JPH1172484A - Flange-related inspection device of atomic reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection device which can automatically inspect the weld, stud bolt ligament section, surface, etc., of a flange through remote control without lowering the water level in a well even when the well is fully filled up with water, can be operated easily and surely, and can be applied to various sizes of atomic reactors. SOLUTION: An inspection device is provided with a supporting means 12 which can be hung down from the top of an atomic reactor 4 and can be positioned and fixed above a flange section 5, a flaw detecting arm driving means 18 supported by the supporting means 12, a flaw detecting arm 19 which is coupled with the driving means 18 and can be moved in the peripheral direction along the upper surface of the flange section 5, and a probe 21 which is supported by the driving section 20 and operated in a horizontal plane. The weld 10 between the body section 6 and flange section 5 of the reactor 4 is inspected by ultrasonic flaw detection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to the soundness of, for example, the surface of a flange located above a reactor pressure vessel of a boiling water reactor, a welded portion, or a stud bolt for mounting an upper lid on the flange. The present invention relates to a flange-related inspection device for a reactor for automatically performing an inspection.

[0002]

2. Description of the Related Art In a reactor pressure vessel (RPV) of a boiling water reactor (BWR), as an inspection for confirming soundness related to a flange, a weld between a body part and a flange part of the reactor pressure vessel is inspected. Inspection, inspection of the ligament part of the stud bolt provided on the flange part for fixing the upper lid, inspection of the stud bolt and nuts and washers attached to this, etc.
For example, five types of inspections are performed.

[0003] As an inspection related to the flange, first, at the time of construction of a nuclear power plant, 100 parts of each part are inspected.
% In-Service Inspection (ISI), which is conducted during the periodic inspection after the operation of the nuclear power plant
For each of the above-mentioned parts, it is obliged to carry out four times (one time / 10 years) during the life of the nuclear power plant.

As an inspection amount per one periodic inspection, about 10 inspections are performed for stud bolts, nuts, and washers, and a welded portion between a trunk portion and a flange portion of a reactor pressure vessel and a stud bolster rigging portion. About 2,000 mm has been inspected.

For stud bolts, nuts and washers, visual inspection (VT) or ultrasonic inspection test (U) on the operation floor in a reactor building
T) is performed, and an ultrasonic flaw detection test is performed on each of the welded portion between the trunk portion and the flange portion of the reactor pressure vessel and the stud bolt rigment portion.

[0006] Conventionally, in an ultrasonic inspection test of a welded portion of a body and a flange portion of a reactor pressure vessel and a stud volt rig- mentment portion, a drainage is removed from a period in which a well is full for refueling. In this state, an inspector performs a manual ultrasonic flaw detection test in which the probe descends to the flange surface and scans the probe.

[0007]

In the above-mentioned prior art, an ultrasonic inspection test of a welded portion between a trunk portion and a flange portion of a reactor pressure vessel and a stud bolt rigment portion is performed manually by an inspector on the flange surface. However, since the radiation amount of the flange surface is higher than that of the operation floor, it has to be replaced by many workers, and the workability is low.

Further, the flange surface is installed at a position 5 m lower than the operation floor, so that the operator must perform an ascending / descending operation, and further, in the manual flaw detection scanning on the flange surface, there is a gap between the stud bolts. There were problems such as the inspector reaching for a troublesome scan of the probe.

Further, this inspection is possible only when the water level in the reactor pressure vessel is below the flange surface, and the water level lower than the flange surface during the regular periodic inspection is
There are only about four days before and after the installation or removal of the reactor pressure vessel head. The ultrasonic inspection of the welded part of the reactor pressure vessel body and flange, and the stud bolster rigment, is conducted by factory inspection and supervision. This was a work that had an impact on the periodical inspection process because it required about two days for the witness inspection by the agency, and the work was limited in time for the inspection.

In addition, a simple polishing operation is performed on the flange surface of the reactor pressure vessel before mounting the reactor pressure vessel head, and a visual inspection of the flange surface is performed by an operator with the naked eye after the polishing is completed. . This visual inspection was an operation that could be performed only after draining the reactor pressure vessel, as described above.

The present invention has been made in view of such circumstances, and the inspection of a welded portion between a reactor body and a flange, the inspection of a ligament portion of a stud bolt, the inspection of a flange surface, and the like are performed by remote scanning. It can be performed automatically, without the need to lower the water level even when the well is full, and scanning is easy and reliable, and it can be applied to reactors of various sizes, reducing exposure, improving work efficiency and improving safety. It is an object of the present invention to provide a flange-related inspection apparatus for a nuclear reactor, which can provide a great advantage in terms of the above aspects.

[0012]

In order to achieve the above object, according to the present invention, a flange-related inspection of a nuclear reactor for inspecting a welded portion between a trunk portion and a flange portion of a nuclear reactor by ultrasonic inspection. An apparatus, a support means which can be suspended from above the reactor and can be positioned and fixed on the upper part of the flange portion, and a flaw detection arm driving means supported by the support means,
A flaw detection arm connected to the flaw detection arm driving means and capable of moving in the circumferential direction along the upper surface of the flange portion; a probe drive section provided on the flaw detection arm; And a probe for performing ultrasonic scanning and ultrasonically flaw-detecting a welded portion between the trunk portion and the flange portion of the nuclear reactor.

According to a second aspect of the present invention, there is provided an inspection apparatus for a flange related to a nuclear reactor for inspecting a ligament portion of a stud bolt provided for fixing an upper lid on a flange portion welded to a body portion of a nuclear reactor by ultrasonic flaw detection. A support means which can be suspended from above the reactor and can be positioned and fixed on the upper part of the flange part, a flaw detection arm drive means supported by the support means, and connected to the flaw detection arm drive means and provided on an upper surface of the flange part. A flaw detection arm that can move in the circumferential direction along the probe, a probe drive unit provided on the flaw detection arm, and a scanning unit that scans on a horizontal plane while being supported by the probe drive unit. A flange-related inspection device for a nuclear reactor, comprising: a probe for flaw detection.

According to a third aspect of the present invention, in the inspection apparatus for a flange of a nuclear reactor according to the first or second aspect, a camera for visual inspection is provided on the flaw detection arm. An inspection device is provided.

According to a fourth aspect of the present invention, in the inspection apparatus for a flange of a nuclear reactor according to any one of the first to third aspects, the support means and the flaw-detecting arm are extendable and contractable in accordance with a change in the size of the reactor. The present invention provides a flange-related inspection device for a nuclear reactor, wherein the inspection device is configured to be capable of performing the following.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a flange-related inspection apparatus for a nuclear reactor according to the present invention will be described below with reference to the drawings.

FIG. 1 is a side view showing an apparatus configuration according to the present embodiment, and FIG. 2 is a plan view of FIG. 3 is a perspective view showing a boiling water reactor to be inspected, FIG. 4 is an explanatory diagram showing a state of ultrasonic inspection at the time of inspection, and FIG. 5 is a process diagram showing an inspection process according to the present embodiment. FIG. 6 is a conventional process diagram shown for comparison.

In the process charts shown in FIGS. 5 and 6, RPV indicates a reactor pressure vessel, CRD indicates a control rod drive mechanism, and NWL indicates a normal operation water level. The normal operation water level is a water level in the reactor during normal operation of the reactor.

As shown in FIG. 3, a reactor well 3 is formed below an operation floor 2 of a reactor building 1,
A reactor pressure vessel 4 is provided below the reactor pressure vessel. At an upper end portion of the reactor pressure vessel 4, a flange portion 5 for installing an upper cover (RPV head) (not shown) is installed by welding with a body portion 6 of the reactor pressure vessel 4. A large number of stud bolts 7 for fixing the upper lid are provided on 5.

At the time of periodic inspection, etc., when the upper lid, steam dryer (dryer), steam separator (separator), etc. are attached / detached, water is filled to the vicinity of the lower part of the flange in the reactor pressure vessel 4, and fuel is taken out and installed. In such a case, water is filled up to the vicinity of the upper surface of the reactor well 3. Conventionally, the ultrasonic inspection test of the welded part of the body part 6 and the flange part 5 of the reactor pressure vessel 4 and the ligament part of the stud bolt is performed when the water level is lowered to the lower part of the flange part 5. The inside of the reactor well 3 was used as an operator space. A transfer device 8 such as a refueling machine or an overhead crane is installed on the operation floor 2, and an operation room 9 having a control panel and the like is arranged.

In FIG. 4, the reactor pressure vessel 4 shown in FIG.
2 shows a welded portion 10 between the body portion 6 and the flange portion 5 and a ligament portion 11 of the stud bolt 7 in an enlarged manner. As shown in FIG. 4, the welded portion 10 between the body portion 6 and the flange portion 5 of the reactor pressure vessel 4 is continuous over the entire circumference of the reactor pressure vessel 4. The ligament portions 11 of the stud bolts 7 are arranged at intervals around the entire circumference of the reactor pressure vessel 4.

As shown in FIGS. 1 and 2, the inspection apparatus for a flange of a nuclear reactor according to the present embodiment can be suspended from above the reactor pressure vessel 4 by a crane or the like. There is a support means 12 which can be positioned and fixed on the upper part of the flange portion 5. The support means 12 comprises a base 14 having a suspension lug 13 and support legs 15 extending horizontally from the base 14. The support leg 15 has a length extending from the center of the reactor pressure vessel 4 to the flange portion 5 and is configured to be extendable and contractible in the length direction.

At both ends of the support leg 15, a positioning ring 17 as positioning means is provided via a bracket 16.
Are provided respectively. This positioning ring 17
Can be detachably fitted to the stud bolt 7 of the flange portion 5 by fitting from above, and a fastener such as an air cylinder (not shown) for fastening the stud bolt 7 is mounted inside the positioning ring 17. Have been.

The base 14 is provided with a flaw detection arm drive unit 18 having a turning motor or the like as a flaw detection arm drive means. The flaw detection arm drive unit 18 is located at the center of the reactor pressure vessel 4 from the flange portion 5. A flaw detection arm 19 extending up to is connected. Thereby, the flaw detection arm 19
As shown in FIG. 2, in a plan view, for example, the center of the reactor pressure vessel 4 can be moved in a circumferential direction along the upper surface of the flange portion 5 with the center of the reactor pressure vessel 4 as a fulcrum. In addition,
The flaw detection arm 19 is also extendable in the length direction.

A probe drive unit 20 having a ball screw mechanism and the like is provided at the tip end of the flaw detection arm 19 for rotation, and an ultrasonic flaw detection device which is supported by the probe drive unit 20 and performs scanning on a horizontal plane. Probe 21 is provided. The probe 21 can be scanned by the probe drive unit 20 in two axial directions orthogonal to each other on a horizontal plane, for example, in the radial direction of the reactor pressure vessel 4 and in the tangential direction orthogonal thereto.
The probe 21 has various functions for vertical flaw detection and oblique flaw detection.

Further, the flaw detection arm 19 is provided with a TV camera 22 for visual inspection capable of changing the viewing direction so that the flange surface and other parts can be visually inspected.

Then, a control / collection cable 23 is connected from the flaw detection arm drive unit 18 to the operation room 9, and the turning operation of the flaw detection arm 19, the probe 21
Scanning, operation of the TV camera 22 and the like can be remotely controlled, and data such as echo or image communication can be performed. Further, each of the above-mentioned components is configured to be detachable from each other, and is configured to be operable underwater.

Next, the operation will be described.

First, when the apparatus of this embodiment is installed on the flange portion 5, the length of the support leg 15 and the flaw detection arm 19 are adjusted in advance according to the size of the reactor pressure vessel 4 to be inspected. And setting the device in the direction of the stud bolt 7 attached to the flange portion 5,
The suspension is performed by a crane or the like via 3.

Then, as shown in FIGS. 1 and 2, a positioning ring 17 is fitted and installed on an arbitrary stud bolt 7, thereby positioning the apparatus. After the positioning is completed, the stud bolt 7 is fastened with the fastener in the positioning ring 17.
To fix the device, thereby completing the installation of the device on the flange portion 5.

When inspecting the welded part between the body part 6 and the flange part 5 of the reactor pressure vessel 4, the probe 21 is placed on the upper surface on the inner peripheral side of the flange part 5. Scanning for moving the probe 21 in two axial directions is performed by the ball screw mechanism of the probe drive unit 20, and the probe drive unit 20 is moved along the circumferential direction of the flange unit 5 by driving the flaw detection arm drive unit 18. This is done by moving. FIG. 4 shows the state of the ultrasonic flaw detection by the probe 21 in this case. For example, the ultrasonic wave a emitted from the probe 21 at the welded portion 10 by the vertical flaw detection or the oblique flaw detection by the ultrasonic wave. Echo detection can be performed.

The above operation is performed by the control / collection cable 23.
Can be performed in the control room 9 by remote control, and the obtained echo data can be collected and analyzed in the control room 9 to check the soundness. Therefore, unlike the conventional case where the inspector performs manual flaw detection at the flange portion 5, the work is easy and the safety is high, and the labor can be reduced and the safety and work efficiency can be greatly improved.

The ligament part 1 of the stud bolt 7
In the case of performing the inspection 1, the stud bolt 7 shown in FIG. 4 is removed, the probe 21 is arranged with the upper surface of the flange portion 5 released, and the probe 21 is scanned in the same manner as described above. And the ultrasonic wave b emitted from the probe 21
Ultrasonic inspection is performed. As shown in FIG.
A hole is formed in the center of the stud bolt 7 so that the probe 21 for detecting a ligament portion can be moved up and down in this hole. In the present embodiment, the probe inside the stud bolt 7 is used. An automatic flaw detection can be performed in place of the inspection by the probe 21. Also in the inspection of the ligament part 11, unlike the case where manual flaw detection is performed, the operation is easy and the safety is high, so that labor can be reduced and the safety and work efficiency can be greatly improved.

Further, the surface of the flange portion 5 is polished at the time of inspection. For the inspection after the polishing operation, a visual inspection by the TV camera 22 provided on the flaw detection arm 19 can be performed remotely. The operation of the TV camera 22 in this case can also be closely observed by turning the flaw detection arm 19, changing the camera posture, and the like. This work can also be performed in detail by remote control, and safety, workability, reliability, and the like can be improved.

In this embodiment, since each component is configured to be operated underwater, all of the above inspections can be performed underwater. Therefore, unlike the conventional example in which the inspector manually performs the inspection, the inspection can be performed in a state where the reactor well 3 is full, and the inspection can be performed in a timely manner. For example, FIG. 5 shows the water level in the well 3 at the time of inspection when this embodiment is applied, and the progress of the work process.

As shown in FIG. 5, in this embodiment, the inspection work can be performed even when the flange is in a submerged state, so that the fuel is taken out from the reactor pressure vessel 4 and then the control rod is driven on the bottom side. When checking the mechanism (CRD),
In parallel with this, a flange-related inspection can be performed. Conventionally, as shown in FIG. 6, the water level is limited to the time when the water level is below the flange portion 5, that is, the time before the fuel is taken out, or the time after the fuel is loaded, and a single process for that is required. In the present embodiment, the well 3
The work can be performed even when the water is full, and can be performed in parallel with other works, so that the work efficiency can be significantly improved.

After the completion of the inspection work, the positioning ring 17 is removed from the stud bolt 7, the apparatus is temporarily placed on the operation floor 2 by a refueling machine or an overhead crane or the like, and after simple derailing, for example, the support legs 15 and the flaw detection arm 19 may be detached from the flaw detection arm 19 drive unit 18, and the support leg 15 and the flaw detection arm 19 may be expanded and contracted to move and store.

Further, since the support leg 15 and the flaw detection arm 19 are configured to be expandable and contractable and can be mounted in response to a change in the size of the reactor, the invention can be applied to plants of different sizes. In particular, in the configuration of the present embodiment in which each component is detachable, the number of components prepared for each plant is extremely small.
Even if 5 and the flaw detection arm 19 are not applicable, the other parts can be shared in other plants in many cases.

[0039]

As described above in detail, according to the present invention, an ultrasonic flaw detection test of a welded portion between a trunk portion and a flange portion of a nuclear reactor and a ligament portion of a stud bolt can be automatically and remotely performed. The device can be mounted on the flange portion using stud bolts, and the device can be mounted and inspected underwater, and can be applied to plants of various sizes. In addition, the inspection of the flange surface can be performed automatically by remote scanning, and even if the water in the reactor well is full, it can be performed without lowering the water level. It can be applied to furnaces, and offers great advantages in terms of reducing exposure, improving work efficiency, and improving safety.

[Brief description of the drawings]

FIG. 1 is a side view showing one embodiment of a flange-related inspection apparatus for a nuclear reactor according to the present invention.

FIG. 2 is a plan view of FIG. 1;

FIG. 3 is a perspective view showing a boiling water reactor to be inspected in the embodiment.

FIG. 4 is an explanatory view showing a state of ultrasonic inspection at the time of inspection according to the embodiment.

FIG. 5 is a process diagram showing an inspection process according to the embodiment.

FIG. 6 is a process diagram showing a conventional inspection process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reactor building 2 Operation floor 3 Reactor well 4 Reactor pressure vessel 5 Flange part 6 Body part 7 Stud bolt 8 Conveying device 9 Operation room 10 Welding part 11 Ligament part 12 Supporting means 13 Hanging ear 14 Base 15 Support leg 16 Bracket 17 positioning ring 18 flaw detection arm drive 19 flaw detection arm 20 probe drive 21 probe 22 TV camera 23 cable

Claims (4)

[Claims] 1. An inspection apparatus for a flange of a nuclear reactor for inspecting a welded portion between a trunk portion and a flange portion of a nuclear reactor by ultrasonic flaw detection, wherein the inspection device can be hung from above the reactor and positioned above the flange portion. A fixing means, a flaw detection arm driving means supported by the supporting means, a flaw detection arm connected to the flaw detection arm drive and capable of moving in a circumferential direction along the upper surface of the flange portion, and a flaw detection arm are provided. A probe drive unit, and a probe supported by the probe drive unit, performing scanning on a horizontal plane, and performing ultrasonic flaw detection on a welded portion between the trunk portion and the flange portion of the reactor. Inspection equipment for flanges of nuclear reactors. 2. A flange-related inspection device for a nuclear reactor, which inspects a ligament portion of a stud bolt provided for fixing an upper lid on a flange portion welded to a body portion of the nuclear reactor by ultrasonic flaw detection. Support means that can be suspended from and positioned and fixed on the upper part of the flange portion,
A flaw detection arm driving means supported by the support means, a flaw detection arm coupled to the flaw detection arm driving means and capable of moving in a circumferential direction along an upper surface of the flange portion, and a probe driving section provided on the flaw detection arm. A probe that is supported by the probe drive section and performs scanning on a horizontal plane to ultrasonically detect the ligament section of the stud bolt. 3. The apparatus for inspecting a flange of a nuclear reactor according to claim 1, wherein a camera for visual inspection is provided on the flaw detection arm. 4. The inspection apparatus for a flange of a nuclear reactor according to claim 1, wherein the support means and the flaw detection arm are extendable and contractable and can be mounted in response to a change in the size of the reactor. A flange related inspection device for a nuclear reactor.