JP2001021689A - Removing method for reactor pressure vessel internal structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the work time and reduce the exposure of workers. SOLUTION: A container vessel 9 containing the finely cut pieces 14 of a reactor pressure vessel internal structure is lifted up from a dryer separator pool 2 and is contained and sealed in a shield vessel 12 placed on an operation floor 10. This shield vessel 12 is placed in an area shield frame 11 on the operation floor 10. By this, contamination of shield vessel 12 surface is drastically reduced. By keeping the container vessel 9 in a state contained inside a shield cylinder 15 of an elevation transport means 16 from the time of drawing up of the container vessel 9 to the time containing in the shield vessel 12 in this case, shielding of the container 9 until containing in the shield vessel 12 is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for safely removing contaminated or activated structures in a reactor pressure vessel of a boiling water reactor or the like. .

[0002]

2. Description of the Related Art Conventionally, in a boiling water reactor or the like, when a structure such as a core shroud is replaced during a service period, as a removal method for discarding and storing a structure removed from the reactor pressure vessel. Adopts the following procedure.

[0003] First, the structure is cut in a reactor pressure vessel and transferred to a DSP (dryer separator pool) near the pressure vessel. Then, the cut pieces of the above structure are further shredded in the DSP, and stored in a shielding container installed in the DSP in a submerged state. A shielding lid is attached to the shielding container in the DSP.

[0004] Thereafter, the shielding container storing the small fragments is D
It is lifted from the SP onto the operation floor and subjected to post-processing such as wiping and decontamination work and surface survey (contamination and dose survey). Then, a sealing process by bolting is performed on the shielding container after the post-processing. The sealed shielding vessel is removed from the reactor building and stored in a solid waste storage or site bunker pool.

[0005]

However, in such a conventional removing method, a large amount of time is required for the above-described series of operations. In particular, wiping and decontamination work on the surface of the shielding container lifted from the DSP requires a great deal of time. Since the shielding effect of the shielding container is relatively low defined by the surface dose at the waste storage place, exposure of the worker performing the wiping operation becomes a problem.

The present invention has been made in consideration of such problems, and reduces the decontamination work on the surface of a shielding container, shortens the work time, and reduces the exposure of workers to atomic energy. An object of the present invention is to provide a method for removing a structure inside a furnace pressure vessel.

[0007]

The first means is to cut a piece of the reactor pressure vessel internal structure taken out of the reactor pressure vessel into a predetermined storage vessel in a pool near the pressure vessel. A shredding step of shredding to a size that can be stored, a shredder storage step of storing the shredded pieces in the storage container installed in the pool, A lifting step of lifting the container from the pool into the shielding cylinder, and transferring the storage container to the shielding container installed on the operation floor near the pool while the storage container is stored in the shielding cylinder by the lifting / lowering transfer means. Transfer step, a container storage step of lowering the storage container from the inside of the shielding cylinder and storing the storage container in the shielding container by the lifting / lowering transfer means, and the shielding container storing the storage container. A shielding lid is attached to the sealing container, and a sealing step of sealing the shielding container, a post-processing step of performing post-processing including necessary decontamination on the surface of the sealed shielding container, and the post-processing is performed. And carrying out a shielding vessel to the outside of the reactor.

According to the first means, the storage container storing the small pieces is pulled up from the pool, and the storage container is stored and sealed in the shielding container installed on the operation floor. Contamination on the surface can be significantly reduced. In this case, during the period from the lifting step to the container storage step, the storage container is stored in the shielding cylinder of the elevating / lowering transfer means, thereby shielding the storage container until the storage container is stored. I have.

Further, since the storage container for storing the small fragments basically does not require a shielding effect, it is possible to reduce the size and weight as compared with the conventional shielding container for storing the small fragments. Therefore, the installation area of the container can be reduced, and stacking is possible because of its light weight, so that more storage containers can be installed in the pool than in the conventional shielding container. Further, since the storage container that is lifted up from the pool and transferred can be made lighter than a conventional shielding container, the load on the lifting and lowering transfer means can be reduced.

A second means is that, in the first means, the shielding container is surrounded by an area shielding gantry installed on the operation floor, and in the transferring step, the shielding container is provided above the area shielding gantry. The bottom of the tube is seated.

[0011] A third means is the second means, wherein the lifting and lowering means is configured to be able to separate the shielding cylinder and other parts, and to interpose between the container storing step and the sealing step. And a separating step of separating the other part of the lifting and lowering transfer means while leaving only the shielding cylinder of the lifting and lowering transfer means on the area shielding gantry. After being hung from the upper opening of the cylinder and attached to the shielding container, the shielding cylinder is removed from the area shielding frame, and the shielding container is sealed.

A fourth means is that, in the first or second means, in the small fragment storing step, a temporary shielding lid is mounted on a storage container in which the small fragment is stored.

[0013] According to the fourth means, in the first or second means, the temporary shielding lid can enhance the shielding property of the upper part of the storage container, so that the exposure of the worker can be further reduced. . In particular, when the present invention is applied to the second means, the shielding cylinder is separated from the lifting / lowering transfer means and left on the area shielding base until the shielding lid is attached to the shielding container as in the third means. No need to keep it. Therefore, the work of separating the shielding cylinder can be omitted, and
Since the mounting of the shielding lid can be performed directly without passing through the shielding cylinder, the working efficiency can be improved.

The fifth means is that, in any one of the first to fourth means, the storage container is provided with a drain hole, so that the pool water in the storage container is naturally drained in the lifting step. That's what I did.

The sixth means is any of the first to fifth means, wherein the elevating and lowering means further includes a watering device provided above the shielding cylinder, and the watering device includes A device is used to sprinkle and wash the periphery of the storage container.

The seventh means is any of the first to sixth means, wherein the lifting and lowering means further comprises a monitoring camera provided above the shielding cylinder, and in any step, the monitoring camera is provided. The inside of the shielding cylinder is monitored by a camera.

Eighth means is the storage container holding device according to any one of the first to seventh means, wherein the lifting and lowering transfer means holds the storage container and moves up and down in the shielding cylinder; A guide device provided in the holding device and the shielding cylinder so as to correspond to each other, and in the lifting step and the container storage process, the guide device controls the storage container holding device and the storage container in a horizontal plane. The rotation and the movement at the position are suppressed.

According to a ninth means, in any one of the first to the eighth means, the lifting / lowering means is provided with a shield above the shielding cylinder.

In a tenth aspect, in any one of the first to ninth aspects, in the sealing step, the shielding lid is attached by a shielding lid holding device that holds and moves the shielding lid up and down. In addition, guide devices respectively corresponding to the shield cylinder and the shield cover holding device of the lifting / lowering transfer means are provided, and in the sealing step, the guide device rotates the shield cover holding device and the shield cover in a horizontal plane. And movement is suppressed.

[0020] An eleventh means according to any one of the first to tenth means, wherein a plurality of the storage containers are used in the small fragment storage step, and at least the storage steps from the lifting step to the sealing step are performed. Is performed continuously.

According to a twelfth means, in any one of the first to eleventh means, the transfer step is performed in a state where a curing treatment is applied to a portion corresponding to a transfer path of the storage container.

In a thirteenth aspect, in any one of the first to twelfth aspects, in the sealing step, before the shielding lid is attached or before the shielding container is sealed, water or inert water is contained in the shielding container. The gas is injected.

In a fourteenth aspect, in any one of the first to thirteenth aspects, in the sealing step, the shielding container is sealed by bolting the shielding container and the shielding lid to each other via packing. It is something to do.

According to a fifteenth means, in the fourteenth means,
The bolt fastening in the sealing step is performed with a predetermined tightening torque using a torque wrench previously installed on the shielding lid.

In a sixteenth aspect, in the fourteenth or fifteenth aspect, after the bolting is performed in the sealing step, a portion of the outer surface of the shielding container and the shielding lid which is likely to be radioactively contaminated. Is covered with a contamination prevention member, and the space between the shielding container or the shielding lid and the contamination prevention member is welded.

According to a seventeenth means, in any one of the first to thirteenth means, in the sealing step, the shielding container is sealed by welding between the shielding container and the shielding lid. Things.

According to the seventeenth means, the first to the first
In any one of the third means, the exposure of the worker can be reduced by automatically sealing the shielding container with an automatic welding machine.

The eighteenth means is the seventeenth means,
The welding in the sealing step is performed by an automatic welding machine previously installed on the shielding lid.

According to a nineteenth aspect, in the seventeenth or eighteenth aspect, after welding in the sealing step, the integrity of the weld is checked.

[0030]

Next, an embodiment of the present invention will be described with reference to the drawings. 1 to 31 are views showing an embodiment of a method for removing an internal structure of a reactor pressure vessel according to the present invention.

[First Embodiment] First, FIGS.
A first embodiment of a method for removing a reactor pressure vessel internal structure according to the present invention will be described with reference to FIG.

<Structure> Hereinafter, the structure of the removing method according to the present embodiment is described as "(A) Method implementation environment", "(B) Structure of lifting / lowering moving means (used for the method)" and "(C) Of each process ".

(A) Implementation Environment of Method First, an implementation environment (equipment) of the method, which is a premise of the removal method of the present embodiment, will be described with reference to FIGS.
In FIG. 2, a DSP (dryer separator pool (pool)) 2 is provided near a reactor pressure vessel 6 surrounded by a reactor well 1. A dryer (steam dryer) 3A and a separator (steam-water separator) 3B taken out of the reactor pressure vessel 6 are installed and stored in the DSP 2 at the back side (when viewed from the pressure vessel 6). ing.

Further, a cutting space 5 is provided on the front side of the DSP 2 (as viewed from the pressure vessel 6), which is partitioned by the partition 4 from the installation area of the dryer 3A and the separator 3B. In the cutting space 5, a cut piece 7 of a reactor pressure vessel internal structure (for example, a shroud or the like) removed from the reactor pressure vessel 6 (as radioactive waste) is temporarily placed. Above this cut piece 7,
A shredding device 8 for further shredding the cut pieces 7 in the DSP 2 is provided.

Next, as shown in FIGS. 1 and 2, the DSP
Inside 2 (on the cutting space 5 side shown in FIG. 1), a storage container 9 for storing the small pieces 14 cut by the shredding device 8 can be submerged. Also,
On the operation floor 10 near the DSP 2, an area shielding frame 11 surrounded by a shielding wall can be installed. Inside of the area shielding frame 11,
A shielding container (dry cask) 12 can be installed. The storage container 9, the area shielding gantry 11, and the shielding container 12 all have, for example, a substantially rectangular parallelepiped shape with an open top.

A curing sheet 13 for preventing contamination is appropriately attached around the shielding container 12 installed in the area shielding frame 11. Note that an overhead crane (not shown) is provided above the operation floor 10 for suspending the vertically moving means 16 shown in FIG.

(B) Structure of the Elevating / Transferring Means Next, the structure of the elevating / transferring means 16 used in the removing method of the present embodiment will be described with reference to FIGS.

As shown in FIGS. 1 and 3, the lifting / lowering transfer means (hanging tool) 16 has a shielding cylinder 15 having, for example, a quadrangular prism shape. A rectangular ceiling plate 26 is detachably mounted on the upper part of the shielding tube 15. As a result, the lifting / lowering transfer means 16 as a whole is
5 and other parts (the ceiling plate 26 and members connected thereto) are configured to be separable. For example, both 1
Such separation can be made possible by using a simple hanging tool such as a pin lock or a shackle for the connection between 5, 26.

A hoist 20 such as an electric chain block is mounted on the bottom side of the ceiling plate 26.
The storage container holding device 21 is suspended in the shielding cylinder 15 by the hoisting machine 20 so as to be able to move up and down. This storage container holding device 21 is, as shown in FIG.
The operation of 3 is configured to perform the gripping / releasing operation of the gripping portion 24 provided on the upper part of the storage container 9. Further, on the upper surface side of the ceiling plate 26, an engaging portion 18 having a pin 19 for detachably connecting the hook 17 of the overhead crane is provided.

Next, as shown in FIG.
Guide devices 32 and 33 corresponding to each other are provided in the storage container holding device 21 and the shielding cylinder 15 of No. 6 respectively. The guide devices 32 and 33 include, for example, a pair of guide rods 32 provided in the shielding cylinder 15 and extending in a substantially vertical direction.
And a pair of guide receivers 33 provided on the storage container holding device 21 to receive the guide rods 32, respectively. The rotation and movement of the storage container holding device 21 (and the storage container 9) in the horizontal plane are suppressed by such guide devices 32 and 33.

Further, as shown in FIG.
A surveillance camera 27 and a lighting device 28 for monitoring the inside of the shielding tube 15 are installed on the back side of the camera (not shown in the drawings other than FIG. 3). The surveillance camera 27 and the lighting equipment 28
In place of, a monitoring hole (not shown) is formed in the ceiling plate 26,
The inside of the shielding cylinder 15 may be monitored from outside through the monitoring hole.

A driving hose 50 for the air cylinder 22, a cable 25 for the hoisting machine 20, and a cable 29 for the monitoring camera 27 extend upward through the ceiling plate 26, respectively. Means and control means. The lifting / lowering transfer means 1
6, for example, by giving the ceiling plate 26 a shielding property,
It is preferable that the upper part of the shielding cylinder 15 be shielded.

(C) Contents of Each Step Next, the contents of each step in the removal method of the present embodiment will be described in the order of the following steps (1) to (10).

As described above in the environment for implementing the method (A), the following steps are premised on the separator 3A taken out of the reactor pressure vessel 6 and the DSP 3 as shown in FIG. The dryer 3B is stacked and stored, and a cutting space 5 is secured via the partition 4. Further, a cut piece 7 of the internal structure of the reactor pressure vessel taken out of the reactor pressure vessel 6 is installed in (the cutting space 5 of) the DSP 2.

(1) Step of installing area shield gantry and shield container First, the area shield gantry 11 and the shield container 12 are installed on the operation floor 1 in advance. In this installation step, the area shielding gantry 11 and the concealing container 12 are loaded and installed using the above-mentioned overhead crane, and the operation floor 10 is laid down as shown in FIG. At this time, the reactor water is filled with the reactor well 1 and the DSP 2.

(2) Installation Step of Storage Container Next, the storage container 9 is submerged in the DSP 2. In this case, the storage container 9 is installed so that the opening of the storage container 9 faces upward so that the small fragments 14 can be easily stored in the next step.

(3) Shredding Step-Small Fragment Storage Step Next, in the DSP 2, the cut pieces 7 of the reactor pressure vessel internal structure are shredded by the shredding device 8 to form
And Then, these small fragments 14 are transferred underwater using a holding device (not shown) in the DSP 2 and stored in the storage container 9 as shown in FIG.

(4) Lifting Step of the Lifting / Transferring Means Next, the lifting / lowering transferring means 1 is placed on the operation floor 10.
6 is carried in, and the hook 17 of the overhead crane is fixed to the joint 18 (see FIG. 3). Then, the lifting / lowering transfer means 16 is lifted by hoisting the overhead crane (see FIG. 1).

(5) Lifting Step Next, the following small steps (5-1) to (5-3) are sequentially performed to move the storage container 9 from the DSP 2 to the shielding cylinder (of the lifting / lowering transfer means 16). Then, a “pulling step” for pulling the wafer into the inside 15 is performed.

(5-1) Descent of Storage Container Holding Device to Storage Container Holding Step (FIG. 5 (a)) In this step, first, the D is operated by operating the above-mentioned overhead crane.
On the storage container 9 (containing the small pieces 14) in SP2,
The lifting / lowering transfer means 16 is positioned. Next, the storage container holding device 21 is lowered into the DSP 2 by the hoisting and lowering unit 16 being unwound by the hoisting machine 20, and seated on the storage container 9 (see FIG. 10).

Then, the storage container holding device 21 shown in FIG.
, The lock pin 23 is actuated by the air cylinder 22, and the holding portion 24 of the storage container 9 is gripped by the lock pin 23, whereby the storage container 9 by the storage container holding device 21.
Is maintained.

(5-2) Ascending Step of Storage Container Holding Apparatus (FIG. 5 (b)) In this step, the hoisting device 20 is wound up by the lifting / lowering transfer means 16 to hold the storage container holding apparatus 9. 21 is raised, and the storage container 9 is pulled up into the shielding tube 15.

In this case, the guide devices 32, 33 (FIG. 4)
), The rotation and movement of the storage container holding device 21 (and the storage container 9) in the horizontal plane are suppressed. However, if necessary, a forcible operation using a stick or the like is added from the outside. Therefore, it is preferable to take care that the storage container holding device 21 and the like do not come into contact with the shielding tube 15. At this time, the state of the storage container holding device 21 and the like in the shielding tube 15 may be monitored by the monitoring camera 27 and the like.

(5-3) Draining step of container (FIG. 5)
(B)) Here, drain holes (not shown) are provided on the lower surface and side surfaces of the storage container 9 so that the pool water of the DSP 2 is naturally drained from the raised storage container 9. It has become. As a result, drainage of the storage container 9 pulled up into the shielding tube 15 is automatically performed.

As shown in FIG. 11, a watering device (watering nozzle) 3 is provided on the back side of the ceiling plate 26 of the lifting / lowering means 16.
1 may be provided so that the sprinkler 31 performs sprinkling washing (decontamination) of the storage container 9 and the storage container holding device 21 before the draining is completed. In this case, the monitoring camera 27 or the like may monitor the state at the time of watering and washing.

(6) Transfer Step (FIGS. 6 to 7A) Next, as shown in FIG. 6, the storage container 9 is stored in the shielding tube 15 by the lifting / lowering transfer means 16 (see FIG. 12). , To the shielding container 12 in the area shielding base 11.

In this step, the curing sheet 13 is laid beforehand on the operation floor 10 which is a transfer route from the DSP 2 to the area shielding frame 11 and around the area shielding frame 11 and the shielding container 12 (see FIG. 2). ). In this case, the curing sheet 13 on the DSP 2 side, in particular,
As shown in FIG. 1, the DSP
Preferably, it covers up to the edge of the second.

Thereafter, as shown in FIG.
The lifting / lowering transfer means 16 in which the storage container 9 is stored is transferred from above the DSP 2 (on the curing sheet 13) to above the area shield base 11 (by operation of the above-mentioned overhead crane). Then, as shown in FIG. 7 (a), the lifting / lowering transfer means 16 is lowered (by operation of the above-mentioned overhead crane), and the bottom of the shielding cylinder 15 is placed on the seating part 34 provided inside the upper part of the area shielding gantry 11. Is seated (see FIG. 13).

Each of the curing sheets 13 is provided with the shielding cylinder 1.
5 before and after sitting on the area shielding frame 11,
It will be disposed of.

(7) Container Storage Step Next, the following small steps (7-1) and (7-2) are sequentially performed so that the storage container 9 is lowered from the inside of the shielding cylinder 15 by the lifting / lowering transfer means 16. Then, the “container storing step” for storing the container in the shielding container 12 is executed.

(7-1) Step of Lowering Storage Container Holding Device (FIGS. 7A and 7B) In this step, the storage container 9 is held by lowering the hoisting machine 20 in the lifting / lowering transfer means 16. The storage container holding device 21 is lowered, and the storage container 9 is lowered from the inside of the shielding tube 15 into the shielding container 12 (see FIG. 14).

(7-2) Release from holding of container holding device to lifting process (FIG. 7B) In this step, first, the container holding device 21 shown in FIG.
, The lock pin 23 is retracted by the air cylinder 22, and the holding of the storage container 9 by the storage container holding device 21 is released. Next, as shown in FIG. 7B, the hoisting machine 20 is wound up by the lifting / lowering transfer means 16, whereby the storage container holding device 21 separated from the storage container 9 is pulled up into the shielding cylinder 15 to the upper limit.

In the above steps (7-1) and (7-2), as in the case of the above-mentioned "(5-2) Ascending step of holding container holding device" (FIG. 5 (b)), the guide is provided. Equipment 32,3
3 (see FIG. 4), rotation and movement of the storage container holding device 21 (and the storage container 9) in the horizontal plane are suppressed. Also, in these steps (7-1) and (7-2), the state of the storage container holding device 21 and the like in the shielding cylinder 15 may be monitored by the monitoring camera 27 and the like.

(8) Separation Step (FIG. 8) Next, only the shielding cylinder 15 of the lifting / lowering transfer means 16 is left on the area shielding gantry 11 (see FIG. 15), and other parts of the lifting / lowering transfer means 16 (see FIG. 15). The ceiling plate 26 and the members 18 and 20 connected thereto are separated. Ceiling panel 2 separated
6 and other parts are removed from the area shield gantry 11 by the overhead crane.

(9) Sealing Step Next, the following small steps (9-1) to (9-3) are sequentially performed to attach the shielding lid 36 to the shielding container 12 in which the storage container 9 is stored. A “sealing step” for sealing the shielding container 12 is executed.

(9-1) Shielding lid mounting step (FIG. 9)
(A)-(b)) In this step, first, the shielding lid holding device 35 holding the shielding lid 36 is lowered from above the shielding cylinder 15 left on the area shielding gantry 11 (see FIG. 16), and the shielding is performed. The shielding lid 36 is seated on the container 12 (FIG. 9A). In this case, the shielding lid holding device 35 has a form of a “suspension jig” suspended from the hook 17 of the overhead crane via the fitting portion 39 (see FIG. 16).

As shown in FIG. 17, the shielding lid holding device 35 and the shielding cylinder 15 are provided with guiding devices 32 and 38, respectively, which correspond to each other. This guide device 32,3
8 includes, for example, the pair of guide rods 32 provided inside the shielding cylinder 15 and a pair of guide receivers 38 provided on the shielding lid holding device 35 to receive the guide rods 32, respectively. . Such a guide device 32,3
8, the shielding lid holding device 51 (and the shielding lid 36)
Rotation and movement in a horizontal plane are suppressed.

Further, as shown in FIG.
A pair of guide pins 37 that fits with the shielding lid 36 is provided on the upper surface 2, and the guide pins 37 can guide and position the seating position of the shielding lid 36. If necessary, the state of the shielding lid holding device 35 and the shielding lid 36 may be monitored from the upper opening of the shielding cylinder 15 using a camera (not shown) attached to the tip of the rod. .

Then, after the shielding lid 36 is seated at a predetermined position on the shielding container 12, the shielding lid holding device 35 is separated at the fitting portion 39 with the hook 17 of the overhead crane.

Next, the shielding cylinder 15 is removed from the area shielding frame 11 using an overhead crane (FIG. 9B). Thereafter, the detached ceiling plate 26 and other members are re-coupled to the removed shielding cylinder 15, and
6 is assembled and temporarily put on the operation floor 10. After removing the shielding cylinder 15, the shielding lid holding device 35 is removed from the joint 51 with the shielding lid 36.

(9-2) Sealing Lid Sealing Step (FIG. 18) In this step, as shown in FIG.
2 and the shielding lid 36 are bolted to each other via a packing (not shown) to seal the shielding container 12. Specifically, bolt holes (not shown) corresponding to a plurality of female screw portions (not shown) provided in the shielding container 12 are formed in the shielding lid 36. And each bolt 40,
Shielding container 1 (through bolt hole of shielding lid 36)
The female screw portion is manually tightened to seal the gap between the shielding container 12 and the shielding lid 36 (via packing).

At this time, as shown in FIG. 18 (b), a final tightening torque of each bolt 40 is given by a predetermined tightening torque by a torque wrench 42 suspended vertically on a shielding lid 36 via a base 41. Tightening may be performed.

In the above-mentioned “(9-1) Shield cover attaching step”, the base 41 with the torque wrench
Alternatively, the shielding lid 36 to which the bolts 40 are attached may be seated on the shielding container 12, and after the shielding cylinder 15 is removed, the bolts 40 may be manually tightened and finally tightened by the torque wrench 42.

As shown in FIG. 19, after the bolts 40 are tightened, portions of the outer surfaces of the shielding container 12 and the shielding lid 36 that are likely to be radioactively contaminated (particularly, difficult to decontaminate such as bolt fastening portions) May be covered with the pollution prevention member 43, and the entire periphery of the pollution prevention member 43 and the shielding container 12 or the shielding lid 36 may be welded.

(9-3) Sealing Container Airtight Test to Sealing Step (FIG. 20) In this step, first, as shown in FIG.
Using the intake and exhaust hoses 44A and 44B communicating inside,
An airtight test of the shielding container 12 is performed. Specifically, after opening the valve 45 interposed in the exhaust hose 44B, an inert gas such as nitrogen is injected into the shielding container 12 from the intake hose 44A. At this time, an inert gas is injected using an oxygen concentration meter (not shown) until the exhaust gas from the hose 44B reaches a predetermined oxygen concentration.

Then, after closing the valve 45, an inert gas is pressurized and injected from the suction hose 44A for a certain period of time, and it is confirmed that there is no gas leakage from the shielding container 12 when the pressure value does not decrease. I do. When there is no gas leakage, the suction and exhaust hoses 44A,
44B is removed, and a sealing process of filling the removed portion with a resin such as silicon is performed.

(10) Post-Processing Step Next, as post-processing to be performed on the surface of the sealed shielding container 12, measurement of the dose equivalent rate on the surface of the shielding container 12 (fixed point survey) and removal of a necessary portion of the surface of the shielding container 12 are performed. Perform dyeing.

(11) Unloading Step Next, the post-processed shielding container 12 is unloaded from the area gantry 11 on the operation floor 10 to the outside of the furnace.
Install in a designated waste storage area such as a solid waste storage.

<Operation and Effect> Next, the operation and effect of the present embodiment having the above-described configuration will be described. According to the present embodiment, the storage container 9 storing the small fragments 14 is
Then, the storage container 9 is stored in the shielding container 12 installed on the operation floor 10 and sealed, so that contamination on the surface of the shielding container 12 can be significantly reduced. For this reason, the decontamination work on the surface of the shielding container 12 in the post-treatment process can be reduced, so that the work time can be reduced and the exposure of workers can be reduced.

Since the storage container 9 for storing the small fragments 14 does not basically require a shielding effect, the size and weight of the storage container 9 can be reduced as compared with a conventional shielding container for storing small fragments. Therefore, since the installation area of the container can be reduced and the stacking is possible because of the light weight, more storage containers 9 can be installed in the DSP 2 than the conventional shielding container. Then, the above-mentioned “(5) Lifting step” to “(9) Sealing step” are continuously performed for each storage container 9 or other steps are collectively performed, thereby improving the overall work efficiency. Can be done.

Further, since the storage container 9 to be lifted and transferred from the DSP 2 can be made lighter than the conventional shielding container, the load on the lifting and lowering transfer means 16 can be reduced.

Although the removal method of the present embodiment has been described using a permanent overhead crane,
This removal method can also be performed using a temporary crane installed on the DSP. Then, by using such a temporary crane, it is not necessary to adjust the connection with other work requiring the overhead crane, and the working efficiency can be further improved.

[Second Embodiment] Next, FIGS.
A second embodiment of the method for removing an internal structure of a reactor pressure vessel according to the present invention will be described with reference to FIG. In the present embodiment shown in FIGS. 21 to 30, the same components as those in the first embodiment shown in FIGS. 1 to 20 are denoted by the same reference numerals, and detailed description will be omitted.

<Configuration> Hereinafter, the configuration of the present embodiment will be described.
"(A) Elevating and transferring means" and "(B) Contents of each step"
This is roughly explained. The “method implementation environment” is the same as in the first embodiment, and a description thereof will not be repeated.

(A) Structure of Elevating / Transferring Means Elevating / lowering transfer means 16 ′ used in the removing method of the present embodiment.
Is different from the lifting / lowering transfer means 16 of the first embodiment in that the shield tube 15 and other parts do not necessarily have to be configured to be separable, and the other structures are the same as those of the first embodiment shown in FIGS. This is the same as the lifting / lowering transfer means 16 of the first embodiment.

(B) Contents of Each Step The removal method of the present embodiment uses the following (3 ′) instead of the steps (3), (8) and (9) in the first embodiment. Steps (8 ′) and (9 ′) are respectively performed, and the other steps are (1), (2), (4) to (7), (10) in the first embodiment. )
And the steps (11) are substantially the same.

(3 ′) Shredding Step-Small Fragment Storing Step (FIG. 21) In this step, first, “(3) Shredding Step-Small Fragment Storing Step” of the first embodiment shown in FIG. As with DSP
2, the cut pieces 7 of the reactor pressure vessel internal structure are cut into a plurality of small pieces 14, and these small pieces 14 are
It is stored in the storage container 9 in the DSP 2.

Next, in this step, as shown in FIG. 21, a temporary shielding lid 49 is attached on the storage container 9 in which the small fragments 14 are stored. The mounting of the temporary shielding cover 49 is performed by underwater remote control from the operation floor 10, for example.

Here, the steps (5), (6) and (7), which are the same as those in the first embodiment, are carried out in the present embodiment.
As shown in FIGS. 22, 23 and 24, respectively,
These drawings are the same as FIGS. 5, 6, and 7, respectively, of the first embodiment except for the temporary shielding lid 49. FIGS. 27 and 28 respectively correspond to the steps shown in FIGS. 22 and 24 (b).

(8 ') Separation Step (FIG. 25) In this step, the lifting / lowering transfer means 16' is removed together with the shielding cylinder 15 from the area shielding base 11 by operating the overhead crane. As a result, as shown in FIG. 25 and FIG. 29, only the shielding container 12 storing the storage container 9 with the temporary shielding lid 49 is set in the area shielding gantry 11.

(9 ′) Sealing Step This step replaces “(9-1) Shielding Cover Mounting Step” in “(9) Sealing Step” of the first embodiment with the following “(9′- 1) Shield cover mounting step ”, and the other steps are the same as“ (9) Sealing step ”of the first embodiment.

(9'-1) Shielding lid mounting step (FIG. 2)
6 (a)-(b)) In this step, unlike the case of the first embodiment, since the shielding cylinder 15 is not left on the area shielding gantry 11, shielding is performed directly from above the area shielding gantry 11. The shielding lid holding device 35 holding the lid 36 is lowered (see FIG. 30), and the shielding lid 36 is seated on the shielding container 12 (FIG. 2).
6 (a)). The other contents in this step are described in “(9-1) Shielding lid attaching step” in the first embodiment.
Is the same as

<Operation and Effect> Next, the operation and effect of this embodiment having the above-described configuration will be described. According to the present embodiment, since the temporary shielding lid 29 can enhance the shielding property of the storage container 9 from above, the exposure of workers can be further reduced.

Further, as in the first embodiment, until the shielding cover 36 is attached to the shielding container 12, the shielding cylinder 15 is separated from the lifting / lowering transfer means 16 to separate the area shielding base 11.
There is no need to keep it on top. For this reason, the shielding cylinder 15
Can be omitted, and the mounting of the shielding lid 36 can be performed directly from the area shielding base 11 without passing through the shielding cylinder 15, so that the working efficiency can be improved.

[Third Embodiment] Next, a third embodiment of the method for removing the internal structure of the reactor pressure vessel according to the present invention will be described with reference to FIG.

<Structure> The structure of this embodiment is the same as that of the first embodiment.
Alternatively, the following “(9′-2) Shielding Container Sealing Step” is executed instead of “(9-2) Shielding Container Sealing Step” in (B) “(9) Sealing Step” of the second embodiment. The other configuration is the same as that of the first embodiment shown in FIGS. 1 to 20 or the second embodiment shown in FIGS. 21 to 30.

(9'-2) Sealing Lid Sealing Step First, as a premise of this step, a groove surface (not shown) is formed at the opening edge of the shielding container 12. In this step, as shown in FIG. 31, when the shielding cover 36 is set on the shielding container 12, the opening edge of the shielding container 12 and the shielding lid 3
6, a welding groove is formed. .
Therefore, the entire periphery of the groove portion is manually or welded by an automatic welding machine 46 to seal the shielding container 12.

In this case, in the "(9-1) or (9'-1) shielding lid attaching step" of the first or second embodiment, the shielding lid 36 to which the automatic welding machine 46 has been attached in advance. After being seated on the shielding container 12, the automatic welding machine 4
6 (see FIG. 31), and welding may be performed by the automatic welding machine 46 (in the above-described first embodiment, the connection of the cable 47 and the welding after the removal of the shielding tube 15). I do).

After the above-mentioned welding, the integrity of the welded portion 48 may be checked. As such a soundness check, for example, means such as a visual inspection, an ultrasonic inspection test or a penetrant inspection test can be used.

<Operation and Effect> Next, the operation and effect of this embodiment having the above-described configuration will be described. In the present embodiment, by performing the automatic welding by the automatic welding machine 46, it is possible to reduce the exposure of the worker in the “shield lid sealing step”.

[0101]

According to the present invention, the storage container storing the small pieces is pulled out of the pool, and the storage container is stored and sealed in the shielding container installed on the operation floor. Pollution can be greatly reduced. For this reason, the decontamination work on the surface of the shielding container in the post-treatment process can be reduced, so that the work time can be reduced and the exposure of workers can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view showing a main part of an implementation environment (equipment) of a method for removing an internal structure of a reactor pressure vessel according to a first embodiment of the present invention.

FIG. 2 is a schematic plan view showing an implementation environment (equipment) of the method according to the first embodiment of the method for removing an internal structure of a reactor pressure vessel according to the present invention.

FIG. 3 is a partially cutaway perspective view showing a configuration of a lifting / lowering transfer means in the first embodiment of the method for removing an internal structure of a reactor pressure vessel according to the present invention.

FIG. 4 is a cross-sectional view showing a guide device of the lifting / lowering transfer means shown in FIG. 3;

FIG. 5 is a schematic longitudinal sectional view showing a “pulling-up step” in the first embodiment of the method for removing an internal structure of a reactor pressure vessel according to the present invention.

FIG. 6 is a schematic longitudinal sectional view showing a “transfer step” in the first embodiment of the method for removing an internal structure of a reactor pressure vessel according to the present invention.

FIG. 7 is a schematic longitudinal sectional view showing a “vessel storage step” in the first embodiment of the method for removing an internal structure of a reactor pressure vessel according to the present invention.

FIG. 8 is a schematic longitudinal sectional view showing a “separation step” in the first embodiment of the method for removing an internal structure of a reactor pressure vessel according to the present invention.

FIG. 9 is a schematic longitudinal sectional view showing a “sealing step” in the first embodiment of the method for removing an internal structure of a reactor pressure vessel according to the present invention.

FIG. 10 is a partially broken perspective view corresponding to “Descent of storage container holding device to storage container holding step” illustrated in FIG.

FIG. 11 is a “water draining step of the storage container” shown in FIG. 5 (b).
FIG.

FIG. 12 is a partially cutaway perspective view corresponding to the “transfer step” shown in FIG. 6;

FIG. 13 is a partially broken perspective view corresponding to “transfer step” to “descent step of storage container holding device” shown in FIG.

FIG. 14 is a partially cutaway perspective view corresponding to “the lowering step of the storage container holding device” to “the release of the storage container holding device to the lifting process” shown in FIGS. 7 (a) and 7 (b).

FIG. 15 is a partially cutaway perspective view corresponding to the “separation step” shown in FIG. 8;

FIG. 16 is a partially cutaway perspective view corresponding to the “shielding lid attaching step” shown in FIG. 9A.

FIG. 17 is a cross-sectional view showing the shielding lid holding device and the shielding cylinder guiding device in the “shielding lid attaching step” shown in FIG. 16;

FIG. 18 is a partially cutaway perspective view showing bolt fastening in a “shield lid sealing step” in the first embodiment of the method for removing a reactor pressure vessel internal structure according to the present invention.

FIG. 19 is a partially cutaway perspective view showing a coating by a contamination preventing member in a “shield lid sealing step” in the first embodiment of the method for removing a reactor pressure vessel internal structure according to the present invention.

FIG. 20 is a partially cutaway perspective view showing “shielding lid airtightness test to sealing process” in the first embodiment of the method for removing the internal structure of the reactor pressure vessel according to the present invention.

FIG. 21 is a schematic longitudinal sectional view showing a “small fragment storage step” in a second embodiment of the method for removing a reactor pressure vessel internal structure according to the present invention.

FIG. 22 is a schematic longitudinal sectional view showing a “pulling-up step” in a second embodiment of the method for removing an internal structure of a reactor pressure vessel according to the present invention.

FIG. 23 is a schematic longitudinal sectional view showing a “transfer step” in a second embodiment of the method for removing an internal structure of a reactor pressure vessel according to the present invention.

FIG. 24 is a schematic longitudinal sectional view showing a “vessel storage step” in a second embodiment of the method for removing a reactor pressure vessel internal structure according to the present invention.

FIG. 25 is a schematic longitudinal sectional view showing a “separation step” in a second embodiment of the method for removing an internal structure of a reactor pressure vessel according to the present invention.

FIG. 26 is a schematic longitudinal sectional view showing a “sealing step” in a second embodiment of the method for removing the internal structure of the reactor pressure vessel according to the present invention.

FIG. 27 is a partially cutaway perspective view corresponding to “the descending step of the storage container holding device” shown in FIG.

FIG. 28 is a partially broken perspective view corresponding to “release of holding of container holding device to lifting process” shown in FIG. 24 (b).

FIG. 29 is a partially cutaway perspective view corresponding to the “separation step” shown in FIG. 25.

FIG. 30: “Shield cover attaching step” shown in FIG.
FIG.

FIG. 31 is a partially cutaway perspective view showing automatic welding in a “shield lid sealing step” in a third embodiment of the method for removing a reactor pressure vessel internal structure according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 reactor well 2 DSP (dryer pool (pool)) 6 reactor pressure vessel 7 structure inside reactor pressure vessel 8 shredding device 9 storage vessel 10 operation floor 11 area shielding stand 12 shielding vessel 13 curing sheet 14 thin Fragment 15 Shielding cylinder 16 Elevating / transferring means 20 Hoisting machine (Electric chain block) 21 Storage container holding device 27 Monitoring camera 31 Sprinkler device 32 Guide rod (Guiding device) 33 Guide receiver (Guiding device) 34 Seating part 35 Shield lid holding device 36 Shield lid 38 Guide receiver (guide device) 40 Bolt 42 Torque wrench 46 Automatic welding machine 49 Temporary shield lid

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mikuni Mamoru Toshiba Plant Construction Co., Ltd., 3-3-21 Isogo, Isogo-ku, Yokohama-shi, Kanagawa Prefecture (72) Inventor Shin Kuribayashi Shin-Sugita, Isogo-ku, Yokohama-shi, Kanagawa 8 Tochiba Yokohama Office, Toshiba Corporation (72) Inventor Hiroaki Kato 3-3-21 Isogo, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Toshiba Plant Construction Corporation (72) Kenji Kurihara Yokohama, Kanagawa Prefecture 8 Shin-Sugita-cho, Isogo-ku, Toshiba Yokohama, Japan

Claims (19)

[Claims] 1. A shredder for cutting a cut piece of a reactor pressure vessel internal structure taken out of a reactor pressure vessel into a size that can be stored in a predetermined storage vessel in a pool near the pressure vessel. A cutting step; a small fragment storing step of storing the small fragments in the storage container installed in the pool; and a lifting / lowering transfer means having a shielding cylinder. A transfer step of transferring the storage container to a shielding container installed on an operation floor near the pool while the storage container is stored in the shielding cylinder by the lifting and lowering transfer means; A container storage step of lowering the storage container from within the shielding cylinder and storing the storage container in the shielding container; and attaching a shielding lid to the shielding container storing the storage container. A sealing step of sealing the shielding container; a post-processing step of performing a post-treatment including necessary decontamination on the surface of the sealed shielding container; and moving the shield container subjected to the post-processing out of the furnace. A method for removing an internal structure of a reactor pressure vessel, comprising: an unloading step of unloading. 2. The method according to claim 2, wherein the shielding container is surrounded by an area shielding gantry installed on the operation floor, and in the transfer step, a bottom of the shielding cylinder is seated on the area shielding gantry. 2. The method according to claim 1, wherein the internal structure of the reactor pressure vessel is removed. 3. The lifting / lowering transfer means is configured to be able to separate the shielding cylinder and other parts, and the shielding cylinder of the lifting / lowering transportation means is provided between the container storing step and the sealing step. And further comprising a separation step of separating the other part of the lifting and lowering transfer means while leaving only the area on the area shielding gantry. 3. The method according to claim 2, further comprising removing the shielding tube from the area shielding base after attaching the shielding container to the container, and sealing the shielding container.
The method for removing the internal structure of a reactor pressure vessel described in the above. 4. The method for removing a reactor pressure vessel internal structure according to claim 1, wherein in the small fragment storing step, a temporary shielding lid is mounted on the storage container in which the small fragment is stored. . 5. The storage container according to claim 1, wherein a drain hole is provided in the storage container so that the pool water in the storage container is naturally drained in the lifting step. The method for removing the internal structure of a reactor pressure vessel according to any one of the first to third aspects. 6. The lifting and lowering means further includes a watering device provided above the shielding cylinder, and in the lifting step, the periphery of the storage container is watered and washed by the watering device. The method for removing an internal structure of a reactor pressure vessel according to any one of claims 1 to 5, wherein 7. The surveillance device according to claim 1, further comprising a monitoring camera provided above the shielding cylinder, wherein the monitoring camera monitors the inside of the shielding cylinder in an optional step. Item 7. The method for removing an internal structure of a reactor pressure vessel according to any one of Items 1 to 6. 8. The storage container holding device for holding the storage container and moving up and down in the shielding cylinder, and the storage container holding device and the shielding cylinder are provided so as to correspond to each other. A guide device, wherein in the lifting step and the container storage step, rotation and movement of the storage container holding device and the storage container in a horizontal plane are suppressed by the guide device. A method for removing an internal structure of a reactor pressure vessel according to any one of claims 1 to 7. 9. The method for removing an internal structure of a reactor pressure vessel according to claim 1, wherein said lifting and lowering means is shielded from above said shielding cylinder. 10. In the sealing step, the shield lid is attached by a shield lid holding device that holds and moves the shield lid up and down. A guide device corresponding to each other is provided, and in the sealing step, rotation and movement of the shield cover holding device and the shield cover in a horizontal plane are suppressed by the guide device. 10. The method for removing an internal structure of a reactor pressure vessel according to any one of claims 9 to 9. 11. A method according to claim 1, wherein a plurality of said storage containers are used in said small fragment storage step, and at least the steps from said lifting step to said sealing step are continuously performed for each storage container. A method for removing a reactor pressure vessel internal structure according to any one of the above. 12. The reactor pressure vessel according to claim 1, wherein the transfer step is performed in a state where a curing treatment is performed on a portion corresponding to a transfer path of the storage container. How to remove internal structures. 13. The method according to claim 1, wherein water or an inert gas is injected into the shielding container before attaching the shielding lid or before sealing the shielding container in the sealing step. 13. The method for removing an internal structure of a reactor pressure vessel according to any one of claims 12 to 12. 14. The shielding container according to claim 1, wherein in the sealing step, the shielding container is sealed by bolting the shielding container and the shielding lid to each other via packing. The method for removing the internal structure of a reactor pressure vessel according to any one of the first to third aspects. 15. The internal structure of the reactor pressure vessel according to claim 14, wherein the bolting in the sealing step is performed with a predetermined tightening torque by a torque wrench previously installed on the shielding lid. How to remove things. 16. In the sealing step, after the bolts are tightened, a portion of the outer surface of the shielding container and the shielding lid, which is likely to be radioactively contaminated, is covered with a contamination preventing member, and the shielding container or the shielding container or 16. The method according to claim 14, wherein the shielding cover and the pollution prevention member are welded to each other. 17. The method according to claim 1, wherein in the sealing step, the shielding container is sealed by welding between the shielding container and the shielding lid. How to remove the structure inside the reactor pressure vessel. 18. The method according to claim 17, wherein the welding in the sealing step is performed by an automatic welding machine installed on the shielding lid in advance. 19. The method for removing an internal structure of a reactor pressure vessel according to claim 17, wherein after welding in said sealing step, the integrity of said welded portion is checked.