JP2010256289A - Method of repairing shroud head, and repair structure of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reuse a shroud head for a core shroud by repairing a guide pin and a suspension rod deformed by an earthquake or the like by an underwater remote operation to make them replaceable. <P>SOLUTION: In this method of repairing the shroud head, when the guide pin or suspension rod of the shroud head 4 temporarily mounted in a DS pool is deformed, a part or the whole of the guide pin disposed in a guide pin bracket 15 of the shroud head 4 is cut and removed in the DS pool 12, a new guide pin 20 is introduced to the removed part and installed in it, or a part or the whole of the suspension rod disposed in a suspension rod bracket of the shroud head 4 is cut and removed in the DS pool 12, a new suspension rod is introduced to the removed part and installed in it. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a shroud head repair method and a repair structure thereof in a boiling water nuclear power plant, and more particularly to a shroud head repair method and a repair structure thereof for exchanging guide pins and suspension rods by remote underwater work.

  The shroud head, which is a nuclear reactor in a boiling water nuclear power plant, has a function of forming an upper core plenum at the core outlet together with the upper shell of the core shroud and guiding steam and water to a steam separator through a standpipe. is there.

  The shroud head is structured to be attached to the top of the core shroud by shroud head bolts provided along the circumferential direction.

  The shroud head is removed from the core shroud during periodic inspection, and is reattached and installed after regular inspection (see Patent Document 1). When removing and reattaching to the shroud head and core shroud, the notch of the shroud head guide pin bracket is inserted into the vertical guide rod attached to the shroud upper ring from the opening of the reactor pressure vessel (RPV). By guiding, the shroud head guides so as not to interfere with the inner wall of the RPV.

  When the shroud head is attached to the core shroud, the shroud head bolt attached to the shroud head and the shroud head bolt lug attached to the core shroud should not interfere with each other. Guide pin brackets attached to the core shroud in the shroud head so that the shroud head can be positioned so that the earthquake-resistant pin hole provided in the trunk does not interfere with the earthquake-proof pin attached to the upper surface of the shroud upper ring. A guide pin is attached. In addition, the suspension rod is inserted into a suspension rod bracket provided on the shroud head.

Japanese Patent Laid-Open No. 5-80187

  During operation of the boiling water nuclear power plant, the shroud head is fixed and installed on the top of the core shroud in the RPV with shroud head bolts. Therefore, even when an earthquake or the like occurs during operation of the nuclear power plant, the possibility that the shroud head moves is small.

  At the nuclear power plant, after removing the equipment (RPV top cover) to be removed in the regular periodic inspection, the steam dryer and steam separator are moved to the DS pool while holding the reactor water, and are temporarily placed in this DS pool. The The steam / water separator is integrally provided with a shroud head. The shroud head is moved and stored in the DS pool for refueling during regular inspections.

  The shroud head is installed on the floor surface of the DS pool at the lower ends of the four suspension rods provided for moving the shroud head.

  If an earthquake occurs with the shroud head installed in the DS pool during a periodic inspection of a nuclear power plant, the shroud head may be shaken due to the acceleration of the earthquake and the sloshing of water in the DS pool, and the suspension rod may be deformed. is there.

  When the amount of deformation of the suspension rod increases, when the shroud head is remounted and installed on the core shroud, the suspension rod interferes with the core shroud, which may cause difficulty in installation of the shroud head.

  Further, if the guide pin attached to the shroud head is also deformed, it may be difficult to re-install the shroud head in the RPV.

  The present invention has been made in consideration of the above-mentioned circumstances, and the guide pin and the suspension rod of the shroud head deformed by an earthquake or the like can be repaired and replaced by underwater remote work, and the shroud head can be used again for the core shroud. An object of the present invention is to provide a repair method and a repair structure for a shroud head.

  Another object of the present invention is to replace a suspension rod that interferes with a shroud head guide pin or a core shroud that has been deformed and loses the guide function, with a new guide pin or suspension rod by underwater remote operation in the DS pool, The shroud head is remounted on the core shroud to provide a usable shroud head repair method and repair structure.

  Another object of the present invention is to secure a sufficient water shielding height above the steam / water separator for the exposure amount during replacement of shroud heads, guide pins and suspension rods by remote underwater work in the DS pool. It is an object of the present invention to provide a method for repairing a shroud head that is sufficiently reduced.

  In order to solve the above-described problem, the shroud head repair method according to the present invention is such that the guide pin or the suspension rod of the shroud head temporarily placed in the DS pool is deformed as described in claim 1. In this case, a part or all of the guide pin provided on the guide pin bracket of the shroud head is cut and removed in the DS pool, and a new guide pin is introduced and installed in the removed part. It is a repair method characterized in that a part or all of the suspension rod provided on the suspension rod bracket of the shroud head is cut and removed in the DS pool, and a new suspension rod is introduced and installed in the removed portion. .

  In order to solve the above-described problem, the shroud head repair structure according to the present invention is a shroud head repair method in which a shroud head is provided above a core shroud, as described in claim 11, wherein the shroud head includes: The guide pin bracket and the suspension rod bracket are fixed to the rim body, and the new guide pin is inserted into the sleeve of the existing guide pin provided in the guide pin bracket. The new guide pin is arranged in the axial direction of the head portion. When the new guide pin is inserted into the existing sleeve, the size of the existing guide pin is the same as the dimension of the head portion in the axial direction of the removed existing guide pin. It is provided in the centering position equivalent to a pin.

  According to the repair method and the repair structure of the shroud head according to the present invention, even if the guide function of the shroud head is lost due to deformation due to an earthquake or the like, and it may interfere with the guide pin bracket of the core shroud, The shroud head can be used again for the core shroud by replacing the guide pins and suspension rods with new guide pins and suspension rods in the DS pool.

The figure which shows the reactor equipment structure with which the reactor pressure vessel of a boiling water reactor is equipped. The figure which shows the temporary placement installation structure in the DS pool of a shroud head and a steam dryer. The fragmentary sectional view which shows the repair structure of the shroud head which concerns on this invention. (A)-(H) are figures which show simply the preparation process in shroud head repair (repair). The figure which shows the hanging rod cutting | disconnection operation | work using a hanging rod cutting | disconnection (EDM) apparatus in shroud head repair. (A) And (B) is a figure which respectively shows the example of attachment structure of the new hanging rod replaced | exchanged in shroud head repair. The figure which shows the other example of attachment of a hanging rod in shroud head repair. The figure which shows the example of a guide pin cutting | disconnection operation | work using a guide pin cutting device in shroud head repair. The figure which shows the drive cutting operation of the guide pin using a guide pin drive cutting (EDM) apparatus in shroud head repair. The figure which shows the cutting | disconnection operation | work using a stopper removal (EDM) apparatus in shroud head repair. The figure which shows the cutting | disconnection operation | work using a rod cutting | disconnection (EDM) apparatus in shroud head repair. The figure which shows a guide pin removal operation | work using a guide pin removal jig | tool in shroud head repair. The figure which shows the assembly | attachment operation | work of a new guide pin using a guide pin assembly apparatus in shroud head repair. The figure which shows the operation | work which tightens a fixed nut using a nut fastening jig | tool in shroud head repair. The figure which shows the rotation stop (caulking) operation | work of a fixing nut using a caulking apparatus in shroud head repair.

  DESCRIPTION OF EMBODIMENTS An embodiment of a shroud head repair method and repair structure according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows a reactor pressure vessel (RPV) 1 provided in a boiling water nuclear power plant (BWR plant), and a core 3 is surrounded by a core shroud 2 provided in the RPV 1. The core shroud 2 is a stainless steel cylinder, and a shroud head 4 is integrally formed on the upper portion of the core shroud 2 by flange bonding. A steam separator 5 is welded onto the shroud head 4 via a stand pipe 6.

  The shroud head 4 forms a core upper plenum 7 on the core outlet side, and the steam / water mixture flow rising separately for each fuel assembly (not shown) is sent to the stand pipe 6 of the steam / water separator 5 by the reactor water upper plenum 7. Mix evenly before entering. A steam dryer 8 is provided above the steam / water separator 5, and dry steam (main steam) dried by the steam dryer is sent to a steam turpin (not shown) through a main steam pipe 9.

  During operation of the nuclear power plant, the shroud head 4 is fixed and installed on a shroud head bolt (not shown) on the upper part of the core shroud 2, and the possibility that the shroud head 4 moves even when an earthquake or the like occurs is small.

  On the other hand, the nuclear power plant is periodically shut down for fuel replacement or the like and periodically inspected. During the regular inspection, as shown in FIG. 2, the reactor well 11 is filled with water using an overhead crane (not shown), and after removing the top cover 1a of the RPV 1, the steam dryer 8 and the steam The separator 5 is sequentially removed, moved underwater to the DS pool (DS pit) 12, and temporarily placed in the DS pool 12. The underwater movement of the steam dryer 8 and the steam separator 5 is also performed using an overhead crane.

  The shroud head 4 removed from the core shroud 5 is moved underwater integrally with the steam separator 5 and the stand pipe 6. The shroud head 4 has a plurality of suspension rods, for example, four suspension rods provided for this movement, and is temporarily placed on the floor surface of the DS pool 12 at the lower end portion of the suspension rods.

  During a periodic inspection, if an earthquake occurs with the shroud head 4 installed in the DS pool 12, the shroud head may be shaken by the acceleration of the earthquake and the sloshing of water in the DS pool 12, and the suspension rod may be deformed. is there. When the amount of deformation of the suspension rod increases, when the shroud head 4 is attached to the core shroud 2, the suspension rod interferes with the core shroud 2 and the guide pin is also deformed, so that the shroud head 4 is reinstalled on the core shroud 2. It becomes difficult.

  Therefore, the shroud head 4 is repaired by replacing the deformed guide pin and suspension rod with a new guide pin and suspension rod. The repair work of the shroud head 4 is performed in the DS pool 12 by underwater remote work. The repaired work of the shroud head 4 replaces the deformed guide pins and suspension bars with new guide pins and suspension bars. The shroud head 4 that has finished the underwater repair work in the DS pool 12 is used to reattach and install the shroud head 4 to the core shroud 2 in the RPV 1.

  FIG. 3 is a partial cross-sectional view showing a state in which the repaired shroud head 4 is attached to the core shroud 2 and remounted.

  The repaired shroud head 4 is installed on the core shroud 2 installed in the RPV 1. On the rim body 4a of the shroud head 4, guide pin brackets 15 are provided, for example, at two locations facing each other in the diametrical direction. The guide pin bracket 15 protrudes radially outward from the rim body 4a of the shroud head 4. A guide groove 14a is formed at the tip of the guide pin bracket 15 so as to be slidably engaged with a guide rod (not shown). Provided. The existing sleeve 16 is fixed to the guide pin flange 15 by an outer peripheral flange 16 a and a sleeve nut 17 at the lower end of the sleeve.

  The shroud head 4 is fixedly provided with a guide pin bracket 15 and a suspension bar bracket (not shown) so as to protrude radially from the rim cylinder 4a.

  A new guide pin 20 is inserted into a sleeve 16 of an existing guide pin provided in the guide pin bracket 15, and the new guide pin 20 has a head portion axis of the existing guide pin that has been removed in the axial direction. Similar to the directional dimension, it has a portion that fits together with the existing sleeve 16.

  When the new guide pin 20 is inserted into the existing sleeve 16, it is provided at a centering position equivalent to the existing guide pin.

  Further, the new guide pin 20 has a portion that fits and fits with the guide pin bracket hole 27 of the core shroud 4 and the existing sleeve 16 of the existing guide pin at the lowest position of the existing guide pin. The new guide pin 20 is a shoulder portion slightly smaller in diameter than the head portion, and is in contact with the lower surface of the existing sleeve 16.

  Thus, a new guide pin 20 with a head (head) is inserted into the existing sleeve 16 from below. The new guide pin 20 protrudes upward through the existing sleeve 16, and a fixing nut 21 is screwed to the protruding portion. The fixing nut 21 is integrally provided with a thin sleeve-like nut skirt 22, and the nut skirt 22 is caulked into a plurality of strips formed on the tip protruding pin rod portion of the new guide pin 20, for example, four axial grooves 23. It is done. By fixing the nut skirt 22 by caulking it in the axial groove 23, the fixing nut 21 is prevented from turning and the loosening is surely prevented.

  Further, an outer flange 25 is provided on the upper shell 2 a of the core shroud 2 installed in the RPV 1, and a guide rod insertion hole 26 and a guide pin bracket hole 27 are provided on the outer flange 25.

  When the repaired shroud head 4 is aligned and installed in the core shroud 2, the guide pins 20 provided in the shroud head 4 are installed through the guide pin bracket holes 27 of the core shroud 2.

  On the other hand, some BWR plants have an earthquake-resistant pin 30 provided on the top of the core shroud 2 as shown in FIG. A plurality of, for example, 36 earthquake-resistant pins 30 are provided along the circumferential dust at the top of the core shroud 2. When the seismic pins 30 are planted and provided in the core shroud 2, seismic pin holes 31 are provided on the opposing surface of the shroud head 4, and each seismic pin 30 engages with each seismic pin hole 31. Installed.

  Thus, in the installation structure of the shroud head 4 in which the repaired shroud head 4 shown in FIG. 3 is attached to the core shroud 2, the new guide pin 20 is fixed to the shroud head 4.

  The new guide pin 20 is configured to have an axial dimension that matches the lowest lowered position of the removed existing guide pin. The axial dimension of the head portion (maximum diameter portion) of the new guide pin 20 is the same as the axial dimension of the existing guide pin that has been removed, and is slightly increased due to interference with the guide pin bracket hole 27 of the core shroud 2. The upper taper portion (shoulder portion) of the trunk portion 20b following the guide pin head portion having a narrow diameter is configured to be engaged with the expanding taper portion 16a on the sleeve lower surface side formed on the existing sleeve 16.

  The new guide pin 20 has a portion that fits and fits with the existing sleeve 16 of the existing guide pin. When the new guide pin 20 is inserted into the existing sleeve 16, the new guide pin 20 has the same core position as the existing guide pin. It is configured to be attached to.

  The new guide pin 20 is mechanically coupled to the existing sleeve 16 of the existing guide pin with a fixing nut 21 and fastened.

  The new guide pin 20 is provided with an axial groove 23 in the rod portion above the threaded portion that engages with the fixing nut 21. On the other hand, a thin nut skirt 22 is provided on the upper surface of the fixing nut 21, and after tightening the fixing nut 21, the nut skirt 22 portion of the fixing nut 21 is caulked along the axial groove 23 of the new guide pin 20. Therefore, the fixing nut 21 is mechanically stopped / loosened.

  Next, with reference to FIG. 4, a shroud head repair preparation process in the shroud head repair work will be described.

  During periodic inspection of the BWR plant, the shroud head 4 is shaken and suspended due to the acceleration of the earthquake and sloshing of the water in the DS pool due to the action of the earthquake that occurred with the shroud head 4 installed in the DS pool 12. There is a possibility that the rod and the guide pin are deformed. When the existing suspension rod or guide pin of the shroud head 4 is deformed, the repair work of the shroud head 4 installed in the DS pool 12 is performed.

  In the repair work of the shroud head 4, a shroud head repair base is prepared as shown in FIG. 4 for repairing the shroud head.

  The shroud head repair mount 35 is carried on an operation floor 36 in the reactor building using an overhead crane, and a carriage elevator (silver hoist) installed on the operation floor 36 across the DS pool 12 is freely mounted. It is temporarily placed in an accessible place (see FIG. 4A).

  At that time, the lower end of the suspension rod 44 of the shroud head 4 and the DS pool 12 interfere with each other, and a simple seal is installed at a portion where the liner of the DS pool 12 may be damaged, and the pool water leaks from the DS pool. Is prevented.

  Further, by dividing the shroud head repair mount 35 into four or more locations, the shroud head repair mount 35 can be placed below the shroud head 4 using a lift of the carriage without using an overhead crane. Can be installed.

  Subsequently, the seal lining installation position mark eye nut is attached to the operation pole, while the carriage is moved onto the suspension rod of the shroud head 4 on the operation floor 36, and the lower end of the suspension rod interferes with the DS pool floor. Temporarily place an eye nut on the floor of the pool. A DS suspension 37 is attached to the overhead crane via a suspension wire, and the DS suspension 37 is attached to the shroud head 4 (see FIG. 4B).

  Subsequently, the overhead crane is raised at a low speed to lift the shroud head 4. At this time, the shroud head 4 is submerged in the pool water of the DS pool 12.

  Thereafter, the shroud head 4 is suspended on the reactor well 11 while being suspended in the DS pool 12 (see FIG. 4C).

  Next, the carriage is moved onto the eyenut on which the carriage is temporarily placed on the operation floor 36, the seal lining 39 is attached to the seal lining attachment device 38, and the pool floor of the DS pool 12 and the suspension bar of the shroud head 4 interfere with each other. (See FIG. 4D).

  After the seal lining 39 is installed, the eye nut is collected with a J hook-shaped operation pole and removed.

  Subsequently, the cart and grapple position are adjusted so that the grapple of the cart is located immediately above the corner 40 of the DS pool. At that time, the position of the carriage and grapple is marked as a reference point.

  Next, the shroud head repair mount 35 temporarily placed on the operation floor 36 is lifted by a grapple of the cart.

  The shroud head repair stand 35 is held at a height where the upper end of the steam separator attached to the shroud head 4 is submerged by 1 m or more from the pool surface of the DS pool 12 in consideration of the exposure dose on the operation floor. The

  When repairing the shroud head 4, the cart previously marked at the installation position of the shroud head repair mount 35 selected from the orientation of the shroud head 4 set in consideration of the installation of each shroud head repair mount 35 And the shroud head repair mount 35 is installed based on the distance from the position of the grapple (see FIG. 4E).

  While confirming that the patch for receiving the shroud head of the DS pool 12 in the groove provided on the floor surface of the shroud head repairing base 35 is straddled, the same as the remaining three shroud head repairing bases 35 are performed. Install.

  At this time, the suspension rod support base is installed on the floor surface of the DS pool 12 where the suspension rod is disposed.

  Thereafter, the shroud head 4 that has been waiting on the reactor well 11 is seated on the shroud head repair base 35 using an overhead crane (see FIG. 4F). When seated, the shroud head bolt is monitored so as not to interfere with the shroud head repair mount 35.

  Subsequently, the DS hanger is removed from the shroud head 4 using an overhead crane, moved to a predetermined position, and separated from the overhead crane at that position.

  Next, a head bolt suspension is attached to the overhead crane, and the shroud head bolts on both sides of the guide pin bracket 15 (see FIG. 3) are removed from the shroud head 4 using this suspension, and stored in the DS pool 12 ( (Refer FIG.4 (g)).

  By removing the target shroud head bolt from the shroud head 4 using the head bolt suspension attached to the overhead crane and storing it, the preparation process for repairing the shroud head is completed, and the shroud head repair work is performed as shown in FIG. ). After the shroud head repair work, the shroud bolt is returned to the shroud head (see FIG. 4 (H)).

  By the way, in the repair work of the shroud head, on the assumption that the shroud head repair mount 35 is installed, the damaged existing suspension rod 44 is removed from the suspension rod bracket of the shroud head 4 and replaced. The pins are removed from the guide pin bracket 15 and replaced.

  The existing guide pins 54 and suspension rods 44 of the shroud head 4 damaged in the DS pool 12 can be cut underwater by a remote cutting device and removed from the shroud head 4. In that case, after the shroud head 4 is installed on the repair base 35, the shroud head bolt that may interfere with the shroud head repair device can be removed and stored using an overhead crane. At that time, the existing guide pin 54 damaged in the shroud head 4 is cut underwater remotely and attached to the site where the new guide pin 20 is removed underwater remotely.

  The repair work of the shroud head 4 is performed in the DS pool 12 of the reactor building. A plurality of, for example, four, existing suspension rods 44 are provided on the outer periphery of the shroud head 4 by suspension rod attachment brackets 45. For example, the existing suspension rods 44 damaged by an earthquake or the like are shown in FIG. The cutting / removing operation is performed by the suspension rod cutting EDM device 46 as a suspension rod remote cutting device from the suspension rod mounting bracket 45 of the shroud head 4.

  In the hanging rod cutting process for repairing the shroud head, the hanging rod cutting EDM device 46 is connected to the EDM power source and the air operation panel.

  It is confirmed that the suspension rod gripping portion 47 and the electrode 48 are operated by operating the air operation panel and the EDM power source. An unshown underwater camera or lighting fixture is put into the DS pool 12 and it is confirmed that the existing hanging rod 44 is reflected on the monitor.

  Then, it installs in the downward direction of the existing suspension bar 44 which cut | disconnects the suspension bar stand which is not shown in figure. At the time of installation, the lower end of the existing suspension bar 44 is fixed, and the existing suspension bar 44 is tilted during cutting to prevent the electrode 48 from being sandwiched.

  Next, the suspension rod cutting EDM device 46 is lifted through a wire rope by a silver hoist as a dolly elevator (not shown) that travels across the DS pool 12.

  The carriage is moved above the existing suspension rod 44 for cutting, and the suspension rod cutting EDM device 46 is suspended to the upper surface of the suspension rod bracket 45 by a silver hoist. When hanging the hanging rod cutting EDM device 48, the shroud head support ring becomes an interference and it is difficult to see from above.

  The silver hoist as an elevator is further lowered, and the suspension rod cutting EDM device 46 is seated on the upper surface of the shroud head rim body 4a.

  After confirming that the suspension rod gripping portion 47 at the upper portion of the suspension rod cutting EDM device 46 sandwiches the existing suspension rod 44, the air operation panel is operated to grip the existing suspension rod 44 and fix the suspension rod cutting EDM device 46. At this time, it is confirmed that the electrode 48 is below the welded portion of the hanging rod bracket 45 and the existing hanging rod 44.

  The suspension rod cutting EDM device 46 is activated, and after confirming that the electrode 48 is rotating, the suspension rod cutting is started below the suspension rod mounting bracket 45.

  When the cutting of the existing hanging rod 44 is completed, the rotary electrode 48 is moved to the initial extraction position.

  The cut existing suspending rod 44 is collected by the suspending rod support base, and then the air operating panel is operated to release the suspension rod gripping portion 47.

  The silver hoist is pulled up and lifted with care so that the suspension rod cutting EDM device 46 does not interfere with the shroud head 4 or the like. Subsequently, an air operation panel is connected to a polishing apparatus (not shown), and it is confirmed that the brush portion operates.

  Attach a polishing device to an operation pole (not shown), hang it up to the hanger bar cut surface, and polish the cut surface with the brush part.

  After removing soot by EDM processing, the polishing apparatus is pulled up.

  The remaining three existing suspension rods 44 are sequentially cut and removed using the suspension rod cutting EDM device 46 in the same procedure. If necessary, the rotating electrode 48 is replaced.

  After the existing suspension rod 44 is cut below the suspension rod mounting bracket 45, the new suspension rod 51 having the same shape as the suspension rod 44 cut and removed at the cut portion is screwed to the portion where FIG. As shown in (B), even if it is screwed together or attached by welding (see the description or drawing of Japanese Patent Application No. 2008-209231), the shroud head mount must be installed in the DS pool 12 As a premise, it is good also as a restoration structure as shown in FIG.

  Further, in the repair work of the shroud head 4, the cutting / removal of the existing guide pins 54 and the mounting of the new guide pins 20 are performed before and after the cutting / removal work of the existing suspension bar 44 and the installation / installation work of the new suspension bar 51.・ Installation work is performed.

  In the repair work of the shroud head 4, the removal work of the existing guide pins 54 is performed as shown in FIGS.

  The shroud head repair is also performed in the DS pool 12, and the removal operation of the existing guide pin 54 damaged by the earthquake is performed using a guide pin cutting EDM device 55 as a guide pin remote cutting device.

  Also in this case, the guide pin cutting EDM device 55 is connected to the EDM power source and the air operation panel, the air operation panel is operated, it is confirmed that the connector gripping part 56 operates, the EDM power source is operated, and the electrode It is confirmed that the operation arm 58 to which 57 is attached rotates about 90 degrees around the rotation shaft 59, for example. The arm 60 that holds the connector 59 of the existing guide pin 54 is set in an open state. The arm 60 is installed in the apparatus main body 61 of the guide pin cutting EDM apparatus 55 and extends laterally from the apparatus main body 61.

  Subsequently, an underwater camera and an illuminator are inserted into the DS pool 12, and it is confirmed that the existing guide pin 54 to be cut is reflected on the monitor.

  A guide pin receiving base is installed below the existing guide pin 54 to be cut using a silver hoist of a carriage traveling across the DS pool 12. The guide pin cutting EDM device 55 is lifted by a silver hoist of the carriage through a wire rope.

  Next, it moves above the existing guide pin 54 for cutting the carriage, and the guide pin cutting EDM device 55 is suspended to the upper surface of the guide pin bracket 15 by the silver hoist. When hanging, the shroud head support ring becomes an obstacle and is difficult to see from above.

  The silver hoist is further lowered, and the guide pin cutting EDM device 55 is seated on the upper surface of the guide pin bracket 15.

  After confirming that the connector gripping portion 56 on the upper part of the guide pin cutting EDM device 55 is sandwiching the connector 59, the air operation panel is operated to grip the connector 59, and the guide pin cutting EDM device 55 is fixed. At this time, it is confirmed that the electrode 57 is below the lower surface of the existing sleeve 16.

  The guide pin cutting EDM device 55 is activated to start cutting the existing guide pins 54. The cut existing guide pins 54 are collected by a guide pin receiving stand. When the cutting is completed, the arm 58 of the electrode 57 is moved to the open position.

  Further, the existing guide pin 54 whose shroud head is damaged can be cut by the remote cutting device 75 at the lower end position of the existing sleeve 16 to remove the head portion of the guide pin.

  The connector grip 56 is released by operating the air operation panel.

  The silver hoist is pulled up and carefully pulled up so that the guide pin cutting EDM device 55 does not interfere with the shroud head 4 or the like.

  A guide pin operating jig is attached to the nut at the upper end of the guide pin, and it is confirmed whether or not the existing guide pin remaining portion can be rotated. When the existing guide pin 54 does not rotate, guide pin driving processing is performed. When the existing guide pin 54a is rotatable, a follow-up process is not necessary, and a stopper removing process is performed.

  Next, as shown in FIG. 9, the guide pin driving EDM device 65 is connected to the power source and the air operation panel.

  It is confirmed by operating the air operation panel that the gripping part operates and the arm lock pin 66 operates.

  It is confirmed that the operating arm 68 to which the EDM power source is operated and the electrode 67 is attached moves up / down, rotates 90 °, and further the electrode 67 rotates. After the operation is confirmed, the operation arm 68 to which the electrode is attached is opened, the operation arm 68 is fixed by the arm lock pin 66, and is set to the lowered position.

  Subsequently, an underwater camera and an illuminator are turned on, and it is confirmed that the guide pin remaining portion 54a to be driven is reflected on the monitor.

  The guide pin driving EDM device 65 is lifted by the silver hoist of the carriage through the wire rope.

  The carriage is moved above the remaining guide pin portion 54 a to be driven and the guide pin drive EDM device 65 is suspended to the upper surface of the guide pin bracket 15 by a silver hoist. When hanging, the shroud head support ring becomes an interference and is difficult to see from above.

  The silver hoist is further lowered, and the guide pin driving EDM device 65 is seated on the upper surface of the guide pin bracket 15.

  After confirming that the connector gripping portion 70 on the upper part of the guide pin driving EDM device 65 sandwiches the connector 59, the air operation panel is operated to grip the connector 59 and fix the guide pin driving EDM device 65.

  The air operation panel is operated, the arm lock pin 66 is pulled out, and the operation arm 68 can be moved.

  The operation arm 68 is rotated by, for example, 90 ° on the EDM operation panel, and the electrode 67 is moved below the guide pin remaining portion 54a. The air operation panel is operated to fix the operation arm 68 with the arm lock pin 66. At this time, the underwater camera confirms that the axes of the electrode 67 and the guide pin remaining portion 54a are substantially aligned.

  The guide pin driving EDM device 65 is activated to start driving the guide pin remaining portion 54a.

  Machining proceeds while monitoring with a camera, and once the machining proceeds to the trapezoidal screw portion 54b in the existing sleeve 16, the machining is temporarily stopped.

  The electrode 67 is lowered, the arm lock pin 66 is released, and the operation arm 68 is returned to the open state. A guide pin operating jig is attached to the nut at the upper end of the guide pin, and it is confirmed whether or not the remaining guide pin 54b can be rotated.

  When the existing guide pin 54 becomes rotatable, the machining is completed, but when the remaining guide pin 54b does not rotate, the follow-up machining is resumed.

  The follow-up process and the confirmation of whether or not the remaining guide pin 54b can be rotated are repeated, and when the remaining guide pin 54b becomes rotatable, the follow-up process is completed. As described above, when the existing guide pin 54 does not rotate, the damaged portion below the threaded portion in the existing sleeve 16 can be removed by the remote cutting device 75 until the existing guide pin 54 can be rotated.

  After the driving process is completed, the electrode is lowered, the arm lock pin 66 is released, and the operation arm 68 is fixed by the arm lock pin 66 in a state where the operation arm 68 is returned to the open state.

  The connector grip 69 is released by operating the air operation panel.

  After the connector gripping portion 69 is released, the silver hoist is pulled up, and the guide pin is driven, and the EDM device 65 is pulled up with care so as not to interfere with the shroud head 4 and the like.

  Thereafter, the other existing guide pin 54 is driven in the same procedure.

  Connect the air control panel to the polisher and check that the brush is working.

  Attach the polishing device to the operation pole, suspend it to the guide pin driving surface, and polish the processing surface with the brush part.

  After removing soot by EDM processing, the polishing apparatus is pulled up.

  Thereafter, as shown in FIG. 10, the stopper removing EDM device 75 is connected to the power source and the air operation panel.

  The air operation panel is operated to confirm that the guide rod gripping portion 71 and the guide pin bracket gripping portion operate. After confirmation, leave it open.

  The EDM power supply is operated to confirm that the electrode 72 slides back and forth. After confirmation, move to the maximum withdrawal position.

  The stopper removing EDM device 75 inserts a socket 78 into a top bit 77 provided in the device main body 76 and confirms that the electrode portion moves up and down. After checking, leave the socket 78 in the middle position.

  An underwater camera and an illuminator are inserted, and it is confirmed that the disc-shaped stopper 79 of the remaining guide pin 54b is reflected on the monitor.

  The stopper removal EDM device 75 is lifted by a silver hoist of the carriage through a wire rope.

  The carriage is moved above the remaining guide pin 54b from which the stopper 79 is removed, and the stopper removing EDM device 75 is suspended to the upper surface of the guide pin bracket 15 by a silver hoist. When hanging, the shroud head support ring becomes an interference and is difficult to see from above.

  The silver hoist is further lowered, and the apparatus main body 76 of the stopper removing EDM apparatus 75 is seated on the upper surface of the guide pin bracket 15.

  After confirming that the guide rod gripping portion 71 at the top of the stopper removing EDM device 76 is sandwiching the rod 80 and confirming that the bottom gripping portion 81 is sandwiching the guide pin bracket 15, operate the air operation panel to The guide pin bracket 15 is gripped and the stopper removing EDM device 75 is fixed.

  Using the operation pole 82, the socket 78 is inserted into the bit 77 at the top of the mounting stopper removing EDM device 75, and the height of the electrode 72 is adjusted to the height of the stopper 79 while checking with a camera.

  Subsequently, the stopper removal EDM device 75 is activated to start the stopper removal processing.

  In the stopper removal processing, after the removal of the stopper 79 is completed up to the diameter of the rod 80 in the range of 180 ° around the stopper 79 of the remaining guide pin 54a, the processing is stopped and the electrode is retracted.

  A guide pin handling jig is attached to the upper portion of the guide pin, and the remaining guide pin 54b is rotated half a turn so that the remaining portion of the stopper 79 faces the electrode 72 side.

  The socket 78 inserted into the bit 77 at the top of the stopper removing EDM device 75 is rotated using the operation pole 82, and the height of the electrode 72 is adjusted to the height of the stopper 79 while checking with the underwater camera.

  The stopper removal EDM device 75 is activated to start the removal processing of the remaining portion of the stopper 79, and the stopper 79 is removed to the outer diameter of the rod 80. It is confirmed that there is no remaining portion of the stopper 79 over the entire circumference. If there is a stopper remaining portion, the stopper remaining portion is removed by the same procedure. After processing, the electrode 72 is retracted.

  After the removal of the stopper 79 is completed, the upper and lower grips 71 and 81 are released by operating the air operation panel.

  The silver hoist is pulled up and pulled up so that the stopper removal EDM device 75 does not interfere with the shroud head 4 or the like.

  The stopper 79 is removed from the other existing guide pin 54 by the same procedure.

  In this way, the stopper 79 attached to the upper part of the pin rod of the existing guide pin 54 can be removed by the remote cutting device 75 so that the outer diameter is equal to or less than the rod outer diameter of the guide pin.

  When the stopper 79 of the existing guide pin 54 is removed over the entire circumference, the stopper removing electrode 72 is replaced with a slit machining electrode. After the stopper removing electrode 72 of the stopper removing EDM device 75 is replaced with a slit machining electrode, the stopper removing EDM device 75 is connected to a power source and an air operation panel.

  The air operation panel is operated to confirm that the guide rod gripping portion 71 and the guide pin bracket gripping portion 81 are operated. After confirmation, the gripping portions 71 and 81 are kept in a state.

  Operate the EDM power supply and confirm that the slit machining electrode slides back and forth. After confirmation, move to the maximum withdrawal position.

  A socket 78 is inserted into the top bit 77 provided in the stopper removing EDM device 75 and it is confirmed that the slit machining electrode portion moves up and down. After confirmation, set to an intermediate position and remove the socket 78.

  Subsequently, an underwater camera and an illuminator are inserted into the DS pool 12, and it is confirmed that the existing guide pin 54 for processing the slit is reflected on the monitor.

  The stopper removal EDM device 75 is lifted by a silver hoist of the carriage through a wire rope.

  The carriage is moved above the existing guide pin 54 for slitting, and the stopper removing EDM device 75 is suspended to the upper surface of the guide pin bracket 15 by a silver hoist. When hanging, the shroud head support ring becomes an interference and is difficult to see from above.

  The silver hoist is further lowered, and the stopper removing EDM device 75 is seated on the upper surface of the guide pin bracket 15.

  After confirming that the guide rod gripping portion 71 guide at the top of the stopper removing EDM device 75 sandwiches the rod 80 and that the bottom gripping portion 81 sandwiches the guide pin bracket 15, the air rod is operated to operate the guide rod 80. Then, the stopper removing EDM device 75 is fixed by holding the guide pin bracket 15.

  Using the operation pole 82, the socket 78 is attached and inserted into the bit 77 at the top of the stopper removing EDM device 75, and the height of the slit machining electrode is adjusted to the height of the lower end of the connector 59 while checking with an underwater camera. At this time, it is confirmed that the slit machining electrode is at the center of the guide rod 80.

  Subsequently, the stopper removing EDM device 75 is activated, and slit processing is started on the top of the pin rod of the existing guide pin 54. Processing is performed until the slit processing electrode penetrates the guide rod 80 portion. After slitting the pin rod top of the existing guide pin 54, the slit machining electrode is retracted.

  After the slit machining is completed, the upper and lower grips 71 and 81 are released by operating the air operation panel.

  The silver hoist is pulled up so that the stopper removing EDM device does not interfere with the shroud head 4 or the like.

  The other existing guide pin 54 is slit by the same procedure.

  Attach the rod handling jig to the upper end of the rod after slitting and secure the jig to the handrail of the DS pool with a rope.

  Slit processing can be performed by the remote cutting device 75 at the center of the upper part of the existing guide pin 54 and the upper part of the guide pin below the connector 59 connecting the operation rod 80.

  Next, as shown in FIG. 11, the rod cutting EDM device 85 is connected to a power source and an air operation panel. Then, it is confirmed that the rod gripping portion 86 is operated by operating the air operation panel.

  It is confirmed that the EDM power source is operated to rotate the rotating electrode 90 and the feed shaft operates.

  Subsequently, an underwater camera and an illuminator are inserted into the DS pool 12 and it is confirmed that the connector 59 to be cut is reflected on the monitor.

  The rod cutting EDM device 85 is lifted through a wire rope by a silver hoist of the carriage.

  The rotating electrode 90 is set at the most drawn-out position so that the rotating electrode 90 does not collide with the structure of the shroud head 4 or the like when it is suspended.

  It moves above the existing guide pin 54 that cuts the carriage, and the rod cutting EDM device 85 is suspended to the upper surface of the guide pin bracket 15 by the silver hoist. When hanging, the shroud head support ring becomes an interference and is difficult to see from above.

  The silver hoist is further lowered, and the rod cutting EDM device 85 is suspended near the connector 59.

  After confirming that the rod gripping portion 86 at the upper part of the rod cutting EDM device 85 sandwiches the guide rod 80, the air operating panel is operated to grip the guide rod 80, and the rod cutting EDM device 85 is fixed. At this time, it adjusts with a silver hoist so that the rotation electrode 90 may become the lower end position of the connector 59. FIG. When the position is shifted, the gripping force is weakened with the air operation panel and the height is adjusted with a silver hoist. When the position is determined, the gripping force is strengthened with the air operation panel and the rod cutting EDM device 85 is fixed.

  After starting the rod cutting EDM device 85 and confirming that the rotating electrode 90 is rotating, cutting of the guide rod 80 is started.

  When the cutting of the guide rod 80 is completed, the rotary electrode 90 is moved to the maximum drawing position.

  The gripping force is weakened with the air operation panel and the height is adjusted with a silver hoist so that the position of the rotary electrode 90 is above the connector 59. When the position is determined, the gripping force is strengthened with the air operation panel and the rod cutting EDM device 85 is fixed. .

  After starting the rod cutting EDM device 85 and confirming that the rotating electrode 90 is rotating, the guide rod 80 is cut and the connector 59 is removed.

  The cut connector 59 is collected by a guide pin receiving stand. Subsequently, the rod operating portion 86 is released by operating the air operation panel.

  The silver hoist is pulled up so that the rod cutting EDM device 85 does not interfere with the shroud head 4 or the like.

  The rope of the rod handling jig that has been secured to the DS pool 12 is unwound, and the guide rod 80 part is pulled out from the shroud head 4 with an overhead crane and temporarily placed in the DS pool 12.

  In the same procedure, the connector 59 of the other existing guide pin 54 is removed, and the guide rod 80 is pulled out from the shroud head 4 and temporarily placed. Thus, the existing guide pin 54 and the connector 59 can be separated by cutting the upper portion of the existing guide pin 54 and the upper portion of the guide pin below the connector 59 connecting the operation rod 80 with the remote cutting device 85.

  Further, the operation rod 80 above the connector 59 connecting the upper portion of the existing guide pin 54 and the operation rod 80 is cut by the remote cutting device 85 to remove the connector 59, and the operation rod 80 is moved to the upper / lower portions of the shroud head 4. Can be pulled out and removed from the ring.

  Further, a guide pin removing jig 96 is attached to the slit provided on the existing guide pin 54, and the existing guide pin 54 is rotated by using the guide pin removing jig 96 so that the guide pin is fixed from the existing sleeve 16 fixed to the guide pin bracket. Can be separated and removed.

  At that time, as shown in FIG. 3, the new guide pin 20 is attached to the existing sleeve 16 while the existing sleeve 16 is attached to the guide pin bracket 15. When the shroud head 4 is installed on the core shroud 2, the new guide pin 20 is attached to the core shroud 2 with a clearance from the guide pin hole (existing sleeve 16) of the guide pin bracket 15 attached to the core shroud 2. A clearance between the seismic pin 30 and the seismic pin hole 31 of the shroud head rim body 4a is formed so as to have an outer diameter that is comparable. The new guide pin 20 is configured not to be screwed together with a screw portion formed on the inner diameter of the existing sleeve 16 fixed to the guide pin bracket 15 so as not to be joined.

  Next, as shown in FIG. 12, the guide pin removal adapter 94 is attached to the nut tightening socket 93 (the O-ring 112 of the socket 93 is fitted and held in the circumferential groove provided in the outer peripheral portion of the guide pin removal adapter 94. ).

  A nut tightening socket 93 is attached to the socket handling jig 95.

  Attach the socket handling jig 95 to the operation pole.

  An underwater camera and an illuminator are inserted into the DS pool 12, and it is confirmed that the existing guide pin 54 to be removed is reflected on the monitor.

  The socket removal jig 95 is moved above the existing guide pin 54 to be removed by the carriage, and the guide pin removal adapter 94 of the nut tightening socket 110 is attached to the top of the pin rod of the existing guide pin 54 using the operation pole 115. . At that time, the convex portion of the guide pin removal adapter 94 is fitted into the slit portion.

  The nut tightening pole 115 is inserted through the holes of the upper and lower support rings of the shroud head 4, the wrench portion is removed, and the guide pin is removed and the adapter 94 is inserted.

  The existing guide pin 54 is removed from the existing sleeve 16 by rotating the nut tightening pole 115.

  The existing guide pin 54 that has fallen off from the existing sleeve 16 is collected by the guide pin receiving frame.

  Subsequently, the nut tightening pole 115 is pulled up, and the socket handling jig 95 is pulled up and collected.

  In the same procedure, the other existing guide pin 54 is removed and recovered.

  After the existing guide pins 54 are removed, the surfaces of the upper and lower surfaces of the existing sleeve 16 that meet the new guide pins 20 are polished with a polishing device to remove the cladding and the like.

  After the existing guide pin 54 is removed from the shroud head 4 in the DS pool 12 and removed, the new guide pin 20 is attached to the removal portion of the existing guide pin 54. In the shroud head repair work, the new guide pin 20 is attached as shown in FIGS.

  The new guide pin 20 has an axial direction that engages at a position corresponding to the lowest position of the existing guide pin 54, and the axial dimension of the head portion 20 a of the new guide pin 20 is the same as that of the existing guide pin 54. The guide pin bracket hole 27 engages with the lower surface of the existing sleeve 16 at a portion slightly smaller in diameter than the head portion 20a in order to escape interference.

  Further, the new guide pin 20 has a portion that fits and fits with the existing sleeve 16 of the existing guide pin 54, and when the new guide pin is inserted into the existing sleeve 16, the new guide pin 20 is equivalent to the existing guide pin 54. It is designed to be attached to the core position. At that time, the new guide pin 20 is mechanically fastened to the existing sleeve 16 of the existing guide pin 54 by the fixing nut 21.

  In the new guide pin mounting operation for repairing the shroud head, as shown in FIG. 13, a guide pin assembly device 100 is provided connected to the air operation panel. The guide pin assembly apparatus 100 includes a guide pin bracket gripping part 101, an air spring part 102, and a rotation stopping cylinder 103. The air operation panel is operated to operate the guide pin bracket gripping portion 101 and the air spring portion 102, and confirm that the detent cylinder 103 is moved substantially horizontally in the front-rear direction. Subsequently, the insertion cylinder 104 of the guide pin assembly apparatus 100 is connected to the manual pump. The manual pump is operated to confirm that the insertion cylinder 104 is raised or lowered.

  Next, the new guide pin 20 is attached to the cup portion 105 of the guide pin assembly apparatus 100. At this time, it is confirmed that the polygon pin 106 at the bottom of the cup, for example, a triangular pin or a square pin is inserted into the square hole provided at the bottom of the new guide pin 20, for example, a square hole, and the new guide pin 20 does not rotate in the cup 105 To do.

  Subsequently, an underwater camera and an illuminator are inserted into the DS pool 12, and it is confirmed that the guide pin bracket 15 to which the new guide pin 20 is attached is reflected on the monitor.

  The guide pin assembling apparatus 100 is lifted by a silver hoist of the carriage via a wire rope.

  The carriage that can travel over the DS pool 12 is moved above the guide pin bracket 15 to which the new guide pin 20 is attached, and the guide pin assembly device 101 is suspended to the upper surface of the guide pin bracket 15 by the silver hoist. Since the shroud head support ring becomes an obstacle when suspended, it is difficult to see from above, so carefully suspend the suspension while checking with an underwater camera.

  The silver hoist is operated and further lowered until the new guide pin 20 is below the guide pin bracket 15. The guide pin assembly device 100 is handled outside the guide pin bracket 15. When suspended to this state, the guide pin assembly apparatus 100 is moved to the center side of the shroud head 4 and the guide pin assembly apparatus 100 is seated on the upper surface of the guide pin bracket 15. When seating, the side surface (inner surface of the cylinder) and end surface of the guide pin bracket 15 are brought into close contact with the seating surface of the apparatus 100.

  Next, the air operation panel is operated, and the guide pin bracket 15 is gripped by the guide pin bracket gripping portion (clamp cylinder) 101, and the guide pin assembly device 100 is fixed to the guide pin bracket 15.

  The manual pump is operated to raise the insertion cylinder 104 and insert the new guide pin 20 into the existing sleeve 16. When inserting, the screw 20a of the new guide pin 20 is inserted with care so as not to be damaged.

  It is confirmed that the expansion taper portion (shoulder portion) 20b of the new guide pin 20 is in contact with the expansion taper portion 16b of the existing sleeve 16, and the state is maintained if they are in contact with no gap.

  It is confirmed that the axial groove 20c provided on the pin rod top of the new guide pin 20 is formed at a position of 0 ° -180 °, 90 ° -270 °, for example.

  The air operation panel is operated and the stop cylinder 103 is set to be pressed from the side of the cup 105.

  Next, as shown in FIG. 14, the fixing nut 21 is attached to the nut tightening socket 110 (On the other hand, the O-ring 112 of the socket 110 is fitted and held in the circumferential groove provided in the outer peripheral portion of the fixing nut 21. ).

  The nut tightening socket 110 is attached to the socket handling jig 95. The socket handling jig 95 is attached to the operation pole 115.

  An underwater camera and an illuminator are inserted, and it is confirmed that the new guide pin 20 inserted into the existing sleeve 16 is reflected on the monitor.

  The top of the pin rod provided with a slit (axial groove) 23 in the axial direction of the new guide pin 20 is moved by moving upwardly above the new guide pin 20 to which the fixing nut 21 is attached by the carriage, connecting the operation pole 115 and passing through the support ring. The fixing nut 21 is inserted, and the nut tightening socket 110 is temporarily placed in the fixing nut 21.

  A wrench is attached to the clamping pole 115 (through the holes of the upper and lower support rings of the shroud head 4 through which the guide rod of the new guide pin 20 has passed), and the wrench is inserted into the nut clamping socket 110.

  By rotating the tightening pole 115, the fixing nut 21 is tightened to fix the new guide pin 20.

  After the fastening of the fixing nut 21 is completed, the socket handling jig 95 is pulled up, the nut fastening socket 114 and the fixing nut 21 are separated, and the socket handling jig 95 is pulled up and collected.

  The air operation panel is operated to return the rotation stop portion cylinder 110 of the guide pin assembling apparatus 100 to the state of being separated from the cup 105 and retracted as shown in FIGS. 13 and 14. Thereafter, the manual pump is operated to lower the insertion cylinder 104, and the cup 105 and the new guide pin 20 are separated.

  Further, the air operation panel is operated to release the gripping cylinder 101 that fixes the guide pin assembly device 100 to the guide pin bracket 15, and the guide pin assembly device 100 is separated from the guide pin bracket 15.

  The silver hoist is pulled up so that the guide pin assembling apparatus 100 does not interfere with the shroud head 4 or the like.

  In the same procedure, the fixing nut 21 is attached and fixed to the other new guide pin 20.

  After fixing the fixing nut 21 to the new guide pin 20, a caulking device 120 is prepared as shown in FIG. 15 in order to stop the fixing nut 21. The manual pump is operated, it is confirmed that the caulking portion of the caulking device 120 is operated, and the caulking portion is set in a retracted state. Also, make sure that there are no leaks from the hose joints.

  Subsequently, an underwater camera and an illuminator are inserted into the DS pool 12, and it is confirmed that the fixing nut 21 attached to the new guide pin 20 is reflected on the monitor.

  The caulking device 120 is lifted through a wire rope by a silver hoist of a carriage that runs over the DS pool 12.

  The carriage is moved above the guide pin bracket 15 for caulking the fixing nut 21, and the caulking device 120 is suspended to the upper surface of the guide pin bracket 15 by the silver hoist. When hanging, the shroud head support ring becomes an obstacle and is difficult to see from above.

  The caulking device 120 is suspended and seated on the guide pin bracket 15, and the nut nut 121 is used to grip the fixing nut 21 to which the new guide pin 20 is fixed using the sleeve nut 17, and the caulking device 120 is fastened. When it is confirmed that fastening of the caulking device 120 is completed, a manual pump is connected to the caulking device 120 via a hose.

  Subsequently, while confirming with a camera, the silver hoist is further lowered, and the guide of the caulking device 120 is inserted into the axial grooves 23 (two locations of 0 ° to 180 °) provided above the new guide pin 20. Further, the caulking device 120 is lowered and seated on the upper surface of the guide pin bracket 15 so that the caulking device 120 covers the fixing nut 21 that fixes the existing sleeve 16.

  The orientation of the caulking portion of the caulking device 120 coincides with the orientation of the axial groove 23 provided in the upper part of the new guide pin 20 inserted and fixed to the existing sleeve 16 of the guide pin bracket 15 (90 ° -270 °). Confirm with the camera. After this confirmation, the manual pump is operated to caulk the nut skirt 22 part integrally provided on the upper part of the fixing nut 21, and is fitted into the axial groove 23 provided on the upper part of the new guide pin 20 to be caulked and stopped.

  The new guide pin 20 is provided with an axial groove 23 above the pin rod of the new guide pin 20 above the screw portion of the fixing nut 21, and a thin nut skirt 22 is provided on the upper surface of the fixing nut 21. After tightening, the nut skirt 22 is caulked along the axial groove 23 of the new guide pin 20 to mechanically prevent the locking nut 21 from rotating / loosening.

  The manual pump is operated and the caulking portion of the caulking device 120 is pulled back evenly.

  In the same procedure, the locking nut 21 of the other new guide pin 20 is stopped (caulked).

  The silver hoist is pulled up with care so that the caulking device 120 does not interfere with the shroud head 4 or the like.

  In this way, when the repair work of the shroud head 4 in the DS pool 12 is completed, the repaired shroud head 4 is suspended by an overhead crane after completion of the fuel exchange work and the like, and is removed from the DS pool 12. It is transferred into the reactor well 11 shown in FIG. 2 and guided into the reactor pressure vessel 1. In the reactor pressure vessel 1, the reactor is guided by a guide rod, suspended on the core shroud 2, and fastened to the core shroud 2 using shroud head bolts. At this time, the steam / water separator 5 is integrally provided in the shroud head 4 via the stand pipe 6, and the steam / water separator 5 is also installed by attaching and installing the shroud head 4 to the core shroud 2. Set.

  Subsequently, the steam dryer 8 temporarily placed in the DS pool 12 is also suspended by an overhead crane, moved underwater to the reactor well 11, and guided into the reactor pressure vessel 1. The steam dryer 8 guided to the reactor pressure vessel 1 is positioned and installed at a required position above the steam / water separator 5.

  Next, similarly using the overhead crane, the reactor pressure vessel upper lid 1a temporarily placed in the equipment pool is moved underwater onto the RPV 1 and fastened by the fastening bolt 1b on the RPV 1. Thus, the repair work of the shroud head 4 is completed due to an earthquake or the like, and the repaired shroud head 4 is prepared for the operation of the RPV plant.

  Even if the shroud head 4 is damaged due to an earthquake or the like, the guide pin 54 and the suspension rod 44 of the deformed shroud head 4 can be replaced. The existing guide pin 54 and the suspension rod 44 can be replaced with the new guide pin 20 and the new suspension rod 51 by underwater remote work in the DS pool 12.

  The shroud head 4 according to the present invention is deformed by an earthquake or the like, the guide function of the shroud head 4 is lost, and there is a possibility that the shroud head 4 may interfere with the guide pin bracket 15 of the shroud head 4 or the core shroud 2. The suspension rod that may interfere with the suspension rod can be replaced with a new guide pin or suspension rod by remote underwater work, and the shroud head 4 can be repaired by underwater remote work.

  The shroud head 4 deformed due to an earthquake or the like can secure a sufficient water shielding height above the steam / water separator 5 by performing repair work using the repair stand 35 in the DS pool 12. . The exposure dose during the replacement work or repair work of the shroud head 4 can be kept sufficiently low.

  In the repair work of the shroud head 4, it is possible to remotely cut and remove the lower part from the suspension bar bracket which is a part of the existing suspension bar part damaged on the assumption that the shroud head repair mount 35 is installed. it can.

  DESCRIPTION OF SYMBOLS 1 ... Reactor pressure vessel (RPV), 1a ... RPV top cover, 2 ... Core shroud, 2a ... Upper trunk, 3 ... Core, 4 ... Shroud head, 5 ... Steam-water separator, 6 ... Stand pipe, 7 ... Upper core Plenum, 8 ... Steam dryer, 9 ... Main steam pipe, 11 ... Reactor well, 12 ... DS pool (DS pit), 15 ... Guide pin bracket, 16 ... Existing sleeve, 16a ... Outer flange, 16b ... Expanding taper (Sleeve bottom surface), 17 ... sleeve nut, 20 ... new guide pin, 20a ... guide pin head, 20b ... guide pin body, 21 ... fixing nut, 22 ... nut skirt, 23 ... axial groove, 25 ... outside Flange, 26 ... guide rod insertion hole, 27 ... guide pin bracket hole, 30 ... earthquake-resistant pin, 31 ... earthquake-resistant pin hole, 35 ... shroud head repair mount, 36 ... operation Floor, 37 ... DS suspension, 38 ... seal lining device, 39 ... seal lining, 40 ... corner of DS pool, 44 ... existing suspension rod, 45 ... suspension rod mounting bracket, 46 ... suspension rod cutting EDM device, 47 ... Suspension rod gripping part, 48 ... Rotating electrode, 51 ... New suspension rod, 54 ... Existing guide pin, 55 ... Guide pin cutting EDM device, 56 ... Connector gripping part, 57 ... Electrode, 58 ... Operating arm, 59 ... Connector, 60 ... Arm 61 ... Device body 65 ... Guide pin driving EDM device 66 ... Arm lock pin 67 ... Electrode 68 ... Operation arm 69 ... Device body 75 ... Stopper removal EDM device 76 ... Device body 77 ... Bit, 78 ... Socket, 79 ... Stopper, 85 ... Rod cutting EDM device, 86 ... Rod gripping part, 90 ... Rotating electrode, 93 ... Nut tightening 94 ... Guide pin removal adapter, 95 ... Socket handling jig, 96 ... Guide pin removal jig, 100 ... Guide pin assembly device, 101 ... Guide pin bracket gripping part, 102 ... Air spring part, 103 ... Non-rotating Cylinder, 104 ... Insert cylinder, 105 ... Cup part, 106 ... Polygonal pin (square pin), 110 ... Socket for nut tightening, 112 ... O-ring, 115 ... Operation pole (nut tightening pole), 120 ... Caulking apparatus.

Claims (12)

If the guide pin or suspension rod of the shroud head temporarily placed in the DS pool is deformed,
A part or all of the guide pin provided on the guide pin bracket of the shroud head is cut and removed in the DS pool, and a new guide pin is introduced and installed in the removed part,
A shroud characterized in that a part or all of the suspension rod provided on the suspension rod bracket of the shroud head is cut and removed in the DS pool, and a new suspension rod is introduced and installed in the removed portion. Head repair method. The shroud head temporarily placed in the DS pool is moved underwater to the reactor well using an overhead crane, the shroud head is temporarily kept in the reactor well, and the shroud head guide pin is placed in the DS pool. The method for repairing a shroud head according to claim 1, wherein a space for repairing the suspension rod is secured. A simple seal is installed at a part where the DS pool liner may be damaged due to interference between the lower end of the shroud head suspension rod and the DS pool liner to prevent leakage of the pool water of the DS pool. The shroud head repair method according to claim 1, wherein the shroud head is repaired. The repair of the shroud head according to claim 1, wherein a shroud head repair stand is divided into four or more locations in the DS pool, and is installed and supported below the shroud head without using an overhead crane. Method. The shroud head repair stand should be kept at a height at which the upper end of the steam separator attached to the shroud head is submerged by 1 m or more from the pool surface of the DS pool in consideration of the exposure dose on the operation floor. The method for repairing a shroud head according to claim 4. The shroud head repair method according to claim 1, wherein the shroud head guide pin and the suspension rod damaged in the DS pool are cut underwater by a remote cutting device and removed from the shroud head. 2. The shroud head bolt, which may interfere with the shroud head repair device, is removed and stored using an overhead crane after the shroud head is installed on the repair base. The shroud head repair method described in 1. The shroud head repair method according to claim 1, wherein the damaged guide pin of the shroud head is cut underwater remotely and attached to the site where the new guide pin is removed underwater remotely. 2. The method of repairing a shroud head according to claim 1, wherein the damaged guide pin of the shroud head is cut by a remote cutting device at a lower end position of the installation sleeve, and the head portion of the guide pin is removed. A guide pin operating jig is attached to the upper part of the pin rod of the guide pin, and it is confirmed whether or not the guide pin can be rotated. The shroud head repair method according to claim 1, wherein the guide pin is removed until the guide pin can be rotated. In the repair structure of the shroud head provided with the shroud head above the core shroud,
The shroud head has a guide pin bracket and a suspension bar bracket fixed to the rim body,
A new guide pin is inserted into the sleeve of the existing guide pin provided in the guide pin bracket,
The new guide pin has a portion in which the axial dimension of the head portion is fitted with the existing sleeve in the same manner as the axial dimension of the removed existing guide pin,
The shroud head repair structure, wherein the new guide pin is provided at a centering position equivalent to the existing guide pin when inserted into the existing sleeve. The new guide pin has a portion that fits and fits with a guide pin bracket hole of the core shroud and a sleeve of the existing guide pin at the lowest position of the existing guide pin,
The shroud head repair structure according to claim 11, wherein the new guide pin is a shoulder portion having a slightly smaller diameter than the head portion and is engaged with the lower surface of the existing sleeve.

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