JP2001242282A - Shroud replacing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shroud replacing method permitting the reuse of an existing product as it is. SOLUTION: In replacing an existing shroud in a reactor pressure vessel 38 with a new shroud 15, the mounting position of an existing shroud head 50 is obtained in advance using an existing shroud head lug 25, a transfer plate 28 and a transfer device 28, and a body of the new shroud 15 reflecting the thus obtained mounting position is manufactured. A body of the existing shroud 15 is then taken out of the reactor pressure vessel 38, and the body of the new shroud 15 and the existing shroud head 50 are installed. Cost required for the replacement of the shroud can be reduced in comparison with a conventional method, and time required for the manufacture of the new shroud can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a new shroud by reusing an existing shroud when replacing an existing shroud installed in a reactor containment vessel of a nuclear power plant. The present invention relates to a shroud replacement method that is installed in a container.

[0002]

2. Description of the Related Art Replacing of reactor internals in a nuclear power plant is disclosed in Japanese Patent Application Laid-Open Nos. 08-2339372 and 09-113666. For the replacement of the shroud, see JP-A-08-152495 and JP-A-11-304978.
It is publicly known by Japanese Patent Publication No.

[0003]

In the case of the replacement of the furnace internals described above, no consideration is given to reusing the existing products. In addition, in the case of the above-described conventional shroud replacement, consideration is given to processing and reusing the existing product, but there is no suggestion to reuse the existing product as it is.

The present invention has been made in view of the above-mentioned situation in the prior art, and an object of the present invention is to provide a shroud replacement method capable of reusing an existing product as it is.

[0005]

In order to achieve the above object, according to the present invention, when replacing an existing shroud in a reactor pressure vessel with a new shroud, an installation position of an existing shroud head is determined in advance, and the obtained position is determined. A new shroud body reflecting the mounting position is manufactured, and then the existing shroud body is taken out from the reactor pressure vessel, and the new shroud body and the existing shroud head are installed.

In the present invention, since the new shroud main body is formed by reflecting the mounting position of the existing shroud head, the existing shroud head can be easily mounted on the new shroud head main body. That is, the existing shroud head can be reused as a component of the new shroud head.

In determining the mounting position of the existing shroud head, the shroud head lug of the existing shroud head may be used.

In this case, the position of the shroud lug may be transferred using the shroud head lug.

Further, when determining the mounting position of the shroud head, it may be determined in the dryer / separator pool.

Further, when reflecting the mounting position of the existing shroud head on the new shroud main body, the shroud lug position may be measured in advance, for example, by a periodic inspection one time before the shroud replacement work.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the shroud replacement method of the present invention will be described below with reference to the drawings. FIG. 1 is a flowchart showing an embodiment of the present invention. Steps 1 to 5 are the transfer work of the shroud lug position performed in the periodic inspection immediately before the shroud replacement work as described later. Step 6 is a shroud production performed during operation of the nuclear power plant. Steps 7 to 14 are installation operations of the shroud measured and manufactured in Steps 1 to 6.

FIG. 3 is a longitudinal sectional view showing the internal structure of a reactor in which one embodiment of the present invention is implemented, and FIG. 4 shows a state of a shroud head fixing portion included in the internal structure of the reactor shown in FIG. 5 is a longitudinal sectional view showing a reactor building in which the reactor internal structure shown in FIG. 3 is arranged, FIG. 6 is a transverse sectional view of the shroud head shown in FIG. 4, and FIG. It is explanatory drawing which shows the state at the time of positioning of the shroud head guide block of the shroud head shown, and a shroud guide block.

FIGS. 3, 4, 5, 6 and 7
The positional relationship between the shroud head lug and the shroud lug will be described. The reactor pressure vessel 38 is located inside the reactor containment vessel 37 shown in FIG. 5, and the shroud 15 is further installed inside the reactor pressure vessel 38. The reactor containment vessel 37, the reactor pressure vessel 38, and the shroud 15 are respectively a reactor containment vessel cover (PCV head) 35 and a reactor pressure vessel cover (RP
V head 1, which is closed by the shroud head 50. Among them, shroud 15 and shroud head 50
As shown in FIGS. 6 and 7, a guide pin 41 is fixed to a shroud head guide block 52 attached at a position of 0 ° and 180 ° in the circumferential direction of the cross section of the shroud head 50. The guide pin 4 is inserted into the guide pin hole 42 of the shroud guide block 53 attached to the shroud 15 using the lower tapered portion as a guide.
Insert 1. After the insertion is completed, shroud head bolt 2
Tighten 6 in order. At the time of tightening, as shown in FIG. 4, the block 51 of the shroud head bolt 26 is placed on the notch of the shroud head lug 24 attached to the shroud head 50, and the notch of the shroud lug 25 attached to the shroud 15 is cut. Shroud head bolt T
The shroud head bolt 26 is set and tightened so that the mold portion 27 comes. By tightening the shroud head bolt 26, the shroud 15 and the shroud head 50 are integrally connected.

Next, an embodiment of a shroud replacement method according to the present invention will be described with reference to FIGS. 1, 2, 3, 5, 10 and the like. First, in step 1 of FIG. 1, the reactor is opened for periodic inspection immediately before shroud replacement work. In Step 2, as shown in FIG.
Move to 4. The shroud head 50 is attached to a lower part of the separator 6, and moves together with the separator 6. The transfer plate 28 at the shroud drag position is set in the dryer / separator pool 34 in advance, and the shroud drag position is transferred as described later in step 3 in parallel with the regular periodic inspection. After the transfer is completed, the dryer 4 and the separator 6 are returned to the wells in step 4, and the reactor is closed in step 5, and the periodic inspection is completed. In step 6, the position of the shroud lug 25 transferred to the transfer plate 28 in the periodic inspection immediately before the shroud replacement work is measured in detail, and a new shroud 15 body is manufactured at the factory during operation of the nuclear power plant. I do. Shroud replacement work starts from step 7. In Step 7, the reactor is opened, and in Step 8, the reactor internals to be reused are removed. In step 9, decontamination in the reactor including the existing shroud 15 body is performed. In step 10, the existing shroud 15 main body is detached from the reactor pressure vessel 38, and in step 11, the existing shroud 15 main body and the in-furnace structure to be discarded are cut in water and carried out of the reactor building. In step 12, the new shroud 15 body is carried into the reactor building, and the reactor pressure vessel 38
Installed inside. Thereafter, in step 13, the new internal structure and the internal structure to be reused are installed in the reactor pressure vessel 38. In step 14, the reactor closing operation is performed, and the shroud replacement work is completed.

The details of the work performed in the periodic inspection immediately before the shroud replacement work will be described with reference to FIG. In step 1A, a work area is set as a preparation work. The work area is the operating floor of the reactor building, and floors, walls, and other equipment are separated from ordinary areas by laying vinyl sheets or the like to prevent the spread of contamination.

The reactor opening operation starts from the next step 2A. In step 2A, the shield plug 36 shown in FIG. 5 is removed from the operating floor by the overhead crane 44, moved to the operating floor, and temporarily placed.

Next, in step 3A, the reactor containment vessel lid (PCV head) 35 is removed from the reactor containment vessel 38, moved to the operating floor, and temporarily placed.

Next, in step 4A, the mirror insulation is carried out by the
8 and move to the operating floor and temporarily place it.

Next, in step 5A, the reactor pressure vessel lid (RPV head) 1 is removed from the reactor pressure vessel 38 by the overhead crane 44, moved to the operating floor and temporarily placed. In the next step 6A, the dryer 4 is removed from the reactor pressure vessel 38, moved into the dryer / separator pool 34 by the overhead crane 44, and temporarily placed. The steps described above are the reactor opening work that is usually performed. Here, in step 1B, in parallel with the operations from step 1A to step 6A, the transfer plate 2 at the shroud drag position shown in FIG.
The wire 8 is placed on the hanging metal fitting 45 attached to the transfer plate 28 by using the overhead crane 44 and placed directly on the bottom of the dryer / separator pool 34. Next, in step 7A, the shroud head bolt 26 is loosened and removed using a dedicated jig, and separated from the shroud 15. Thereafter, the separator 6 is moved by the overhead crane 44 onto the transfer plate 28 disposed in the dryer / separator pool 34 and temporarily placed. The shroud head 50 moves together with the separator 6. Next, the transfer operation of the shroud drag position is performed from step 8A.

FIG. 8 is a perspective view of a main part showing the state of the shroud lug during the position transfer included in the flow chart shown in FIG. 2, and FIG. 10 has already been partially explained.
FIG. 9 is a longitudinal sectional view showing the reactor building at the time of transfer of the position of the shroud drag shown in FIG. 8. Steps 8A to 14A will be described with reference to FIG.
The transfer device 29 for transferring the position of the shroud lug is mounted by attaching a wire to the eyebolt 40 and using a dedicated pole to mount the transfer device 29 on the notch of the shroud head lug 24 mounted on the shroud head 50. The transfer device 29 placed on the shroud head lug 24 is pressed and fixed to the notch of the shroud head lug 24 by a fixing cylinder 30a driven by air supplied from an air hose 33a. The air-driven fixing cylinder 30 a also presses the shroud head lug 24 between the pair of opposed shroud head lugs 24 to fix the transfer device 29.

In step 9A, the transfer device 29 fixed as described above moves the pin 32 downward by the transfer cylinder 30b driven by air supplied from the air hose 33b, and strikes the transfer plate 28. Then, the position of the shroud drag 25 is transferred. The transfer of the position of the shroud drag 25 is performed for all the shroud drags 25. In this case, one transfer device 29 may be set to the shroud head lug 24 for transfer, or a plurality of transfer devices may be set to the shroud head lug 24 for transfer.
All operations of the transfer device 29 are performed remotely.

Next, in step 10A, when the transfer at the position of the shroud lug 25 is completed, the supply of air to the transfer device 29 is stopped, and the transfer device 2 to the shroud head lug 24 is stopped.
Release the fixation of 9. The transfer device 29 is detached from the shroud head lug 24 using a special pole with a wire wrapped around the eyebolt 40 again, and is taken out of the dryer / separator pool 34 while sprinkling water.

In step 11A, the separator 6 is moved from the dryer / separator pool 34 using the overhead crane 44, and in step 11B, the transfer plate 28 is moved from the dryer / separator pool 34 to the ceiling in parallel with the reactor closing operation. It is collected using the crane 44. At the time of recovery, the radioactive material is transferred to the transfer plate 28
There is a possibility that it is on the top, so while spraying water,
Pull up from the separator pool 34.

Next, in step 12B, the imprint marks 39 at the shroud drag position stamped on the transfer plate 28 at the collected shroud drag position are removed at 0 ° in the circumferential direction of the transfer plate 28 as shown in FIG. The dimension is measured with the guide pin hole 42 set at 180 ° as a base point.

FIG. 11 is a diagram illustrating elements considered in determining the shroud drag position included in the flowchart shown in FIG. 2, and FIG. 12 is a diagram illustrating other elements considered in determining the shroud drag position. . Step 13B will be described with reference to FIGS. 11 and 12. The width of the newly manufactured shroud lug is determined from the dimensions measured in step 12B. In making the decision, see FIG.
12, the manufacturing tolerance A of the inner width of the shroud lug 25, FIG.
1, the deviation of the guide pin 41 due to the production tolerance B of the shroud head bolt ring portion 49, the production tolerance C of the diameter of the guide pin 41 and the production tolerance D of the guide pin hole 42, and the relative positions of the shroud lug 25 and the shroud head lug 24. Each tolerance of the deviation amount is accumulated, and the shroud drag 25
And the minimum gap amount of the shroud head bolt 26 is calculated. Based on the calculated value, evaluate whether or not the amount of deviation between the actual measurement value measured in step 12B and the design instruction value at the time of construction or previous installation, when considering the minimum gap amount, interferes with each other, In case of interference, use shroud lug 2
Change the inner width of 5.

When the inner width of the shroud lug 25 is changed, if the shroud head bolt 26 is tightened to the shroud lug 25, does the shroud head bolt T-shaped portion 27 shown in FIG. To evaluate.

If there is no problem in the evaluation in step 13B, the position of the shroud lug 25 is determined based on the evaluation result, and the production of a new shroud 15 is started in step 14B. The transfer method of the shroud drag position has been described above.
The reactor closing operation starts from the next step 11A.

In step 11A, the separator 6 is removed from the dryer / separator pool 34 by the overhead crane 4
Pull up at 4, move into the reactor pressure vessel 38 and install. Next, in Step 12A, the dryer 4 is moved from the dryer / separator pool 34 to the overhead crane 44.
Then, it is moved into the reactor pressure vessel 38 and mounted. Next, in step 13A, the reactor pressure vessel lid (RPV head) 1 is moved into the reactor pressure vessel 38 by the overhead crane 44 and attached. Next, step 14A
Mirror insulation was installed at the overhead crane 4
At 4, move to the containment vessel 37 and mount it. Next, in step 15A, the reactor containment vessel lid (PCV head) 35 is
Go to and install. Next, in step 16A, the shield plug 36 is moved by the overhead crane 44 and attached to the operating floor. Finally, step 17A
In, the work area set on the operating floor of the reactor building is dismantled and the surroundings are cleared.

According to the present embodiment in which the shroud 15 is replaced as described above, the existing shroud head 50 can be reused as it is as a component of the new shroud 15, and the cost required for replacing the shroud 15. And the time required to manufacture a new shroud can be reduced. Also,
By transferring the position of the shroud lug 25 to the new shroud 15 in advance by using the shroud head lug 24, the position of the shroud lug 25 can be transferred accurately, and the installation position when the shroud head 50 is mounted on the new shroud 15 Neither fine adjustment nor measures to be taken when the shroud head bolt 26 cannot be inserted are not required, so that the mounting operation is facilitated, so that the mounting time of the shroud head 50 can be shortened and the exposure accompanying the mounting of the shroud head 50 can be reduced. . Since the position of the shroud lug 25 can be measured by the periodic inspection immediately before the shroud replacement work, it is possible to shorten the process related to the shroud replacement work and the time required for inspecting the position of the actual shroud lug 25. .

When the transfer of the position of the shroud lug 25 is performed, the transfer device 29 having the function of fixing the device is used, so that the device can be easily attached / detached, and the time required for attachment / detachment can be reduced and the exposure can be reduced. Further, since no equipment other than the transfer device 29 is used, foreign matter can be prevented from entering the dryer / separator pool 34.

By using the transfer plate 28 at the shroud drag position in addition to the transfer device 29, the position of the shroud drag 25 can be accurately transferred and set.
It is possible to shorten the process related to the shroud replacement work and to reduce the time and exposure required for the shroud lug 25 actual product position survey.

The time at which the shroud lug position is transferred is not limited to the periodic inspection immediately before the shroud replacement work is performed, but may be performed two or three times before.

[0033]

As described above, according to the present invention, the existing shroud head can be used as it is as a component of the new shroud, the cost required for shroud replacement can be reduced as compared with the conventional shroud, and the new shroud can be reduced. Can be shortened.

[Brief description of the drawings]

FIG. 1 is a flowchart showing one embodiment of a shroud replacement method of the present invention.

FIG. 2 is a flowchart relating to shroud drag position transfer included in an embodiment of the present invention.

FIG. 3 is a longitudinal sectional view showing an internal structure of a nuclear reactor in which one embodiment of the present invention is implemented.

FIG. 4 is a perspective view of a main part showing a state of a shroud head fixing portion included in the internal structure of the nuclear reactor shown in FIG. 3;

5 is a longitudinal sectional view showing a reactor building in which the reactor internal structure shown in FIG. 3 is arranged.

FIG. 6 is a cross-sectional view of the shroud head shown in FIG.

FIG. 7 is an explanatory view showing a state in which the shroud head block and the shroud guide block of the shroud head shown in FIG. 6 are positioned.

8 is a perspective view of a main part showing a state at the time of position transfer of a shroud drag included in the flowchart shown in FIG. 2;

9 is a perspective view showing a transfer plate used for position transfer of the shroud lug shown in FIG. 8;

FIG. 10 is a longitudinal sectional view showing the reactor building at the time of transfer of the position of the shroud lug shown in FIG. 8;

FIG. 11 is an explanatory diagram showing elements considered in determining the shroud drag position included in the flowchart shown in FIG. 2;

FIG. 12 is an explanatory diagram showing other elements considered in determining the shroud drag position included in the flowchart shown in FIG. 2;

[Explanation of symbols]

1 ... Reactor pressure vessel (RPV) lid, 4 ... Dryer, 6
... Separator, 15 ... Shroud, 24 ... Shroud head lug, 25 ... Shroud lug, 26 ... Shroud head bolt 27 ... Shroud head bolt T-shaped part, 28
... Transfer plate, 29 ... Transfer device, 34 ... Dryer
Separator pool, 35 ... Reactor containment vessel (PCV)
Lid, 36 Shield plug, 37 Reactor containment vessel, 3
Reference numeral 8: Reactor pressure vessel, 39: Indentation mark, 40: Eye bolt, 41: Guide pin, 42: Guide pin hole, 44: Overhead crane, 45: Suspension fitting, 49: Shroud head bolt ring part, 50: Shroud head .

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takao Hasegawa 4-6-1 Kanda Surugadai, Chiyoda-ku, Tokyo Nuclear Power Plant, Hitachi, Ltd. (72) Inventor Akira Sonobe 3-1-2, Bentencho, Hitachi City, Ibaraki Prefecture Hitachi Kyowa Engineering Co., Ltd.

Claims (5)

[Claims] When replacing an existing shroud in a reactor pressure vessel with a new shroud, a mounting position of an existing shroud head is determined in advance, and a new shroud body reflecting the determined mounting position is manufactured. A shroud replacement method, comprising taking out an existing shroud main body from a pressure vessel and installing the new shroud main body and the existing shroud head. 2. The shroud replacement method according to claim 1, wherein a shroud head lug of the existing shroud head is used to determine a mounting position of the existing shroud head. 3. The shroud replacement method according to claim 2, wherein a shroud lug position is transferred using the shroud head lug. 4. The shroud replacement method according to claim 1, wherein a mounting position of the shroud head is determined in a dryer / separator pool. 5. The shroud lug position according to any one of claims 1 to 4, wherein the shroud lug position is determined in advance by a periodic inspection one time before shroud replacement work when reflecting the mounting position of the existing shroud head on the new shroud main body. Shroud replacement method characterized by measuring.