JP2007163209A - Nuclear reactor output distribution measuring system and nuclear reactor output distribution measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nuclear reactor output distribution measuring system for full-time measurement having a simple and easy-to-replace structure and a nuclear reactor output distribution measuring method. <P>SOLUTION: This nuclear reactor output distribution measuring system for measuring output distribution inside a reactor core stored in a nuclear reactor pressure vessel is equipped inside the pressure vessel with: a plurality of heating units provided at a plurality of longitudinal positions of fuel rods for generating heat according to the dose of gamma rays generated owing to nuclear fission; and optical fiber provided at positions with heat from the heating units transmitted thereto. This system is equipped outside a nuclear reactor containment vessel for therein storing the pressure vessel with a temperature distribution measuring part for finding temperature distribution at a plurality of positions as information serving as a basis for finding output distribution based on Raman scatter light in the optical fiber. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a reactor power distribution measuring system and a reactor power distribution measuring method for measuring a power distribution inside a reactor core used in a nuclear power plant or the like.

  In general, a nuclear power reactor is a device that maintains a fission chain reaction of nuclear fuel material such as uranium while controlling it. For example, a plurality of rod-shaped uranium fuels constitute the core of a nuclear reactor, and are stored in a reactor pressure vessel together with control rods and a coolant (for example, water). In order to ensure radiation safety, the reactor pressure vessel is stored inside the reactor containment vessel, and the reactor containment vessel is installed inside the reactor building. In a nuclear power plant, heat generated by a fission chain reaction that proceeds while being controlled by control rods is extracted from the inside of the core through the coolant to the outside of the core to the turbine installed outside the reactor building. The generator that is sent out and directly connected to this is turned to generate electricity. Specifically, for example, water as a coolant is heated inside the reactor core to become steam and supplied to the turbine.

  On the other hand, in the power system, the system frequency is stably maintained by stabilizing the output of the generator. Based on the principle described above, stabilization of the output of the generator depends on stabilization of heat (heat output) generated by the fission chain reaction in the core. For this stabilization, for example, the control rod described above must be moved appropriately to protect the nuclear fuel material. By the way, the movement of the control rod is carried out while measuring not only the total amount of heat output but also the spatial distribution of heat output inside the core. Generally, this spatial distribution of heat output is referred to as power distribution and is one of core performance. That is, in order to stably maintain the system frequency in the power system, it is essential to manage the core performance of the nuclear reactor in the nuclear power plant.

Since the thermal output mentioned above is proportional to the number of fission inside the core, the neutron flux generated by the nuclear fission inside the core is measured directly during the operation of the reactor, and the thermal output is obtained based on this neutron flux. Can do. Therefore, for example, a plurality of fission-type neutron detectors such as a fission ionization chamber are installed in the core of a boiling water reactor as a local power range monitor (LPRM) for obtaining the power distribution. (For example, refer to Patent Document 1 and Patent Document 2.) Here, the boiling water reactor is a reactor of the type in which the coolant described above is water, which is converted into steam inside the reactor pressure vessel and sent to the turbine. For example, according to the disclosure of Patent Document 1, a plurality of neutron detectors are installed independently in the vertical direction inside the core (that is, the longitudinal direction of the fuel rod), and the neutron flux in the local region is provided for each individual neutron detector. Is measured. Thereby, the power distribution inside the core can be measured, and thus the core performance can be managed.
JP 2004-20250 A JP 2002-116283 A

  By the way, the fission type neutron detector disclosed in Patent Document 1 and Patent Document 2 described above is said to require periodic calibration because its detection sensitivity deteriorates with the passage of time of use. In particular, in the measurement of the power distribution described above, calibration is essential because it is necessary to obtain the relative relationship of the measurement results from a plurality of neutron detectors. As such calibration means, (1) mobile in-core instrumentation (TIP: Traversing In-Core Probe) (patent document 1 mentioned above) or (2) gamma thermometer (patent document 2 mentioned above) is disclosed. ing.

  In the mobile core instrumentation, a guide tube is provided in the vicinity of a plurality of neutron detectors fixed in the vertical direction inside the core in parallel with these, and another neutron detector for calibration is installed in this guide tube. This is a calibration means that is movable in the vertical direction. Based on the measurement result of the movable neutron detector, gain adjustment is performed for each of a plurality of fixed neutron detectors. However, a moving mechanism is required for such movement, so that the configuration is complicated, resulting in high costs.

  On the other hand, a gamma thermometer is a calibration means for a gamma ray detector that measures the dose of gamma rays generated in the process of fission chain reaction through the amount of heat generated when the gamma rays are absorbed by a heating element. This gamma thermometer is a rod-shaped heating element provided in parallel with a plurality of fixed neutron detectors in the vertical direction inside the core, and a position facing the fixed neutron detectors. Are provided with a plurality of thermocouples discretely. Assuming a predetermined relationship between the temperature of the heating element and the degree of fission caused by gamma rays, each of the fixed neutron detectors is compared with the results of temperature measurements using multiple thermocouples in the vertical direction. Adjust the gain. However, in the gamma thermometer, each of a plurality of thermocouples constituting the gamma thermometer has a wiring, and further includes a heater wire as a calibration means for the thermocouple itself. For this reason, since it becomes bulky as a detector, in addition to occupying the space inside the reactor pressure vessel, replacement work becomes difficult with exposure.

  Further, it is said that it is difficult to always measure the power distribution with both the mobile in-core instrumentation and the gamma thermometer alone. That is, in the mobile in-core instrumentation, the neutron detector cannot be moved frequently because it deteriorates with the movement, and therefore, the continuous measurement alone is not practical. In addition, with a gamma thermometer, the calibration of the thermocouple itself is inefficient, so that it is difficult to always measure by itself. That is, in any case, for constant measurement, for example, it is necessary to use it together with the above-mentioned local output region monitor composed of a neutron detector, resulting in a complicated configuration.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a reactor power distribution measurement system and a reactor power distribution measurement method for continuous measurement having a simple and easily replaceable configuration. There is to do.

  The invention for solving the above-mentioned problems is a reactor power distribution measurement system that measures the power distribution inside the core stored in the reactor pressure vessel, and is provided at a plurality of positions in the longitudinal direction of the fuel rods. A plurality of heating elements that generate heat in accordance with a dose of gamma rays generated due to fission, and an optical fiber provided at a position where heat from the plurality of heating elements is transmitted are contained in the reactor pressure vessel. A temperature distribution measuring unit for obtaining temperature distributions at the plurality of positions as information serving as a basis for obtaining the output distribution based on Raman scattered light in the optical fiber; It is provided outside the reactor containment vessel.

  According to this reactor power distribution measurement system, the temperature distribution measurement unit converts the temperature of the heating element provided at each of a plurality of positions in the longitudinal direction of the fuel rod into, for example, Raman scattered light in one optical fiber. Can be measured based on. If the temperature of each heating element depends on the dose of gamma rays that is further proportional to the degree of fission that is proportional to the thermal output at each location, the relative value of the temperature at each location will depend on the power distribution inside the core. It will be equivalent. Therefore, if it is provided in the vicinity of the fuel rod and in parallel therewith, the output distribution in the longitudinal direction of the fuel rod can be measured with a single optical fiber. In this case, for example, a plurality of conventional neutron detectors and the like are not necessary.

  In general, when measuring the temperature distribution in the axial direction of an optical fiber based on Raman scattered light, for example, access for incident pulse light and reception of scattered light may be made from only one end of the optical fiber. ing. Therefore, for example, by extending one end of the optical fiber provided inside the reactor core to the outside of the reactor containment vessel and connecting it to the temperature distribution measurement unit, the occupied space inside the reactor pressure vessel can be suppressed. . Due to such a configuration, it is easy to install and remove the optical fiber from the reactor pressure vessel.

  Furthermore, since the optical fiber is a continuum, it does not require calibration or the like of the optical fiber and can always be used for measurement of Raman scattered light. For example, if a plurality of heating elements are fixed in the vicinity of a plurality of conventional neutron detectors or inside the reactor core instead of the neutron detectors, they can be used at all times. Therefore, the power distribution inside the core can be constantly measured.

  From the above, a reactor power distribution measurement system for continuous measurement having a simple and easily replaceable configuration is provided.

In the reactor power distribution measurement system, the power distribution may be the temperature distribution.
According to this reactor power distribution measurement system, the temperature distribution at a plurality of positions obtained by the temperature distribution measurement unit becomes the power distribution at the plurality of positions as it is. Thereby, the power distribution inside the core is efficiently measured.

In the reactor power distribution measurement system, the power distribution conversion unit that converts the temperature distribution obtained by the temperature distribution measurement unit into the power distribution having a correlation with the temperature distribution further includes the reactor containment vessel. You may prepare outside.
According to this reactor power distribution measurement system, the temperature distribution at a plurality of positions obtained by the temperature distribution measurement unit is converted into a plurality of positions at a plurality of positions by the power distribution conversion unit based on, for example, a predetermined relationship between temperature and output. Converted to output distribution. Thereby, if the said predetermined relationship is used, the power distribution inside a core will be measured efficiently.

In the reactor power distribution measurement system, the plurality of heating elements may be heat conductive materials.
According to this reactor power distribution measurement system, the power distribution is effectively reduced by a metal (heat conducting material such as iron) that has higher gamma-ray stopping power and higher efficiency in converting its kinetic energy into heat than non-metals. It can be measured. In addition, since iron is cheap among metals, the reactor power distribution measurement system is cheaper.

  An invention for solving the above-mentioned problem is a reactor power distribution measuring method of a reactor power distribution measuring system for measuring a power distribution inside a core stored in a reactor pressure vessel, wherein the length of a fuel rod is A plurality of heating elements that generate heat according to the dose of gamma rays generated due to nuclear fission provided at a plurality of positions in the direction, and an optical fiber provided at a position where heat from the plurality of heating elements is transmitted, In the reactor pressure vessel, and the temperature distribution at the plurality of positions is used as information serving as a basis for obtaining the output distribution based on the Raman scattered light in the optical fiber. Obtained outside the reactor containment vessel.

  A reactor power distribution measurement system and a reactor power distribution measurement method for continuous measurement having a simple and easily replaceable configuration are provided.

=== Configuration of Reactor Power Distribution Measurement System ===
A configuration example of the reactor power distribution measurement system 10 of the present embodiment will be described with reference to FIG. FIG. 1 is a schematic diagram showing a configuration example of the reactor power distribution measurement system 10 and its peripheral parts according to the present embodiment. Note that the reactor power distribution measurement system 10 of the present embodiment is a system provided in a boiling water reactor, but is not limited to this, for example, a system provided in a pressurized water reactor. Also good.

  The core 2 of the boiling water reactor according to the present embodiment is configured by further combining a plurality of units of fuel assemblies 3 formed by bundling a plurality of fuel rods made of uranium oxide having a plurality of pellet shapes. It is. The core 2 is housed in a steel reactor pressure vessel 1 together with a control rod (not shown) and internal structures such as water (not shown) as a primary coolant. The reactor pressure vessel 1 is stored in a reactor containment vessel 4 made of steel or reinforced concrete in order to ensure radiation safety in the event of an abnormality. At the time of abnormality, the concentration of radioactive material inside and outside the reactor containment vessel 4 differs, that is, the reactor containment vessel 4 functions to prevent the radioactive material from being released to the outside.

  As illustrated in FIG. 1, the reactor power distribution measurement system 10 of the present embodiment includes heating elements 101 and 201, optical fibers 103 and 203, temperature measurement devices 110 and 210, and a process control computer 500. And is configured. In the present embodiment, the heating elements 101 and 201 and the main portions of the optical fibers 103 and 203 are provided inside the nuclear reactor containment vessel 4, and the remaining portions of the optical fibers 103 and 203 and the temperature measurement device 110. 210 and the process control computer 500 are provided outside the reactor containment vessel 4. The temperature measuring devices 110 and 210 and the process control computer 500 may be further separated by, for example, a wall of a reactor building (not shown), or both of them may be a reactor building (not shown). It may be installed outside.

<<< Internal configuration of the containment vessel >>>
The heating elements 101 and 201 are a plurality of and discretely arranged parallel to the vertical direction (longitudinal direction) of the fuel assembly 3, and are materials that generate heat according to their dose when irradiated with gamma rays. Generally, the dose of gamma rays generated in the fission chain reaction of uranium having a mass number of 235 inside the core 2 is assumed to be proportional to the fission number, that is, the heat output. The heating elements 101 and 201 of this embodiment use this principle, and are for detecting the heat output by the fission chain reaction in the local region where the heating elements 101 and 201 are located based on the temperature. . Specifically, the heating elements 101 and 201 of the present embodiment are, for example, four strings 100 and 200 arranged at predetermined positions around the fuel assembly 3 formed by bundling a plurality of fuel rods. It is fixed to. The total number and discreteness (or density) of the heating elements 101 and 201 in the vertical direction are determined according to the measurement accuracy of the output distribution. That is, the measurement accuracy improves as the total number of the heating elements 101 and 201 in the vertical direction increases and the discreteness decreases (or the density increases). In the illustration of FIG. 1, two strings 100, 200 are provided adjacent to one fuel assembly 3, and four heating elements 101a, 101b, 101c, 101d, 201a are provided for each of the strings 100, 200. , 201b, 201c, and 201d are arranged for convenience of illustration only. In addition, the heating elements 101 and 201 of the present embodiment are mainly made of iron (thermal conductive material), but are not limited to this. For example, they have high gamma ray blocking ability and heat their kinetic energy. Any material can be used as long as it has a high efficiency of conversion into the material. As a material having such properties, a metal is preferable to a non-metal, and iron is more preferable from the viewpoint of lower cost.

  The optical fiber 103 is in the vicinity of the heating elements 101a, 101b, 101c, and 101d discretely fixed in the vertical direction described above, is arranged in parallel with these, and has flexibility. The same applies to the optical fiber 203 and the like. Here, “near” means a position where heat from each of the heating elements 101a, 101b, 101c, and 101d can be transmitted. Specifically, the optical fibers 103 and 203 according to the present embodiment are provided in the lower part 1b of the reactor pressure vessel 1 in the tube parts (for example, dry tubes) 102 and 202 further provided in the strings 100 and 200 described above. And is fixed at the lower part 1b. While the strings 100 and 200 need to be installed from the upper part 1a of the reactor pressure vessel 1, the optical fibers 103 and 203 are flexible and have a simple configuration, so that the lower part of the reactor pressure vessel 1 is used. Installation and removal from 1b is possible. On the other hand, for example, conventional neutron detectors and gamma thermometers disclosed in Japanese Patent Application Laid-Open No. 2004-20250 and Japanese Patent Application Laid-Open No. 2002-116283 have a lower portion 1b of the reactor pressure vessel 1 in the replacement. Therefore, work involving water leakage, work in the upper part 1a, and the like were necessary. Therefore, the optical fibers 103 and 203 according to the present embodiment have an effect that the exposure in the replacement work can be reduced as compared with the conventional case and that the so-called periodic inspection is not critical. In the illustration of FIG. 1, there are two optical fibers, but this is merely for convenience of illustration, and there may be one optical fiber in this embodiment, or three or more.

  The strings 100 and 200 described above may use conventional strings used for fixing a neutron detector as a local output region monitor (LPRM), for example. The tube sections 102 and 202 described above may use a conventional mobile in-core instrumentation (TIP) guide tube for calibrating the neutron detector. That is, for example, a part of the conventional system disclosed in Japanese Patent Application Laid-Open Nos. 2004-20250 and 2002-116283 is reused to reduce the reactor power distribution measurement system 10 of the present embodiment. It can be realized at a cost.

<<< External configuration of reactor containment vessel >>>
The temperature measuring devices 110 and 210 are devices that measure the temperature at each position in the axial direction of the optical fibers 103 and 203 based on the Raman scattered light in the optical fibers 103 and 203 described above. In the present embodiment, one end portions of the optical fibers 103 and 203 extended from the lower portion 1b of the reactor pressure vessel 1 are further extended to the outside of the reactor containment vessel 4 and connected to the temperature measuring devices 110 and 210, respectively. The In the present embodiment, for example, the plurality of temperature measuring devices 110 and 210 correspond to the plurality of optical fibers 103 and 203, respectively. Therefore, as will be described later, the temperature distribution in the axial direction of all the optical fibers 103 and 203 is determined. Measurements can be made almost simultaneously.

  The process control computer 500 is an information processing apparatus having a function of controlling the plurality of temperature measuring devices 110 and 210 described above to measure the temperature distribution described above. The process control computer 500 includes a distribution database 501 that stores the temperature distribution in the axial direction of the optical fibers 103 and 203 measured by the temperature measuring devices 110 and 210 described above as temperature distribution data 501a. Based on the distribution data 501a, the power distribution in the core 2 is obtained. The distribution database 501 further stores the obtained output distribution as output distribution data 501b. A part of the output distribution data 501b can be displayed on the display 502 included in the process control computer 500.

  In the present embodiment, one or a plurality of temperature measuring devices 110 and 210 and the process control computer 500 constitute a temperature distribution measurement unit, and the output distribution conversion unit is a part of the process control computer 500. Is.

<<< Temperature measuring device >>>
The above-described temperature measuring device 110 will be described in more detail with reference to FIG. This figure is a block diagram showing a configuration example of the temperature measuring device 110 of the present embodiment.

  The temperature measuring apparatus 110 according to the present embodiment mainly includes an optical demultiplexer 111, light sources 112a and 112b, light receivers 113 and 114, A / D converters 115 and 116, and a control unit 117. Has been.

  The optical demultiplexer 111 has a function of separately dividing Stokes light and anti-Stokes light, for example, of Raman scattered light described later, into respective wavelengths. The light sources 112 a and 112 b are lasers that generate pulsed light incident on the optical fiber 103. In the present embodiment, the two light sources 112a and 112b are used in order to increase the intensity of the pulsed light. However, the present invention is not limited to this. For example, one or three or more light sources may be used. The light receivers 113 and 114 have a function of receiving Stokes light and anti-Stokes light, respectively, and converting the light intensity into an electric signal (analog signal). The A / D converters 115 and 116 have a function of converting an analog signal corresponding to the light intensity of Stokes light and anti-Stokes light into a digital signal.

  As will be described later, for example, the control unit 117 simultaneously triggers two light sources 112a and 112b to simultaneously generate pulsed light, and two A / D converters 115, at predetermined time intervals (Δt) described later, 116 has a function of simultaneously acquiring an electrical signal from 116 and calculating the above-described light intensity ratio. Further, as will be described later, the control unit 117 also has a function of obtaining the temperature with respect to the axial position of the optical fiber 103, for example, from the light intensity ratio obtained from time t to time (t + Δt).

=== Reactor power distribution measurement method ===
A reactor power distribution measurement method by the reactor power distribution measurement system 10 having the above-described configuration will be described with reference to FIG. This figure is a flowchart showing the operation procedure of the temperature measuring apparatus 110 and the process control computer 500 of the present embodiment. Hereinafter, the temperature measuring device 110 and the process control computer 500 will be collectively referred to as an output distribution measuring unit.

  First, the output distribution measuring unit simultaneously generates pulsed light from the two light sources 112a and 112b (S100). Specifically, the process control computer 500 transmits a signal for simultaneously generating pulsed light from the two light sources 112a and 112b to the control unit 117 of the temperature measuring device 110.

  The two pulse lights are incident on one end of the optical fiber 103 through the optical demultiplexer 111. The pulsed light in the medium constituting the optical fiber 103 propagates toward the other end while generating Raman scattering in the medium at each position in the axial direction of the optical fiber 103. Here, “each position in the axial direction” means, for example, a central position in the axial direction in a predetermined region (for example, region A or region B in FIG. 2) of the optical fiber 103.

  For example, Stokes light and anti-Stokes light (backscattered light) generated by Raman scattering in the medium of the region A (FIG. 2) of the optical fiber 103 has an optical fiber 103 having a light intensity ratio RA that reflects the temperature of the region A. It is supposed to go to one end of the. The time from when the temperature measuring device 110 receives the pulsed light until it receives the Stokes light and the anti-Stokes light generated in the region A is represented by 2 · LA / c. Here, “LA” is the distance between the temperature measuring device 110 and the region A of the optical fiber 103, and “c” is the speed of light. Similarly, the time from when the temperature measuring device 110 receives the pulsed light until it receives the Stokes light and the anti-Stokes light generated in the region B (FIG. 2) is expressed by 2 · LB / c. From the above, the temperature measuring apparatus 110 acquires the light intensity ratio RB corresponding to the temperature of the region B when the time (2 · LB / c) has elapsed from the step 100 described above, and the time (2. When only LA / c) has elapsed, the light intensity ratio RB corresponding to the temperature of the region A is acquired.

  Based on the principle described above, the output distribution measurement unit generally acquires the light intensity ratio R from time t to time (t + Δt) (S101). Specifically, the control unit 117 of the temperature measuring device 110 executes the operation of step S101. The time t is equivalent to the elapsed time from step S100 described above, and the time increment Δt is determined based on a predetermined clock provided in the control unit 117, for example.

  Next, the output distribution measurement unit converts the time t acquired in step S101 described above into a position (distance in the axial direction of the optical fiber 103 starting from the temperature measurement device 110, that is, c · t / 2), The light intensity ratio R is converted into temperature based on a predetermined arithmetic expression and stored in a memory (not shown) (S102). Specifically, the control unit 117 of the temperature measuring device 110 executes the operation of step S102.

  Next, the output distribution measuring unit determines whether or not the time t acquired in step S101 described above has reached a predetermined time t (MAX) (S103), and if not (S103: YES). The operation for acquiring the light intensity ratio R is performed again between time (t + Δt) and time (t + 2 · Δt) (S104 and S101).

  As described above, by repeating the operations in steps S101 to S104, the temperatures at all positions of the optical fiber 103 are stored in the memory (not shown). Specifically, the control unit 117 of the temperature measuring device 110 repeatedly executes the operations in steps S101 to S104. The predetermined arithmetic expression described above may be stored in, for example, the memory (not shown) described above. The above-described t (MAX) is the maximum time for receiving the Raman scattered light for one pulse light generated in the above-described step S100, and is stored in, for example, the above-described memory (not shown). Also good.

  If the time t acquired in step S101 described above has reached the predetermined time t (MAX) described above (S103: NO), the output distribution measuring unit will store the temperature stored in the memory (not shown) described above. The distribution is stored in the distribution database 501 as temperature distribution data 501a (S105). Specifically, the process control computer 500 executes the operation of step S105.

  When the process control computer 500 performs overall control of the plurality of temperature measuring devices 110 and 210, the temperature distribution data 501a indicates the temperature distribution for each of the corresponding optical fibers 103 and 203. (See FIG. 4 (a)). FIG. 4A is a chart showing a configuration example of the temperature distribution data 501a of the present embodiment. According to the figure, the temperature distribution data 501a is generated in the vertical direction (Z-axis direction in FIG. 1) for each of a plurality of optical fibers arranged, for example, uniformly in the horizontal plane (XY plane in FIG. 1) inside the core 2. ) Of each position (A, B, C, D, etc.).

  Next, the power distribution measurement unit reads the temperature distribution data 501a from the distribution database 501, converts the temperature into the heat output inside the core 2 based on a predetermined arithmetic expression, and outputs it as the power distribution data 501b in the distribution database 501. Store (S106). Specifically, the process control computer 500 executes the operation of step S106. The predetermined arithmetic expression described above may be stored in, for example, the memory (not shown) described above.

  Next, the output distribution measuring unit reads the output distribution data 501b from the distribution database 501 and, for example, in the vicinity of each fuel assembly (“fuel assembly P” and “fuel assembly Q” in FIG. 4B). With respect to the arranged optical fiber, the value of the heat output corresponding to the positions A, B, C, D, etc. in the core axis direction (Z-axis direction in FIG. 1) (“furnace output (%)” in FIG. 4B) Is displayed on the display 502 as a graph. FIG. 4B is a schematic diagram showing a display example of the output distribution data 501b on the display 502 of the present embodiment. Here, when a plurality of optical fibers are arranged in the vicinity of one fuel assembly, the value of the heat output corresponding to the plurality of optical fibers is set for each position (A, B, C, D, etc.). These may be added together and displayed on the display 502 as a graph. For example, a reactor operator can efficiently manage the core by referring to the display 502.

  Next, the output distribution measuring unit resets the above-described time t to zero (S108), and performs the operation of the above-described step S100 to update the output distribution (FIG. 4B) displayed on the display 502. Try again. Specifically, the process control computer 500 executes the operations of steps S108 and S100.

  In the reactor power distribution measurement system 10 of the present embodiment, the temperatures of the heating elements (for example, heating elements 101a, 101b, 101c, 101d) provided at each of a plurality of positions in the vertical direction inside the core 2 are as follows. Measurement is performed based on the Raman scattered light in one optical fiber 103. Therefore, for example, a plurality of conventional neutron detectors are not required for measuring the output distribution. Further, as described above, the occupied space inside the reactor pressure vessel 1 can be suppressed, and the installation and removal operations of the optical fibers 103 and 203 with respect to the reactor pressure vessel 1 are easy. Furthermore, since the optical fibers 103 and 203 are continuous bodies, they do not require calibration or the like, and can always be used for measurement of Raman scattered light, and the heating elements 101 and 201 can also be used at all times. Therefore, the power distribution inside the core 2 can be always measured. From the above, it can be said that the reactor power distribution measurement system 10 of the present embodiment is a system for continuous measurement having a simple and easily replaceable configuration.

  The above-described embodiment is intended to facilitate understanding of the present invention, and is not intended to limit the present invention. The present invention is changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof.

It is a schematic diagram which shows the structural example of the reactor power distribution measurement system of this Embodiment, and its peripheral part. It is a block diagram which shows the structural example of the temperature measuring apparatus of this Embodiment. It is a flowchart which shows the operation | movement procedure of the temperature measurement apparatus of this Embodiment and the computer for process control. (A) is a chart which shows the example of a structure of the temperature distribution data of this Embodiment, (b) is a schematic diagram which shows the example of a display of the output distribution data in the display of this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reactor pressure vessel 1a Upper part 1b Lower part 2 Core 3 Fuel assembly 4 Reactor containment vessel 10 Reactor power distribution measurement system 100, 200 Strings 101, 201 Heating element 102, 202 Tube part 103, 203 Optical fiber 110, 210 Temperature Measuring device 111 Optical demultiplexer 112a, 112b Light source 113, 114 Light receiver 115, 116 A / D converter 117 Control unit 500 Process control computer 501 Distribution database 501a Temperature distribution data 501b Output distribution data 502 Display

Claims (5)

A reactor power distribution measurement system for measuring a power distribution inside a core stored in a reactor pressure vessel,
Provided at a plurality of positions in the longitudinal direction of the fuel rod, a plurality of heating elements that generate heat according to the dose of gamma rays generated due to fission, and a position where heat from the plurality of heating elements is transmitted An optical fiber provided inside the reactor pressure vessel,
A temperature distribution measuring unit for obtaining temperature distributions at the plurality of positions as information serving as a basis for obtaining the output distribution based on Raman scattered light in the optical fiber, a reactor storing the reactor pressure vessel A reactor power distribution measurement system provided outside the containment vessel.   The reactor power distribution measurement system according to claim 1, wherein the power distribution is the temperature distribution.   The power distribution conversion unit that converts the temperature distribution obtained by the temperature distribution measurement unit into the power distribution correlated with the temperature distribution is further provided outside the reactor containment vessel. Item 4. The reactor power distribution measurement system according to Item 1.   The reactor power distribution measurement system according to any one of claims 1 to 3, wherein the plurality of heating elements are heat conductive materials. A reactor power distribution measurement method for a reactor power distribution measurement system for measuring a power distribution inside a core stored in a reactor pressure vessel,
Provided at a plurality of positions in the longitudinal direction of the fuel rod, a plurality of heating elements that generate heat according to the dose of gamma rays generated due to fission, and a position where heat from the plurality of heating elements is transmitted An optical fiber provided inside the reactor pressure vessel,
Based on Raman scattered light in the optical fiber, the temperature distribution at the plurality of positions is information outside the reactor containment vessel that stores the reactor pressure vessel as information that is a basis for obtaining the output distribution. A reactor power distribution measurement method for a reactor power distribution measurement system.

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