Degradation measurement device, degradation measurement system, and degradation measurement method

Abstract

To provide a degradation measurement device, degradation measurement system, and degradation measurement method, which enable improvement in measurement accuracy of degradation of a control rod drive mechanism without having to disassemble the same.SOLUTION: A degradation measurement device 100 is provided, comprising a processor configured to compute a degradation indicator (such as frictional torque on a sliding part caused by rotation) of a control rod drive mechanism 1 based on a leakage amount Lg of fluid from a gland packing 7 of the control rod drive mechanism 1.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a degradation measurement device, a degradation measurement system, and a degradation measurement method. [Background technology]

[0002] The control rod drive mechanism used in nuclear power plants has a control rod attached to its upper end, and controls the reaction rate of the reactor by inserting or withdrawing the control rod into the core. It is an important device for the operation and safety of nuclear power plants.

[0003] The control rod drive mechanism is installed at the bottom of the reactor, with the control rods attached to the top. The control rod drive mechanism consists of a part called the control rod drive mechanism main body that moves the control rods up and down, a part called the spool piece that seals the internal fluid inside the reactor to prevent it from leaking to the outside, and a motor at the bottom that supplies driving force to the control rod drive mechanism main body.

[0004] Control rod drive mechanisms are inspected periodically and maintained to ensure normal operation. A known method for determining the degree of deterioration of equipment with sliding parts due to rotation, such as the control rod drive mechanism, without disassembling the equipment is to measure the friction torque due to the sliding resistance applied to the motor during rotation and use this friction torque as the degree of deterioration (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-194671 Summary of the Invention [Problem to be solved by the invention]

[0006] The control rod drive mechanism main body, spool piece, and motor that make up the control rod drive mechanism can be disassembled and inspected individually, but disassembly of the control rod drive mechanism main body in particular takes time. The torque applied to the motor is generated by two friction torques: the ball screw contained in the control rod drive mechanism main body and the gland packing contained in the spool piece. Therefore, conventional methods that measure the amount of deterioration from the friction torque applied to the motor cannot obtain the friction torque of the control rod drive mechanism main body alone, making it difficult to determine the appropriate time to disassemble and inspect the control rod drive mechanism main body.

[0007] An object of the present invention is to provide a deterioration measurement device, a deterioration measurement system, and a deterioration measurement method that can improve the accuracy of measuring the deterioration of a control rod drive mechanism without disassembling the control rod drive mechanism. [Means for solving the problem]

[0008] In order to achieve the above object, a deterioration measurement device as an example of the present invention includes a processor that calculates an index of deterioration of the control rod drive mechanism based on the amount of fluid leakage from the gland packing of the control rod drive mechanism. [Effects of the Invention]

[0009] According to the present invention, it is possible to improve the accuracy of measuring deterioration of a control rod drive mechanism without disassembling the control rod drive mechanism. Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0010] [Figure 1] Diagram of the control rod drive mechanism for degradation measurement [Figure 2] Control rod drive mechanism deterioration measurement flow [Figure 3] Example of the relationship between leakage rate and friction torque in gland packing [Figure 4] Diagram of the control rod drive mechanism deterioration measurement system [Figure 5]Another example of the relationship between leakage rate and friction torque in gland packing DETAILED DESCRIPTION OF THE INVENTION

[0011] [Example 1] An embodiment of the present invention will be described below with reference to Figures 1, 2, and 3. Figure 1 is a diagram of a control rod drive mechanism for degradation measurement, Figure 2 is a flow chart for measuring degradation of the control rod drive mechanism, and Figure 3 is an example of the relationship between leakage rate and friction torque in a gland packing. The objective of this embodiment is to measure the amount of degradation of the control rod drive mechanism itself without disassembling the control rod drive mechanism, for example.

[0012] As shown in Figure 1, the control rod drive mechanism 1 is installed at the bottom of the reactor 2, with the control rod 3 attached to the top. The control rod drive mechanism 1 is mainly composed of three elements: from the top, the control rod drive mechanism body 4, which contains a ball screw 5 and moves the control rod 3 up and down by the rotation of the ball screw 5; the middle spool piece 6, which contains a gland packing 7 and seals the internal fluid in the reactor 2 to prevent it from leaking to the outside; and the motor 8 at the bottom, which rotates the ball screw 5.

[0013] A torque meter 10 (torque sensor) that measures the torque applied to the motor 8 is installed between the ball screw 5 and the motor 8. A flow path 9 is provided in the spool piece 6, through which fluid inside the reactor 2 that has leaked from the gland packing 7 flows. A flow meter 11 (flow rate sensor) is installed in the flow path 9. The torque meter 10 measures the friction torque acting on the motor when it is driven. The flow meter 11 measures the amount of internal fluid leaking from the gland packing 7.

[0014] Next, a method for determining the degree of deterioration of the control rod drive mechanism main body 4 from the measured values ​​of the torque applied to the motor 8 and the amount of leakage from the gland packing will be described with reference to Figures 2 and 3. First, the torque Tm applied to the motor and the amount of leakage Lg from the gland packing are measured using the method described above (see S12 in Figure 2). Next, a relational expression between the amount of leakage from the gland packing and the friction torque of the gland packing, as shown in Figure 3, is obtained by testing or the like, and the amount of leakage Lg from the gland packing described above is converted into the friction torque Tg of the gland packing using this relational expression (S13 in Figure 2).

[0015] Since the torque Tm applied to the motor 8 is the sum of the friction torque Tg due to the gland packing 7 and the friction torque Tb due to the ball screw 5 of the control rod drive mechanism main body 4, the friction torque Tb due to the ball screw 5 of the control rod drive mechanism main body 4 is calculated by subtracting the friction torque Tg of the gland packing, which is obtained by converting the leakage amount Lg from the gland packing, from the measured torque Tm applied to the motor 8 using equation (1) (see S14 in Figure 2).

[0016]

number

[0017] According to the first embodiment, by measuring the torque Tm applied to the motor 8 and the leakage amount Lg from the gland packing, and using the relational expression between the leakage amount Lg of the gland packing 7 and the friction torque Tg, it is possible to measure the friction torque Tb of the ball screw 5 contained in the control rod drive mechanism main body 4 as the amount of deterioration of the control rod drive mechanism main body 4 without disassembling the control rod drive mechanism 1.

[0018] In this embodiment, the explanation is given assuming that the gland packing 7 and the ball screw 5 are the sources of the friction torque applied to the motor 8. However, if there is another cause of the friction torque, the friction force can be measured in advance and subtracted from the torque Tm applied to the motor to measure the friction torque Tb of the control rod drive mechanism main body.

[0019] [Example 2] Next, a second embodiment will be described with reference to Fig. 4. In the second embodiment, a description of the components having the same functions as those assigned with the reference numerals already shown in the first embodiment will be omitted. In the second embodiment, the measurement system of the first embodiment is modified.

[0020] 4 is a configuration diagram of a control rod drive mechanism deterioration measurement system 20. This system has a unit 21 for measuring the torque applied to the motor installed in the control rod drive mechanism 1, a unit 22 for measuring the amount of leakage from the gland packing, a unit 23 for converting the amount of leakage into friction torque, a database 24 (relationship between the amount of leakage Lg and friction torque Tg of the gland packing 7), a unit 25 for calculating the friction torque of the control rod drive mechanism main body 4, and a unit 26 for displaying the friction torque of the control rod drive mechanism main body 4.

[0021] The measurement unit 21 (torque sensor) and the measurement unit 22 (flow rate sensor) are provided in the control rod drive mechanism 1. The conversion unit 23 and the friction torque calculation unit 25 are realized, for example, by a processor executing a program. The database 24 is stored in a storage device. The display unit 26 is a display device such as a monitor. The deterioration measurement device is, for example, a computer, and is composed of a processor (CPU, etc.), a storage device (memory, HDD, etc.), a display device (display, etc.), etc.

[0022] The torque Tm applied to the motor and the leakage amount Lg from the gland packing are measured by a torque measuring unit 21 that measures the torque applied to the motor 8 and a leakage amount measuring unit 22 that measures the leakage amount from the gland packing, both of which are installed in the control rod drive mechanism 1. The measured leakage amount Lg is sent to a leakage amount to friction torque converting unit 23, where the leakage amount Lg is converted into the friction torque Tg of the gland packing using the relational equation between the gland packing, leakage amount, and friction torque (see FIG. 3) stored in a database (relationship between gland packing leakage amount and friction torque) 24.

[0023] The converted friction torque Tg and the torque Tm applied to the motor are sent to friction torque calculation unit 25 of the control rod drive mechanism main body, which calculates friction torque Tb of the rod drive mechanism main body based on equation (1). The calculated friction torque Tb of the control rod drive mechanism main body is sent to friction torque display unit 26 of the control rod drive mechanism main body, which displays the calculated friction torque Tb.

[0024] According to the second embodiment, the torque Tm applied to the motor 8 and the leakage amount Lg from the gland packing are measured by a measurement unit 21 for measuring the torque Tm applied to the motor 8 and a measurement unit 22 for measuring the leakage amount Lg from the gland packing 7, both of which are installed in the control rod drive mechanism 1. This allows the system to automatically display the friction torque Tb of the control rod drive mechanism main body 4, and the degree of deterioration of the control rod drive mechanism main body 4 can be easily grasped.

[0025] The main features of Examples 1 and 2 can be summarized as follows.

[0026] As shown in FIG. 4, the deterioration measurement device 100 includes a processor that calculates an index of deterioration of the control rod drive mechanism 1 (e.g., the friction torque of the sliding part due to rotation) based on the amount of fluid leakage Lg from the gland packing 7 of the control rod drive mechanism 1.

[0027] Since the amount of fluid leakage Lg from the gland packing 7 is correlated with the friction torque Tg of the gland packing 7, the friction torque Tg of the gland packing 7 is reflected in the indicator of deterioration of the control rod drive mechanism 1. As a result, the accuracy of measuring the deterioration of the control rod drive mechanism 1 can be improved without disassembling the control rod drive mechanism 1.

[0028] In the embodiment, the indicator of deterioration is the friction torque (friction torque Tb due to the ball screw 5) of the control rod drive mechanism main body 4 that moves the control rod 3 up and down in the control rod drive mechanism 1. As shown in Fig. 4, the processor derives the friction torque Tg of the gland packing 7 from the leakage amount Lg (conversion unit 23). The processor calculates the friction torque (friction torque Tb due to the ball screw 5) of the control rod drive mechanism main body 4 from the difference (Tm - Tg) between the torque Tm applied to the motor 8 of the control rod drive mechanism 1 and the friction torque Tg of the gland packing 7 (calculation unit 25, formula (1)).

[0029] This makes it possible to calculate the friction torque of the control rod drive mechanism main body 4 without disassembling the control rod drive mechanism 1. Furthermore, it can be determined that the larger the friction torque of the control rod drive mechanism main body 4 (friction torque Tb due to the ball screw 5), the more deteriorated the control rod drive mechanism main body 4 is. In this case, for example, a correspondence relationship between the leakage amount Lg and the friction torque Tg of the gland packing 7 (a database linking the leakage amount with the friction torque, an equation expressing the relationship between the leakage amount and the friction torque, or machine learning parameters in which the leakage amount is input and the friction torque is output, etc.) is stored in a storage device. The processor uses this correspondence relationship to derive the friction torque Tg of the gland packing 7 corresponding to the leakage amount Lg from the leakage amount Lg.

[0030] The processor may calculate the friction torque of the control rod drive mechanism main body 4 by subtracting the friction torque due to contact between the control rod 3 and the fuel from the difference (Tm-Tg) between the torque Tm applied to the motor 8 and the friction torque Tg of the gland packing 7 (calculation unit 25, Figure 4).

[0031] This causes the friction torque caused by contact between the control rod 3 and the fuel to be reflected in the indicator of deterioration of the control rod drive mechanism 1. As a result, the accuracy of measuring deterioration of the control rod drive mechanism 1 can be further improved. In this case, for example, a correspondence relationship between the temperature of the fluid in the reactor and the friction torque caused by contact between the control rod and the fuel (such as a database linking temperature and friction torque, an equation expressing the relationship between temperature and friction torque, or machine learning parameters that use temperature as input and friction torque as output) is stored in a storage device. Using this correspondence relationship, the processor derives the corresponding friction torque caused by contact between the control rod and the fuel from the temperature of the fluid in the reactor measured by the temperature sensor.

[0032] 5, the deterioration measurement device 100 may include a storage device that stores a first correspondence relationship between the leakage amount Lg and the friction torque Tg of the gland packing 7 while the reactor is operating, and a second correspondence relationship between the leakage amount Lg and the friction torque Tg of the gland packing 7 while the reactor is shut down. When the reactor is operating, the processor derives the friction torque Tg of the gland packing 7 corresponding to the leakage amount Lg from the leakage amount Lg using the first correspondence relationship. When the reactor is shut down, the processor derives the friction torque Tg of the gland packing 7 corresponding to the leakage amount Lg from the leakage amount Lg using the second correspondence relationship.

[0033] This allows the friction torque Tg of the gland packing 7 to be calculated according to the operating state of the reactor, thereby further improving the accuracy of measuring the deterioration of the control rod drive mechanism 1. Note that contact between the control rod 3 and the fuel occurs due to thermal expansion of the pressure vessel during operation.

[0034] 4, the deterioration measurement device 100 is provided with a display device that displays the friction torque (friction torque Tb caused by the ball screw 5) of the control rod drive mechanism main body 4. This allows the user to check the friction torque of the control rod drive mechanism main body 4, which is an index of deterioration.

[0035] 4, the deterioration measurement system 20 includes a deterioration measurement device 100 and a control rod drive mechanism 1. This makes it possible to improve the accuracy of measuring the deterioration of the control rod drive mechanism 1 without disassembling the control rod drive mechanism 1.

[0036] As shown in FIG. 1, the control rod drive mechanism 1 comprises a control rod drive mechanism main body 4, a spool piece 6, a motor 8, and a flow sensor (flow meter 11). The control rod drive mechanism main body 4 has a ball screw 5, and the rotation of the ball screw 5 moves the control rod 3 up and down. The spool piece 6 has a gland packing 7 around the ball screw 5, which seals the fluid inside the reactor so that it does not leak to the outside. The motor 8 rotates the ball screw 5. The flow sensor (flow meter 11) measures the flow rate of the fluid leaking from the gland packing 7. The index of deterioration is the friction torque Tb of the ball screw 5. This makes it easy to calculate the friction torque Tb of the ball screw 5, which is an index of deterioration.

[0037] In this embodiment, the deterioration measurement system 20 includes a torque sensor (torque meter 10) that measures the torque Tm applied to the motor 8. This makes it possible to directly measure the torque Tm applied to the motor 8.

[0038] Instead of the torque sensor (torque meter 10), the deterioration measurement system 20 may include a current sensor that measures the current of the motor 8. The processor calculates the torque Tm applied to the motor 8 from the measured value of the current of the motor 8.

[0039] This makes it possible to indirectly measure the torque Tm applied to the motor 8. In this case, for example, a correspondence relationship between the measured value of the current of the motor 8 and the torque Tm applied to the motor 8 is stored in a storage device. The processor uses this correspondence relationship to derive the torque Tm applied to the motor 8 from the measured value of the current of the motor 8 measured by the current sensor.

[0040] As shown in Fig. 1, the control rod drive mechanism 1 includes a gap 7A provided between both ends of a gland packing 7 and a flow path 9 communicating with the gap 7A. A flow sensor (flow meter 11) is provided in the flow path 9. This makes it possible to measure the leakage amount Lg of the fluid leaking from the gland packing 7 while suppressing leakage of the fluid toward the motor 8 side.

[0041] The deterioration measurement method includes a step in which the deterioration measurement device 100 of the control rod drive mechanism 1 calculates an index of deterioration of the control rod drive mechanism 1 (e.g., the friction torque of the sliding part due to rotation) based on the amount of fluid leakage Lg from the gland packing 7 of the control rod drive mechanism 1.

[0042] This improves the accuracy of measuring the deterioration of the control rod drive mechanism 1 without disassembling the control rod drive mechanism 1. In the embodiment, the deterioration measurement method is mainly performed by a processor, but it may also be performed by a person. Also, only measurements such as torque measurement and motor current measurement may be performed by a person.

[0043] The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0044] Furthermore, the above-described configurations, functions, etc. may be realized in part or in whole by hardware, for example, by designing them as integrated circuits. Furthermore, the above-described configurations, functions, etc. may be realized in software by a processor interpreting and executing a program that realizes each function. Information such as the programs, tables, and files that realize each function can be stored in a memory, a recording device such as a hard disk or SSD (Solid State Drive), or a recording medium such as an IC card, SD card, or DVD.

[0045] The embodiment of the present invention may be in the following form.

[0046] (C1) A method for measuring deterioration of a control rod drive mechanism, characterized by measuring the amount of leakage from a gland packing.

[0047] (C2). A method for measuring deterioration of a control rod drive mechanism according to (C1), characterized in that the amount of leakage from the gland packing is converted into friction torque of the gland packing using a relational equation between the amount of leakage from the gland packing and friction torque, and the friction torque of the control rod drive mechanism itself is measured by subtracting this friction torque of the gland packing from the torque applied to the measured motor.

[0048] (C3). A method for measuring deterioration of a control rod drive mechanism according to (C1), characterized in that the method is a system having a means for calculating the friction torque of the gland packing from the relational equation between the amount of leakage from the gland packing, the amount of leakage of the gland packing, and the friction torque, a means for calculating the friction torque of the control rod drive mechanism main body by subtracting the friction torque of the gland packing from the torque applied to the motor, and a means for displaying the calculated friction torque of the control rod drive mechanism main body.

[0049] According to (C1)-(C3), the deterioration amount of the control rod drive mechanism main body 4 can be measured without disassembling the control rod drive mechanism. [Explanation of symbols]

[0050] 1...Control rod drive mechanism 2…Nuclear reactor 3...Control rod 4...Control rod drive mechanism main body 5...Ball screw 6...Spool piece 7...Gland packing 7A...gap 8...Motor 9...Flow path 10...Torque meter 11...Flowmeter 12...Process 1 in the control rod drive mechanism deterioration measurement flow 13...Process 2 in the control rod drive mechanism deterioration measurement flow 14...Process 3 in the control rod drive mechanism deterioration measurement flow 20...Control rod drive mechanism deterioration measurement system 21...Measuring unit for torque applied to the motor 22...Measuring part of leakage amount from gland packing 23...Conversion section of leakage amount into friction torque 24...Database (Relationship between leakage amount of gland packing and friction torque) 25... Friction torque calculation section of the control rod drive mechanism body 26...Friction torque display unit of the control rod drive mechanism body

Claims

1. A deterioration measurement device comprising a processor that calculates an index of deterioration of a control rod drive mechanism based on the amount of fluid leakage from a gland packing of the control rod drive mechanism.

2. The deterioration measurement device according to claim 1, the indicator of deterioration is a friction torque of a control rod drive mechanism body that moves a control rod up and down in the control rod drive mechanism, The processor: deriving a friction torque of the gland packing from the leakage amount; The friction torque of the control rod drive mechanism body is calculated from the difference between the torque applied to the motor of the control rod drive mechanism and the friction torque of the gland packing. A deterioration measurement device characterized by:

3. The deterioration measurement device according to claim 2, The processor: The friction torque of the control rod drive mechanism body is calculated by subtracting the friction torque due to contact between the control rod and fuel from the difference between the torque applied to the motor and the friction torque of the gland packing. A deterioration measurement device characterized by:

4. The deterioration measurement device according to claim 2, a first correspondence relationship between the leakage amount and the friction torque of the gland packing during operation of the nuclear reactor; a storage device that stores a second correspondence relationship between the leakage amount and the friction torque of the gland packing while the reactor is shut down; The processor: When the reactor is in operation, deriving a friction torque of the gland packing corresponding to the leakage amount from the leakage amount using the first correspondence relationship; When the reactor is shut down, the friction torque of the gland packing corresponding to the leakage amount is derived from the leakage amount using the second correspondence relationship. A deterioration measurement device characterized by:

5. The deterioration measurement device according to claim 2, A display device is provided to display the friction torque of the control rod drive mechanism body. A deterioration measurement device characterized by:

6. A deterioration measurement system comprising the deterioration measurement device according to claim 1 and a control rod drive mechanism.

7. The deterioration measurement system according to claim 6, The control rod drive mechanism a control rod drive mechanism body having a ball screw and moving the control rod up and down by rotation of the ball screw; a spool piece having the gland packing around the ball screw and sealing the reactor fluid to prevent leakage to the outside; a motor that rotates the ball screw; a flow rate sensor that measures the flow rate of fluid leaking from the gland packing, The indicator of deterioration is the friction torque of the ball screw. A deterioration measurement system characterized by:

8. The deterioration measurement system according to claim 7, A torque sensor is provided to measure the torque applied to the motor. A deterioration measurement system characterized by:

9. The deterioration measurement system according to claim 7, a current sensor for measuring a current of the motor; The processor: Calculating the torque applied to the motor from the measured current of the motor A deterioration measurement system characterized by:

10. The deterioration measurement system according to claim 7, The control rod drive mechanism a gap provided between both ends of the gland packing; a flow path communicating with the gap, The flow rate sensor is provided in the flow path. A deterioration measurement system characterized by:

11. A deterioration measurement method comprising the step of calculating an index of deterioration of a control rod drive mechanism based on the amount of fluid leakage from a gland packing of the control rod drive mechanism.

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