JP6147490B2 - Steam generator disassembly method - Google Patents

Description

  The present invention relates to a method for disassembling a used steam generator.

  For example, a steam generator as a heat exchanger used in a pressurized water reactor (PWR) is provided with a heat transfer tube, a steam / water separator, and a moisture separator inside a substantially sealed body. ing. In this steam generator, high-temperature primary cooling water pressurized from the reactor flows through the heat transfer tubes and is returned to the reactor. And since the said heat exchanger tube is heated when a primary cooling water flows into a heat exchanger tube, the secondary coolant introduced in the trunk | drum is heated and it is set as a vapor | steam.

  This steam generator is removed at the time of replacement or when the reactor is decommissioned. As described above, since the primary cooling water from the nuclear reactor passes through the inside of the heat transfer tube, the steam generator is exposed to radiation and includes radioactivity. Therefore, generally, the removed steam generator is stored as radioactive waste in a storage in the nuclear power generation facility as it is (see, for example, Patent Document 1).

  By the way, the steam generator is, for example, a large one with an outer diameter of 4.5 m, a length (height) of 21 m, and a weight of 300 t. To store the steam generator as it is in a storage in the nuclear power generation facility, the steam generator is large. A vault is required. However, since it is assumed that the number of steam generators to be stored will increase in the future, it is necessary to prepare a larger storage, but it is necessary to secure a place for a larger storage in the nuclear power generation facility. It is a difficult situation.

  For this reason, it is considered to dismantle the steam generator, reduce the volume of radioactive waste, and dispose of it. In this case, the steam generator is in a state in which the length direction is set horizontally, and the upper body is provided with the steam separator and the moisture separator, and the lower part is provided with the heat transfer tube. It is cut into cylinders, each of which is cut into smaller pieces and disassembled (see, for example, Patent Document 2).

JP-A-8-43577 JP 2011-33349 A

  In Patent Document 2, in disassembling the lower shell, both ends of the heat transfer tube are laser-cut between adjacent tube support plates, and the heat transfer tube is appropriately collected. According to this method, the working time can be shortened compared to the case where thousands of heat transfer tubes are cut by a grindstone. However, since heat transfer tubes are supplied with primary cooling water from a nuclear reactor and exposed to radiation, it is desired to further shorten the work time.

  The present invention solves the above-described problems, and an object thereof is to provide a steam generator disassembly method capable of rationally dismantling the steam generator by further shortening the work time for cutting the heat transfer tube. And

  In order to achieve the above-mentioned object, a steam generator disassembly method according to a first aspect of the present invention includes an upper trunk whose upper end is closed on the upper side of a cylindrical barrel, and a tube sheet on the lower end on the lower side of the barrel. A plurality of heat transfer tubes formed in an inverted U shape in the lower body are surrounded by a tube group outer tube. Steam generated by being inserted into and supported by a plurality of upper and lower tube support plates in a state of being connected to each of the water chambers, each of which is inserted and fixed to the tube plate and divided in the water chamber mirror. A method of disassembling a vessel, wherein the body portion is cut into the upper body side and the lower body side, and the heat transfer tube is exposed by partially removing the lower body and the tube group outer cylinder. Wire of a wire saw in the gap between one straight portion and the other straight portion constituting the U-shape of the heat transfer tube that is exposed Inserting and cutting the one straight portion of the heat transfer tube together and cutting the other U-shaped straight portion of the exposed heat transfer tube together. And

  According to this steam generator dismantling method, the wire saws cut one U-shaped straight portion and the other straight portion of the plurality of heat transfer tubes together, thereby reducing the work time for cutting the heat transfer tubes. Can be shortened. In particular, by inserting the wire saw wire through the gaps between the U-shaped straight portions of the plurality of heat transfer tubes, and cutting one U-shaped straight portion and the other straight portion of the plurality of heat transfer tubes together. Since the frictional resistance applied to the wire of the wire saw is reduced, the consumption of the wire is suppressed. For this reason, it becomes possible to reduce exchange of a wire and to improve work efficiency. As a result, the steam generator can be rationally disassembled.

  Further, the method for disassembling the steam generator according to the second invention comprises the steps of providing a plurality of holes along the cutting direction in the lower body or the tube group outer cylinder in the first invention. A step of inserting a wire saw wire between the holes and cutting between the holes, and then inserting a wire saw wire between the cut portion and the other hole to cut each of the holes And continuously cutting the lower body or the tube group outer cylinder.

  According to this steam generator disassembly method, the lower barrel or tube group outer cylinder is cut by a hole compared to the method of cutting the wire saw wire around the outer side of the lower barrel or tube group outer cylinder. By partially cutting along the direction, the frictional resistance applied to the wire is reduced, so that the consumption of the wire is suppressed. For this reason, it becomes possible to reduce exchange of a wire and to improve work efficiency. As a result, the steam generator can be rationally disassembled.

  The steam generator disassembly method of the third invention is the method of disposing a plurality of holes along the circumferential direction between the tube plate in which all the heat transfer tubes are cut and the water chamber mirror in the first invention. A step of inserting a wire saw wire between the two holes and cutting between the two, and then inserting a wire saw wire between the cut portion and the other hole A step of cutting the gap between the levers to make the holes continuous and separating the tube plate and the water chamber mirror.

  According to this steam generator disassembly method, the tube plate and the water chamber mirror are separated by a hole, compared to the method in which a wire saw wire is wound around the tube plate and the water chamber mirror in the circumferential direction. By partially cutting along the cutting direction, the frictional resistance applied to the wire is reduced, so that the consumption of the wire is suppressed. For this reason, it becomes possible to reduce exchange of a wire and to improve work efficiency. As a result, the steam generator can be rationally disassembled.

  According to a fourth aspect of the present invention, there is provided a method for disassembling a steam generator, wherein the tube plate separated from the water chamber mirror uses a tube hole of the tube plate into which the heat transfer tube is inserted. A step of inserting and cutting the wire of the wire saw, and then inserting the wire of the wire saw between the cut portion and the other tube hole and cutting the space between them to make the tube holes continuous. And a step of cutting the plate into small pieces.

  According to this steam generator disassembly method, the tube plate is partially cut along the cutting direction using the tube hole, compared to the method of cutting the wire saw around the tube plate. Thus, since the frictional resistance applied to the wire is reduced, the consumption of the wire is suppressed. For this reason, it becomes possible to reduce exchange of a wire and to improve work efficiency. As a result, the steam generator can be rationally disassembled.

  Moreover, the disassembly method of the steam generator of 5th invention is a 3rd invention. WHEREIN: About the said water chamber mirror cut away from the said tube sheet, a plurality of holes are provided in the said water chamber mirror along the cutting direction. A step of inserting a wire saw wire between the two holes and cutting the gap between the two holes, and then inserting a wire saw wire between the cut portion and the other hole. And cutting each of the water chamber mirrors into small pieces by continuously cutting the holes.

  According to this steam generator disassembly method, compared to the method of cutting the wire saw wire around the water chamber mirror, the water chamber mirror is partially cut along the cutting direction by the hole. Since the frictional resistance applied to the wire is reduced, the consumption of the wire is suppressed. For this reason, it becomes possible to reduce exchange of a wire and to improve work efficiency. As a result, the steam generator can be rationally disassembled.

  According to a sixth aspect of the present invention, there is provided a steam generator disassembling method according to the first aspect of the present invention, in the case of cutting the upper body side into small pieces, a step of providing a plurality of holes in the upper body along the cutting direction; Next, a step of inserting a wire of a wire saw between the two holes and cutting between them, and then inserting a wire of a wire saw between the cut portion and the other hole and cutting between them And a step of cutting each of the upper bodies into small portions by continuing the holes.

  According to this steam generator disassembly method, the upper drum is partially cut along the cutting direction by a hole as compared with a method in which a wire saw wire is wound around the outer side of the upper drum in the circumferential direction. Thus, since the frictional resistance applied to the wire is reduced, the consumption of the wire is suppressed. For this reason, it becomes possible to reduce exchange of a wire and to improve work efficiency. As a result, the steam generator can be rationally disassembled.

  A steam generator disassembling method according to a seventh aspect of the present invention includes, in any one of the first to sixth aspects, a step of cutting the body portion into a tubular shape, and an inside and outside of the tubular shape. And inserting a wire of a wire saw into a small cut.

  According to this steam generator disassembly method, the body portion is cut into a cylindrical shape, and a wire saw wire is inserted into the inside and outside of the cylindrical shape to cut it into a small size, so that the frictional resistance applied to the wire saw wire is reduced. Therefore, the consumption of the wire can be suppressed. For this reason, it becomes possible to reduce exchange of a wire and to improve work efficiency. As a result, the steam generator can be rationally disassembled.

  The steam generator disassembling method according to an eighth aspect of the present invention includes, in any one of the first to seventh aspects, a pulley that deforms a wire shape of the wire saw, and the wire is pulled by the pulley. The step of cutting the corner of the member to be cut by being arranged obliquely with respect to the cutting direction, and the member to be cut by cutting the corner and then placing the wire perpendicular to the cutting direction by the pulley And a step of cutting.

  According to this steam generator disassembly method, the frictional resistance to the wire is reduced by starting to cut the corner of the member to be cut rather than arranging the wire along the end face of the member to be cut and starting to cut it. Therefore, cutting is easy and wear of the wire is suppressed. For this reason, it becomes possible to reduce exchange of a wire and to improve work efficiency. As a result, the steam generator can be rationally disassembled.

  According to the present invention, it is possible to rationally dismantle the steam generator by further shortening the work time for cutting the heat transfer tube.

FIG. 1 is a schematic configuration diagram showing a nuclear power generation facility. FIG. 2 is a schematic cross-sectional side view of the steam generator. FIG. 3 is a process diagram showing a procedure for dismantling the steam generator. FIG. 4 is a process diagram showing a procedure for dismantling the steam generator. FIG. 5 is a process diagram showing a procedure for dismantling the steam generator. FIG. 6 is a process diagram showing a procedure for dismantling the steam generator. FIG. 7 is a process diagram showing a procedure for dismantling the steam generator. FIG. 8 is a process diagram showing a procedure for dismantling the steam generator. FIG. 9 is a process diagram showing a procedure for dismantling the steam generator. FIG. 10 is a process diagram showing a procedure for dismantling the steam generator. FIG. 11 is a process diagram showing a procedure for dismantling the steam generator. FIG. 12 is a process diagram showing a procedure for dismantling the steam generator. FIG. 13 is a process diagram showing a procedure for dismantling the steam generator. FIG. 14 is a schematic view showing a method of cutting the steam generator. FIG. 15 is a schematic view showing a method of cutting the steam generator. FIG. 16 is a schematic view showing a method of cutting the steam generator. FIG. 17 is a schematic view showing a method of cutting the steam generator. FIG. 18 is a schematic view showing a method of cutting the steam generator. FIG. 19 is a process diagram showing another disassembly procedure of the steam generator. FIG. 20 is a process diagram showing another disassembly procedure of the steam generator. FIG. 21 is a process diagram showing another disassembly procedure of the steam generator. FIG. 22 is a process diagram showing another disassembly procedure of the steam generator. FIG. 23 is a process diagram showing another disassembly procedure of the steam generator. FIG. 24 is a process diagram showing another disassembly procedure of the steam generator. FIG. 25 is a process diagram showing another disassembly procedure of the steam generator. FIG. 26 is a process diagram showing another disassembly procedure of the steam generator. FIG. 27 is a process diagram showing another disassembly procedure of the steam generator. FIG. 28 is a process diagram showing another disassembly procedure of the steam generator.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

  The steam generator disassembled in the present embodiment is applied in a nuclear power generation facility. FIG. 1 is a schematic configuration diagram showing a nuclear power generation facility, and FIG. 2 is a schematic side sectional view of a steam generator.

  In the present embodiment, for example, as shown in FIG. 1, a pressurized water reactor (PWR: Pressurized Water Reactor) 112 is applied to the nuclear power plant. The pressurized water reactor 112 uses light water as a reactor coolant and a neutron moderator, generates high-pressure high-temperature water that does not boil throughout the primary system, and sends this high-pressure high-temperature water to a steam generator to generate steam by heat exchange. This steam is sent to a turbine generator to generate electricity.

  In the nuclear power generation facility having this pressurized water reactor 112, the pressurized water reactor 112 and the steam generator 1 are stored inside the reactor containment vessel 111. The pressurized water reactor 112 and the steam generator 1 are connected via cooling water pipes 114 and 115. The cooling water pipe 114 is provided with a pressurizer 116, and the cooling water pipe 115 is provided with a cooling water pump 117. In this case, light water is used as the moderator and the primary cooling water, and the primary cooling system is controlled by the pressurizer 116 so as to maintain a high pressure state of about 160 atm in order to suppress boiling of the primary cooling water in the core. Yes. Therefore, in the pressurized water reactor 112, light water as primary cooling water is heated by low-enriched uranium or MOX as fuel, and the high-temperature primary cooling water is maintained at a predetermined high pressure by the pressurizer 116. It is sent to the steam generator 1 through the pipe 114. In the steam generator 1, heat exchange is performed between the high-pressure and high-temperature primary cooling water and the secondary cooling water, and the cooled primary cooling water is returned to the pressurized water reactor 112 through the cooling water pipe 115.

  The steam generator 1 is connected to a turbine 118 and a condenser 119 provided outside the reactor containment vessel 111 via cooling water pipes 120 and 121, and a water supply pump 122 is provided in the cooling water pipe 121. ing. The turbine 118 is connected to a generator 123, and the condenser 119 is connected to a water intake pipe 124 and a drain pipe 125 for supplying and discharging cooling water (for example, seawater). Therefore, the steam generated by exchanging heat with the high-pressure and high-temperature primary cooling water in the steam generator 1 is sent to the turbine 118 through the cooling water pipe 120, and the turbine 118 is driven by this steam to generate the generator 123. To generate electricity. The steam that has driven the turbine 118 is cooled by the condenser 119 and then returned to the steam generator 1 through the cooling water pipe 121.

  As shown in FIG. 2, the steam generator 1 has a body portion 2 that is elongated in the vertical direction and has a sealed hollow cylindrical shape. The lower part of the body 2 is slightly smaller in diameter than the upper half, and connects the lower body 2a forming the lower half, the upper body 2b forming the upper half, and the lower body 2a and the upper body 2b. It is composed of a substantially truncated cone-shaped cone cylinder 2c and an upper mirror 2d provided at the upper end of the upper cylinder 2b.

  The steam generator 1 is provided with a tube group outer cylinder 3 having a cylindrical shape disposed at a predetermined distance from an inner wall surface in a lower body 2a. The tube group outer cylinder 3 includes a cylindrical portion 3a whose lower end portion is formed in a cylindrical shape, and a conical portion 3b formed in a truncated cone shape so that its upper end portion extends outward while extending outward. Have. The tube group outer cylinder 3 is extended so that the lower end part of the cylindrical part 3a may be near the tube sheet 4 arrange | positioned at the lower end part of the lower trunk | drum 2a. The conical part 3 b is disposed at the position of the conical cylinder 2 c of the body part 2. A heat transfer tube group 5A is provided in the tube group outer tube 3. The heat transfer tube group 5 </ b> A is composed of a plurality of heat transfer tubes 5 having an inverted U shape and elongated in the vertical direction. Each heat transfer tube 5 is formed in a U shape by an arc portion 5a and a straight portion 5b extending linearly from each end of the arc portion 5a. And the heat exchanger tube 5 is arrange | positioned facing the circular arc part 5a upwards, while the edge part of each linear part 5b is penetrated and fixed to the tube hole 4a of the tube sheet 4, and several places of the longitudinal direction in the linear part 5b Is supported by the tube group outer cylinder 3 via each tube support plate 6. The tube support plate 6 is formed with a plurality of heat transfer tube insertion holes 6a, and supports the heat transfer tubes 5 by inserting the heat transfer tubes 5 into the heat transfer tube insertion holes 6a.

  Incidentally, as described above, the heat transfer tube group 5A including the plurality of U-shaped heat transfer tubes 5 has the arc portion 5a of the heat transfer tube 5 disposed at the upper end thereof. The heat transfer tube group 5A forms a heat transfer tube layer in which the heat transfer tubes 5 are arranged so that the diameter of the arc portion 5a increases from the center toward the outside, and the outermost peripheral heat transfer tube 5 is stacked on the arranged heat transfer tube layers. By changing the diameter of the arc portion 5a, the upper end portion is formed in a hemispherical shape. In the heat transfer tube group 5A, a gap 5c that is continuous in the radial direction of the trunk portion 2 (lower barrel 2a) is formed at the center and between the straight portions 5b of the U-shaped heat transfer tube 5. Is done. This gap 5 c coincides with the position of a partition wall 8 described later provided in the water chamber mirror 7. Further, the heat transfer tube group 5 </ b> A is provided with a bracing member 14 in order to suppress fluid excitation vibration that may be generated when the primary cooling water passes through the heat transfer tubes 5.

  The steam generator 1 is provided with a water chamber mirror 7 below the tube plate 4, and the interior of the water chamber mirror 7 is partitioned by a partition wall 8 into an inlet side water chamber 7A and an outlet side water chamber 7B. The inlet side water chamber 7A is in communication with the end of one straight portion 5b of each heat transfer tube 5, and the outlet side water chamber 7B is in communication with the end of the other straight portion 5b of each heat transfer tube 5. Further, the inlet-side water chamber 7A is formed with an inlet nozzle 7Aa that communicates with the outside of the trunk portion 2, and the outlet-side water chamber 7B is formed with an outlet nozzle 7Ba that communicates with the exterior of the trunk portion 2. The inlet nozzle 7Aa is connected to a cooling water pipe 114 to which primary cooling water is sent from the pressurized water reactor 112, and the outlet nozzle 7Ba is cooled to send the primary cooling water after heat exchange to the pressurized water reactor 112. A water pipe 115 is connected.

  The steam generator 1 includes an air / water separator 9 that separates feed water into steam and hot water inside the upper body 2b, and moisture that removes the moisture from the separated steam so that it is close to dry steam. A separator 10 is provided. Further, a water supply pipe 11 for supplying secondary cooling water from the outside into the lower body 2a is inserted between the steam separator 9 and the heat transfer tube group 5A at the lower part of the upper body 2b. . In addition, the steam generator 1 pipes the secondary cooling water supplied from the water supply pipe 11 into the lower body 2a between the lower body 2a and the tube group outer cylinder 3 in the lower body 2a. A water supply path 12 that is folded back by the plate 4 and is raised along the heat transfer tube group 5A is formed. Further, in the steam generator 1, a steam discharge port 13 is formed in the upper mirror 2d. The steam outlet 13 is connected to a cooling water pipe 120 that sends steam to the turbine 118, and the water supply pipe 11 supplies secondary cooling water in which the steam used in the turbine 118 is cooled by the condenser 119. For this purpose, a cooling water pipe 121 is connected.

  In the steam generator 1, the primary cooling water heated in the pressurized water reactor 112 is sent to the inlet side water chamber 7A, circulates through the plurality of heat transfer tubes 5, and reaches the outlet side water chamber 7B. On the other hand, the secondary cooling water cooled by the condenser 119 is sent to the water supply pipe 11 and rises along the heat transfer pipe group 5 </ b> A through the water supply path 12 in the trunk portion 2. At this time, heat exchange is performed between the high-pressure and high-temperature primary cooling water and the secondary cooling water in the trunk portion 2. Then, the cooled primary cooling water is returned to the pressurized water reactor 112 from the outlet side water chamber 7B. On the other hand, the secondary cooling water subjected to heat exchange with the high-pressure and high-temperature primary cooling water rises in the body portion 2 and is separated into steam and hot water by the steam separator 9. The separated steam is sent to the turbine 118 from the steam outlet 13 after the moisture is removed by the moisture separator 10.

  As described above, in the steam generator 1, since the primary cooling water from the nuclear reactor passes through the heat transfer tube 5, the heat transfer tube 5 is exposed to radiation and includes radioactivity. Therefore, generally, the steam generator 1 removed from the primary cooling system is stored as a radioactive waste in a storage in the nuclear power generation facility for a certain period. Thereafter, the steam generator 1 is dismantled and disposed of in a form in which the volume of radioactive waste is reduced.

  3 to 13 are process diagrams showing a procedure for disassembling the steam generator. As shown in FIG. 3, the steam generator 1 is dismantled on the floor of the processing facility 100 in a state where the steam generator 1 is placed horizontally by the support frame 101. In the present embodiment, in the steam generator 1 placed horizontally, the longitudinal direction corresponding to the up and down direction at the time of use is referred to as an axial direction and is indicated by a symbol L. The steam generator 1 placed horizontally on the floor of the processing equipment 100 in this way is entirely covered with the green house 102 when dismantling. The green house 102 has an opening that can be opened and closed on the ceiling, and a cargo handling hook 103 of an overhead crane is inserted through the opening.

  In disassembling the steam generator 1, first, as shown in FIG. 3, in the state where the steam generator 1 is placed horizontally, the inside of the inlet-side water chamber 7A, the outlet-side water chamber 7B, and the heat transfer pipe 5 For example, decontamination is performed by blast decontamination.

  Next, as shown in FIG. 4, the upper body 2b is cut from the conical body 2c together with the internal members (the steam separator 9 and the moisture separator 10). The upper body 2b has a steam / water separator 9, a moisture separator 10 and a water supply pipe 11 therein.

  Subsequently, as shown in FIG. 5, the conical cylinder 2 c is cut from the lower cylinder 2 a and the conical part 3 b is cut from the tube group outer cylinder 3. Thereby, the circular arc part 5a of the heat exchanger tube 5 appears. The cone body 2c and the cone portion 3b are carried out of the green house 102 using the cargo handling hook 103, cut into small pieces at a separately prepared dismantling place, and accommodated in a storage container (not shown).

  Subsequently, as shown in FIG. 6, the arc portion 5 a of the heat transfer tube 5 is cut. As described above, the arc member 5a of the heat transfer tube 5 is provided with the anti-vibration member 14, and these are removed simultaneously with the cutting of the arc portion 5a of the heat transfer tube 5. For this reason, the remaining heat transfer tube 5 has a form in which only the straight portion 5 b is inserted and supported straight by the tube support plate 6. Since the arc portion 5a of the heat transfer tube 5 thus formed is exposed to the radiation in contact with the primary cooling water, it is cut, compressed, or bent small in the reactor containment vessel 111, and leakage of radiation. Is stored in a storage container (not shown).

  Subsequently, as shown in FIG. 6, the lower body 2 a is partially cut and separated as shown by a one-dot chain line, and the cylindrical portion 3 a of the tube group outer tube 3 is also partially cut and separated in the same manner. As shown in FIG. 7, it removes based on the arrangement | positioning space | interval of the tube support plate 6, and exposes a part of straight part 5b of the heat exchanger tube 5. As shown in FIG. Subsequently, as shown in FIG. 8, a part of the exposed straight portion 5 b of the heat transfer tube 5 is cut based on the arrangement interval of the tube support plates 6. By repeating the steps shown in FIGS. 6 to 8, the lower body 2a, the tube group outer tube 3, the heat transfer tube 5 and the tube support plate 6 leave the tube plate 4 and the water chamber mirror 7 as shown in FIG. To be removed. The lower body 2a, the tube group outer tube 3, the straight portion 5b of the heat transfer tube 5 and the tube support plate 6 thus exposed are exposed to radiation with the straight portion 5b of the heat transfer tube 5 contacting the primary cooling water. Therefore, it is housed in a storage container (not shown) in which radiation leakage is prevented.

  Subsequently, as shown in FIG. 10, the remaining tube plate 4 and the water chamber mirror 7 are rotated by 90 ° using the reversing mount 105 so that the tube plate 4 side is turned down. Next, as shown in FIG. 11, the tube plate 4 and the water chamber mirror 7 are cut and separated. Then, the tube plate 4 and the water chamber mirror 7 are cut into small pieces. Since the tube plate 4 and the water chamber mirror 7 thus configured are exposed to radiation in contact with the primary cooling water, they are accommodated in a storage container (not shown) in which leakage of radiation is prevented.

  Further, as shown in FIG. 4, the upper body 2 b separated from the conical body 2 c is connected to the green house 102 using the cargo handling hook 103 together with the internal members (the steam separator 9, the moisture separator 10 and the water supply pipe 11). And is cut into small pieces at a separately prepared dismantling place and stored in a storage container (not shown). As shown in FIG. 12, the cutting of the upper body 2b is dismantled with the upper mirror 2d standing up. Then, as shown in FIG. 12, first, the upper mirror 2d is cut into small pieces as indicated by a one-dot chain line. Subsequently, as shown in FIG. 13, the upper body 2 b is cut into small pieces as indicated by a one-dot chain line.

  14 to 18 are schematic views showing a method of cutting the steam generator. In the disassembling procedure described above, each part can be cut by the wire saw 20. As shown in FIGS. 14 to 18, in the wire saw 20, a diamond blade (not shown) is provided on an annular wire 20a having flexibility, and the wire 20a is circulated and fed by a cutting machine 20b. Then, the member to be cut inside the annular shape of the wire 20a is cut.

  In FIG. 14, a lower body 2a, an upper body 2b, a conical body 2c, an upper mirror 2d, a tube group outer cylinder 3, a tube support plate 6 and a water chamber mirror are cut members 21 having a cylindrical portion using a wire saw 20. 7 shows a method of cutting in the circumferential direction. That is, as shown in FIG. 14, a plurality of holes 21 a are formed along the circumferential direction of the member 21 to be cut. Next, the wire 20a of the wire saw 20 is annularly inserted between the two holes 21a, and the wire 20a is circulated and fed by the cutting machine 20b to cut between the holes 21a. Next, the wire 20a of the wire saw 20 is inserted in an annular shape between the cut portion and the other hole 21a, and the space between the two is cut to make each hole 21a continuous, and the member 21 to be cut is cut into small pieces. The cutting method shown in FIG. 14 can also be applied when cutting the member 21 to be cut in the axial direction L.

  FIG. 15 shows a method of cutting the member to be cut 21 cut into a cylindrical shape in the axial direction L using the wire saw 20 by the cutting method shown in FIG. That is, as shown in FIG. 15, the wire 20a of the wire saw 20 is inserted into the inside and outside of the cylindrical shape of the member 21 to be cut, and the wire 20a is circulated and fed by the cutting machine 20b to be cylindrical. Is cut into small pieces in the circumferential direction.

  FIG. 16 shows a method of cutting the heat transfer tube group 5 </ b> A (heat transfer tube 5) using the wire saw 20. As described above, the heat transfer tube group 5 </ b> A is a gap that is continuous in the radial direction of the body portion 2 (lower body 2 a) at the center and between the straight portions 5 b of the U-shaped heat transfer tube 5. 5c is formed. Therefore, the wire 20a of the wire saw 20 is inserted into the U-shaped gap 5c of the heat transfer tube 5 in an annular shape, and the wire 20a is circulated and fed by the cutting machine 20b to cut one end side of the U-shape of the heat transfer tube 5 together. To do. Next, the U-shaped other end side of the heat transfer tube 5 is cut together in the same manner, so that the heat transfer tube 5 is separated from the tube plate 4 side. That is, in the heat transfer tube group 5A, the wire 20a of the wire saw 20 is annularly inserted into the gap 5c formed between one linear portion 5b connected by the arc portion 5a and the other linear portion 5b, and then cut. The machine 20b circulates and feeds the wire 20a and cuts one straight portion 5b of the heat transfer tube group 5A together. Next, the other straight portion 5b of the heat transfer tube group 5A is cut together in the same manner, whereby the heat transfer tube 5 is separated from the tube plate 4 side.

  FIG. 17 shows a method of cutting the tube plate 4 (or the tube support plate 6) using the wire saw 20. The tube sheet 4 has a tube hole 4a through which the U-shaped end of the heat transfer tube 5 is inserted. The tube support plate 6 has a heat transfer tube insertion hole 6a through which the straight portion 5b of the heat transfer tube 5 is inserted. Therefore, the wire 20a of the wire saw 20 is inserted in an annular shape using the tube hole 4a (or the heat transfer tube insertion hole 6a) through which the heat transfer tube 5 is inserted, and the wire 20a is circulated and cut by the cutting machine 20b. Next, the wire 20a of the wire saw 20 is annularly inserted between the cut portion and the other tube hole 4a (or the heat transfer tube insertion hole 6a), and the space is cut between each tube hole 4a (or each heat transfer tube insertion hole). 6a) is continued in the cutting direction C, and the tube plate 4 (or the tube support plate 6) is cut into small pieces.

  In FIG. 18, the wire saw 20 has a plurality (at least two) of pulleys 20c that deform the annular shape of the wire 20a in the annular shape of the wire 20a, and cutting using the wire saw 20 having the pulley 20c is performed. Shows how. 18 to be cut includes a lower body 2a, an upper body 2b, a conical body 2c, an upper mirror 2d, a tube group outer cylinder 3, a tube plate 4, and a water chamber mirror 7. First, as shown in FIG. 18A, the wire 20a is disposed obliquely with respect to the cutting direction C by the pulley 20c to cut the corner 21b of the member 21 to be cut. Next, after cutting the corner portion 21b, the wire 20a is arranged perpendicular to the cutting direction C by the pulley 20c to cut the member 21 to be cut.

  Thus, the steam generator 1 can be cut into small pieces by the wire saw 20.

  By the way, the disassembly procedure of the steam generator 1 mentioned above is an example, and the disassembly procedure of the steam generator 1 can be considered in addition. For example, there are a disassembly procedure shown in FIGS. 19 to 21 and a disassembly procedure shown in FIGS. 22 to 28.

  The disassembling procedure shown in FIGS. 19 to 21 is different in the steps from FIG. 5 to FIG. 9 described above. That is, the disassembly procedure of the heat transfer tube group 5A (heat transfer tube 5) is different.

  As shown in FIG. 5, after the arc portion 5 a side of the heat transfer tube group 5 </ b> A appears, as shown in FIG. 19, the lower body 2 a and a part of the tube group outer cylinder 3 on the tube plate 4 side are separated. Thereby, the tube sheet 4 side of the heat transfer tube group 5A appears.

  Subsequently, as shown in FIG. 20, the arc portion 5 a of the heat transfer tube 5 and the end portion on the tube plate 4 side of the straight portion 5 b of the heat transfer tube 5 fixed to the tube plate 4 are cut.

  Subsequently, as shown in FIG. 21, the heat transfer tube processing device 30 is installed in the green house 102 on the side where the arc portion 5 a of the heat transfer tube 5 is removed. The heat transfer tube processing device 30 includes a frame 31, an inspection unit 32, a compression unit 33, and a bending unit 34. The frame 31 is fixed to the green house 102. The inspection unit 32 is provided on the frame 31 and inspects the heat transfer tube 5 in a nondestructive manner. Non-destructive inspection includes, for example, eddy current inspection. As an inspection item, a plug, a sleeve, or the like provided for repairing the heat transfer tube 5 is discovered. For example, as shown in FIG. 21, the compression unit 33 compresses and crushes the heat transfer tube 5 between a pair of rollers in a flat shape. That is, the compression unit 33 reduces the volume from the tubular heat transfer tube 5 by crushing the heat transfer tube 5. In addition, the compression part 33 is provided so that the strength of the compression force which compresses the heat exchanger tube 5 can be adjusted by changing the space | interval of a pair of roller. The bent portion 34 is formed by bending or folding the heat transfer tube 5. Specifically, in the deformation of bending the heat transfer tube 5 by the bent portion 34, the heat transfer tube 5 is wound in a spiral shape by rotating a rotating shaft that holds the end of the heat transfer tube 5, as shown in FIG. To. The bent portion 34 reduces the maximum passing dimension from the linear heat transfer tube 5 by deforming the heat transfer tube 5 by bending or bending it. In addition, the bending part 34 is provided so that the strength of the bending force which bends the heat transfer tube 5 can be adjusted by changing the rotational torque of the rotating shaft.

  Then, as shown in FIG. 21, from the side where the arc portion 5a of the heat transfer tube 5 is removed, the straight portion 5b of the heat transfer tube 5 is extended along its extending direction (axial direction L). Pull out straight from part 2. The straight portion 5b of the heat transfer tube 5 is pulled out by, for example, fixing the tip of the wire to the end of the straight portion 5b from which the arc portion 5a of the heat transfer tube 5 is removed, and pulling the wire. Here, the base end of the wire is fixed to the bent portion 34, and the wire is pulled by the bent portion 34. The drawn straight portion 5b of the heat transfer tube 5 passes through the inspection portion 32, undergoes nondestructive inspection, is compressed through the compression portion 33, and is bent through the bent portion 34. Then, the straight portions 5b of all the heat transfer tubes 5 are similarly drawn out and processed. Further, when a plug, a sleeve, or the like is found in the heat transfer tube 5 by nondestructive inspection by the inspection unit 32, the compression force in the compression unit 33 or the bending force in the bending unit 34 is increased and adjusted.

  After the heat transfer tube 5 is disassembled, the remaining lower body 2a, tube group outer tube 3, and tube support plate 6 are cut into small pieces. As a result, the tube plate 4 and the water chamber mirror 7 are left as shown in FIG.

  In the disassembling procedure shown in FIGS. 19 to 21 as well, the wire saw 20 is used to cut a small size similarly to the cutting method described above.

  In the dismantling procedure shown in FIGS. 22 to 28, the steam generator 1 installed in an upright state is disassembled in the reactor containment vessel 111 as it is. As shown in FIG. 22, the steam generator 1 is surrounded by a steam generator chamber wall 111a of a concrete structure including concrete and steel, and is positioned and fixed to the steam generator chamber wall 111a with a steel material or the like. Yes. As described above, the steam generator 1 is positioned and fixed in the reactor containment vessel 111 while being surrounded by the steam generator chamber wall 111a, thereby achieving earthquake resistance. Further, although not shown in the figure, the upper part of the reactor containment vessel 111 has a structure inside the reactor containment vessel 111, for example, a container lid in the pressurized water reactor 112, or a structure inside the pressurized water reactor 112. A polar crane is provided for the purpose of lifting the core structure.

  In dismantling the steam generator 1, first, the inlet nozzle 7Aa (see FIG. 2) is disconnected from the cooling water pipe 114 (see FIG. 1), and the outlet nozzle 7Ba (see FIG. 2) is connected to the cooling water pipe. 115 (see FIG. 1). The inlet nozzle 7Aa and the outlet nozzle 7Ba may remain connected to the cooling water pipe 114 and the cooling water pipe 115.

  Subsequently, as shown in FIG. 23, the upper body 2b and the upper mirror 2d are cut from the cone body 2c. Then, the cut upper trunk 2b side (including the upper mirror 2d, the steam separator 9, the moisture separator 10 and the water supply pipe 11) is lifted by a polar crane and outside the steam generator chamber wall 111a. It is transported into the furnace containment vessel 111 and removed.

  Subsequently, as shown in FIG. 24, the conical cylinder 2c is cut from the lower cylinder 2a, and the conical part 3b of the tube group outer cylinder 3 is cut from the cylindrical part 3a. Then, the separated conical cylinder 2c and the conical portion 3b are lifted by a polar crane, transported into the reactor containment vessel 111 outside the steam generator chamber wall 111a, and removed. Thereby, the circular arc part 5a of the heat exchanger tube 5 appears. The removed cone body 2c and the cone portion 3b are cut into small portions in the reactor containment vessel 111.

  Subsequently, as shown in FIG. 25, the arc portion 5a of the heat transfer tube 5 is cut, lifted by a polar crane, and transported and removed into the reactor containment vessel 111 outside the steam generator chamber wall 111a.

  Subsequently, as shown in FIG. 26, a part of the upper side of the lower body 2 a and a part of the upper side of the tube group outer cylinder 3 are cut based on the arrangement interval of the tube support plates 6, and the tube support plates 6 of that portion are cut. Are respectively lifted by a polar crane, transported into the reactor containment vessel 111 outside the steam generator chamber wall 111a, and removed. Thereby, a part of upper part of the heat exchanger tube 5 appears. Part of the removed lower shell 2a, part of the tube group outer cylinder 3, and the tube support plate 6 are cut into small pieces in the reactor containment vessel 111.

  Subsequently, a part of the upper side of the lower body 2a, a part of the upper side of the tube group outer cylinder 3, and a part of the upper side of the straight portion 5b of the heat transfer tube 5 which is obtained by removing the tube support plate 6 are directly below the part. The pipe support plate 6 is cut based on the interval between the pipe support plates 6 and lifted by a polar crane, and is removed from the steam generator chamber wall 111a outside the steam generator chamber wall 111a. In this case, it is preferable to cut the lower end (lower end on the tube support plate 6 immediately below) of the heat transfer tube 5 while suspending the upper end of the heat transfer tube 5 with a polar crane, and suspending the plurality of heat transfer tubes 5 at the same time. More preferred. The heat transfer tube 5 is finely disassembled in the reactor containment vessel 111, or compressed, or bent small.

  Subsequently, as shown in FIG. 27, the above steps are repeated downward until all the heat transfer tubes 5, the lower shell 2a, the tube group outer tube 3, and the tube support plate 6 are removed.

  Subsequently, as shown in FIG. 27, in a state where the tube plate 4 and the water chamber mirror 7 are integrated, the tube is lifted by a polar crane as it is, outside the steam generator chamber wall 111a and in the reactor containment vessel 111. Remove it by transporting it in. As shown in FIG. 11, the tube plate 4 and the water chamber mirror 7 are cut into small pieces after being cut. Alternatively, as shown in FIG. 28, the tube plate 4 and the water chamber mirror 7 are separated from the water chamber mirror 7 by lifting the tube plate 4 from the water chamber mirror 7 and lifting the tube plate 4 from the steam generator chamber wall 111a. Alternatively, the water chamber mirror 7 may be lifted by a polar crane and transported into the reactor containment vessel 111 outside the steam generator chamber wall 111a to be removed.

  Also in the disassembling procedure shown in FIGS. 22 to 28, the wire saw 20 is used to cut a small size in the same manner as the cutting method described above.

  As described above, in the method of disassembling the steam generator 1 according to the present embodiment, the upper body 2b whose upper end is closed on the upper side of the cylindrical body 2 and the tube on the lower side on the lower side of the body 2 are arranged. A plurality of heat transfer tubes 5 formed in an inverted U shape in the lower body 2a. The lower body 2a includes a lower body 2a provided with a plate 4 and a water chamber mirror 7 provided below the tube plate 4. Each of the water chambers 7A and 7B is inserted and supported by a plurality of upper and lower tube support plates 6 in a state surrounded by the group outer cylinder 3, and each end portion is inserted and fixed in the tube plate 4 and divided in the water chamber mirror 7. The steam generator 1 dismantling method provided in communication with each other includes a step of cutting the body 2 into an upper body 2b side and a lower body 2a side, and a lower body 2a and a tube group outer tube 3 A step of partially removing and exposing the heat transfer tube 5, one straight portion 5 b and the other straight portion 5 b constituting the U-shape of the exposed heat transfer tube 5, The step of inserting the wire 20a of the wire saw 20 into the gap 5c and cutting one U-shaped straight portion 5b of the heat transfer tube 5 together, and the other U-shaped straight portion 5b of the exposed heat transfer tube 5 In the same manner, and cutting.

  According to this method of disassembling the steam generator 1, the wire transfer saw 5 cuts the U-shaped one straight part 5b and the other straight part 5b of the plurality of heat transfer pipes 5 together, thereby The work time for cutting can be further shortened. In particular, the wire 20a of the wire saw 20 is inserted into a gap 5c between one straight portion 5b of the U-shape of the plurality of heat transfer tubes 5 and the other straight portion 5b, and one straight line of the U-shape of the plurality of heat transfer tubes 5 is inserted. By cutting the part 5b and the other straight part 5b together, the frictional resistance applied to the wire 20a of the wire saw 20 is reduced, so that the consumption of the wire 20a is suppressed. For this reason, it is possible to reduce the exchange of the wire 20a and improve the working efficiency. As a result, the steam generator 1 can be rationally disassembled.

  In the method for disassembling the steam generator 1 according to the present embodiment, a step of providing a plurality of holes 21a along the cutting direction in the lower body 2a or the tube group outer tube 3, and then two holes 21a. A step of inserting the wire 20a of the wire saw 20 between them and cutting the space between them, and then inserting the wire 20a of the wire saw 20 between the cut portion and the other hole 21a and cutting the space between them. 21a is made continuous, and the lower body 2a or the tube group outer cylinder 3 is cut into small pieces.

  According to the method of disassembling the steam generator 1, compared with the method of cutting the wire 20a of the wire saw 20 around the outer side of the lower barrel 2a or the tube group outer tube 3 in the circumferential direction, the lower barrel 2a is formed by the hole 21a. Alternatively, by partially cutting the tube group outer tube 3 along the cutting direction, the frictional resistance applied to the wire 20a is reduced, so that the consumption of the wire 20a is suppressed. For this reason, it is possible to reduce the exchange of the wire 20a and improve the working efficiency. As a result, the steam generator 1 can be rationally disassembled.

  Moreover, in the dismantling method of the steam generator 1 of this embodiment, a plurality of holes 21a are provided along the circumferential direction between the tube plate 4 from which all the heat transfer tubes 5 are cut and the water chamber mirror 7. Next, the step of inserting the wire 20a of the wire saw 20 between the two holes 21a and cutting the gap between the two holes 21a, and the step of inserting the wire 20a of the wire saw 20 between the cut portion and the other hole 21a. A step of inserting and cutting the space between the holes 21a to separate the tube plate 4 and the water chamber mirror 7 from each other.

  According to this dismantling method of the steam generator 1, compared with the method of cutting the wire 20a of the wire saw 20 in the circumferential direction between the tube plate 4 and the water chamber mirror 7, the tube plate 4 is cut by the hole 21a. Since the frictional resistance applied to the wire 20a is reduced by partially cutting along the cutting direction for separating the water chamber mirror 7 and the water chamber mirror 7, wear of the wire 20a is suppressed. For this reason, it is possible to reduce the exchange of the wire 20a and improve the working efficiency. As a result, the steam generator 1 can be rationally disassembled.

  Moreover, in the dismantling method of the steam generator 1 of this embodiment, about the tube plate 4 separated from the water chamber mirror 7, a wire saw is used using the tube hole 4a of the tube plate 4 through which the heat transfer tube 5 is inserted. The step of inserting and cutting the 20 wires 20a, and then inserting the wire 20a of the wire saw 20 between the cut portion and the other tube hole 4a and cutting the space between them to make each tube hole 4a continuous. Cutting the tube sheet 4 into small pieces.

  According to this dismantling method of the steam generator 1, compared with the method of cutting the wire 20a of the wire saw 20 around the tube plate 4, the tube plate 4 is cut along the cutting direction using the tube hole 4a. Since the frictional resistance applied to the wire 20a is reduced by partially cutting the wire 20a, consumption of the wire 20a is suppressed. For this reason, it is possible to reduce the exchange of the wire 20a and improve the working efficiency. As a result, the steam generator 1 can be rationally disassembled.

  Moreover, in the dismantling method of the steam generator 1 of the present embodiment, for the water chamber mirror 7 separated from the tube plate 4, a step of providing a plurality of holes 21a in the water chamber mirror 7 along the cutting direction; Next, the step of inserting the wire 20a of the wire saw 20 between the two holes 21a and cutting the gap between the two holes 21a, and then inserting the wire 20a of the wire saw 20 between the cut portion and the other hole 21a A step of cutting the space between the levers to make the holes 21a continuous and cutting the water chamber mirror 7 small.

  According to the method for disassembling the steam generator 1, the water chamber mirror 7 is partially cut along the cutting direction by the hole 21a as compared with the method of cutting the wire 20a of the wire saw 20 around the water chamber mirror 7. Since the frictional resistance applied to the wire 20a is reduced by cutting the wire 20a, the consumption of the wire 20a is suppressed. For this reason, it is possible to reduce the exchange of the wire 20a and improve the working efficiency. As a result, the steam generator 1 can be rationally disassembled.

  Further, in the method of disassembling the steam generator 1 of the present embodiment, when the upper body 2b side is cut small, a step of providing a plurality of holes 21a along the cutting direction in the upper body 2b, The step of inserting the wire 20a of the wire saw 20 between the two holes 21a and cutting the gap between the two holes 21a, and then cutting the gap between the cut portion and the other hole 21a by inserting the wire 20a of the wire saw 20 And a step of continuously cutting the upper body 2b by making the holes 21a continuous.

  According to this method of disassembling the steam generator 1, compared to the method of cutting the wire 20a of the wire saw 20 around the outer side of the upper barrel 2b in the circumferential direction, the upper barrel 2b is cut along the cutting direction by the hole 21a. By partially cutting, the frictional resistance applied to the wire 20a is reduced, so that the consumption of the wire 20a is suppressed. For this reason, it is possible to reduce the exchange of the wire 20a and improve the working efficiency. As a result, the steam generator 1 can be rationally disassembled.

  Further, in the method of disassembling the steam generator 1 of the present embodiment, the step of cutting the body portion 2 into a cylindrical shape and the wire 20a of the wire saw 20 are inserted into the inside and outside of the cylindrical shape to make it small. Cutting.

  According to the method for disassembling the steam generator 1, the body 2 is cut into a cylindrical shape, and the wire 20a of the wire saw 20 is inserted into the inside and outside of the cylindrical shape and cut into small pieces. Since the frictional resistance applied to the wire 20a is reduced, the consumption of the wire 20a is suppressed. For this reason, it is possible to reduce the exchange of the wire 20a and improve the working efficiency. As a result, the steam generator 1 can be rationally disassembled.

  Further, in the method for disassembling the steam generator 1 of the present embodiment, the pulley 20c that deforms the form of the wire 20a of the wire saw 20 is provided, and the wire 20a is disposed obliquely with respect to the cutting direction by the pulley 20c. Cutting the corner 21b of the member to be cut 21, and cutting the corner 21b and then cutting the member 21 by placing the wire 20a perpendicular to the cutting direction with the pulley 20c. ,including.

  According to the method for disassembling the steam generator 1, the wire 20a is started by cutting the corner portion 21b of the member to be cut 21 rather than arranging the wire 20a along the end face of the member to be cut 21 and starting cutting. Since the frictional resistance is reduced, cutting is easy and consumption of the wire 20a is suppressed. For this reason, it is possible to reduce the exchange of the wire 20a and improve the working efficiency. As a result, the steam generator 1 can be rationally disassembled.

DESCRIPTION OF SYMBOLS 1 Steam generator 2 Body part 2a Lower body 2b Upper body 2c Conical body 2d Upper mirror 3 Tube group outer cylinder 3a Cylindrical part 3b Conical part 4 Tube plate 4a Tube hole 5A Heat transfer tube group 5 Heat transfer tube 5a Arc part 5b Linear part 5c Gap 6 Tube support plate 6a Heat transfer tube insertion hole 7 Water chamber mirror 7B Exit side water chamber 7A Inlet side water chamber 8 Bulkhead 20 Wire saw 20a Wire 20b Cutting machine 20c Pulley 21 Cut member 21a Hole 21b Corner

Claims (8)

It has an upper barrel whose upper end is closed on the upper side of the cylindrical barrel, and a lower barrel which is provided with a tube sheet at the lower end and a water chamber mirror on the lower side of the barrel. A plurality of heat transfer tubes formed in an inverted U shape in the lower body are inserted and supported by a plurality of upper and lower tube support plates in a state surrounded by a tube group outer cylinder, and each end portion is the tube plate A steam generator dismantling method provided in communication with each water chamber that is inserted and fixed to the water chamber divided in the water chamber mirror,
Cutting the body part into the upper body side and the lower body side;
Partially removing the lower body and the tube group outer cylinder to expose the heat transfer tube;
Inserting a wire of a wire saw into a gap between one straight line portion and the other straight line portion constituting the U-shape of the exposed heat transfer tube, and cutting the one straight line portion of the heat transfer tube together; ,
Next, the step of collectively cutting the other U-shaped straight part of the heat transfer tube that is exposed after the one straight part,
A method for disassembling a steam generator, comprising: A step of providing a plurality of holes along a cutting direction in the lower trunk or the tube group outer cylinder;
Next, inserting a wire saw wire between the two holes and cutting between them,
Next, a step of inserting a wire saw wire between the cut portion and the other hole and cutting the space between the holes to continuously cut the lower trunk or the tube group outer cylinder,
The steam generator disassembly method according to claim 1, wherein the steam generator is disassembled. Providing a plurality of holes along the circumferential direction between the tube plate from which all the heat transfer tubes have been cut and the water chamber mirror;
Next, inserting a wire saw wire between the two holes and cutting between them,
Next, a step of inserting a wire saw wire between the cut portion and the other hole and cutting the gap between the holes to separate the tube sheet and the water chamber mirror,
The steam generator disassembly method according to claim 1, wherein the steam generator is disassembled. About the tube plate separated from the water chamber mirror,
Inserting and cutting a wire saw wire using a tube hole of the tube plate through which the heat transfer tube is inserted; and
Next, a step of inserting a wire saw wire between the cut portion and the other tube hole, cutting the space between them and continuing each tube hole to cut the tube plate small,
The method for disassembling a steam generator according to claim 3. About the water chamber mirror separated from the tube plate,
Providing the water chamber mirror with a plurality of holes along a cutting direction;
Next, inserting a wire saw wire between the two holes and cutting between them,
Next, a step of inserting a wire saw wire between the cut portion and the other hole, cutting the space between the holes, and continuously cutting the water chamber mirror,
The method for disassembling a steam generator according to claim 3. When cutting the upper trunk side small,
Providing the upper body with a plurality of holes along the cutting direction;
Next, inserting a wire saw wire between the two holes and cutting between them,
Next, a step of inserting a wire saw wire between the cut portion and the other hole and cutting the space between the holes to continuously cut the upper body,
The steam generator disassembly method according to claim 1, wherein the steam generator is disassembled. Cutting the barrel into a tubular form;
Inserting a wire saw wire into the inside and outside of the cylindrical shape and cutting it into small pieces;
The steam generator disassembly method according to claim 1, wherein the steam generator is disassembled. It has a pulley that deforms the wire form of the wire saw,
Cutting the corner of the member to be cut by arranging the wire obliquely with respect to the cutting direction by the pulley; and
Cutting the member to be cut by cutting the corner and then placing the wire perpendicular to the cutting direction by the pulley; and
The steam generator disassembly method according to claim 1, wherein the steam generator is disassembled.

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