JP2001108784A - Method for replacing neutron measurement housing and device used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for replacing an ICM housing efficiently in a short time if the need to replace it arises during a service period. SOLUTION: Prior to executing work of replacing the ICM housing, a guide pipe for inserting a device into a flange surface of an RPV(reactor pressure vessel), an installation jig, and a shielding body equipped with a cable processing device are installed, and reactor water is drained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for replacing a neutron measurement (ICM) housing in a reactor pressure vessel (RPV) with a newly manufactured one during a service period of a nuclear power plant, and particularly to a reactor water level. ICM suitable for reducing the number of times of lifting and lowering work, reducing work time, and reducing worker exposure
The present invention relates to a method for replacing a housing.

[0002]

2. Description of the Related Art During the operation of a nuclear power plant, RP
As a replacement method for replacing the ICM housing in the V with a newly manufactured one, there is a technique proposed in Japanese Patent No. 2540474.

According to Japanese Patent No. 2540474, a new IC is disclosed.
When attaching the M housing to the RPV and performing welding, the RPV
The procedure is such that a build-up seat is formed at the bottom and the formed build-up seat and the ICM housing are mounted and welded (hereinafter abbreviated as J welding). In the construction, the welding is performed in the air, and the installation and removal of the welding equipment is performed in water. In addition, in order to form the overlay, it is necessary to insert an electric discharge machine and perform hole machining and outer machining for mounting a new ICM housing in water after the overlay welding.

[0004] Neutron Measurement (ICM) Guide Tube and New ICM
The connection of the housing was made by applying steam to the joint using the shape memory alloy.

[0005]

When the conventional technique is applied to an ICM housing replacement operation during a service period,
There is a need for a high-precision overlay welding apparatus for forming an overlay for mounting and welding an ICM housing to an RPV. Further, since an EDM device is inserted in water to perform the work of shaping the overlay, a large number of devices are required. In the construction, the build-up welding and the J-welding of the new ICM housing are performed in the air, and the installation and removal work of the welding device is performed in the water. Since the operation of filling the reactor water and draining the RPV takes a considerable amount of time,
There is also a problem that the CM housing replacement process is lengthened.

[0006] Further, the connection between the ICM guide tube and the new ICM housing has a problem that a large amount of steam is required at a high temperature because steam is applied to the coupling using the shape memory alloy for fastening.

The present invention has been made in view of the above circumstances, and has as its object to provide a method for efficiently replacing an ICM housing in a short period of time when it becomes necessary to replace the ICM housing during service. I do.

[0008]

According to the present invention, RPV is first used.
After removing the equipment inside, insert the processing machine into the ICM housing from below the RPV, and insert J from the inner surface of the ICM housing.
The weld and the ICM guide tube are cut and the ICM housing is carried out of the RPV. Next, replace the new ICM housing with R
Carry in from below the PV and use the existing ICM housing or I
Weld and attach to CM guide tube and overlay.

As described above, according to the present invention, a new RP
The formation can be efficiently performed in a short period of time without forming the overlay on the inner surface of the V and not using the joint of the shape memory alloy.

According to the fourth and fifth aspects of the present invention, the number of operations for raising and lowering the reactor water level can be reduced, so that a reduction in the period can be expected.

According to the seventh and eighth aspects of the present invention, since the operation of raising and lowering the reactor water level is not required, a further reduction in the period can be expected.

According to the ninth aspect of the present invention, it is possible to easily perform the J-beveling for J-welding the ICM housing at the narrow bottom of the RPV.

According to the tenth aspect of the present invention, the narrow RPV
After connecting the ICM guide tube and the ICM housing at the bottom, the ICM housing can be attached to the RPV and welded by using a horseshoe-shaped welding head.

According to the eleventh aspect of the present invention, the apparatus is an RPV.
When installed on the bottom, it is possible to pass through the core region with a high dose in a short time, so that radiation deterioration of the apparatus can be reduced. In addition, since the guide pipe is provided with the insertion rail, the device can be positioned in the circumferential direction at the upper portion of the RPV, so that it is not necessary to adjust the position of the device in the circumferential direction at the bottom of the RPV. It can be performed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows an RPV 1 and an internal structure of a boiling water reactor, in which a dryer 2, a separator 3, a shroud 4, and the like are installed.
The upper lattice plate 5 for supporting and supporting the fuel, the core support plate 6, and the like are attached to the fuel cell.

At the bottom of the RPV 1, an ICM housing 7 is provided.
And the control rod drive mechanism (CRD) housing 8 is RPV1
Is mounted by welding through the ICM housing 7
The ICM guide tube 9 is attached to the upper part of the upper part by welding. The ICM housing 7 and the ICM guide tube 9 are provided with an ICM monitor body (not shown) containing a neutron measuring device.
The ICM monitor is inserted from above the M guide tube 9 and monitors the output of the reactor. In FIG. 2, reference numeral 10 denotes a build-up seat formed of high nickel steel (Inconel) on the periphery of the through hole on the inner surface side of the RPV 1, reference numeral 11 denotes a groove formed above the build-up seat, and reference numeral 12 denotes a high nickel steel formed at the groove. (Inconel) weld. The ICM housing 7 penetrates the RPV 1 and the upper part of the ICM housing 7 is J-welded on the inner surface side of the RPV 1. The ICM housing 7 is formed of stainless steel. Particularly, in the nuclear power plant constructed earlier, stainless steel having a high carbon content is used, so that the RPV and the ICM are used.
Stress corrosion cracking may occur in the ICM housing 7 near the weld with the housing, for example, the ICM housing immediately above the weld 12.

FIG. 3 shows a guide pipe 13, an installation jig 14, and a cable treatment device for inserting the device into the RPV flange surface when the device is set from above the RPV by draining the reactor water, which is the main part of the present invention. Shield 1 with 15
6 shows a state in which the ICM housing replacement method is installed and the ICM housing replacement method is performed.

The guide pipe 13 has a cylindrical split structure. The shield pipe 16 installed on the RPV flange surface penetrates the upper grid plate 5 and the core support plate 6 in the RPV to form a C pipe.
Installed on RD housing. An insertion rail for adjusting the circumferential direction at the time of installation of the apparatus is attached to the inner surface of the guide pipe 13, and the lower end of the guide pipe 13 has a half-shape so that the apparatus can be extended.

FIG. 4 is a flowchart showing a method of replacing the ICM housing according to the present embodiment. First, in step S1, furnace equipment such as the dryer 2 and the separator 3 attached to the RPV 1 is removed.
Take it out from the inside and store it in a designated place.
Make the PV bottom accessible.

Next, in step S2, the reactor water level is set to RP
After lowering to just below the V-flange surface and installing the guide pipe 13, the installation jig 14, the cable processing device 15, and the shield 16, all the reactor water inside the RPV 1 is drained in step S3. This makes it possible to attach and remove the device, which was performed underwater in the conventional method, in the air, so that it can be performed efficiently in a short time.

Subsequently, in step S4, a processing machine is inserted into the ICM housing 7 from below the RPV 1, and
The guide tube 9 is cut from the inner surface. FIG. 5 shows a state where the ICM guide tube is cut.

Subsequently, in step S5, a processing machine is inserted into the ICM housing 7 from below the RPV 1, and the ICM housing at the upper end of the J weld 12 is cut from the inner surface. At this time, the cut upper ICM housing 7a is attached to the surrounding CRD housing via the ICM housing holder, and is held so as not to drop (not shown). FIG. 6 shows a state where the ICM housing is cut.

Next, in order to pull out and remove the lower ICM housing 7b, the ICM at the lower end of the J welded portion 12 is removed.
A notch 17 is machined from the inner surface of the housing. FIG.
Fig. 3 shows a state in which a notch is formed in an ICM housing.

In the above-mentioned work steps, it is also possible to cut the ICM housing 7 in step S5 first and then cut the ICM guide tube 9 in step S4.

In step S6, the cut upper ICM
RP for the housing 7a and the lower ICM housing 7b
V Forcibly pull it out from below and remove it, then carry it out of the RPV. FIG. 8 shows a state in which the ICM housing is carried out of the RPV.

Subsequently, in step S7, a processing machine is inserted from below the RPV 1 to process the groove 18 at the lower end of the ICM guide tube 9 in the RPV. Similarly, in step S8, a processing machine is inserted below the RPV 1 to process the J groove 19 of the overlay 10 in the RPV. FIG. 9 shows the ICM guide tube 9.
The groove 18 is processed, and the overlay 10 on the inner surface of the RPV 1 is J
This shows a state where the groove 19 has been processed.

In the working steps described above, it is possible to first machine the groove 19 of the overlay 10 in step S8 and then machine the groove 18 of the ICM guide tube 9 in step S7.

In step S9, a penetrating inspection is performed on the 19 J-grooves of the overlay 10 processed in step S8. In step S10, the grooved new ICM housing 20 is inserted from below the RPV 1, the groove is aligned with the ICM guide tube 9, and the inner surface welding machine is inserted from below the new ICM housing 20 to perform welding 21. FIG. 10 shows a state where the ICM guide tube and the new ICM housing are welded.

Next, from above the RPV 1, a J welder is inserted into the RPV 1 using a guide pipe 13, a mounting jig 14, and a shield 16 having a cable processing device 15 for inserting the device into the RPV flange surface. Then, the new ICM housing 20 is J-welded 22 to the overlay 10 in the RPV 1. FIG. 11 shows the new ICM housing welded to the RPV.

FIG. 12 is a view showing a configuration of a processing head for processing the J groove 19 of the overlay 10 in the RPV 1 by inserting the same into the RPV from below the RPV. In FIG. 12, the cutter 23 is connected to a bevel gear 25 via a rotation shaft 24. The bearing 26 is connected to the bevel gear 27 and the bevel gear 32 via a shaft 33. The bevel gear 2 is provided on the drive shaft 29.
8. Bevel gears 31 are individually attached to the drive shaft 30.

When the drive shaft 29 and the drive shaft 30 are rotated at the same speed in different (opposite) directions, respectively, the bevel gear 27 and the bevel gear 32 rotate in different directions. A rotation operation can be provided, and the cutter 23 can perform the rotation operation 34 via the rotation shaft 24.

On the other hand, when the driving shaft 30 is fixed by applying the rotation operation 36 to only the driving shaft 29, the bevel gear 32 does not rotate, so that the bevel gear 25 does not rotate and is fixed. Since only the bevel gear 27 rotates, the cutter 23, the rotating shaft 24, and the bearing 26 can swing 35 about the shaft 33.
Further, even while the cutter 23 is rotating, the swing operation 35 can be performed by changing the number of rotations of the drive shaft 29 and the drive shaft 30.

FIG. 13 is a view showing a configuration of a welding head for inserting a new ICM housing into a build-up seat in the RPV by inserting the new ICM housing into the overlay by using a guide pipe from above the RPV. In FIG. 13, the upper horseshoe-shaped outer cylinder 40 is connected to the welding head installation jig 38 by an arm 39, and the center of the upper horseshoe-shaped outer cylinder 40 is moved to the center position of the ICM guide tube 9 by swinging the arm 39. You can move. The upper horseshoe-shaped outer cylinder 40 is provided with clamping mechanisms 41 and 42, and the upper horseshoe-shaped outer cylinder 40 is
It can be clamped to the CM guide tube 9.

The lower horseshoe-shaped outer cylinder 44 is connected to the upper horseshoe-shaped outer cylinder 40 by a rotation drive unit 43, and can rotate around the ICM guide tube 9. The lower horseshoe-shaped outer cylinder 44 is provided with a welding torch up / down driving unit 45 so that the welding torch 46 can be moved up and down. Further, if the lower horseshoe-shaped outer cylinder 44 is formed into a shape having a waterproof function, the apparatus can be installed underwater.

[0035]

According to the present invention, when the ICM housing in the RPV is replaced with a new one during the operation of the nuclear power plant, the number of times of raising and lowering the reactor water level is reduced, and the work time is reduced. Exposure can be reduced.

Further, according to the processing machine and the welding machine of the present invention, the J groove processing and welding can be performed even in the narrow RPV bottom, so that the work can be performed efficiently and in a short time.

[Brief description of the drawings]

FIG. 1 is a diagram showing a reactor pressure vessel and a reactor internal structure of a boiling water reactor.

FIG. 2 is a diagram showing an ICM housing mounting portion.

FIG. 3 is a diagram showing a state in which reactor water is drained and the apparatus is set from above the RPV.

FIG. 4 is a flowchart of an ICM housing replacement method according to an embodiment of the present invention.

FIG. 5 is a diagram showing a state in which an ICM guide tube is cut.

FIG. 6 is a diagram showing a state in which the ICM housing is cut.

FIG. 7 is a diagram showing a state in which a notch is formed in an ICM housing.

FIG. 8 is a diagram showing a state in which the ICM housing is carried out of the RPV.

FIG. 9 is a view showing a state in which a groove and a J groove of the ICM guide tube are processed.

FIG. 10 is a diagram showing a state where an ICM guide tube and a new ICM housing are welded.

FIG. 11 is a view showing a state where a new ICM housing is J-welded to an RPV.

FIG. 12 is a diagram showing a configuration of a processing head for processing a J groove.

FIG. 13 is a diagram showing a configuration of a J welding head for welding an ICM housing.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reactor pressure vessel (RPV), 2 ... Dryer, 3 ... Separator, 4 ... Shroud, 5 ... Upper lattice plate, 6 ... Core support plate, 7 ... Existing ICM housing, 7a ... Cut-off existing ICM housing, 7b: Cut-down existing ICM housing, 8: CRD housing, 9: ICM
Guide pipe, 11: groove, 12: J welding, 13: guide pipe, 14: installation jig, 15: cable processing device, 16
... shield, 17 ... cut, 18 ... groove of ICM guide tube,
19 ... J groove, 20 ... New ICM housing, 21 ... Weld, 22 ... J weld, 23 ... Cutter, 24 ... Rotary shaft, 2
5 ... bevel gear, 26 ... bearing, 27, 28, 31, 32 ...
Bevel gear, 29, 30 ... drive shaft, 33 ... shaft, 34, 3
6, 37: rotation operation, 35: swing operation, 38: welding head installation jig, 39: arm, 40: upper horseshoe-shaped outer cylinder, 4
1, 42: clamp, 43: rotary drive, 44: lower horseshoe-shaped outer cylinder, 45: welding torch vertical drive, 46: welding torch, 47: swing operation.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koichi Kurosawa 3-1-1, Sachimachi, Hitachi-shi, Ibaraki Pref. Hitachi, Ltd. Hitachi Works, Ltd. (72) Inventor Masayuki Nishino 3-2-2, Sachimachi, Hitachi-shi, Ibaraki No. 2 Within Hitachi Engineering Services Co., Ltd. (72) Inventor Yoshinori Suzuki 3-2-2 Sachicho, Hitachi City, Ibaraki Prefecture Within Hitachi Engineering Services Co., Ltd. (72) Inventor Motomasa Fuse, Sachimachi Hitachi City, Ibaraki Prefecture 3-1-1, Hitachi, Ltd.Hitachi Works, Ltd. (72) Inventor Haruo Fujimori 7-1-1, Omika-cho, Hitachi City, Ibaraki Pref.Hitachi, Ltd.Hitachi Research Laboratory Co., Ltd. 6-9 Takaracho, Kure City Inside the Kure Factory of Babcock Hitachi Co., Ltd. (72) Inventor Mitsuo Matsumoto 6-9 Takaracho Kure City, Hiroshima Prefecture Bukokku Hitachi Ltd. Wu in the factory

Claims (11)

[Claims] 1. A cylindrical neutron measuring housing, which penetrates a cladding formed on an inner surface of a reactor pressure vessel and is attached and welded to the cladding, and an upper part thereof is welded to a neutron measuring guide tube. In the replacement method, a processing machine is inserted into the neutron measurement housing from below the reactor pressure vessel, and from the inner surface of the neutron measurement housing, the neutron measurement housing above the attachment weld and the attachment weld, or The neutron measurement guide tube is cut, and the neutron measurement housing is carried out of the reactor pressure vessel.After that, a new neutron measurement housing is carried in from below the reactor pressure vessel, and the existing neutron measurement housing or A method for replacing a neutron measurement housing, wherein the neutron measurement guide tube is attached to the overlay by welding. 2. The method for replacing a neutron measurement housing according to claim 1, wherein the neutron measurement housing below the mounting weld is cut and pulled below the reactor pressure vessel, and then the mounting is performed. Cut the neutron measurement housing or neutron measurement guide tube above the weld,
A method of replacing the neutron measurement housing, comprising fixing the neutron measurement housing or the neutron measurement guide tube above the cut portion with a jig, and then cutting the attachment weld. 3. The method for replacing a neutron measurement housing according to claim 1, wherein the neutron measurement housing or the neutron measurement guide tube above the mounting weld portion is cut, and the neutron measurement housing above the cut portion. Alternatively, fix with a neutron measurement guide tube and a jig, then cut the neutron measurement housing below the attachment weld and pull it down below the reactor pressure vessel, and then cut the attachment weld. A method for replacing a neutron measurement housing. 4. The method for replacing a neutron measurement housing according to claim 1, wherein the cutting of the existing neutron measurement housing and the neutron measurement guide tube is performed from below the reactor pressure vessel by draining reactor water. A method for replacing a neutron measurement housing. 5. The method for replacing a neutron measurement housing according to claim 1, wherein the existing neutron measurement housing and the neutron measurement guide tube are cut off, and the new neutron measurement housing and the existing neutron measurement housing or the neutron measurement guide tube are replaced. A method for replacing the neutron measurement housing, wherein the welding is performed from below the reactor pressure vessel after draining the reactor water. 6. The method for replacing a neutron measurement housing according to any one of claims 1 to 5, wherein the new installation welding of the new neutron measurement housing and the overlay is performed from above the reactor pressure vessel. A method for replacing a neutron measurement housing, wherein the method is performed by setting up a machine. 7. The method for replacing a neutron measurement housing according to any one of claims 1 to 5, wherein the new installation welding of the new neutron measurement housing and the cladding seat is performed by removing reactor water and setting the reactor pressure. A method for replacing a neutron measurement housing, wherein the method is performed by setting a welding machine from above a container. 8. A method for replacing a neutron measurement housing according to claim 1, wherein a processing machine or a welding machine is set from above the reactor pressure vessel by draining reactor water. A method for replacing a neutron measurement housing, comprising: installing a shield provided with a guide pipe and an installation jig for inserting the processing machine or the welding machine into a flange surface of a reactor pressure vessel. 9. A processing machine for mounting and welding a cladding seat of a reactor pressure vessel for mounting and welding a new neutron measurement housing, comprising: a bevel gear facing a processing machine head; A processing machine comprising: a cutter attached to a bevel gear meshing with a bevel gear; and a drive mechanism for individually imparting a rotating operation to the opposed bevel gear. 10. A welding machine for newly mounting and welding a new neutron measurement housing and a cladding seat of a reactor pressure vessel, wherein a welding head is housed in a horseshoe-shaped outer tube, and a neutron measurement guide tube is provided in the horseshoe-shaped outer tube. A welding machine comprising: a mechanism that is clamped to an outer surface and that rotates with respect to the neutron measurement guide tube; and wherein the welding head has a function of moving up and down with respect to the horseshoe-shaped outer tube. 11. A guide pipe for use in the method according to claim 8, for mounting a processing machine or a welding machine from an upper part of a reactor pressure vessel, wherein the guide pipe has a cylindrical split structure. A guide pipe comprising an insertion rail for adjusting a circumferential direction when the processing machine or the welding machine is installed in a cylindrical pipe.