JP2004061394A - Cutting method for reactor pressure vessel, and pitch holding fixture used in cutting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting method for a reactor pressure vessel used as central equipment, when a nuclear power plant is dismantled, which can be executed easily at a low cost and is highly useful and feasible, and also to provide a pitch-holding fixture used in the execution of the method. <P>SOLUTION: A plurality of cutting faces are defined in the reactor vessel in parallel, in the axial direction, a plurality of cutting part which pierce a pressure vessel wall are formed at the cutting faces, the pitch-holding fixtures are set here, then the fixtures are held at these positions, and the cutting faces are cut in this state. Thus, a gap between cutting lines by a cutter blade is prevented for becoming narrow, because of interposition of the fixtures, and possibility of applying a weight on the cutter blade is eliminated so that the reactor pressure vessel of a heavy structure cut stably and appropriately by a simple method. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for cutting a nuclear reactor pressure vessel used as a core device of a nuclear power plant when dismantling the nuclear power plant, and a pitch hold jig used for executing the cutting method. It is.
[0002]
[Prior art]
A nuclear power plant developed as a typical example of the peaceful use of nuclear power has been commercialized in Japan for over 30 years and less than 40 years (Japan Nuclear Power Tokai Power Plant: 1966 (Commercial operation commenced in July), and there have been few cases where the operation was terminated during this period, and since there is a certain cooling period required after the operation is completed, there has been no example of actual dismantling.
[0003]
However, in the U.S. and Europe, which is ahead of Japan in this field, actual examples of dismantling have begun to appear.Especially as a treatment of pressure vessels corresponding to heavy structures, after filling the inside of the pressure vessel with concrete etc., bury it deep underground A method or a method of cutting the pressure vessel into a plurality of pieces and burying the same in the ground in the same manner as described above is employed.
[0004]
Among these methods, when looking at the cutting process, a turntable is installed at the bottom of the pressure vessel that extends vertically and is installed at the side space position of the pressure vessel that is installed vertically. A cutting device is arranged, the cutting device is operated from the side peripheral surface while rotating the pressure vessel with a turntable, and the image of the cutting device that cuts with a cutting tool from the peripheral surface of the work rotating around the vertical axis is used as the pressure container. May be sliced along a horizontal plane perpendicular to the vertical axis.
[0005]
Further, as another cutting method, an arc cutting device or a plasma cutting device is taken in and installed in the pressure vessel that extends in the vertical direction and is erected, and these cutting devices are installed vertically in the pressure vessel. In some cases, the pressure vessel is moved along the inner peripheral surface of the same pressure vessel in a horizontal plane perpendicular to the axis, and cut in the same manner as above.
[0006]
[Problems to be solved by the invention]
However, among the cutting methods for cutting a pressure vessel in the United States and Europe, which are performed by rotating the pressure vessel with a turntable, the method is provided below the pressure vessel in order to connect various conduits to the pressure vessel. It is necessary to carry out parts from a narrow space, assemble them, and install them to support them from the lower surface of the pressure vessel. Preparatory work with cost is required.
[0007]
Also, in the method of cutting from the inside of the pressure vessel by a thermal cutting method such as an arc cutting device or a plasma cutting device, a large amount of cutting gas, fume and molten residue is generated, and radioactive substances are generated by these gases and fumes. It is necessary to take care to avoid mixing, adhering, scattering and diffusion into the wastewater. For this reason, special waste gas treatment equipment is required for safety, for example, a filter for removing particulate matter and a filter for removing molecular matter are required. And the like, and the cost must be increased.
[0008]
In such a situation, the present invention is difficult and costly for dismantling a pressure vessel, which is expected to increase in Japan in the near future in the near future, as in the cutting method leading in Europe and the United States. An object of the present invention is to provide a useful and highly feasible method for cutting a nuclear reactor, which can be implemented easily and at low cost, and a pitch hold jig used for the method, in place of a method directly connected to the up.
[0009]
[Means for Solving the Problems]
The present invention has been made in order to solve the above-described problems, and as a first means, a plurality of cut surfaces perpendicular to the longitudinal axis of the reactor pressure vessel in the horizontal direction are determined in parallel in the longitudinal axis direction, A plurality of cut portions are formed by penetrating the pressure vessel wall portion in the horizontal direction at a position corresponding to the cut surface of, a pitch hold jig is installed at each cut portion, and the pitch hold jig is held at that position, It is an object of the present invention to provide a method for cutting a reactor pressure vessel, in which each of the determined cut surfaces is sequentially cut by a cutting blade to make the reactor pressure vessel into a ring shape.
[0010]
That is, according to the first means, a plurality of cut surfaces of the reactor pressure vessel are determined in parallel to the axial direction, and a plurality of cut portions are formed by penetrating the pressure vessel wall at each cut surface position. After the holding jig is installed, the holding jig is held at that position, and the cutting surface is cut in this state. Therefore, the cutting is performed along the cutting surface in the horizontal direction to perform the cutting. After the cutting blade passes, cutting lines at regular intervals are sequentially formed.However, since a pitch hold jig is installed and held at a cut portion formed at a position corresponding to the cutting surface, the cutting line by the cutting blade is cut. The interval is not narrowed, so that there is no possibility that a load is applied to the cutting blade, and the reactor pressure vessel of the heavy structure can be cut stably and appropriately by a simple method.
[0011]
Further, as a second means, the present invention is used in the method for cutting a reactor pressure vessel in the first means, and is formed through a pressure vessel wall portion at a predetermined cut surface of the reactor pressure vessel. A horizontal portion inserted into the cut portion, an inner locking portion vertically projecting from the horizontal portion, and an outer locking provided at an end of the horizontal portion facing the inner locking portion. A holding member for integrally holding the outer locking portion at an end of the horizontal portion as an extension thereof at the outer locking portion. A biasing member that moves the outer locking portion to its own weight rotation position by releasing the holding of the holding member, and a pitch formed having a rotation fulcrum that rotatably supports the outer locking portion. This is to provide a hold jig.
[0012]
That is, according to the second means, when the reactor pressure vessel is cut along a predetermined cutting plane in the first means, a pitch hold jig used to hold the gap between the cutting lines without narrowing it. The tool includes a horizontal portion inserted into a cut portion formed through the pressure vessel wall portion at a cut surface, an inner locking portion protruding from the horizontal portion, and an outer member provided at an end of the horizontal portion. The outer locking portion is formed with a holding member, a biasing member, a pivot point, and the like, and the outer locking portion is formed by extending the end portion of the horizontal portion. It changes into a form that is held integrally in a shape, a form in which the holding form is released to be in its own weight rotating state, and a form in which it becomes perpendicular to the horizontal portion by rotating its own weight. This ensures that the pitch hold jig is securely held in the notch and the cutting Load without narrowing the interval between the cutting lines formed by eliminating the possibility of acting on the cutting blade by, in which the cutting of the reactor pressure vessel of heavy construction stable and has adequate feasible.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is an explanatory view schematically illustrating an outline of a method of cutting a reactor pressure vessel according to the present embodiment, FIG. 2 is an explanatory view schematically illustrating an outline of a cutting apparatus used for cutting, and FIG. FIG. 4 is an explanatory view showing an outline of a pitch hold jig used in this case, including an operation change in the order of (a), (b) and (c). FIG. 4 shows a situation where the pitch hold jig of FIG. ), (B), (c) in order, FIG. 5 illustrates stepwise changes in the operation of the pitch hold jig, (a) from the top, (b) from the side (C) is an explanatory view of the final situation as viewed from the front.
[0014]
The mainstream of commercial nuclear reactors is a so-called light water reactor using water (H ₂ O) as a coolant, but the light water reactor is further divided into a boiling water type and a pressurized water type. You.
[0015]
The boiling water reactor pressure vessel and the pressurized water reactor pressure vessel have the same basic structure in which both the reactor pressure vessels are erected upright, but the latter is a pressure vessel. In order to circulate the primary coolant to the outside, the inlet and outlet bulges like a nozzle, and the support part of the pressure vessel can be formed here. The support structure will be different.
[0016]
Although there is a difference as described above, both are likely to be exposed to the place of dismantling in the near future, and both will require an efficient dismantling method, but in this embodiment, A boiling water reactor pressure vessel will be described directly as a target, and a pressurized water reactor pressure vessel will be described below as being applicable as an applied modification thereof.
[0017]
That is, in the present embodiment, reference numeral 1 denotes a pressure vessel of a nuclear reactor, in which a lower mirror 1a is supported by a support skirt 5, and is disposed in an installation space 4 surrounded by a partition wall 8 made of concrete or the like. I have.
[0018]
Here, the pressure vessel 1, after a commercial operation for a certain period determined as, for example, 30 years, after a further cooling period of 5 to 10 years in consideration of the decay period of radioactivity, The fuel rod and the control rod are removed, and the pressure vessel 1 itself is shown as being imagined to be dismantled.
[0019]
The pressure vessel 1 is in a state where it is scheduled to be cut into a plurality of pieces along a horizontal plane orthogonal to its axis, and a plurality of cutting lines 2 (cutting lines 2) Are included in the cut surface. In the present specification, the cut surface is a general term for both the surface to be cut and the cut surface.)
[0020]
Also, in FIG. 1, a cutout portion 7 is shown in a rectangular shape at a position including the cutting line 2 for each of the cutting lines 2, but the cutout portion 7 will be described in detail later. I do.
[0021]
FIG. 2 schematically shows a cutting apparatus for cutting the pressure vessel 1 along a cutting line 2, wherein 10 is an upper mount installed on the pressure vessel 1 for this cutting operation, and 11 is an upper mount. The hoist 11 is connected to a support 13 disposed in the pressure vessel 1 by a cable covered with a cover 12 so that the support 13 can be moved vertically.
[0022]
The support base 13 rotates to cut the wall surface of the pressure vessel 1, a main drive motor 19 that rotationally drives the cutting blade 15, and moves the cutting blade 15 along the peripheral surface of the pressure vessel 1. A turning motor 16, a lifting / lowering motor 17 capable of vertically moving the cutting blade 15, and a radial feed motor 18 for feeding the cutting blade 15 toward the wall surface of the pressure vessel 1 to cut and cut the wall surface. I support.
[0023]
The support table 13 is formed of a disk-shaped or radial arm-shaped member centered on the axis of the pressure vessel 1, and clamps 14 at three or more positions on the outer circumference circle, preferably at four positions at 90 ° intervals. It is provided so that the position of the support base 13 can be fixed with respect to the pressure vessel 1 so that the horizontality of the cut surface is maintained.
[0024]
FIG. 3 shows the pitch hold jig 3 installed in the cutout portion 7.
That is, the pitch hold jig 3 has a horizontal portion 31 and an end protruding from the horizontal portion 31 in the vertical direction at the end of the horizontal portion 31 which is the inner side of the pressure vessel 1 when it is installed in the cut portion 7. And an outer locking portion 33 connected to the horizontal portion 31 on the opposite side of the inner locking portion 32.
[0025]
The outer locking portion 33 has, on an end surface that contacts the horizontal portion 31, a convex ridge 33 a that fits into a concave groove 31 a provided on the end surface of the horizontal portion 31, and a pin 36 that is offset from the center. When the groove 31a and the ridge 33a are disengaged from each other, the pin 36 can be used as a fulcrum to rotate with respect to the horizontal portion 31.
[0026]
A spring 35 is disposed concentrically with the pin 36 at a position where the pin 36 is supported on the horizontal portion 31, and the outer locking portion 33 is directed outward of the pressure vessel 1 via the pin 36. Energized, the concave groove 31a and the ridge 33a act so as to release the fitting.
[0027]
On the other hand, the horizontal portion 31 and the outer locking portion 33 are provided with a wire passage for guiding the wire 34 to the wall portion thereof, and a tension is applied to the wire passage toward the inside of the pressure vessel 1 through the wire 34. When this state is maintained, the engagement between the concave groove 31a and the ridge 33a is maintained against the urging force of the spring 35, and the outer locking portion 33 is formed as an extension of the horizontal portion 31. It can be maintained in a state of being integrally connected to the camera.
[0028]
This form is shown in FIGS. 3A to 3C separately for each operation stage, and FIG. 3A shows a state of initial setting. The pitch hold jig 3 includes a concave groove 31a and a convex ridge 33a. Are fitted and the wire 34 is tensioned to resist the urging force of the spring 35 so that the outer locking portion 33 and the horizontal portion 31 are integrated.
[0029]
Next, when the wire 34 is removed, as shown in FIG. 3B, the force against the urging force of the spring 35 is removed, and the outer locking portion 33 is moved out of the pressure vessel 1 via the pin 36 by the spring 35. And the engagement between the groove 31a and the ridge 33a is released.
[0030]
At the next moment, as shown in FIG. 3 (c), the outer locking portion 33 is rotated by 90 ° using its own weight with the pin 36 at a position deviated from the center as a fulcrum. The inner locking portion 32, the horizontal portion 31, and the outer locking portion 33 form a substantially U-shaped cross section.
[0031]
Next, in the present embodiment, a procedure for cutting the pressure vessel 1 as a part of the dismantling of the reactor will be described.
[0032]
As described above with reference to FIG. 1, a plurality of cutting lines 2 perpendicular to the coaxial line are defined at predetermined intervals in the axial direction of the pressure vessel 1, and a plurality of cutting lines 2 Cut portions 7 are formed at four locations, for example, at 90 ° intervals.
[0033]
The notch 7 is formed by using the cutting device described with reference to FIG. 2. If necessary, the cutting blade 15 may use a tool suitable for penetrating the notch 7 in the thickness direction of the wall of the pressure vessel 1. It can be appropriately selected and used.
[0034]
One cut surface (corresponding to one of the cutting lines 2) of the pressure vessel 1 in which the cuts 7 are formed in this manner has a form shown in FIG. 4A, and each of the cuts 7 has a pitch. When the holding jig 3 is inserted and installed from the inside of the pressure vessel 1 to the outside, the configuration shown in FIG. 4B is obtained. When the pitch holding jig 3 is further held at that position, the configuration shown in FIG. Become.
[0035]
The progress of the installation and holding of the pitch hold jig 3 with respect to the cut portion 7 can be more clearly understood from FIG. 3 or FIG.
That is, a pitch hold jig in which the horizontal portion 31 and the outer locking portion 33 are integrated with the cut portion 7 formed as shown in FIG. 4A by the tension of the wire 34 as shown in FIG. When 3 is installed, the configuration shown in FIG.
[0036]
In this state, in each of FIGS. 5A and 5B, the movement and change of the pitch hold jig 3 are indicated by the first (left side in the figure) white arrow and the center white arrow. The pitch hold jig 3 is installed at this position using a handling device such as a manipulator (not shown) as necessary.
[0037]
Next, when the wire 34 of the pitch hold jig 3 is removed by another manipulator or the like (not shown), the situation of FIG. 4 (b) progresses to FIG. 4 (c), which is shown in FIGS. 3 (b) to 3 (c). 5 (a) and 5 (b), it corresponds to the part shown by the white arrow on the last right side, and as shown in FIG. 3 (c) and FIG. Is rotated by 90 ° with the pin 36 as a pivot point, and the outer locking portion 33 and the inner locking portion 32 work together to hold the pitch hold jig 3 so as not to drop from the installation position of the cut portion 7. It becomes the form which did.
[0038]
When the pitch hold jig 3 is held at the position including the cutting line 2 in this manner, even if the cutting proceeds along the cutting line 2, it corresponds to the cutting trace of the cutting blade 15 along the cutting line 2. The “pitch” is “held” at a predetermined interval, and there is no possibility that the cutting blade 15 is pressed to make it impossible to continue cutting, and is completely different from the conventional thermal cutting method. There is no danger of contaminants being scattered or diffused by fumes or generated gas as in arc cutting or plasma cutting, and the pressure vessel 1 of a heavy structure can be appropriately cut by a simple procedure and a simple device. is there.
[0039]
Note that the pressure vessel 1 has a thickness of about 100 to 250 mm, and the cutting capability in the thickness direction of the cutting blade 15 that is practically used is about 10 to 20 mm per stroke. Since the cutting along the cutting line 2 needs to be repeated ten and several times, the timing of forming the cut portion 7 is determined by various combinations of the cutting in the circumferential direction by the cutting blade 15 along the cutting line 2 and various combinations. Can be selected.
[0040]
For example, it is possible to form the cut portion 7 first, during the circumferential cutting, or before performing the final cutting in the circumferential direction. Before the separation and cutting are performed, the notch 7 may be formed at an appropriate timing, and the pitch hold jig 3 may be installed and held there.
[0041]
In addition, in the present embodiment, the boiling water reactor pressure vessel has been described as a direct object, but the present invention can be similarly applied to the pressurized water reactor pressure vessel as described above. Requires a supporting skirt disposed below the mirror portion, such as a boiling water type, in addition to a supporting portion of a primary coolant circulating port provided in a bulging shape on the side of the pressure vessel.
[0042]
As described above, the present invention has been described with reference to the illustrated embodiments. However, the present invention is not limited to such embodiments, and it goes without saying that various changes may be made to the specific structure within the scope of the present invention. Absent.
[0043]
【The invention's effect】
As described above, according to the invention described in claim 1 of the present application, a plurality of cut planes that are orthogonal to the longitudinal axis of the reactor pressure vessel in the horizontal direction are determined in parallel in the longitudinal axis direction, and at positions corresponding to the respective cut planes. A plurality of cut portions are formed by penetrating the pressure vessel wall portion in the horizontal direction, a pitch hold jig is installed at each cut portion, and the pitch hold jig is held at that position, and each of the predetermined cuts is determined. Since the reactor pressure vessel cutting method is configured so that the surface is sequentially cut with a cutting blade to make the reactor pressure vessel into a ring shape, after installing a pitch hold jig in the cut portion, By holding at a position and cutting the cut surface in this state, cutting lines at regular intervals are sequentially formed after the cutting blade performing the cutting passes, but cutting by the cutting blade with the intervention of a pitch hold jig. The distance between the reactors is not narrowed, so that the load is not applied to the cutting blade, and the reactor pressure vessel of the heavy structure can be cut stably and appropriately in a useful and highly feasible reactor. A method for cutting the pressure vessel was obtained.
[0044]
According to the second aspect of the present invention, a horizontal portion inserted into a cut portion formed through a pressure vessel wall portion at a predetermined cut surface of the reactor pressure vessel, and a vertical portion from the horizontal portion. Forming a pitch hold jig having an inner locking portion protruding in the direction, and an outer locking portion provided at an end of the horizontal portion facing the inner locking portion. The locking portion includes a holding member that integrally holds the outer locking portion at an end of the horizontal portion in an extended portion thereof, and a rotation of the outer locking portion by its own weight by releasing the holding member. The pitch used in the cutting method of the reactor pressure vessel according to claim 1, wherein the biasing member is formed having a biasing member that moves to the moving position, and a rotation fulcrum that rotatably supports the outer locking portion. Since the holding jig is configured, the reactor pressure vessel is determined in advance by the reactor pressure vessel cutting method according to claim 1. A pitch hold jig composed of a horizontal portion inserted into the cut portion, an inner locking portion protruding from the horizontal portion, and an outer locking portion provided at an end of the horizontal portion when cutting at the cut surface. The tool holds the pitch hold jig easily and securely in the notch by the cooperation of the holding member, biasing member, rotation fulcrum, etc. It is possible to obtain a useful pitch hold jig that can stably and appropriately perform cutting of a reactor pressure vessel of a heavy structure without eliminating a possibility that a load is applied to a cutting blade without reducing a distance between formed cutting lines. It is something that can be done.
[Brief description of the drawings]
FIG. 1 is an explanatory view schematically illustrating an outline of a method for cutting a reactor pressure vessel according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram schematically illustrating an outline of a cutting device used for cutting in the present embodiment.
FIG. 3 is an explanatory diagram showing an outline of a pitch hold jig used for cutting, including an operation change in the order of (a), (b), and (c).
FIG. 4 is an explanatory diagram showing a situation in which the pitch hold jig of FIG. 3 is installed in a stepwise manner in the order of (a), (b), and (c).
FIGS. 5A and 5B are diagrams for explaining the operation change of the pitch hold jig in a stepwise manner, wherein FIG. 5A is a top view, FIG. 5B is a side view, and FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pressure vessel 1a Mirror part 2 Cutting line 3 Pitch hold jig 4 Installation space 5 Support skirt 6 Lower space 7 Notch 8 Partition wall 10 Upper gantry 11 Hoist 12 Cover 13 Support pedestal 14 Clamp 15 Cutting blade 16 Rotating motor 17 Elevating motor 18 Diameter feed motor 31 Horizontal part 31a Groove 32 Inner locking part 33 Outer locking part 33a Convex line 34 Wire 35 Spring 36 Pin

Claims (2)

A plurality of cut surfaces perpendicular to the longitudinal axis of the reactor pressure vessel in the horizontal direction are defined in parallel at the longitudinal axis direction, and a plurality of cuts are made by penetrating the pressure vessel wall horizontally at positions corresponding to the respective cut surfaces. Forming, installing a pitch hold jig at each notch, holding the same pitch hold jig at that position, sequentially cutting each of the predetermined cut surfaces with a cutting blade, and cutting the reactor pressure vessel into a ring shape. A method for cutting a reactor pressure vessel. A horizontal portion inserted into a cut portion formed through the pressure vessel wall at a predetermined cut surface of the reactor pressure vessel, an inner locking portion projecting vertically from the horizontal portion, A pitch hold jig is formed having an outer locking portion provided at an end of the horizontal portion opposite to the outer locking portion, and the outer locking portion includes the outer locking portion. A holding member integrally held at an end of the horizontal portion in the form of an extension thereof, an urging member for moving the outer locking portion to its own weight rotation position by releasing the holding of the holding member, A pitch hold jig which is formed having a rotation fulcrum for rotatably supporting the locking portion, and which is used in the method for cutting a reactor pressure vessel according to claim 1.

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