefficients respectively; v. ofas，vsRespectively anti-stokes light and stokes light frequencies, wherein delta v is a Raman frequency offset, and h is a Planck constant; k is Boltzmann constant; alpha is alphaas，αsThe radiation loss coefficients of the anti-stokes light and the stokes light respectively; t is the thermodynamic temperature value at L;
then the optical switch is switched to the second end point to enable the optical pulse 2 emitted by the light source to enter the temperature measuring optical fiber along the anticlockwise direction to obtain the light intensity ratio of the anti-Stokes light to the Stokes light at the L position, namely the backward Raman scattered light intensity ratio R in the anticlockwise direction2(T)；
Wherein Z is the total length of the temperature measuring optical fiber;
r is obtained1(T) and R2The geometric mean of (T) is:
the ratio of the light intensity at the reference fiber is:
T0is the temperature at the reference fiber inside the demodulator;
r (T) and R (T)0) The temperature expression on the temperature measuring optical fiber obtained by the division is as follows:
t is the thermodynamic temperature value at L, which is calculated from the time of the return of the backward raman scattered light, i.e., L ═ vt/2, T is the time from the light emitted by the light source to the light received by the demodulator, and v is the speed at which the light propagates in the optical fiber.
Compared with the prior art, the invention has the following advantages and beneficial effects:
the invention can realize real-time continuous measurement of the temperature of the surge tube by adopting one or two temperature measuring optical fibers, and effectively monitor the temperature stratification phenomenon of the whole surge tube; the optical fiber sensor is anti-electromagnetic interference, miniaturized, uncharged and intrinsically safe; the special optical fiber with radiation resistance and high temperature resistance is adopted, so that the reliability is high in the application of a nuclear power plant; the temperature measurement error of the optical fiber sensor in the irradiation field is calibrated, and the measurement precision is effectively improved.
Drawings
In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and that for those skilled in the art, other related drawings can be obtained from these drawings without inventive effort. In the drawings:
fig. 1 is a schematic structural diagram of an embodiment of the present invention.
Reference numbers and corresponding part names in the drawings:
1-temperature measuring optical fiber, 2-wave tube, 3-demodulator, 4-computer and 5-1X 2 optical switch.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.
Example 1
A temperature monitoring optical fiber sensing system of a nuclear power surge pipe comprises a temperature measuring optical fiber 1, a demodulator 3 and a computer 4 which are connected in sequence; temperature measurement optic fibre 1 arranges to the loop form along the surge tube 2 surface, and temperature measurement optic fibre both ends are connected with photoswitch 5 both ends in the demodulator 3 respectively, and light gets into temperature measurement optic fibre 1 from clockwise and anticlockwise respectively, and computer 4 carries out the geometric mean value to clockwise and anticlockwise backward raman scattered light intensity ratio and calculates and obtain the real-time temperature on surge tube 2 surface. In this embodiment 1, the temperature measuring optical fiber 1 is arranged on the surface of the surge tube 2 in a loop form, and the real-time temperature of the surface of the surge tube 2 is estimated by calculating the geometric mean value of the ratio of the intensity of the backward raman scattering light in the temperature measuring optical fiber 1 in the clockwise direction and the counterclockwise direction. The temperature measurement optical fiber 1 adopted in this embodiment 1 has the characteristics of high temperature resistance and radiation resistance, and is arranged on the surface of the surge tube 2, so that the surge tube 2 is not damaged, the temperature of the whole surge tube 2 can be monitored in real time, and the real-time monitoring of the surge tube 2 is realized with a simple structure and at low cost. And the optical loop direction of this embodiment 1 includes two clockwise and anticlockwise loop directions, fully eliminates the influence that the loss coefficient difference of anti-stokes light and stokes light under the irradiation environment causes the temperature measurement precision, makes the temperature of the ripple tube 2 that measures more accurate, more closely to the actual dynamic temperature of the ripple tube 2.
In a possible embodiment, the temperature measuring optical fiber 1 is a special multimode optical fiber with radiation resistance and high temperature resistance. In this embodiment, the core of the multimode fiber is pure silica, and the cladding is fluorine-doped silica. The coating is made of metal.
In a possible embodiment, the temperature measuring optical fiber 1 is arranged on the inner surface of the insulating layer of the surge tube 2, so that the measured value is closer to the actual temperature of the surge tube, the temperature measuring optical fiber 1 is positioned in an ionizing radiation field, the demodulator 3 is positioned between the primary instruments, and the computer 4 is positioned in a control room. The temperature measuring optical fiber 1 is arranged on the surface of the fluctuation pipe 2, namely the temperature measuring optical fiber 1 is positioned in a reactor factory, namely an ionizing radiation field, the demodulator 3 connected with the temperature measuring optical fiber 1 is positioned between primary instruments with weaker irradiation intensity, and the computer 4 in communication connection with the demodulator 3 is positioned in a human movable control room. The irradiation intensity of the control room, the primary instrument room and the fluctuation pipe 2 is sequentially enhanced.
In a possible embodiment, the temperature measuring fiber 1 is one, and a 1 × 2 optical switch 5 is disposed in the demodulator 3, and the 1 × 2 optical switch 5 is used for switching the optical path direction in the temperature measuring fiber 1. The 1X 2 optical switch 5 is used for switching the optical path direction in the temperature measuring optical fiber 1, the 1X 2 optical switch 5 can switch the optical path direction in the temperature measuring optical fiber 1 from the clockwise direction to the anticlockwise direction, then from the anticlockwise direction to the clockwise direction, and then according to the backward Raman scattering light intensity conditions of the clockwise direction and the anticlockwise direction, the real-time temperature of the wave tube 2 is monitored.
In a possible embodiment, there are two thermometric optical fibers 1, and a 1 × 2 optical switch 5 is disposed in the demodulator 3, and the 1 × 2 optical switch 5 is used for switching the optical path directions in the two thermometric optical fibers 1. The light path direction in one temperature measuring optical fiber 1 is switched to the clockwise direction through the 1 multiplied by 2 optical switch 5, the light path direction in the other temperature measuring optical fiber 1 is switched to the anticlockwise direction, and the two directions in the two temperature measuring optical fibers can simultaneously measure the intensity condition of backward Raman scattered light and monitor the real-time temperature of the fluctuation tube 2.
Example 2
In this embodiment 2, on the basis of embodiment 1, the defect that the conventional measurement method cannot perform comprehensive and continuous measurement on the temperature stratification of the surge tube is overcome, and a distributed optical fiber temperature sensing system for monitoring the temperature field of the surge tube of the nuclear power plant is provided, which can perform continuous measurement on the surface temperature of the pipeline by using a special radiation-resistant and high-temperature-resistant multimode optical fiber and calibrate the temperature measurement error of the optical fiber sensor in the radiation environment, thereby realizing continuous and accurate monitoring of the temperature field of the surge tube 2 and effectively improving the safety of the nuclear power plant.
Specifically, as shown in fig. 1, the present embodiment includes a temperature measuring optical fiber 1, a demodulator 3, and a computer 4, where the temperature measuring optical fiber 1 is connected to the computer 4 through the demodulator 3. Wherein, the temperature measuring optical fiber 1 is a special multimode optical fiber with radiation resistance and high temperature resistance, the optical fiber is fixed (for example, welded) on the upper surface and the lower surface of the surge tube 2 to form a loop form, and the whole optical fiber is arranged on the inner surface of the heat insulation layer of the surge tube 2; a 1 multiplied by 2 optical switch 5 is embedded in the demodulator 3, and the optical switch controls the incident light to enter the temperature measuring optical fiber 1 from the end point I of the temperature measuring optical fiber 1 clockwise and then enter the temperature measuring optical fiber 1 from the end point II anticlockwise; an optical switch is arranged in the demodulator 3, the temperature measuring optical fibers are arranged in a loop form, two paths of signals which clockwise enter the temperature measuring optical fibers and anticlockwise enter the temperature measuring optical fibers are used as a geometric average value, and the average value can eliminate loss caused by irradiation, optical fiber bending and the like.
The computer 4 calculates the geometric mean value of the ratio of the intensity of the backward Raman scattered light of the clockwise path and the anticlockwise path, and the mean value is only related to the temperature and is not related to the irradiation attenuation, thereby eliminating the problem that the irradiation causes the temperature measurement precision to be deteriorated. The temperature measurement optical fiber 1 is arranged on a fluctuation tube 2 in a reactor factory building, and the problem of temperature measurement precision deterioration caused by ionizing radiation and radiation is solved by adopting a special optical fiber and a calibration method. The demodulator 3 is placed between the primary instruments, the computer 4 is placed in the control room, and neither the demodulator 3 nor the computer 4 can bear ionizing radiation.
Example 3
In this embodiment 3, based on embodiment 2, a method for monitoring a temperature of a nuclear power fluctuation tube includes switching a 1 × 2 optical switch 5 to a first endpoint of a temperature measurement optical fiber 1, emitting an optical pulse 1 from a light source into the temperature measurement optical fiber 1 from the first endpoint in a clockwise direction, obtaining a total length Z of the temperature measurement optical fiber 1, and obtaining an anti-stokes light-to-stokes light intensity ratio R at a distance L from the first endpoint1(T)：
Wherein, Kas，KsAnti-stokes light and stokes light scattering cross section coefficients respectively; v. ofas，vsRespectively anti-stokes light and stokes light frequencies, wherein delta v is a Raman frequency offset, and h is a Planck constant; k is Boltzmann constant; alpha is alphaas，αsThe radiation loss coefficients of the anti-stokes light and the stokes light respectively; t is the thermodynamic temperature value at L.
Then the optical switch is switched to the second end point to enable the optical pulse 2 emitted by the light source to enter the temperature measuring optical fiber 1 along the anticlockwise direction to obtain the light intensity ratio R of the anti-Stokes light to the Stokes light at the L position2(T)：
R is obtained1(T) and R2The geometric mean of (T) is:
since Z is the total length of the temperature measuring fiber 1, Z is constant, so exp [ - (α)as-αs)Z]L is the same as any point on the thermometric optical fiber 1, that is, the position on the fiber where Raman scattering occurs, and R (T) is temperature dependent and radiation attenuation independent.
Let T be the temperature at the reference fiber inside the demodulator 30The ratio of the light intensity at the reference fiber is
R (T) and R (T)0) The temperature expression on the temperature measuring optical fiber 1 obtained by the division is as follows:
in non-irradiation environment, alpha is not consideredas、αsIs considered to be aasAnd alphasEqual, i.e. exp [ - (alpha)as-αs)Z]Is 1. But alpha under irradiation environmentasAnd alphasThe difference is large, the two can not be considered to be equal, the embodiment considers the difference of loss coefficients of anti-Stokes light and Stokes light in the irradiation environment, calibrates the temperature measurement error of the optical fiber sensor in the irradiation field, and effectively improves the measurement precision.
Compared with the traditional mode of measuring the temperature of the fluctuation tube 2 by using a platinum resistance thermometer, the real-time continuous measurement of the temperature of the pipeline can be realized by using one temperature measuring optical fiber 1 in the embodiment 3, and the temperature stratification phenomenon of the whole fluctuation tube 2 is effectively monitored. The optical fiber sensor is anti-electromagnetic interference, miniaturized, uncharged and intrinsically safe. The special optical fiber with radiation resistance and high temperature resistance is adopted, and the reliability is higher when the optical fiber is applied to a nuclear power plant. By calculating the geometric mean value of the light intensity ratio of the anti-Stokes light to the Stokes light in the clockwise direction and the anticlockwise direction, the temperature measurement error caused by the difference of the loss coefficients of the anti-Stokes light and the Stokes light is eliminated, and the measurement precision is effectively improved.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. A temperature monitoring optical fiber sensing system of a nuclear power fluctuation tube is characterized by comprising a temperature measuring optical fiber, a demodulator and a computer which are sequentially connected; the temperature measurement optical fiber is arranged in a loop form along the surface of the surge tube, two ends of the temperature measurement optical fiber are respectively connected with two ends of an optical switch in the demodulator, the optical switch enables light to respectively enter the temperature measurement optical fiber from the clockwise direction and the anticlockwise direction through switching, and the computer carries out geometric mean value calculation on the backward Raman scattering light intensity ratio of the clockwise direction and the anticlockwise direction so as to obtain the real-time temperature of the surface of the surge tube.
2. The fiber optic nuclear power surge tube temperature monitoring sensing system according to claim 1, wherein the optical switch is a 1 x 2 optical switch, and the 1 x 2 optical switch makes light enter the temperature measuring fiber in clockwise and counterclockwise directions under the control of a computer.
3. The fiber optic nuclear power surge tube temperature monitoring sensing system according to claim 2, wherein the temperature measuring fiber is one, and the optical switch is switched in time sequence to allow light to enter the temperature measuring fiber from clockwise and counterclockwise directions, respectively.
4. The fiber optic nuclear power surge tube temperature monitoring sensing system according to claim 2, wherein there are two temperature measuring fibers, and the optical switch simultaneously directs light into one temperature measuring fiber from a clockwise direction and the other temperature measuring fiber from a counterclockwise direction.
5. The nuclear power surge tube temperature monitoring optical fiber sensing system as claimed in claim 1, wherein the temperature measuring optical fiber is a special multimode optical fiber with radiation resistance and high temperature resistance.
6. The nuclear power surge tube temperature monitoring fiber optic sensing system of claim 5, wherein the core of the multimode fiber is pure silica and the cladding is fluorine-doped silica.
7. The nuclear power surge tube temperature monitoring fiber optic sensing system of claim 5, wherein the coating of the multimode fiber is metallic.
8. The system of claim 1, wherein the temperature measuring fiber is disposed on the inner surface of the thermal insulation layer of the surge tube, the temperature measuring fiber is located in the ionizing radiation field, the demodulator is located between the primary instruments, and the computer is located in the control room.
9. A temperature monitoring method for a nuclear power fluctuation tube is characterized in that temperature measuring optical fibers are arranged along the surface of the fluctuation tube, two ends of each temperature measuring optical fiber are respectively connected with two ends of an optical switch in a demodulator, the optical switch enables light to respectively enter the temperature measuring optical fibers from the clockwise direction and the anticlockwise direction through switching, a computer carries out geometric mean value calculation on the ratio of the backward Raman scattering light intensity of the clockwise direction and the anticlockwise direction, and the real-time temperature of the surface of the fluctuation tube is obtained by combining the temperature of a reference optical fiber in the demodulator.
10. The method for monitoring the temperature of the nuclear power fluctuation tube according to claim 9, wherein the two ends of the optical switch are respectively an endpoint one and an endpoint two, the light source emits the light pulse 1 to enter the temperature measurement optical fiber from the endpoint one along the clockwise direction, and the anti-stokes light intensity ratio and the stokes light intensity ratio at the position where the distance from the endpoint one is L, namely the clockwise backward raman scattered light intensity ratio R1(T)；
Kas，KsAnti-stokes light and stokes light scattering cross section coefficients respectively; v. ofas，vsRespectively anti-stokes light and stokes light frequencies, wherein delta v is a Raman frequency offset, and h is a Planck constant; k is Boltzmann constant; alpha is alphaas，αsThe radiation loss coefficients of the anti-stokes light and the stokes light respectively; t is the thermodynamic temperature value at L;
then the optical switch is switched to the second end point to enable the optical pulse 2 emitted by the light source to enter the temperature measuring optical fiber along the anticlockwise direction to obtain the light intensity ratio of the anti-Stokes light to the Stokes light at the L position, namely the backward Raman scattered light intensity ratio R in the anticlockwise direction2(T)；
Wherein Z is the total length of the temperature measuring optical fiber;
r is obtained1(T) and R2The geometric mean of (T) is:
the ratio of the light intensity at the reference fiber is:
T0is the temperature at the reference fiber inside the demodulator;
r (T) and R (T)0) And (3) dividing to obtain a temperature expression at the position L on the temperature measurement optical fiber as follows:
t is the thermodynamic temperature value at L, which is calculated from the time of the return of the backward raman scattered light, i.e., L ═ vt/2, T is the time from the light emitted by the light source to the light received by the demodulator, and v is the speed at which the light propagates in the optical fiber.
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|---|---|---|---|---|
| WO2004074821A1 (en) * | 2003-02-20 | 2004-09-02 | Sensor Highway Limited | Temperature compensation to an optical fibre sensor for measuring moisture |
| CN105043586A (en) * | 2015-05-28 | 2015-11-11 | 华中科技大学 | Few-mode fiber based Raman distributed temperature measurement system and temperature measurement method |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004074821A1 (en) * | 2003-02-20 | 2004-09-02 | Sensor Highway Limited | Temperature compensation to an optical fibre sensor for measuring moisture |
| CN105043586A (en) * | 2015-05-28 | 2015-11-11 | 华中科技大学 | Few-mode fiber based Raman distributed temperature measurement system and temperature measurement method |
Non-Patent Citations (2)
| Title |
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| 向美琼 等: "光纤传感技术在核电厂的应用研究", 自动化仪表, vol. 40, no. 6, 30 June 2019 (2019-06-30), pages 132 - 136 * |
| 王志强;孙启昌;: "分布式光纤温度检测技术在气体管道泄漏检测中的应用探讨", 石油工程建设, no. 1, 17 May 2009 (2009-05-17), pages 77 - 80 * |
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