JPH0763874A - Inside machining device of neutron flux monitor housing of reactor - Google Patents

Abstract

PURPOSE:To provide a device for uniformly machining and cutting ICM (neutron flux monitor) housing in the neighborhood of a weld part of RPV (reactor pressure vessel) and an ICM housing at the time when repair work of the ICM housing attached to RPV of a reactor is performed. CONSTITUTION:A machining head 9 inserted in an ICM housing is passed therethrough, drive force from a machining drive mechanism set in the lower side of the ICM housing is transmittably disposed through a machining shaft 18 which radially has resilience, simultaneous opening and closing is radially performed on the machining head 9, and a plurality of operable cutting tools 13 are arranged circumferentially uniformly. In addition, the machining head 9 is disposed to rotatably and upward and downward to be driven by the machining drive mechanism, and a cutting stopper 17 for restricting a cutting quantity is provided on the machining head 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a neutron flux monitor housing (hereinafter, referred to as "RPV") mounted on a reactor pressure vessel (hereinafter, referred to as "RPV"), which is used during the operation period of a nuclear power plant.
The present invention relates to an inner surface processing apparatus for cutting the inner surface of the ICM housing in the vicinity of a welded portion between the RPV and the ICM housing when repairing the ICM housing).

[0002]

2. Description of the Related Art The boiling water reactor RPV ICM housing is constructed as shown in FIG.

That is, a through hole 1A is provided in an RPV 1 having a weld overlay 1B formed on the inner surface of a lower mirror 1C with an Inconel material or the like, and an ICM housing 2 is welded through a welded portion 3 through the through hole 1A. Has been done.

The conventional boiling water reactor ICM housing 2 uses a SUS304 type steel pipe.
Various preventive maintenance methods have been proposed, assuming stress corrosion cracking in the welded portion 3 of the CM housing 2 or in the vicinity thereof.

The conventional preventive maintenance method is partially described in, for example, Japanese Patent Laid-Open No. 3-135794 as a method of performing this type of processing, but the construction of the processing apparatus and the processing method are not specifically described. can not see.

Further, a method of processing the lower part of the welded portion from the inner surface side of the ICM housing and cutting is described in, for example, Japanese Patent Application Laid-Open No. 2-128195 and Japanese Patent Application Laid-Open No. 2-102493. No specific description is found regarding the device configuration or processing method.

[0007]

The ICM housing 2 is connected to the RPV 1 at the welded portion 3, and due to the heat effect of the welded portion 3 during welding, the ICM housing 2 has the lower portion 2 of the welded portion 3.
It is assumed that there is a bend between A and the upper part 2B, and if the inner surface is evenly cut across the ICM housings 2A and 2B across the welded part 3 in the preventive maintenance method, consider the expected bend. It is necessary to

In the preventive maintenance method, when the lower portion 2A of the ICM housing 2 is cut from directly below the welded portion 3,
It is conceivable to mechanically cut the portion directly below the welded portion 3 from the inside of the ICM housing 2 to perform the cutting. However, depending on the processing method, the cutting tool penetrates the cylinder of the lower portion 2A of the ICM housing and is outside. There is a possibility that processing damage may occur on the inner surface of the through hole 1A of the RPV1.

In the above-mentioned prior art, there is no description of specific means for solving these problems, and the technology for a processing apparatus for actually performing processing has not been established.

An object of the present invention is an IC that is supposed to bend.
An inner surface machining device for an ICM housing, which evenly cuts the inner surface of the M housing 2 above and below the welded portion 3, and
Immediately below the welded portion 3 of the ICM housing 2, the inner surface of the through hole 1A of the RPV 1 is uniformly machined without causing scratches, and it is possible to easily cut by pulling.
It is to provide an inner surface processing apparatus for a CM housing.

[0011]

[Means for Solving the Problems] One of the above-mentioned objects is IC
The machining head inserted into the M housing is passed through the ICM housing, and is arranged to be able to transmit drive power from a machining drive mechanism installed on the lower side of the ICM housing via a machining shaft having elasticity in the radial direction. A plurality of cutting bits that can be simultaneously opened and closed in the radial direction with respect to the ICM housing are uniformly arranged in the circumferential direction in the machining head, and the machining head is rotatably driven by the machining drive mechanism. Further, the processing head is disposed so as to be driven by the processing drive mechanism along the axial direction of the ICM housing, and these driving operations are simultaneously and continuously performed by the processing drive mechanism so that the processing head is inserted into the ICM housing. The processing head can be achieved by continuously cutting the inner surface of the ICM housing.

Another object of the above object is to limit the cutting amount in accordance with the wall thickness of the cylinder of the existing neutron flux monitor housing with respect to the cutting operation of a plurality of cutting tools of the inner surface processing apparatus. This can be achieved by providing a cutting stopper that prevents cutting through the cylinder of the existing neutron flux monitor housing and continuously cutting.

[0013]

In the cutting process of the inner surface of the cylinder of the ICM housing, the plurality of cutting tools, which are inserted in the inner surface of the cylinder of the ICM housing and are evenly arranged in the circumferential direction, cancel the radial reaction forces. To work in
It is possible to cut the wall thickness of the cylinder uniformly over the entire circumference without causing uneven machining in the circumferential direction. Furthermore, by giving the processed shaft radial elasticity, it is possible to follow the bending of the ICM housing in the axial direction, and it is possible to evenly cut the wall thickness of the cylinder in the axial direction. .

By the combination of the above-mentioned actions, even in the ICM housing which is supposed to be bent, the cutting can be performed uniformly in the axial direction and the circumferential direction.

The cutting stopper, which is set so that the cutting amount of the cutting tool is slightly shorter than the wall thickness of the cylinder of the ICM housing to be cut, excessively cuts the cylinder of the ICM housing when processing the cylinder of the ICM housing. There is no risk of processing scratches on the inner surface of the through hole of the RPV.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 shows the RPV substructure of a boiling water reactor. The RPV is composed of an RPV body 1D, an RPV lower mirror 1C and an RPV upper lid (not shown), and the RPV 1 is a pedestal (not shown) of a reactor containment vessel by a skirt 4.
It is fixed on. The ICM housing 2 is RP
It is fixed to the V lower mirror 1C.

In FIG. 5, the ICM housing 2 has an RPV lower mirror 1.
It is sectional drawing which shows the state fixed to C. RPV lower mirror 1
A build-up weld 1B such as Inconel material is formed on the inner surface of C, and the ICM housing 2 penetrates the RPV lower mirror 1C and is welded to the build-up weld 1B via a weld portion 3.

FIG. 1 is a structural diagram showing a state before a cutting operation of an ICM housing inner surface processing apparatus processing head according to an embodiment of the present invention, and FIG. 2 is a structural diagram showing a state after the cutting operation.

The processing head cover 10 of the processing head 9 has a plurality of cutting arms 12 through a plurality of support pins 11.
Is attached so as to be pivotable with respect to each support pin 11, and a cutting tool 13 is attached to one end 12A of each cutting arm 12.

Further, inside each cutting arm 12, a conical cutting cam 15 and a returning cam 16 are slidable with respect to both ends 12A and 12B of the cutting arm 12 coaxially via a cam rod 14. Installed.

Here, the machining drive mechanism (not shown) causes the cam rod 14 to move upward with respect to the machining head cover 10, whereby the cutting cams 15 simultaneously push out one end 12A of all the cutting arms 12 in the radial direction. The cutting tool 13 on each cutting arm 12 also moves in the radial direction at the same time, and simultaneously performs a cutting operation with respect to an ICM housing (not shown) placed outside the machining head 9.

Further, when the cam rod 14 descends with respect to the machining head cover 10, the return cam 16 simultaneously pushes out the other ends 12B of all the cutting arms 12 in the radial direction, whereby all the cutting arms 12 are moved. The one end 12A is simultaneously pulled back in the radial direction, and the cutting tool 13 is also pulled back at the same time.

Further, the processing head cover 10 is rotationally driven and vertically driven by a processing drive mechanism (not shown) through a processing shaft 18 having elasticity in the radial direction. At this time, of course, the cam rod 14 is also given elasticity in the radial direction.

When cutting for the purpose of cutting, the cutting amount of the cutting tool 13 is limited according to the thickness of the cylinder of the ICM housing. It is provided inside 10. Here, for the purpose of cutting, instead of using a plurality of cutting tools, one cutting tool is provided, and a plurality of rollers that receive a cutting reaction force are provided at opposing positions to cancel the cutting reaction force. Conceivable.

In this case, a rotary cutting type cutting tool may be used instead of the cutting tool.

FIG. 3 is a structural diagram of an ICM housing inner surface processing apparatus processing drive mechanism according to an embodiment of the present invention.

A machining shaft 18 for transmitting a machining force to a machining head (not shown) inserted in the ICM housing 2 is rotatably mounted on a moving base 21 and mounted on the moving base 21 via a drive belt 19. The rotation driving force is transmitted from the rotation driving motor 20. Further, the cam rod 14 passing through the inside of the processing shaft 18 is connected to a cam rod screw 22, and the cam rod screw 22 is driven by a notch drive motor 26 attached to the moving base 21 via a drive belt 25.
By the rotating operation of No. 4, the machining shaft 18 is driven in the axial direction. At this time, the cam rod 14 is rotatably connected to the cam rod screw 22 via the bearing 23, and the cam rod 14 is moved in the axial direction of the machining shaft 18 without hindering the rotational movement of the cam rod 14 rotating with the machining shaft 18. Can be driven to.

Further, the movable base 21 is vertically driven on the fixed base 30 in the axial direction of the ICM housing 2 by the nut 27, the screw 28 and the vertical drive motor 29. The machining drive mechanism 31 having the above-described configuration continuously performs each driving operation by the machining drive control device (not shown).
It can be performed in combination, whereby the intended processing can be performed on the inner surface of the ICM housing 2.

FIG. 6 is a general layout view of an ICM housing inner surface processing apparatus according to an embodiment of the present invention. The inside of the ICM housing 2 is sealed with reactor water by a water seal cap 8 attached to the upper part.
The machining head 9 which is inserted from the bottom into the inside of the R, through the machining shaft 18 and the cam rod (not shown), R
It is connected to the processing drive mechanism 31 installed on the platform 7 in the PV pedestal 5, and the processing drive force is transmitted.

A machining drive control device 32 for controlling the driving operation of the machining drive mechanism 31 is installed outside the RPV pedestal 5 and can remotely control the machining drive mechanism 31.

In FIG. 7, the inner surfaces of the lower portion 2A and the upper portion 2B of the ICM housing 2 are continuously and uniformly machined 2 across the welded portion 3.
An example of processing when C is applied is shown.

FIG. 8 shows a processing example in which the lower portion 2A of the welded portion 3 of the ICM housing 2 is subjected to a cutting process 2D to cut the welded portion 3 immediately below the welded portion 3. This cutting processing was given
The lower part 2A of the ICM housing 2 is a pulling device (not shown)
Thus, the ICM housing 2A can be easily cut by pulling it downward.

[0034]

According to the present invention, the inner surface of the ICM housing in the vicinity of the welded portion can be evenly cut, and the portion directly below the welded portion can be cut without causing scratches on the inner surface of the RPV through hole. , Is effective in improving reliability in advancing repair work of the ICM housing.

[Brief description of drawings]

FIG. 1 is a structural diagram of a processing head of a neutron flux monitor housing inner surface processing apparatus according to an embodiment of the present invention (before cutting operation).

FIG. 2 is a structural view of a neutron flux monitor housing inner surface processing apparatus processing head according to an embodiment of the present invention (after cutting operation).

FIG. 3 is a structural diagram of a neutron flux monitor housing inner surface processing apparatus drive mechanism according to an embodiment of the present invention.

FIG. 4 is a schematic sectional view showing an RPV lower structure.

FIG. 5 is a sectional view of a welded portion between an ICM housing and an RPV.

FIG. 6 is an overall layout diagram of a neutron flux monitor housing inner surface processing apparatus according to an embodiment of the present invention.

FIG. 7 is a vertical cross-sectional view of an example of uniform processing of the inner surface of an ICM housing by a neutron flux monitor housing inner surface processing apparatus according to an embodiment of the present invention.

FIG. 8 is a vertical cross-sectional view of an example of cutting the inner surface of an ICM housing by a neutron flux monitor housing inner surface processing apparatus according to an embodiment of the present invention.

[Explanation of symbols]

1 ... Reactor pressure vessel (RPV), 1A ... Through hole, 1B ...
Overlay welding, 1C ... RPV lower mirror, 1D ... RPV body, 2 ... Neutron flux monitor housing (ICM housing), 2A ... I
CM housing lower part, 2B ... ICM housing upper part, 2
C ... Uniform processing part, 2D ... Cutting processing part, 3 ... Welding part, 4 ...
Skirt, 5 ... RPV pedestal, 6 ... Core support plate, 7
... Platform, 8 ... Water seal cap, 9 ... Machining head, 10 ... Machining head cover, 11 ... Support pin, 12
... cutting arm, 13 ... cutting tool, 14 ... cam rod, 15 ... cutting cam, 16 ... return cam, 17 ... cutting stopper, 18 ... machining shaft, 19 ... drive belt,
20 ... Rotational drive motor, 21 ... Moving base, 22 ... Cam rod screw, 23 ... Bearing, 24 ... Nut,
25 ... Drive belt, 26 ... Cut drive motor, 27 ... Nut, 28 ... Screw, 29 ... Vertical drive motor, 30
... Fixed base, 31 ... Machining drive mechanism, 32 ... Machining drive control device.

(72) Inventor Hideyasu Furukawa 3-1-1, Saiwaicho, Hitachi City, Ibaraki Hitachi Ltd. Hitachi factory (72) Koichi Kurosawa 3-1-1, Saiwaicho, Hitachi, Ibaraki Stock company Hitachi Ltd.Hitachi factory

Claims (2)

[Claims] 1. A penetrating wall of a reactor pressure vessel,
In a cylindrical existing neutron flux monitor housing coupled by a welded portion on the inner surface side of the reactor pressure vessel, in cutting the inner surface of the welded portion near the existing neutron flux monitor housing, the neutron flux monitor A processing drive mechanism that performs multiple drive operations is installed below the housing,
From below inside the existing neutron flux monitor housing,
A machining head having a plurality of cutting bits is evenly inserted on the circumference, and the machining head is connected to the machining drive mechanism by a machining shaft having elasticity in the radial direction, and is rotationally driven by the rotation drive operation of the machining drive mechanism. At the same time, the plurality of cutting bits of the processing head are simultaneously opened and closed in the radial direction by the cutting driving operation of the processing driving mechanism to perform the cutting operation, and the processing head is further driven by the vertical driving operation of the processing driving mechanism. Performing up-and-down operation, by combining the above operations, the plurality of cutting tools of the processing head, the inner surface of the existing neutron flux monitor housing, continuously performs a cutting process, characterized in that the neutron flux of the reactor Inner surface processing equipment for monitor housing. 2. The cutting operation of a plurality of cutting bits according to claim 1, wherein the cutting amount is limited in accordance with the wall thickness of the cylinder of the existing neutron flux monitor housing, and the cutting tool has the existing neutron flux monitor. An inner surface processing device for a neutron flux monitor housing of a nuclear reactor, which is provided with a notch stopper that prevents cutting through a cylinder of a housing, and continuously performs cutting on the inner surface of an existing neutron flux monitor housing. .