JP3861142B2 - Reactor pressure vessel cutting method and pitch hold jig used in the cutting method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of cutting a nuclear reactor pressure vessel used as a central device of the nuclear power plant when dismantling the nuclear power plant and the like, and a pitch hold jig used for executing the cutting method. It is.
[0002]
[Prior art]
The nuclear power plant developed as a typical example of the peaceful use of nuclear power has been in commercial use in Japan for over 30 years and less than 40 years (Japan Nuclear Power Generation Tokai Power Station: 1966) (Commercial operation started in July), and there are few examples where the operation was terminated during this period, and since a certain cooling period is required after the operation for dismantling, there are no examples of actual dismantling yet.
[0003]
However, in Europe and the United States, which precedes Japan in this field, examples of dismantling have begun to appear. Especially as a treatment of pressure vessels that hit heavy structures, concrete is filled inside the pressure vessels and then buried deep underground. A method, or a method of cutting the same pressure vessel into a plurality of pieces and then embedding it in the ground in the same manner as described above.
[0004]
Among these methods, when seeing the cutting process, a turntable is installed at the bottom of the pressure vessel extending vertically, and at the side space position of the pressure vessel installed upright. The pressure vessel is arranged according to the image of a cutting device in which a cutting device is arranged, the cutting device is operated from a side circumferential surface while the pressure vessel is rotated by a turntable, and the workpiece is cut from the circumferential surface of the workpiece rotating around the vertical axis. Is cut along a horizontal plane perpendicular to its longitudinal axis.
[0005]
Further, as another cutting processing method, an arc cutting device or a plasma cutting device is taken in and installed in a pressure vessel standing and extending in the vertical direction, and these cutting devices are installed in the vertical direction of the pressure vessel. Some of them are moved along the inner peripheral surface of the same pressure vessel on a horizontal plane perpendicular to the axis, and cut into a ring as described above.
[0006]
[Problems to be solved by the invention]
However, among the methods of cutting the pressure vessel that have been preceded in Europe and the United States, the method of cutting while rotating the pressure vessel with a turntable is provided below the pressure vessel to connect various conduits to the pressure vessel. It is necessary to carry out difficult work in an extremely limited space by carrying in parts from a narrow space and assembling them and installing them so as to support them from the lower surface of the same pressure vessel. , Costly preparatory work is required.
[0007]
Further, 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, fumes and molten residues are generated, and radioactive substances are generated from these gases and fumes. Special waste gas treatment equipment for safety, for example, a particulate matter removal filter and a molecular matter removal filter are required. Etc., and the cost is inevitably increased.
[0008]
Under such circumstances, the present invention has a high degree of difficulty and cost in the dismantling process of a pressure vessel, which is expected to be further increased in Japan in the near future, like the cutting method that precedes in the United States and Europe. It is an object of the present invention to provide a useful and highly feasible method of cutting a nuclear reactor and a pitch hold jig used therefor, which can be carried out easily and at low cost, instead of the method directly connected to the up.
[0009]
[Means for Solving the Problems]
The present invention has been made to solve the above-mentioned problems. As a first means, a plurality of cutting planes that are orthogonal to the vertical axis of the reactor pressure vessel in the horizontal direction are defined in parallel in the vertical axis direction, respectively. A plurality of cuts are formed by penetrating the pressure vessel wall in the horizontal direction at a position where it hits the cut surface, and a pitch hold jig is inserted and installed in each cut, and the tip of the pitch hold jig is rotated. Accordingly, the pitch holding jig is held so as not to drop off from the position by being locked to the cut portion, and the predetermined cut surfaces are sequentially cut with a cutting blade to make the reactor pressure vessel into a circular shape. A method for cutting a reactor pressure vessel is provided.
[0010]
That is, according to the first means, a plurality of cut surfaces of the reactor pressure vessel are defined in parallel to the axial direction, a plurality of cut portions are formed by penetrating the pressure vessel wall portion at each cut surface position, and a pitch is formed here. After the hold jig is inserted and installed, the tip is rotated so that it is locked to the notch and the pitch hold jig is held so that it does not fall off from that position, and the cutting surface is cut in this state. As the cutting operation proceeds along the horizontal cutting plane, cutting lines with a constant interval are sequentially formed after the cutting blade that performs the cutting passes, but is formed at a position corresponding to the cutting plane. the cut portion easily pitch hold jig because it is readily installed securely held, the distance between the cutting line by the cutting blade do not decrease and thereby O load is applied to the cutting tool Re no longer stable cutting of the reactor pressure vessel of heavy construction by a simple method, it is obtained by way and be properly performed.
[0011]
Further, the present invention is used as a second means for the method of cutting a reactor pressure vessel in the first means, and is formed by penetrating the pressure vessel wall at a predetermined cut surface of the reactor pressure vessel. A horizontal portion inserted into the cut portion, an inner locking portion protruding in the vertical direction from the horizontal portion, and an outer locking provided at an end of the horizontal portion facing the inner locking portion. A pitch-holding jig, and the outer locking portion is the same as a holding member that integrally holds the outer locking portion at the end of the horizontal portion in the shape of an extension thereof. A pitch formed by a biasing member that moves the outer locking portion to its own weight rotation position by releasing the holding member, and a rotation fulcrum that rotatably supports the outer locking portion. A holding jig is provided.
[0012]
That is, according to the second means, when the reactor pressure vessel is cut at the predetermined cutting surface in the first means, the pitch hold treatment used to hold the cutting line without reducing the interval between the cutting lines. The tool includes a horizontal portion inserted into a cut portion formed through the pressure vessel wall portion at the cut surface, an inner locking portion protruding from the horizontal portion, and an outer engagement provided at an end portion of the horizontal portion. The outer locking portion is formed with a holding member, an urging member, a rotation fulcrum and the like, and the outer locking portion is an end portion of the horizontal portion. In a form that is integrally held in a shape, a form that is released from the holding form and is in a self-rotating state, and a form that is perpendicular to the horizontal portion by rotating the self-weight. This ensures that the same pitch hold jig is held in the notch and allows the cutting tool to pass through. 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]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is an explanatory diagram for schematically explaining an outline of a method for cutting a reactor pressure vessel according to the present embodiment, FIG. 2 is an explanatory diagram for schematically explaining an outline of a cutting apparatus used for cutting, and FIG. FIG. 4 is an explanatory view showing an outline of the pitch hold jig used in the process including changes in operation in the order of (a), (b), and (c), and FIG. 4 shows a situation in which the pitch hold jig of FIG. ), (B), and (c) are step-by-step explanatory views, FIG. 5 is a step-by-step illustration of changes in the operation of the pitch hold jig, (a) from the top, and (b) from the side. From (c), it is explanatory drawing which looked at the final situation from the front.
[0014]
The so-called light water reactors, which use water (H ₂ O) as a coolant, dominate the commercial reactors, but the light water reactors are further divided into boiling water type and pressurized water type. The
[0015]
Although the boiling water reactor pressure vessel and the pressurized water reactor pressure vessel have the same basic structure in which the reactor pressure vessel is erected with the vertical direction long, the latter is a pressure vessel. In order to circulate the primary coolant outside, the inlet and outlet swells in the shape of a nozzle, and the support part of the pressure vessel can be formed here, but the former is structured to support via a skirt. The support structure will be different.
[0016]
Although there are differences as described above, both may be exposed to the field of dismantling in the near future, and both will require an efficient dismantling technique, but in this embodiment, A boiling water reactor pressure vessel will be directly targeted, and a pressurized water reactor pressure vessel will be described below as an application modification.
[0017]
That is, in the present embodiment, reference numeral 1 denotes a reactor pressure vessel, the lower mirror portion 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. Yes.
[0018]
Here, after the commercial operation for a certain period such as 30 years, for example, after the end of the commercial operation, the pressure vessel 1 is further subjected to a certain cooling period of 5 to 10 years in consideration of the decay period of radioactivity, The fuel rods and control rods are removed, and the pressure vessel 1 itself is shown as an image of the situation of entering the dismantling operation.
[0019]
The pressure vessel 1 is in a state scheduled to be cut into a plurality along a horizontal plane orthogonal to the axis thereof, and a plurality of cutting lines 2 (cutting lines) are provided at the position of the cutting plane where the cutting is scheduled. In the present specification, the cut surface is a generic term for both the surface to be cut and the cut surface.
[0020]
Further, in FIG. 1, for each of the cutting lines 2, a cut portion 7 is shown in a rectangular shape at a position including the cut line 2. The cut portion 7 will be described in detail later. To do.
[0021]
FIG. 2 shows an outline of a cutting device for cutting the pressure vessel 1 along the cutting line 2. Reference numeral 10 denotes an upper frame installed on the upper portion of the pressure vessel 1 for the cutting operation, and 11 denotes an upper frame. The hoist 11 is connected to a support base 13 disposed in the pressure vessel 1 by a rope covered with a cover 12 so that the support base 13 can be moved in the vertical direction.
[0022]
The support 13 rotates a cutting blade 15 that 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 motor 17 that can move the cutting blade 15 up and down, and a radial feed motor 18 that feeds the cutting blade 15 toward the wall surface of the pressure vessel 1 and performs cutting and cutting with respect to the wall surface. Support.
[0023]
The support base 13 is formed of a disk-shaped or radial arm-shaped member centered on the axis of the pressure vessel 1, and clamps 14 are provided at three or more positions on the outer circumference circle, preferably at four positions at 90 ° intervals. The position of the support base 13 can be fixed with respect to the pressure vessel 1 so that the level of the cut surface is maintained.
[0024]
FIG. 3 shows the pitch hold jig 3 installed in the cut portion 7.
In other words, the pitch hold jig 3 protrudes from the horizontal portion 31 in the vertical direction at the end of the horizontal portion 31 and the horizontal portion 31 which is the inner side of the pressure vessel 1 when the pitch hold jig 3 is installed in the cut portion 7. An inner locking portion 32 fixed to the inner locking portion 32 and an outer locking portion 33 connected to the horizontal portion 31 on the opposite side of the inner locking portion 32 are provided.
[0025]
The outer locking portion 33 is provided with a ridge 33a that fits into a groove 31a provided on the end surface of the horizontal portion 31 on the end surface in contact with the horizontal portion 31, and a pin 36 at a position displaced from the center. Provided, when the fitting between the groove 31a and the ridge 33a is released, the pin 36 is used as a fulcrum to be rotatable with respect to the horizontal portion 31.
[0026]
Further, a spring 35 is disposed concentrically with the pin 36 at the support position of the pin 36 on the horizontal portion 31 side, and the outer locking portion 33 is directed outward of the pressure vessel 1 through the pin 36. The 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 meat pressure portion, and tension is applied to the wire passage through the wire 34 toward the inside of the pressure vessel 1, When this state is maintained, the fitting of the groove 31a and the protrusion 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 is designed to be able to maintain a state where it is integrally connected to.
[0028]
This form is shown separately for each operation stage as FIGS. 3 (a) to 3 (c). FIG. 3 (a) shows an initial setting state, and the pitch hold jig 3 has a groove 31a and a ridge 33a. And the outer locking portion 33 and the horizontal portion 31 are integrated against the urging force of the spring 35 by applying tension to the wire 34.
[0029]
Next, when the wire 34 is removed, as shown in FIG. 3 (b), the force against the urging force of the spring 35 disappears, and the outer locking portion 33 is removed from the pressure vessel 1 via the pin 36 by the spring 35. The groove 31a and the protrusion 33a are disengaged from each other.
[0030]
At the next moment, as shown in FIG. 3 (c), the outer locking portion 33 is rotated 90 ° using its own weight with the pin 36 at a position displaced from the center as a fulcrum, and the pitch hold jig 3 The inner locking part 32, the horizontal part 31, and the outer locking part 33 form a substantially U-shaped cross section.
[0031]
Next, in the present embodiment, a description will be given with a procedure for cutting the pressure vessel 1 as part of the reactor dismantling.
[0032]
As described above with reference to FIG. 1, a plurality of cutting lines 2 orthogonal to the coaxial line are defined at a predetermined interval in the axial direction of the pressure vessel 1, and a plurality of cutting lines 2 are circumferentially arranged at positions including the cutting lines 2. Cut portions 7 are formed at four locations, for example, at 90 ° intervals.
[0033]
The cutting portion 7 is formed by using the cutting apparatus described with reference to FIG. 2, but if necessary, the cutting blade 15 uses a tool suitable for penetrating the cutting portion 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 cut portions 7 are formed in this way has the form shown in FIG. 4 (a), and each cut portion 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, and when the pitch holding jig 3 is further held at that position, the configuration shown in FIG. Become.
[0035]
The progress of installation and holding of the pitch holding jig 3 with respect to the cut portion 7 can be understood more clearly from FIG. 3 or FIG.
That is, the pitch holding jig in which the horizontal portion 31 and the outer locking portion 33 are integrated with the notch 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]
This state is also shown in FIGS. 5 (a) and 5 (b), where the movement and change of the pitch hold jig 3 are indicated by the first white arrow (left side in the figure) 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) if necessary.
[0037]
Next, when the wire 34 of the pitch hold jig 3 is removed by another manipulator or the like not shown, the state of FIG. 4B progresses to FIG. 4C, which is shown in FIGS. 3B to 3C. 5 (a) and 5 (b), this corresponds to the portion indicated by the white arrow on the last right side, and as shown in FIGS. 3 (c) and 5 (c), the outer locking portion 33 is provided. Is rotated 90 ° with the pin 36 as a pivot, and the outer locking portion 33 and the inner locking portion 32 are held together to hold the pitch hold jig 3 so that it does not fall off from the installation position of the cut portion 7. It will be in the form.
[0038]
When the pitch hold jig 3 is held at a position including the cutting line 2 in this way, even if the cutting progresses 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” by keeping a predetermined interval, and there is no possibility that the cutting blade 15 is pressed and the cutting cannot be continued, and is completely different from the conventional thermal cutting method. There is no fear that contaminants are 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 with a simple procedure and a simple device. is there.
[0039]
The pressure vessel 1 has a thickness of about 100 to 250 mm, and the cutting blade 15 provided for practical use has a cutting direction in the thickness direction of about 10 to 20 mm per stroke. Since the cutting along the cutting line 2 needs to be repeated ten times or more, the timing of forming the cut portion 7 is determined by various combinations of cutting in the circumferential direction by the cutting blade 15 along the cutting line 2 and various combinations. Can be selected.
[0040]
For example, the timing of whether the cut portion 7 should be formed first, in the middle of circumferential cutting, or before the final cutting in the circumferential direction may be considered. If it is before separation and cutting, an appropriate timing may be selected to form the cut portion 7, 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 as described above, it can be similarly applied to a pressurized water reactor pressure vessel, in which case In addition to the support part of the circulation port part of the primary coolant provided in a bulging form on the side of the pressure vessel, a support skirt arranged below the mirror part is required like a boiling water type.
[0042]
Although the present invention has been described with reference to the illustrated embodiment, the present invention is not limited to this embodiment, and it goes without saying that various modifications 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 cutting planes that are perpendicular to the vertical axis of the reactor pressure vessel in the horizontal direction are defined in parallel in the vertical axis direction, and at positions corresponding to the respective cutting planes. A plurality of cut portions are formed by penetrating the pressure vessel wall portion in the horizontal direction, a pitch hold jig is inserted and installed in each cut portion, and the tip of the pitch hold jig is rotated to the cut portion. Reactor pressure that locks and holds the pitch hold jig so that it does not fall off from that position, and cuts each of the defined cut surfaces sequentially with a cutting blade to make the reactor pressure vessel into a circular shape. since constitute a cutting method of the container, the cut the cutting portions of the same pitch hold jig by a simple operation of rotating the tip after installing plug the pitch hold jig unit Engagement locks by held reliably so as not to fall off from its position, by cutting the cut surface in this state, the cutting line of the predetermined intervals after the cutting tool to perform the cutting passes are sequentially formed, The interval between the cutting lines by the cutting blade is not narrowed by the pitch hold jig, so that there is no possibility that the load will be applied to the cutting blade, and it is possible to stably cut the reactor pressure vessel of the heavy structure with a simple method, and It was possible to obtain a useful and highly feasible cutting method of a reactor pressure vessel that can be appropriately performed.
[0044]
Further, according to the invention described in claim 2, a horizontal portion inserted into a cut portion formed through the pressure vessel wall portion at a predetermined cut surface of the reactor pressure vessel, and a vertical portion from the horizontal portion. A pitch-holding jig having an inner locking portion protruding in a direction and an outer locking portion provided at an end of the horizontal portion so as to face the inner locking portion, The locking portion includes a holding member that integrally holds the outer locking portion at the end of the horizontal portion in the shape of an extension thereof, and the outer locking portion is rotated by its own weight by releasing the holding member. The pitch used for the cutting method of the reactor pressure vessel of Claim 1 formed with the urging member which moves to a moving position, and the rotation fulcrum which supports the outer locking part rotatably. 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. When the cut surface is cut, 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 the end of the horizontal portion. The tool holds the pitch hold jig in the notch part easily and reliably by the cooperation of the holding member, the urging member, the rotation fulcrum, etc., which corresponds to the detailed structure of the outer locking part. A useful pitch hold jig capable of stably and appropriately performing cutting of a reactor pressure vessel of a heavy structure is obtained by eliminating the possibility that a load is applied to the cutting blade without reducing the interval between the formed cutting lines. It was possible.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram 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 for schematically explaining 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 operation changes in the order of (a), (b), and (c).
FIG. 4 is an explanatory view showing a state in which the pitch hold jig of FIG. 3 is installed step by step in the order of (a), (b), and (c).
FIGS. 5A and 5B are diagrams illustrating stepwise changes in the operation of the pitch hold jig. FIG. 5A is an explanatory view of the final state viewed from the top, 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 | tool 4 Installation space 5 Support skirt 6 Lower space 7 Cut part 8 Partition wall 10 Upper mount 11 Hoist 12 Cover 13 Support base 14 Clamp 15 Cutting blade 16 Turning motor 17 Lifting motor 17 18 radial feed motor 31 horizontal portion 31a groove 32 inner locking portion 33 outer locking portion 33a ridge 34 wire 35 spring 36 pin

Claims (2)

A plurality of cut surfaces that are orthogonal to the vertical axis of the reactor pressure vessel in the horizontal direction are defined in parallel in the vertical axis direction, and a plurality of cut portions are formed by penetrating the pressure vessel wall portion in the horizontal direction at positions corresponding to the respective cut surfaces. The pitch hold jig is inserted and installed in each notch, and the tip of the pitch hold jig is rotated so that it is locked to the notch so that the pitch hold jig does not fall off from that position. The reactor pressure vessel cutting method is characterized in that the reactor pressure vessel is cut into a circular shape by sequentially cutting each of the determined cut surfaces with a cutting blade.   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, an inner locking portion projecting vertically from the horizontal portion, A pitch holding jig is formed by having an outer locking portion provided at an end of the horizontal portion so as to face the direction locking portion, and the outer locking portion includes the outer locking portion described above. A holding member that is integrally held at the end of the horizontal portion in the shape of its extension, a biasing member that moves the outer locking portion to its own weight rotation position by releasing the holding member, and the outer side The pitch hold jig characterized by having a rotation fulcrum for pivotally supporting the locking portion and being used in the method of cutting a reactor pressure vessel according to claim 1.

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