JP2013076631A - Nuclear power plant inspection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nuclear power plant inspection apparatus capable of suitably performing replacement of an imaging apparatus.SOLUTION: A camera unit 6 in the nuclear power plant inspection apparatus includes two CCD cameras 21, 31, a shield plate 22, driving motors 32a, 32b for moving the shield plate 22, and shield plate driving wires 33a, 33b. The shield plate 22 covers the front of the CCD camera 31 and photographing up to inspection time is performed by the CCD camera 21. A dosage rate of radiant rays made incident on the CCD camera 21 is found out based on the number of pixels of radiation noise included in an image obtained by photographing using the CCD camera 21, and a cumulative dose of the CCD camera 21 is found out by integrating the dosage rates. When the found cumulative dose exceeds a set cumulative dose, a control unit 34 rotates the driving motors 32a, 32b and moves the shield plate 22 up to the front of the CCD camera 31.

Description

  The present invention relates to a nuclear plant inspection apparatus, and more particularly, to a nuclear plant inspection apparatus suitable for inspecting the state of a reactor internal structure and a fuel assembly in a nuclear reactor under a high radiation dose rate environment.

  For example, a diving apparatus having a television camera is carried into the water in a region below the core in the reactor pressure vessel, and the state of the bottom of the furnace is checked while moving the diving apparatus in the water. 233980. The diving device is equipped with an integrated dosimeter.

  In addition, the mobile inspection device described in JP-A-59-92397 is equipped with a radiation dosimeter. The dose rate is measured by a radiation dosimeter, the integrated value of the measured dose rate is monitored, and the replacement timing of the electronic circuit in the mobile inspection device is displayed. Japanese Patent Application Laid-Open No. 11-17785 describes a radiation-resistant imaging device. This radiation-resistant imaging device corrects a video signal that has fluctuated due to the influence of radiation by a signal corresponding to the integrated amount of irradiation in the imaging device.

JP-A-8-233980 JP 59-92397 A Japanese Patent Laid-Open No. 11-17785

  When the inspection device is used under a high radiation dose in the nuclear reactor, the circuit mounted on the inspection device is damaged by the radiation. In JP-A-8-233980, a diving apparatus that has been moving at the time of inspection in a nuclear reactor based on depth information obtained from a depth meter provided in the diving apparatus and dose rate distribution information in the nuclear reactor, The first exposure dose is obtained, and the second exposure dose received by the diving device before the diving device is recovered from the reactor is obtained. The remaining life dose is obtained by subtracting the total dose of the third exposure dose received by the diving apparatus before work, and the remaining life time of the parts provided in the diving apparatus is calculated based on this remaining life dose. Based on the remaining lifetime, it is possible to know the usage limit and replacement time of the part. Although it is not necessary to install radiation dosimeters in the diving device, it is necessary to install multiple radiation dosimeters in the reactor in order to obtain dose rate distribution information in the reactor. In addition, because the dose rate distribution information in the reactor is calculated based on the measurement results measured with multiple radiation dosimeters in the reactor, the accuracy of the calculated dose rate distribution information is not very good. The accuracy of the obtained remaining lifetime is not good.

  In Japanese Patent Laid-Open No. 59-92397, a radiation dosimeter is provided in a mobile inspection device, and based on the radiation dose irradiated to the mobile inspection device measured by this radiation dosimeter, an integrated value of radiation dose The lifetime of the parts mounted on the mobile inspection device is predicted based on this integrated value. Since the mobile inspection device is provided with a radiation dosimeter, the life accuracy of the mounted parts obtained in Japanese Patent Laid-Open No. 59-92397 is higher than that of the diving device described in Japanese Patent Laid-Open No. 8-233980. Will also improve. However, in the mobile inspection device described in Japanese Patent Application Laid-Open No. 59-92397, a radiation dosimeter must be installed in order to obtain the lifetime other than the television camera.

  In the radiation-resistant imaging device described in Japanese Patent Laid-Open No. 11-17785, the video signal that has fluctuated due to the influence of radiation is corrected, so that imaging can be performed for a time that is practical even in a high radiation environment, and a low dose rate is achieved. Under the environment, the imaging time can be extended. However, in an ultra-high radiation environment where molten nuclear fuel material exists, it is difficult to correct a captured image by image processing as disclosed in JP-A-11-17785.

  The objective of this invention is providing the nuclear power plant inspection apparatus which can perform switching of an imaging device more appropriately.

  A feature of the present invention that achieves the above-described object is that an inspection object is imaged based on a plurality of imaging devices, an irradiation device that irradiates the inspection object, and image information of the inspection object obtained by imaging by the imaging device. And a determination device for determining switching of the imaging device to be performed.

  Since switching of the imaging device is determined based on the image information of the imaging device, switching of the imaging device can be performed more appropriately.

  Preferably, the apparatus includes a radiation shield that covers the front surface of the imaging device, a shield moving device that moves the radiation shield, and a determination device thereof. When the imaging device used for imaging is switched, the shield moving device is controlled to perform radiation. It is desirable to include a control device that moves the shield from the front surface of one imaging device to the front surface of another imaging device.

  According to the present invention, it is possible to more appropriately switch the imaging device.

It is a block diagram of the nuclear power plant inspection apparatus which is one suitable Example of this invention. It is a general-view figure of the camera unit of the nuclear power plant inspection apparatus shown in FIG. It is a detailed block diagram of the camera unit shown in FIG. FIG. 2 is a flow chart showing a procedure for camera replacement in the nuclear power plant inspection apparatus shown in FIG. 1. FIG. FIG. 5 is a flow chart showing a detailed procedure for monitoring the accumulated dose shown in FIG. 4. FIG. It is explanatory drawing which shows the example of the image image | photographed with the CCD camera shown in FIG. 3, (A) is explanatory drawing which shows an example of the captured image when a radiation dose rate is high, (B) is when a radiation dose rate is low. It is explanatory drawing which shows an example of a captured image. It is explanatory drawing which shows the histogram of the image obtained by imaging | photography, (A) is explanatory drawing which shows the histogram with respect to FIG. 6 (A), (B) is explanatory drawing which shows the histogram with respect to FIG. 6 (B).

  Examples of the present invention will be described below.

  A nuclear power plant inspection apparatus that is a preferred embodiment of the present invention will be described with reference to FIGS. 1, 2, and 3. A schematic configuration of a nuclear power plant that performs inspection using the nuclear power plant inspection apparatus of the present embodiment will be described. The reactor containment vessel 2 is installed in the reactor building 1, and the reactor 3 is installed in the reactor containment vessel 2.

  The nuclear power plant inspection apparatus of the present embodiment includes a camera fixing jig 5, a camera unit 6, and a control device 8. The camera unit 6 is attached to the tip of the camera fixing jig 5, and the control device 8 is connected to the control device 8 by the cable 7 wired through the camera fixing jig 5. The control device 8 is connected to the display device 9 and the operation panel 10. The control device 8, display device 9 and operation panel 10 are placed outside the reactor building 1.

  The detailed structure of the camera unit 6 will be described with reference to FIGS. The camera unit 6 has a casing 12 made of a radiation shielding material having the external shape shown in FIG. In addition to the casing 12, the camera unit 6 includes CCD cameras (imaging devices) 21 and 31, shielding plates 22, illumination devices 23a and 23b, driving motors 32a and 32b, shielding plate driving wires 33a and 33b, a control unit 34, and a power supply unit. 35. The CCD cameras 21 and 31, the shielding plate 22, the illumination devices 23 a and 23 b, the drive motors 32 a and 32 b, the shielding plate drive wires 33 a and 33 b, the control unit 34 and the power supply unit 35 are installed in the casing 12. Illumination devices 23a and 23b are installed on the left and right sides of the front surface of the casing 12, and a pair of CCD cameras 21 and 31 are disposed between these illumination devices. Since the CCD cameras 21 and 31 are arranged between the illumination devices 23a and 23b, it is possible to ensure the visibility of the photographing target. A CMOS camera or other electronic imaging device may be used instead of the CCD camera.

  The illumination devices 23a and 23b are connected to the power supply unit 35 by cables 24a and 24b. The power supply unit 35 is connected to an external power supply by a cable (not shown) wired through the camera fixing jig 5. A control unit 34 connected to the cable 7 is connected to the CCD cameras 21 and 31 and the drive motors 32a and 32b, respectively. A shielding plate driving wire 33a attached to the shielding plate 22 is wound around a rotating drum (not shown) attached to the rotating shaft of the driving motor 32a. A shielding plate driving wire 33b attached to the lead shielding plate 22 is wound around another rotating drum (not shown) attached to the rotating shaft of the driving motor 32b. The attachment position of the shielding plate drive wire 33a to the shielding plate 22 is 180 ° opposite to the attachment position of the shielding plate drive wire 33b to the shielding plate 22 in the horizontal direction. The shielding plate 22 may be made of tungsten, which is a radiation shielding material, instead of lead.

  An example in which the inside of the reactor containment vessel 2 is inspected using the camera unit 6 will be described. A camera insertion port 4 is formed in the upper cover of the reactor containment vessel 2, and the camera unit 6 and the camera fixing jig 5 attached to the camera unit 6 are inserted into the reactor containment vessel 2 through the camera insertion port 4. . After the camera unit 6 and the camera fixing jig 5 are inserted into the reactor containment vessel 2, the camera insertion port 4 is sealed.

  When the inside of the nuclear reactor 3 is inspected by the camera unit 6, the camera insertion port 4 is formed in each of the upper cover of the reactor containment vessel 2 and the upper cover of the reactor pressure vessel of the nuclear reactor 3, and the atoms are inserted through these camera insertion ports. The camera unit 6 and the camera fixing jig 5 are inserted into the furnace pressure vessel, and their camera insertion ports are sealed.

  After the camera unit 6 is disposed in the reactor containment vessel 2, the worker 11 operates the operation panel 10 to input a control command for the camera unit 6 to the control device 8. This control command is transmitted from the control device 8 to the control unit 34 of the camera unit 6 through the cable 7. Based on the control command, the control unit 34 performs rotation control of the drive motor as described later. In the camera unit 6 arranged in the reactor containment vessel 2, the shielding plate 22 is arranged in front of the CCD camera 31 as shown in FIG. 3 before being inserted into the reactor containment vessel 2. For this reason, the state in the reactor containment vessel 2 is photographed by the CCD camera 21 in which the shielding plate 22 is not disposed on the front surface. The CCD camera 21 photographs the state of the reactor containment vessel 2 through the opening 32 formed in the casing 12. At the time of photographing, the CCD camera 21 enters the radiation incident through the opening 32. The CCD camera 21 is damaged by incident radiation and eventually cannot output a normal image. For this reason, the CCD camera used for photographing needs to be replaced from the CCD camera 21 to the CCD camera 31 at a certain point in time.

  The process of replacing the CCD camera in the camera unit 6 will be described based on the processing procedure shown in FIGS. The processing procedure shown in FIGS. 4 and 5 is executed by the control device 8.

  The accumulated dose is monitored (step S1). The cumulative dose is monitored by executing steps S11 to S19 shown in FIG. The illumination device is turned off (step S11). The control device 8 controls the power supply unit 35 to stop the supply of electricity to the lighting devices 23Aa and 23b. As a result, the illumination devices 23Aa and 23b are turned off. The lighting devices 23Aa and 23b are turned off to prevent the radiation noise from being measured correctly when the image of the object photographed by the CCD camera causes halation and the white portion having the same color as the radiation noise increases. An image of the inspection object is captured (step S12). An image of the inspection object obtained by photographing with the CCD camera 21 is input to the control device 8 via the control unit 34. This image is displayed on the display device 9. When the inspection object is imaged by the CCD camera 21, the shielding plate 22 blocks the front part of the CCD camera 31 of the opening 32 formed in the casing 12, and the inspection object is imaged by the CCD camera 31. Is not done.

  An image obtained by photographing with the CCD camera 21 will be described with reference to FIG. An image 35a shown in FIG. 6A is an image of the inspection object 36a having a high radiation dose rate. The image 35a having a high radiation dose rate includes radiation noise 37 in the form of white particles in addition to the image of the inspection target 36a. An image 35b shown in FIG. 6B is an image of the inspection object 36b having a low radiation dose rate. The image 35b having a high radiation dose rate includes radiation noise 37, but the amount of radiation noise 37 is smaller than that of the image 35a having a high radiation dose rate. Thus, the radiation noise 37 is large in the image 35a having a high radiation dose rate, and is reduced in the image 35b having a low radiation dose rate. In the nuclear power plant inspection apparatus of the present embodiment, by using the property of the radiation noise 37, the dose rate of the radiation incident on the camera is estimated using the image obtained by photographing with the CCD camera, and this dose rate. The CCD camera replacement is determined by quantitatively determining the exposure dose of the CCD camera, which is the integrated value of.

  After step S12, the lighting device is turned on (step S13). The control device 8 controls the power supply unit 35 to supply electricity to the lighting devices 23Aa and 23b. As a result, the illumination devices 23Aa and 23b are turned on. The captured image is binarized (step S13). The control device 8 binarizes the image input in step S12.

  Then, a histogram is calculated (step S15). The control device 8 calculates a histogram (a relationship between whiteness and the number of pixels) using the binarized image. FIGS. 7A and 7B show examples of the histogram calculated in step S15. In the histogram 38 (FIG. 7A) for the image 35a with a large amount of radiation noise 37 (see FIG. 6A), the value on the right end of the horizontal axis indicating the number of white pixels, that is, the amount of radiation noise 39 increases. In the histogram 40 (FIG. 7B) for the image 35b with a small amount of radiation noise 37 (see FIG. 6B), the value on the right end of the horizontal axis indicating the number of white pixels, that is, the amount of radiation noise 41 decreases.

  The dose rate of the radiation incident on the camera is calculated (step S16). The control device 8 calculates the dose rate of radiation incident on the CCD camera 21 using the calculated number of pixels in the white portion of the histogram. This dose rate is calculated by multiplying the number of pixels by a preset count α. Next, the cumulative dose is read (step S17). The control device 8 reads the accumulated dose due to the radiation irradiated to the CCD camera 21 from the internal memory of the control device 8 until the previous inspection work of the nuclear power plant of this embodiment. A cumulative dose is calculated (step S18). The control device 8 adds the dose rates calculated in step S16, and calculates the cumulative dose up to the present time in the current inspection work. And the control apparatus 8 adds the accumulated dose calculated | required by step S17 to the accumulated dose read by step S17, and calculates | requires a total accumulated dose. The calculated cumulative dose is stored (step S19). The control device 8 registers the calculated total accumulated dose in the internal memory of the control device 8.

  It is determined whether to replace the camera (step S2). The control device 8 determines whether the total accumulated dose is equal to or greater than the set accumulated dose. If the total accumulated dose is less than the set accumulated dose, the determination result in step S2 is “NO”. If the determination result in step S2 is “NO”, it is determined whether the inspection is finished (step S5). If the inspection by the nuclear power plant inspection device has not been completed, the determination result of step S5 is “NO”, and each procedure of steps S1 to S5 is repeated until the determination result of step S5 is “YES”. . When the determination result of step S5 is “YES”, the inspection by the nuclear power plant inspection device is finished.

  In step S2, when the total cumulative dose is greater than or equal to the set cumulative dose, the determination result in step S2 is “YES”. When the determination result of step S2 is “YES”, the procedures of steps S3 and S4 are executed.

  The shielding plate is moved (step S3). When it is determined “YES” in the determination process of step S <b> 2, the control device 8 outputs a shielding plate movement command to the control unit 34. The control unit 34 having input the shielding plate movement command rotates the driving motor 32a so that the shielding plate driving wire 33a is wound around the rotating drum connected to the rotation shaft of the driving motor 32a, and the shielding plate driving wire 33b is driven. Each of the drive motors 32a and 32b is controlled to rotate the drive motor 32b so as to be rewound from the rotary drum connected to the rotation shaft of the motor 32b. As a result, in FIG. 3, the shielding plate 22 moves from the left to the right in the opening 32 formed in the casing 12 so that the shielding plate 22 is positioned in front of the CCD camera 21, and the CCD camera in the opening 32 is formed. The part which exists in the front of 21 is plugged up. When the shielding plate 22 is positioned on the front surface of the CCD camera 21 and closes the portion of the opening 32 existing on the front surface of the CCD camera 21, the rotation of the drive motors 32 a and 32 b is stopped by the control unit 34. By such movement of the shielding plate 22, the CCD camera for photographing is switched from the CCD camera 21 to the CCD camera 31 during the inspection work in the reactor containment vessel 2 using the nuclear plant inspection apparatus of this embodiment. . For this reason, the radiation emitted from the inspection object is not incident on the CCD camera 21 but is incident on the CCD camera 31. As described above, after the CCD camera is switched, an image of the inspection object is taken by the CCD camera 31.

  After the switching of the CCD camera in step S3 is completed, the accumulated dose is reset (step S4). After the CCD camera is switched from the CCD camera 21 to the CCD camera 31, the control device 8 deletes accumulated dose data such as the total accumulated dose for the CCD camera 21 stored in the internal memory.

  According to the present embodiment, the image information obtained by photographing with the CCD camera (for example, the CCD camera 21), in particular, the image information of radiation noise included in the image information is incident during the photographing of the CCD camera. Therefore, the CCD camera can be switched more appropriately. Replacing the CCD camera based on the value of the number of pixels (the number of radiation noises, that is, the amount of radiation noise) of the radiation noise 37 included in the image obtained by photographing with the CCD camera, that is, the value of the number of white pixels Therefore, it is possible to more accurately determine the switching time of the CCD camera.

  Since it is determined whether or not the CCD camera needs to be replaced based on the image information obtained by photographing with the CCD camera, the present embodiment uses the dose rate used for obtaining the cumulative dose used for the determination of the replacement time. It is not necessary to provide the radiation detector used in the conventional example for detection.

  Further, a spare CCD camera (for example, a CCD camera 31) is provided in the camera unit 6, and when it is decided to replace the CCD camera, a shielding plate (radiation shield) covering the front surface of the spare CCD camera. Since the photographing is started with the spare CCD camera, the present embodiment can switch the CCD camera used for photographing in a short time. For this reason, the inspection time interrupted by the switching of the CCD camera is very short, and the inspection can be performed substantially continuously even when the CCD camera is switched.

  Since the CCD camera 21 is switched to the CCD camera 31 in the camera unit 6, the inspection time can be extended in one nuclear power plant inspection apparatus.

  DESCRIPTION OF SYMBOLS 1 ... Reactor building, 2 ... Reactor containment vessel, 3 ... Reactor, 4 ... Camera insertion port, 5 ... Camera fixing jig, 6 ... Camera unit, 7 ... Camera cable, 8 ... Control apparatus, 9 ... Display apparatus DESCRIPTION OF SYMBOLS 10 ... Controller, 21, 31 ... CCD camera, 22 ... Shielding board, 23a, 23b ... Illuminating device, 32a, 32b ... Drive motor, 33a, 33b ... Shielding board drive wire, 34 ... Control unit, 35 ... Power supply unit.

Claims (4)

  Based on a plurality of imaging devices, an irradiation device that irradiates the inspection object, and image information of the inspection object obtained by imaging by the imaging device, switching of the imaging device that images the inspection object is determined. An inspection device for a nuclear power plant comprising a determination device.   A radiation shield that covers a front surface of the imaging device; a shield moving device that moves the radiation shield; and the determination device, and controls the shield moving device when switching the imaging device used for imaging. The nuclear plant inspection device according to claim 1, further comprising: a control device that moves the radiation shield from a front surface of one imaging device to a front surface of another imaging device.   The nuclear power plant inspection device according to claim 1, further comprising the control device that performs the switching determination based on image information of radiation noise included in the image information.   The nuclear power plant inspection device according to claim 1, further comprising the control device that performs the switching determination based on information on a number of white pixels included in the image information.

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