JP2660114B2 - Inspection method and inspection device for internal pump welds - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[Object of the Invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for inspecting a welded portion of an internal pump using a radiation transmission tester, and more particularly to a welded portion of an internal pump casing fixed to a reactor pressure vessel nozzle. The present invention relates to an inspection method and an inspection device for an internal pump welded portion for confirming and inspecting a Uranami bead portion.

[0003]

2. Description of the Related Art In a boiling water reactor as a light water reactor, a coolant (reactor water) accommodated in a reactor pressure vessel is:
It is returned to the reactor core as coolant again by the reactor recirculation system. This reactor recirculation system has an external recirculation method in which the coolant inside the reactor pressure vessel is once taken out and then guided to the core again.The coolant is recirculated in the reactor pressure vessel, and the coolant is recycled to the core. There is an internal recirculation system to guide. Of these, the internal recirculation system is the advanced boiling water reactor (ABW).
R) and an internal pump is provided.

[0004] As shown in FIG. 7, a plurality of internal pumps 1, for example, 8 at the bottom (lower mirror) of the reactor pressure vessel 2.
10 to 10 units are installed at intervals in the circumferential direction. Specifically, a plurality of reactor pressure vessel nozzles (RPV nozzles) 3 are integrally formed at the bottom of the reactor pressure vessel 2, and the RP
The pump casing 4 of the internal pump 1 is fixed to the V nozzle 3 by welding through the nozzle hole 3a of the reactor pressure vessel 2 from below, and is set in a suspended state.

[0005] The internal pump 1 is a reactor pressure vessel 2
It has a pump motor section 5 located outside and a pump impeller section 6 located inside the reactor pressure vessel 2, and the pump impeller section 6 is installed in a downcomer section 8 formed outside a core shroud 7. The internal pump 1 controls the core recirculation flow rate by changing the pump flow rate.

[0006] The pump casing 4 of the internal pump 1 is fixed to the RPV nozzle 3 by welding and suspended in a hanging state. Internal pump casing 4
If a welding defect due to poor fusion occurs in the welded portion 9, cracks may be generated near the welded portion, and the cracks may gradually grow and leak paths may be formed. May develop into a leak.

Accordingly, in order to improve the soundness of the welded portion 9 of the pump casing of the internal pump, welding defects and potential defects at the welded portion 9 of the pump casing 4 and its vicinity are accurately and reliably confirmed. Need to be inspected.

[0008]

However, in the conventional boiling water reactor, the internal pump casing 4
The gap between the sleeve and the RPV nozzle 3 is as small as several mm, for example, about 8 mm. A vibration-proof pad 4a is formed in the pump casing 4 of the internal pump 1 in the circumferential direction. Since the pad 4a is fitted into the lower part of the nozzle hole of the RPV nozzle 3, the accessibility of the inspection device is poor, and the position corresponding to the welded portion of the internal pump casing cannot be accessed.

In particular, once the internal pump casing 4 is fixed to the RPV nozzle 3 by welding, the welded portion 9 of the pump casing is simply checked and inspected from the nozzle hole side, and the back bead portion of the welded portion 9 is formed. The test could not be performed. For this reason, it has been difficult to confirm and inspect a welding defect due to a welding defect in the welded portion 9 of the internal pump casing 4 or a dent in the penetration bead portion.

The present invention has been made in view of the above-described circumstances, and improves the inspection property by making it possible to easily access a welded portion of an internal pump casing by using a radioactive test device, and to improve the welding condition of the welded portion. It is an object of the present invention to provide an inspection method and an inspection apparatus for an internal pump welded part, which can accurately and reliably check and inspect the welded part and improve the soundness of the welded part. [Configuration of the invention]

[0011]

According to a first aspect of the present invention, there is provided a method for inspecting an internal pump welded portion, comprising the steps of: In the method for inspecting a welded portion of an internal pump casing for inspecting a welded portion of an internal pump, a radiation generator is installed at the reactor pressure vessel nozzle, and a radiation source unit of the radiation generator is adapted to the welded part by an elevation drive device. Set the film holder in the inner position, and circumferentially push the film holder with the film into it from the access opening of the nozzle skirt into the sleeve-like gap between the reactor pressure vessel nozzle and the internal pump casing. After connecting to the holder elevating and holding device inserted from the access opening,
Activate the fluid cylinder to raise the film holder within the sleeve-like gap, set the film at the outer position corresponding to the weld, and then apply radiation from the source of the radiation generator to the weld. In this method, a film is shot by irradiating under the shooting conditions described above, and the welded portion is inspected.

According to another aspect of the present invention, there is provided an inspection apparatus for an internal pump welded portion, the internal pump casing being fixed to a nozzle of a reactor pressure vessel. In an inspection apparatus for an internal pump welded part for inspecting a welded part, a radiation generator is installed on the reactor pressure vessel nozzle, and the radiation generator is provided with a lifting drive device for raising and lowering a radiation source part. An opening for access is formed in the nozzle skirt of the nozzle of the reactor pressure vessel, and a film holder with a film is freely inserted into and removed from the access opening into the sleeve-shaped gap between the reactor pressure vessel nozzle and the internal pump casing. And a holder elevating and holding device detachably connected to the film holder. Was inserted from the opening, it is obtained by holding the film holder with the holder elevating holding device welds corresponding outside position in the sleeve-like gap.

[0013]

According to the method and the apparatus for inspecting a welded portion of an internal pump according to the present invention, an access opening is formed in a nozzle skirt of a reactor pressure vessel nozzle, and a reactor pressure vessel nozzle (RPV) is formed from the access opening. Nozzle) and the film holder with the film inserted into the sleeve-shaped gap of the internal pump casing in the circumferential direction, and the fluid cylinder is operated while the pressed film holder is held by the holder elevating and holding device which is similarly pushed. Then, the film holder is raised within the sleeve-shaped gap, and the film mounted on the film holder is accurately set at the position corresponding to the weld of the internal pump casing weld.

On the other hand, a radiation generator is installed on the RPV nozzle, and the radiation source of the radiation generator is set at an inner position corresponding to the welded portion by a lifting drive.

After the setting of the radiation source unit of the radiation generating apparatus and the setting of the film mounted on the film holder are completed, the radiation source unit irradiates the internal pump casing welding portion with radiation under required photographing conditions. The film is photographed and the welded parts are checked and inspected.

At this time, the radiation generator is installed on the RPV nozzle and its source can be easily set at the inner position corresponding to the welded portion, while the film holder with the film is inserted from the access opening and the holder is held up and down. It is held by the device and moves up and down in the sleeve-like gap by the fluid cylinder to access the welded part and can be set at the outer position corresponding to the welded part, so that the inspection of the welded part of the internal pump casing is improved, and the Uranami bead part Confirmation inspection of welding defects such as dents can be performed, and inspection of welding defects and welding defects of the welded portion of the internal pump casing can be performed accurately, reliably, and accurately.

[0017]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a partial cross section of the bottom (lower mirror) of a reactor pressure vessel 10 provided in a boiling water reactor as a light water reactor. A plurality of reactor pressure vessel nozzles (RPV nozzles) 11 are integrally formed around the bottom of the reactor pressure vessel 10, and an internal pump 1
The top of the second pump casing 13 is fixed by welding. The internal pump casing 13 is inserted from below the reactor pressure vessel 10 through the nozzle hole 14, and the top is fixed to the RPV nozzle 11 in a suspended state by welding. A vibration-proof pad 15 is formed in the internal pump casing 13 in a circumferential direction, and the pad 15 is fitted into a lower portion of the nozzle hole 14 to provide a vibration damping action to the pump casing 13 of the internal pump 12.

The RPV nozzle 11 has a nozzle skirt 16 projecting below the reactor pressure vessel 10, and an access opening 17 is formed in the nozzle skirt 16. Further, the RPV nozzle 11 and the internal pump 12
A sleeve-shaped gap 18 is formed between the pump casing 13 and the sleeve-shaped gap 18.
mm or more, for example, about 18 mm. The hole diameter d ₁ of the nozzle hole 14 of the RPV nozzle 11 is, for example, 348 mmφ, and the outer diameter d ₂ of the mouth of the internal pump casing 13 is, for example, 312 mmφ.

The film holder 2 shown in FIG. 2 is opened from the access opening 17 of the nozzle skirt 16 of the RPV nozzle 11.
0 and the holder elevating and lowering holding device 21 are removably inserted.
The film holder 20 is formed of a flexible strip-shaped thin plate, and the insertion end side and the insertion end side of the film holder 20 are removably connected by a one-touch type attachment / detachment (stop) 22 to form a ring. You. Film holder 20
May be divided into two parts, and the two divided holder elements may be connected to each other by a one-touch type attachment / detachment metal fitting 22 to form a ring shape.

On the inside of the film holder 20, a lead plate 23 for shielding radiation is stretched, while a film mounting tool 25 (such as a holding guide groove or a holding hook) for holding the film 24 in a packable manner. 6 (C) is provided, and the film 24 with the pack is detachably attached to the inner peripheral side of the film holder 20 by the film attachment device 25.

On the other hand, the holder elevating and holding device 21
It has a stepped (or single stepped) holding structure, and has flexible band-shaped holding plates 27 and 28. The belt-like holding plates 27 and 28 may be a single plate or a structure that can be divided into several parts in the circumferential direction.
The insertion end sides of the insertion parts 7 and 28 are detachably connected to the insertion end side by one-touch type attachment / detachment fittings 29, and are configured in a ring shape.

The holder elevating and holding device 21 shown in FIG. 2 has an upper holding plate 27 and a lower holding plate 28 in a two-stage structure. Air cylinders 30 as fluid cylinders are provided at substantially equal intervals on the outer peripheral side of both holding plates 27, 28.
31 are provided in pairs with each other. The piston rods 32, 33 of the air cylinders 30, 31 forming a pair extend in a direction approaching each other, and their tips are detachably connected by concave and convex fitting.

An air cylinder 35 as a fluid cylinder is also provided between the air cylinders 30 of the upper holding plate 27, and a one-touch detachable fitting 3 is attached to the tip of a piston rod 36 extending upward from the air cylinder 35.
7 is fixed, and the detachable metal fitting 37 is removably connected to a receiving metal (bracket) 37a provided at a position corresponding to the film holder.

The air cylinders 30, 31, 35 fixed to the upper and lower holding plates 37, 28 of the holder elevating and lowering holding device 21 are connected to a supply / discharge pipe 39 via a control box 40 to provide a compressed air cylinder as a pressure fluid source. The air cylinders 30, 31, and 35 are operated by the control of the control box 40 and can be moved up and down. At this time, the stroke of each of the air cylinders 30, 31, and 35 is adjusted such that the film 24 with the pack held in the film holder 20 is set at an outer position corresponding to the welded portion of the internal pump casing 13.

On the other hand, the RPV nozzle 11 is provided with an X-ray generator 44 as a radiation generator. A γ-ray generator may be provided instead of the X-ray generator 44. The X-ray generator 44 includes an X-ray generator 45, and the RPV nozzle 1
A gantry 47 is fixed to the top of the unit 1 via a plurality of support legs 46.

A lifting drive 50 driven by a motor 48 is mounted above the X-ray generator 45. The lifting drive device 50 is connected to a control box 52 via a control cable 51, and its operation is controlled by operating the control box 52. The screw shaft 55 attached to the nut 54 is driven to rotate by the motor 48 of the lifting drive device 50 via the speed reducer 49, and the rotation of the screw shaft 55 causes the guide shaft 5 to rotate.
The X-ray generator 45 is moved up and down by being guided by 5, 56, and its elevation position is measured by a potentiometer (not shown).

Below the X-ray generator 45, for example, 3 can be engaged with the inner peripheral wall of the internal pump casing 13.
A guide device 59 having a plurality of guide rollers 58 is provided, and the guide device 59 smoothly guides the X-ray generator 45 up and down. A cooling fan 60 driven by a motor is provided above the guide device 59.
By driving the fan 0, heat generated from the X-ray generator 45 is removed.

The X-ray generator 45 contains a high-pressure transformer and an X-ray tube in a corrosion-resistant aluminum sleeve-like casing 61 and is sealed with SF ₆ gas or the like. The operation of the X-ray generator 45 can be controlled by the controller 63. The controller 6
The remote controller 3 is connected to a remote controller 65 via a remote controller cable 64 as necessary, so that the remote controller 65 can perform a remote control operation. Reference numeral 66 denotes a power cable, and 67 denotes an alarm lamp.

The base 47 of the X-ray generator 44 has an X
A borescope 70 is provided to adjust the position of the source of the line generator 45, and the tip of the borescope 70 is set at the center of the weld bead of the internal pump casing weld 71. The source position adjustment of the X-ray generator 45
The elevation drive device 50 is operated while looking at the borescope 70, and the radiation source unit (X-ray tube position) 72 is set so as to be located at the center of the position corresponding to the welding portion.

Next, the inspection procedure of the internal pump weld will be described.

The weld 71 of the internal pump 12 to the RPV nozzle 11 of the pump casing 13 is inspected during welding (about three layers) and after all layers are welded in order to improve the soundness of the weld. Prior to this inspection, the lifting drive 5 including the X-ray generator 44 and the borescope 70
0, a film holder 20, a film 24 with a pack, and a holder elevating and holding device 21 are prepared.

Then, the internal pump casing 1
After setting a perforated penetrameter (not shown) on the welding portion 71 on the inner surface of the elevating drive device 5 as shown in FIG.
The X-ray generator 44 provided with 0 is set on the upper end of the RPV nozzle 11 and fixed.

After fixing the X-ray generator 44 to the RPV nozzle 11, in order to adjust the position of the source of the X-ray generator 45,
The borescope 70 is set at the center of the weld bead, and the elevation drive device 50 is driven while watching the borescope 70 so that the source 72 of the X-ray generator 45 is located at the center of the inner position corresponding to the weld. I do. After this setting, aging is performed to use the X-ray generator 45 of the X-ray generator 44 in a stable state.

On the other hand, as shown in FIG. 6B, the access opening 17 formed in the nozzle skirt 16 of the RPV nozzle 11 simultaneously or before and after the installation of the X-ray generator 44 and the adjustment of the position of the radiation source. The film holder 74 is inserted as needed.

Subsequently, as shown in FIG. 6 (C), the film 24 with the pack is mounted on the belt-like film holder 20 over almost the entire surface, and is integrated with the film holder 20. The film holder 20 on which the film 24 with the pack is mounted is moved from the access opening 17 of the nozzle skirt 16 through the RPV.
The packed film 24 is pushed inward in the sleeve-shaped gap 18 between the nozzle 11 and the pump casing 13, with the inserted film 24 facing inward. (FIG. 5D).

Next, the inserted film holder 20 is slightly lifted in the sleeve-like gap 18, and the upper holding plate 27 of the holder elevating and holding device 21 is moved while maintaining this lifted state, as shown in FIG. Push in the circumferential direction. When the upper holding plate 27 is pushed in the circumferential direction, the film holder 20 is sequentially connected by the one-touch type attachment / detachment fitting 37 attached to the tip of the piston rod 36 of the air cylinder 35 as a fluid cylinder. At this time, the air cylinder 35 is in a retracted position where it does not operate. In this manner, the upper holding plate 27 is pushed in the circumferential direction while being sequentially connected to the film holder 20, and the insertion tip side and the insertion end side thereof are one-touch detachable fittings 29.
To form a ring.

After the upper holding plate 27 is pushed in to form a ring, the lower holding plate 28 is pushed in the circumferential direction while the holding plate 27 is slightly lifted. When the lower holding plate 28 is inserted, the air cylinder 3
The distal end portions of the piston rods 32 and 33 of the 0 and 31 are sequentially fitted to the upper and lower holding plates 27 by asperity fitting. After the lower holding plate 28 is inserted into the sleeve-like gap 18 from the access opening 17, the lower holding plate 28
One-touch type attachment / detachment fittings 29
To form a ring.

Subsequently, by operating the control box 40, each of the air cylinders 30, 31,
35, the film holder 20 is lifted in the sleeve-like gap 18 by the holder lifting / lowering holding device 21,
As shown in FIG. 2 and FIG. 6 (F), the film 24 with the pack is set so as to come to the outer position corresponding to the welded portion.

After the film holder 20 is set at a predetermined position, a high voltage is applied to the X-ray generator 45 to irradiate X-rays under predetermined photographing conditions, for example, 1 minute, and then stop irradiation for 1 minute. X-rays are simultaneously radiated to the welded portion 71 over the entire circumference under imaging conditions in which the OFF action is repeated several times, and film photography is performed.

After taking a film by X-ray irradiation, the holder elevating and lowering device 21 and the film holder 20 are taken out from the access opening 17 in the reverse order of the assembling procedure, and the X-ray generator 44 is moved from the RPV nozzle 11 by the X-ray generator 44. Removal and inspection of the pump casing weld 71 of one internal pump 12 are completed. This inspection is performed for each welded portion of each internal pump 12, and the soundness of the welded portion is confirmed and inspected. If any welding defects or defects are found, repairs are made or replaced with new ones depending on the degree of the defects or defects.

[0042]

As described above, in the present invention,
Utilizing the access opening provided in the nozzle skirt of the reactor pressure vessel nozzle, a film holder or a holder elevating and holding device with a film is installed in the sleeve-like gap between the reactor pressure vessel nozzle and the internal pump casing. Since the inserted and inserted film holder can be set securely and smoothly to the outside position corresponding to the welded part of the pump casing by the holder elevating and holding device,
The weldability has been improved, and the radiation emitted from the source of the radiation generator installed at the reactor pressure vessel nozzle can be filmed through the weld. Welding defects such as dents in the wave bead can be accurately and reliably checked and inspected, and the soundness of the weld can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view partially showing a bottom sectional structure of a reactor pressure vessel of a boiling water reactor.

FIG. 2 is a perspective view of a film mounting device, showing a main part of an inspection device for an internal pump welded portion according to the present invention.

FIG. 3 is a sectional view showing a portion A in FIG. 2;

FIG. 4 is a diagram showing an X-ray generator installed in a reactor pressure vessel nozzle.

FIG. 5 is a configuration diagram showing a radiation test apparatus used in the inspection apparatus for an internal pump welded portion of the present invention.

6 (A) to 6 (F) are explanatory views illustrating an inspection procedure by an inspection device for an internal pump welded portion according to the present invention.

FIG. 7 is a sectional view showing an attached state of the internal pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Reactor pressure vessel 11 Reactor pressure vessel nozzle 12 Internal pump 13 Internal pump casing 14 Nozzle hole 15 Vibration-proof pad 16 Nozzle skirt 17 Access opening 18 Sleeve-shaped gap 20 Film holder 21 Holder lifting and lowering device 22 One-touch type Detachable fitting 24 Packed film 27, 28 Holding plate 29 One-touch type detachable fitting 30, 31, 35 Air cylinder (fluid cylinder) 40 Control box 44 X-ray generator (radiation generator) 45 X-ray generator 46 Support leg 50 Elevation Drive device 59 Guide device 60 Cooling fan 63 Controller 65 Remote controller 70 Borescope

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kiyoshi Ohno 2 in 4 Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside the Toshiba Keihin Works (56) References JP-A-4-285894 (JP, A) 1987-198740 (JP, A) JP-A 1-120751 (JP, U) JP-A 56-142354 (JP, U) JP-A 59-149049 (JP, U)

Claims (2)

(57) [Claims] 1. A method for inspecting an internal pump welded portion of an internal pump casing fixed to a reactor pressure vessel nozzle, wherein a radiation generator is installed on the reactor pressure vessel nozzle, The source part of the generator is set at the inner position corresponding to the welded part by the lifting drive, and the film holder with the film is inserted through the access opening of the nozzle skirt into the sleeve of the reactor pressure vessel nozzle and the internal pump casing. After the film holder is pushed in the circumferential direction into the gap and the pushed film holder is connected to the holder lifting / holding device inserted from the access opening, the fluid cylinder is operated to raise the film holder in the sleeve-like gap. Then, the film is set at the outer position corresponding to the welded portion, and then, A method for inspecting an internal pump welded portion, comprising irradiating the welded portion with radiation from a radiation source unit of the radiation generating device under a required photographing condition, photographing a film, and inspecting the welded portion. 2. An inspection apparatus for an internal pump welded portion for inspecting a welded portion of an internal pump casing fixed to a reactor pressure vessel nozzle, wherein a radiation generator is installed on the reactor pressure vessel nozzle, While the generator has a lifting drive for raising and lowering the source unit,
An access opening is formed in the nozzle skirt of the reactor pressure vessel nozzle, and a film holder on which a film is mounted can be freely inserted and removed from the access opening into the sleeve-shaped gap between the reactor pressure vessel nozzle and the internal pump casing. A holder elevating and holding device detachably connected to the film holder is inserted from the access opening, and the film elevating and holding device is used to connect the film holder to the outside corresponding to the welded portion in the sleeve-shaped gap. Inspection device for internal pump welds, characterized in that it is held in position.