JP2008190968A - Ultrasonic flaw detection device and its flaw detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately and quickly perform ultrasonic flaw detection of a welding part of a shroud support cylinder and its proximity in an aerial space. <P>SOLUTION: This ultrasonic flaw detection device comprises a chamber mechanism 2 forming a closed space in contact with a surface of a part to be flaw-detected, a propagation medium filling mechanism 4 for filling the space in this chamber mechanism with ultrasonic propagation medium, a phased array ultrasonic probe 5 disposed movably inside the chamber mechanism, an ultrasonic flaw detector 6 for performing ultrasonic flaw detection by moving the probe inside the chamber mechanism, and a chamber support mechanism for supporting the chamber mechanism and moving it in the direction of flaw detection. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention provides an ultrasonic inspection method for inspecting a welded portion existing in a shroud support cylinder installed in a nuclear reactor and a nearby structure portion in an atmospheric atmosphere during inspection and repair of a nuclear power plant. The present invention relates to a flaw detection apparatus and an ultrasonic flaw detection method.

  In nuclear power plants, inspections to confirm the integrity of the reactor and repairs after the inspections are performed. When inspecting or repairing the reactor pressure vessel in a boiling water reactor, remove the in-reactor equipment after decontamination of the reactor pressure vessel, and shroud support cylinder and shroud support plate (baffle plate) ) And other inspections near the bottom of the furnace.

  With reference to FIG. 9, the shroud support used as the ultrasonic flaw detection site | part in the reactor pressure vessel of a boiling water reactor and the structure part of the vicinity of it are demonstrated easily. As shown in FIG. 9, a core shroud 102 constituting the core is disposed inside the reactor wall 101 of the reactor pressure vessel 100. The core shroud 102 is supported by welding sequentially from below through a shroud support leg 103 rising from the bottom of the furnace wall 101 and a shroud support cylinder 104 disposed on the shroud support leg 103. Hereinafter, a welded portion between the bottom of the furnace wall 101 and the shroud support leg 103 is referred to as an “H11 welded portion”, and a reference numeral “111” is attached to the drawing. Further, a welded portion between the shroud support leg 103 and the shroud support cylinder 104 is referred to as an “H10 welded portion”, and a reference numeral “110” is attached to the drawing.

  A shroud support plate 105 is joined by welding between the furnace wall 101 rising from the furnace bottom and the core shroud 102. The shroud support plate 105 is formed with a jet pump diffuser hole 106 for supporting a diffuser portion of a jet pump (not shown) that is a nuclear reactor recirculation pump. Hereinafter, a welded portion between the furnace wall 101 and the core shroud 102 is referred to as an “H9 welded portion”, and a symbol “H109” is attached to the drawing. Further, a welded portion between the core shroud 102 and the shroud support plate 105 is referred to as an “H8 welded portion”, and a reference numeral “108” is attached to the drawing.

With regard to such inspection of welded parts, conventionally, ultrasonic flaw detection has been performed in order to confirm the soundness of the welded part of the shroud support cylinder and the vicinity thereof. As ultrasonic flaw detection in a nuclear reactor, underwater flaw inspection using an underwater vehicle has been proposed (see, for example, Patent Document 1). On the other hand, when ultrasonic flaw detection is performed on a welded portion such as a shroud support cylinder and a shroud support plate and the vicinity thereof, flaw detection by a direct contact method using a single probe is also performed in the air. When ultrasonic flaw detection is performed on the welded portion of the shroud support and its vicinity in the air space, direct flaw detection using a single probe is performed.
JP 2005-30773 A

  As described above, when ultrasonic flaw detection is performed on the welded portion of the shroud support cylinder existing in the reactor in the air space and the vicinity thereof, flaw detection is performed by a direct contact method using a single probe. With this method, it is difficult to accurately size the crack depth due to the influence of the surface shape of the object, and when all the welds are subjected to ultrasonic testing, the inspection time becomes very long. There is a problem.

  The present invention has been made to solve such a problem, and an object of the present invention is to accurately and quickly ultrasonically detect a welded portion of a shroud support cylinder and its vicinity in an air space.

  In order to achieve the above object, the present invention provides an ultrasonic flaw detection apparatus that ultrasonically flaws a welded portion existing in a shroud support cylinder installed in a nuclear reactor and a structure portion in the vicinity thereof in an air atmosphere. A chamber mechanism that forms a closed space in contact with the surface of the site to be inspected, a propagation medium filling mechanism that fills the space in the chamber mechanism with an ultrasonic propagation medium, and is movable inside the chamber mechanism. A provided phased array ultrasonic probe, an ultrasonic flaw detector that performs ultrasonic flaw detection by moving the probe in the chamber mechanism, and a chamber support that supports the chamber mechanism and moves in the flaw detection direction. An ultrasonic flaw detector provided with a mechanism is provided.

  Further, in the present invention, using this ultrasonic flaw detector, the shroud support cylinder installed in the nuclear reactor at the time of the nuclear reactor inspection and the welded portion existing in the structure portion in the vicinity thereof under an atmospheric atmosphere. An ultrasonic flaw detection method for ultrasonic flaw detection, in which a chamber mechanism, a propagation medium filling mechanism, a phased array ultrasonic probe, an ultrasonic flaw detector, and a chamber support mechanism are carried into the shroud support cylinder and the structure in the vicinity thereof. An instrument installation step, a chamber-mechanism is brought into contact with the surface of the flaw detection site to form a closed space, and the chamber mechanism is filled with an ultrasonic propagation medium. Ultrasonic flaw detection by the phased array ultrasonic probe in the air moved along the inspection target site by the chamber support mechanism To provide an ultrasonic flaw detection method characterized by comprising a inspection step of performing.

  According to the present invention, ultrasonic welding of a shroud support cylinder and its vicinity in a nuclear reactor pressure vessel of a nuclear reactor, particularly a boiling water reactor, is performed accurately and quickly by water immersion phased array flaw detection in an air space. It is possible to perform flaw detection.

  Hereinafter, a case where an embodiment of an ultrasonic flaw detection apparatus and an ultrasonic flaw detection method according to the present invention is applied to a reactor pressure vessel of a boiling water reactor will be described with reference to the drawings.

[First Embodiment (FIGS. 1, 2 and 3)]
FIG. 1 is a schematic explanatory view showing an installation state of the ultrasonic flaw detector according to the first embodiment of the present invention. FIG. 1 shows the inspection of the welded portion (H8 welded portion) 108 between the core shroud 102 and the shroud support plate 105 near the upper side of the shroud support cylinder 104 installed in the reactor pressure vessel 100, and the shroud support plate. A state is shown in which an inspection of a welded portion (H9 welded portion) 109 between 105 and the furnace wall 101 is inspected upward from below.

  As shown in FIG. 1, the ultrasonic flaw detector 1 includes a chamber mechanism 2 that forms a closed space in contact with the lower surface of the H8 weld 108 that is a flaw detection site. The chamber mechanism 2 is set to be disposed obliquely upward corresponding to a welded portion existing in the shroud support cylinder 102 and a shroud support plate 105 which is a structure portion in the vicinity thereof, that is, an H8 welded portion 108. In addition, a water injection / drainage mechanism 4 as a propagation medium filling mechanism is provided to fill or drain water 3 as an ultrasonic propagation medium into the space in the chamber mechanism 2. A phased array ultrasonic probe (hereinafter abbreviated as “ultrasonic probe”) 5 is movably provided inside the chamber mechanism 2.

  Further, an ultrasonic flaw detector 6 for performing an ultrasonic flaw for obtaining a flaw detection result by performing an instruction to move the ultrasonic probe 5 within the chamber mechanism 2, an ultrasonic transmission and reception, and a chamber mechanism 2 are supported. A carriage 7 is provided as a chamber support mechanism that moves in the flaw detection direction. Further, a scanner 8 for moving the ultrasonic probe 5 inside the chamber mechanism 2 is provided, and a scanner control panel 14 for operating the scanner 8 is also provided. The chamber mechanism 2 is supported on the carriage 7 via a spring mechanism 9 so that a pressing force is applied in the direction of the flaw detection part. The above apparatus is supported by a work platform 10 assembled at the bottom of the reactor pressure vessel 100.

  The work platform 10 is installed using a control rod drive mechanism housing (CRD housing) 107 or the like, and rises upward and extends toward the furnace wall 101 through the opening 104a of the shroud support cylinder 104 or the like. . The work platform 10 has a work floor 11 at a position below the shroud support plate 105, and has support parts 12 and 13 extending sideways and upward of the work floor 11, and these support parts 12 and 13 are furnaces. The wall 101 and the shroud support plate 105 are fixedly supported.

  FIG. 2 is an enlarged view of the ultrasonic flaw detector 1 shown in FIG. As shown in FIG. 2, the chamber mechanism 2 has an opening 16 in which, for example, a part of the casing 15 on the rectangular parallelepiped (the upper left two parts in FIG. 2) is cut, and the opening 16 is made of a flexible material. The watertight holding mechanism 17 is configured to be closed. By this watertight holding mechanism 17, the chamber mechanism 2 can be filled with water 3 and held. The chamber mechanism 2 is connected to the water injection / drainage mechanism 4 via the water injection / drainage tube 18 so that the water amount necessary for flaw detection can be supplied and drained after the inspection.

  The ultrasonic probe 5 provided inside the chamber mechanism 2 is supported by the scanner 8 through a connector 19 so as to be movable. The scanner 8 has, for example, an arcuate guide member 20, and a connecting tool 19 of the ultrasonic probe 5 is supported on the guide member 20 via a moving piece 21. Thereby, as indicated by an arrow a in FIG. 2, the ultrasonic probe 5 can detect the H8 welded portion 108 which is a flaw detection portion.

The spring mechanism 9 that supports the chamber mechanism 2 on the carriage 7 presses the outer surface of the casing 15 of the chamber mechanism 2 with an elastic force in a three-dimensional direction toward the opening 16 of the casing 15 by, for example, a metal spring 22. be able to. A fluid spring mechanism using a cylinder mechanism may be provided instead of the metal spring 22. By such a spring mechanism 9, the chamber mechanism 2 can be brought into close contact with the H8 welded portion 108 via the watertight holding mechanism 17 in a state in which the chamber mechanism 2 can swing. The ultrasonic probe 5 is connected to the ultrasonic flaw detector 6 by a cord 23, and the scanner 8 and the scanner control panel 14 are connected by a cord 24.

  FIG. 3 shows an air reservoir removing mechanism 25 in the chamber mechanism 2. When performing an ultrasonic flaw detection using a phased array ultrasonic probe, if an air (air) pool is generated in the water 3 which is a propagation space of the ultrasonic wave transmitted from the ultrasonic probe 5, the ultrasonic wave does not propagate. This causes trouble. As a solution, in this embodiment, an air reservoir removing mechanism 25 is provided. For example, as shown in FIG. 4, an air hole 26 is provided in the upper part of the chamber mechanism 2, and means for removing air from the air hole 26 to the outside is provided. In order to guide air in the direction of the air hole 26, a water injection nozzle (not shown) or the like is provided in the vicinity of the ultrasonic probe 5 so that underwater air is guided from the pouring / draining mechanism 4 to the air hole 26. It is desirable to have a configuration.

  In the above embodiment, the H8 welded portion 108 and the H9 welded portion 109 existing in the shroud support cylinder 104 installed in the reactor pressure vessel 100 at the time of the nuclear reactor inspection and the structural portion in the vicinity thereof are maintained in the atmosphere. And can be ultrasonic flaw detection. As a procedure in this case, the following steps are performed.

  That is, the chamber mechanism 2, the propagation medium filling mechanism pouring / draining mechanism 4, the ultrasonic probe 5, the ultrasonic flaw detector 6, An equipment installation process for carrying in and installing a carriage 7 as a chamber support mechanism is performed. Next, a closed space is formed by bringing the chamber mechanism 2 into contact with the surface of the flaw detection site, and a flaw detection preparation step is performed in which the chamber mechanism 2 is filled with water 3 as an ultrasonic propagation medium. Then, the chamber mechanism 2 is moved along the H8 welded portion 108 and the H9 welded portion 109, which are to-be-detected parts, by the carriage 7 which is a chamber support mechanism, and ultrasonic flaw detection by the ultrasonic probe 5 is performed in the air. Specifically, the following steps (1) to (4) are performed.

(1) After reaching the flaw detection site, the chamber mechanism 2 is pressed against the target site by the spring mechanism 9 which is a chamber pressing mechanism.

(2) After that, the chamber mechanism 2 is filled with water 3 using the pouring / draining mechanism 4. At this time, since there is a watertight holding mechanism 17 in the gap between the chamber mechanism 2 and the target structure, the inside of the chamber mechanism 2 can be always filled with water 3.

(3) After filling the chamber mechanism 2 with water 3, the probe 5 is driven by the scanner control panel 14 to perform flaw detection. At this time, the scanner 8 can control the driving direction, the driving speed, and the like by the scanner control panel 14.

(4) After the flaw detection, the water 3 inside the chamber is drained by using the pouring / draining mechanism 4. After draining, the device is moved to the next target site, and after reaching the next target site, the above procedure is repeated to perform flaw detection.

  According to the present embodiment described above, it is possible to place the ultrasonic flaw detector 6, the scanner control panel 14, and the pouring / draining mechanism 4 on the work floor 11 of the work platform 10, while an operator monitors the apparatus and the like. The flaw detection image displayed on the ultrasonic flaw detector 6 and the scanner 8 can be controlled.

[Second Embodiment (FIG. 4)]
In the present embodiment, an ultrasonic flaw detection apparatus suitable for flaw detection of the H10 weld 110 and the H11 weld 111 will be described. FIG. 4 is an enlarged view of a main part of the configuration for inspecting the H10 welded part 110.

  As shown in FIG. 4, the configuration of the present embodiment is basically the same as that of the first embodiment, but the orientation and installation position of the apparatus are different from those of the first embodiment. That is, in this embodiment, the ultrasonic flaw detection apparatus 1 includes the chamber mechanism 2 that forms a closed space in contact with the upper surface of the H10 weld 110 that is the flaw detection site. The chamber mechanism 2 has a configuration in which a suspension mechanism 31 is attached to the shroud support cylinder 102 and the chamber mechanism 2 is suspended from the suspension mechanism 31 via a spring mechanism 9. The other configurations are substantially the same as those in the first embodiment except for the orientation, and therefore, the same reference numerals as those in the first embodiment are given to FIG.

  According to the present embodiment, the H10 welded part 110 and the H11 welded part 111 can be flaw-detected by setting the direction in an inclined state that is inclined obliquely downward.

[Third Embodiment (FIGS. 5, 6, and 7)]
FIG. 5 is an overall view showing the overall configuration and the in-furnace arrangement configuration of the present embodiment. FIG. 6 is an enlarged view showing the work platform 10 shown in FIG. 5, and FIG. 7 is an enlarged view showing the rail portion shown in FIG.

  As shown in FIG. 5, this embodiment differs from the above embodiment in that the chamber support mechanism is not a carriage that runs on a work platform installed in the reactor pressure vessel 100, but the shroud support cylinder 104 or its vicinity. In this structure, a rail 42 suspended by a rail suspension mechanism 41 is applied. That is, in this embodiment, a tracked vehicle structure that moves along the rail 42 provided on the shroud support plate 105 that is a structural portion in the vicinity of the shroud support cylinder 104 is applied. About another structure, it is substantially the same as that of the said embodiment.

  FIG. 6 shows the configuration of the work platform. As shown in FIG. 6, the work platform 10 has a work floor 11 below the shroud support plate 105, and has support portions 12 and 13 extending sideways and upward of the work floor 11. The parts 12 and 13 are fixedly supported by the furnace wall 101 and the shroud support plate 105.

  FIG. 7 shows the configuration of the rail 42 in an enlarged manner. The rail 42 is supported by the jet pump diffuser hole 106 of the shroud support plate 105, and the chamber mechanism 2 shown in FIG. 5 can be moved along the H8 weld 108. That is, as shown in FIG. 5, it is installed in the circumferential direction of the reactor pressure vessel 100.

  According to the present embodiment, when the flaw detection range is wide, the flaw detection time can be shortened by installing the rail 42. In the ultrasonic flaw detector 1 of the present embodiment, a joint portion (not shown) for passing the rail 42 is separately installed in the chamber mechanism 2 that is an ultrasonic flaw detection head, so that the reactor pressure vessel 100 is passed through the rail 42. The ultrasonic probe 5 can be easily driven in the circumferential direction. The driving by the rail 42 may be an electric or manual method. According to the present embodiment, it is possible to quickly perform an ultrasonic flaw detection work.

  When the ultrasonic flaw detector 1 according to the present embodiment is used, the jet pump diffuser hole 106 and the access hole cover hole (not shown) are closed with a closing lid or the like. By installing this closing lid, the inside of the chamber mechanism 2 can be kept watertight even in the vicinity of the jet pump diffuser hole 106 and the access hole cover hole. Note that when closing the jet pump diffuser hole 106, it is necessary to provide a closing lid so as not to interfere with the joint portion of the rail 42. At the time of inspection, the lid 42 is installed in advance on the rail 42, the work platform 10, the jet pump diffuser (not shown), and the access hole cover, and the same operation as in the first embodiment is performed.

  By using this gantry, it is possible to place the ultrasonic flaw detector 6, the scanner control panel 14, and the water injection / drainage mechanism 4 on the gantry, and the flaw detection image displayed on the flaw detector while an operator monitors the apparatus. And the scanner can be controlled.

[Fourth Embodiment (FIG. 8)]
FIG. 8 shows a fourth embodiment of the present invention. In the present embodiment, it is premised that the vehicle is moved by a carriage or the like. However, as an alternative measure, a method of providing a self-propelled mechanism in the ultrasonic flaw detection head is also conceivable. This is means for driving the ultrasonic testing head in the circumferential direction of the reactor pressure vessel 100 by means of two arms 50 and 51 and a drive mechanism 53. A drive wheel 52 that is driven by a motor or the like (not shown) is provided at the tip of the arm 51. The drive mechanism 53 is provided with a motor that serves as a drive source for the drive wheels, a cylinder mechanism (not shown) for expanding and contracting the arms 50 and 51, and the like. When this device is used, a flaw detector (not shown), a control panel of the device, a water injection / drainage mechanism, etc. are installed on the furnace bottom or the operation floor.

  According to the present embodiment, ultrasonic flaw detection can be performed without driving the apparatus by an operator or the like.

1 is a schematic configuration diagram showing an ultrasonic flaw detector according to a first embodiment of the present invention. Explanatory drawing which expands and shows the principal part of FIG. The expanded sectional view which expands and shows FIG. 2 further. The schematic block diagram which shows the ultrasonic flaw detector by 2nd Embodiment of this invention. The schematic block diagram which shows the ultrasonic flaw detector by 3rd Embodiment of this invention. Explanatory drawing which expands and shows the mount frame shown in FIG. Explanatory drawing which expands and shows the rail shown in FIG. The block diagram which shows the ultrasonic flaw detector by 4th Embodiment of this invention. The cross-sectional view which shows the structure in the reactor pressure vessel of ABWR.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Chamber mechanism, 2 ... Chamber mechanism, 3 ... Water, 4 ... Drainage mechanism, 5 ... Ultrasonic probe, 6 ... Ultrasonic flaw detector, 7 ... Dolly, 8 ... Scanner, 9 ... Spring mechanism, 10 ... Work platform, 11 ... Work floor, 12 ... Supporting part, 13 ... Supporting part, 14 ... Scanner control panel, 12 ... Housing, 16 ... Opening part, 17 ... Watertight holding mechanism, 16 ... Opening part, 18 ... Water injection tube , 19, connector, 20 guide member, 21 moving piece, 22 metal spring, 23 cord, 24 cord, 25 cord, 25 air trap removal mechanism, 26 air hole, 100 reactor pressure Vessel, 102, furnace wall, 102, core shroud, 103, shroud support leg, 104, shroud support cylinder, 105, shroud support plate.

Claims (4)

An ultrasonic flaw detection apparatus that performs ultrasonic flaw detection in an air atmosphere on a shroud support cylinder installed in a nuclear reactor and a structure near the shroud support cylinder. A chamber mechanism for forming a closed space, a propagation medium filling mechanism for filling the space in the chamber mechanism with an ultrasonic propagation medium, and a phased array ultrasonic probe movably provided in the chamber mechanism; An ultrasonic flaw detector that performs ultrasonic flaw detection by moving the probe in the chamber mechanism, and a chamber support mechanism that supports the chamber mechanism and moves it in the flaw detection direction. Sonic flaw detector. The chamber support mechanism is a carriage that runs on a work platform installed in a nuclear reactor, a track vehicle that is supported by a rail provided on the shroud support cylinder or a structure in the vicinity thereof, or the shroud support or 2. The ultrasonic flaw detector according to claim 1, wherein the ultrasonic flaw detector is a trackless vehicle that moves along the surface of the structure portion in the vicinity thereof. The ultrasonic flaw detector according to claim 1 or 2, wherein the chamber mechanism is oriented in an upward, downward, lateral, or inclined state corresponding to a welded portion present in the shroud support cylinder and a structure portion in the vicinity thereof. . The ultrasonic flaw detector according to any one of claims 1 to 3, wherein a welded portion present in a shroud support cylinder installed in the nuclear reactor during a nuclear inspection and a structural portion in the vicinity thereof. Is an ultrasonic flaw detection method in an air atmosphere, wherein a chamber mechanism, a propagation medium filling mechanism, a phased array ultrasonic probe, and an ultrasonic flaw detection are provided in the shroud support cylinder and the structure in the vicinity thereof. A device installation process in which a chamber and a chamber support mechanism are carried in, and a flaw detection method in which a closed space is formed by bringing the chamber mechanism into contact with the surface of the site to be inspected and the chamber mechanism is filled with an ultrasonic propagation medium. A phased array ultrasonic wave in the air by moving the chamber mechanism along the inspection site by the chamber support mechanism; Ultrasonic flaw detection method characterized by comprising a inspection step of performing ultrasonic flaw detection by probe.

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