Method and apparatus for dismantling a calandria container underwater

Abstract

The present invention provides an underwater dismantling method and apparatus that can safely dismantle a calandria vessel and fuel lines while reducing worker exposure, using various devices attached to an operating mechanism installed in the calandria vessel. [Solution] The present invention provides an underwater dismantling method that includes a step of filling the inside of a concrete bolt in which a calandria container is provided with water, a step of dismantling the RM-deck to release the concrete bolt, a step of installing an operating device, a step of cutting and dismantling the upper part of the calandria container and the fuel pipes located inside it, and a step of cutting and dismantling the lower part of the container and the fuel pipes located inside the lower part.

Description

Technical Field

[0001] The present invention relates to an underwater dismantling method and device for a calandria vessel, and more particularly, to an underwater dismantling method and device for a calandria vessel that can safely dismantle the calandria vessel and fuel pipes in an underwater environment while reducing radiation exposure of workers, by using various types of devices attached to an operating machine provided on the calandria vessel.

Background Art

[0002] Generally, among nuclear facilities used for nuclear power generation, a heavy water reactor facility includes a calandria, a calandria vault that houses the calandria therein, and known components located inside and outside the calandria. Conventionally, there have been cases where some of the components located inside and outside the calandria have been replaced, but there are no cases where the entire heavy water reactor facility including the calandria has been dismantled.

[0003] When dismantling a reactor of a heavy water reactor-type nuclear facility, radiation exposure occurs due to the dismantling. Therefore, it is required to prevent such exposure and reduce or prevent the occurrence of contamination due to diffusion of radioactive contaminants and the like. However, at present, there is a problem that measures for stable and effective dismantling of heavy water reactor-type nuclear power plants either do not exist or are insufficient.

Summary of the Invention

Problem to be Solved by the Invention

[0004] An object of the present invention is to provide an underwater dismantling method and device for a calandria vessel that can safely dismantle the calandria vessel and fuel pipes in an underwater environment while reducing radiation exposure of workers, by using various types of devices attached to an operating machine provided on the calandria vessel.

[0005] The technical problems that this invention aims to solve are not limited to those described above, and other technical problems not mentioned will be clearly understood by those with ordinary skill in the art to which this invention pertains from the following description. [Means for solving the problem]

[0006] To solve the above problems, one embodiment of the present invention provides a method for dismantling a calandria container underwater, comprising: a filling step of filling the inside of a concrete vault on which a calandria container is provided with water; an opening step of dismantling an RM-deck (Reactivity-Mechanism deck) to release the concrete vault; an installation step of installing an operating device in the calandria container; an upper part dismantling step of using the operating device to cut and dismantle the upper part of the calandria container and the fuel pipes located inside the upper part of the calandria container; and a lower part dismantling step of using the operating device to cut and dismantle the lower part of the calandria container and the fuel pipes located inside the lower part of the calandria container.

[0007] In one embodiment, the operating device in the installation step is provided on rails at both ends of the calandria container, and the operating device in the upper dismantling step and the lower dismantling step is movable along the rails in the circumferential direction of the calandria container.

[0008] Depending on the embodiment, the upper dismantling step may include a first container dismantling step of cutting the upper part of the calandria container using a first cutting device and a second cutting device attached to the operating device, and a first fuel pipe dismantling step of cutting both ends of the fuel pipes located inside the upper part of the calandria container using a second cutting device attached to the operating device.

[0009] Depending on the embodiment, the lower dismantling step may include a second fuel pipe dismantling step of cutting both ends of the fuel pipes located inside the lower part of the calandria container using a second cutting device attached to the operating device, and a second container dismantling step of cutting the lower part of the calandria container using a first cutting device and a second cutting device attached to the operating device.

[0010] Depending on the embodiment, the process may further include, prior to the first container dismantling step, mounting a pair of first cutting devices to the operating machine so as to be spaced apart from each other in the circumferential and longitudinal directions of the calandria container, and mounting a pair of second cutting devices so as to be spaced apart from each other in the circumferential and longitudinal directions of the calandria container.

[0011] Depending on the embodiment, a first swapping step may be further included, after the first container dismantling step and before the first fuel pipe dismantling step, in which the pair of second cutting devices are mounted on the operating device parallel to each other and facing each other in the longitudinal direction of the calandria container.

[0012] Depending on the embodiment, a second swapping step may be further included, after the second fuel pipe dismantling step and before the second vessel dismantling step, in which the pair of first cutting devices and the pair of second cutting devices are swapped in the operating device so that the pair of first cutting devices are mounted on the operating device so that they are spaced apart from each other in the circumferential and longitudinal directions of the calandria vessel, and the pair of second cutting devices are mounted so that they are spaced apart from each other in the circumferential and longitudinal directions of the calandria vessel.

[0013] In some embodiments, during the first fuel pipe dismantling step and the second fuel pipe dismantling step, both ends of the fuel pipe may be simultaneously cut by a pair of second cutting devices mounted on the operating device parallel to each other and facing each other in the longitudinal direction of the calandria container.

[0014] To solve the above problems, one embodiment of the present invention provides an underwater dismantling device for a calandria container, comprising: rail sections provided at both ends of a calandria container disposed inside a concrete bolt; an operating device provided on the rail sections; a first cutting device attached to the operating device for cutting the calandria container; and a second cutting device attached to the operating device for cutting the calandria container and fuel pipes disposed inside the calandria container.

[0015] In one embodiment, the rail section is a double rail, provided on the upper side of the calandria container, and expandable toward the lower side of the calandria container.

[0016] In some embodiments, the operating device includes a main body provided on the rail so as to traverse the longitudinal direction of the calandria container, and a pair of movable parts provided on the main body so as to be movable along the longitudinal direction, each having a first extending part extending in one direction along the circumferential direction of the calandria container and a second extending part extending in the other direction, wherein the first extending part is provided with a first mounting part to which the first cutting device is attached, and the second extending part is provided with a second mounting part to which the second cutting device is attached.

[0017] In one embodiment, the first cutting device is movable in the longitudinal direction relative to the first mounting portion and in a vertical direction toward or away from the calandria container.

[0018] In one embodiment, the second mounting portion is movable along the circumferential direction on the second extending portion.

[0019] In some embodiments, the second cutting device includes a second wheel saw, the second wheel saw being vertically movable within the second cutting device toward or away from the calandria container.

[0020] Depending on the embodiment, each of the movable parts may be detachably provided on the main body, and when cutting the calandria container, the first mounting portion of one of the pair of movable parts and the second mounting portion of the other may be arranged parallel to each other in the longitudinal direction, and when cutting the fuel pipe, the second mounting portion of one of the pair of movable parts and the second mounting portion of the other may be arranged parallel to each other in the longitudinal direction. [Effects of the Invention]

[0021] According to the present invention, by using various types of devices attached to an operating device installed in the calandria vessel, the calandria vessel and fuel pipes can be safely dismantled in an underwater environment while reducing the radiation exposure of workers. In particular, since the RM-deck is dismantled and the concrete bolts are opened after the inside of the concrete bolts are filled with water, radioactive contaminants inside the concrete bolts do not disperse, and the radiation exposure of workers can be reduced.

[0022] Furthermore, by adjusting the installation direction of the movable part, the arrangement of the pair of first cutting devices and the pair of second cutting devices attached to the operating device can be effectively changed. Specifically, when cutting a calandria container, the pair of first cutting devices and the pair of second cutting devices may be arranged intersecting (diagonally), and when cutting a fuel pipe, the pair of second cutting devices may be arranged parallel to each other so that both ends of the fuel pipe are cut simultaneously. This allows for effective cutting of both the calandria container and the fuel pipe.

[0023] The effects of the present invention are not limited to those described above, but should be understood to include all effects that can be inferred from the detailed description of the present invention or the configuration of the invention as described in the claims. [Brief explanation of the drawing]

[0024] [Figure 1] This figure shows a method for dismantling a calandria container underwater according to one embodiment of the present invention. [Figure 2]FIG. 1 is a diagram showing a state after a water filling step in FIG. 1. [Figure 3] FIG. 1 is a diagram showing a state of a calandria vessel after an installation step and an attachment step in FIG. 1. [Figure 4] It is a diagram showing a state where a rail portion in FIG. 3 is expanded. [Figure 5] It is a separated diagram showing an underwater dismantling apparatus for a calandria vessel in FIG. 3. [Figure 6] It is a diagram showing a state where a first cutting device cuts an upper portion of the calandria vessel during a first vessel dismantling step of FIG. 1, with a second cutting device omitted. [Figure 7] It is a partially enlarged view of FIG. 6. [Figure 8] It is a diagram showing a state where a second cutting device cuts a fuel tube during a first fuel tube dismantling step of FIG. 1. [Figure 9] It is a diagram showing a state after the first fuel tube dismantling step of FIG. 1 and before a second fuel tube dismantling step, with the first cutting device omitted. DESCRIPTION OF EMBODIMENTS

[0025] Hereinafter, preferred embodiments of the underwater dismantling method and apparatus for a calandria vessel according to the present invention will be described with reference to the accompanying drawings.

[0026] In addition, terms described below are defined in consideration of the functions in the present invention, and may vary depending on the intentions or conventions of users and operators. The following embodiments do not limit the scope of rights of the present invention, and are merely illustrative matters of the components presented in the claims of the present invention.

[0027] In order to clearly describe the present invention, portions unrelated to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification. Throughout the specification, when it is described that a certain portion "comprises" a certain component, unless specifically stated to the contrary, this does not mean that other components are excluded, but means that other components can be further included.

[0028] Furthermore, throughout the specification, components referred to as "~part" may be two or more components combined into one, or one component may be subdivided into two or more based on more detailed functions. In addition, each of the components described below may perform some or all of the functions performed by other components, in addition to its own main function, and it goes without saying that some of the functions of the main function performed by each component may be exclusively performed by other components.

[0029] A method for dismantling a calandria container underwater according to one embodiment of the present invention includes a water filling step (S1), an opening step (S2), an installation step (S3), an upper part dismantling step (S4), and a lower part dismantling step (S5).

[0030] In the filling step (S1), the inside of the concrete bolt 100, which is equipped with a calandria container 200, is filled with water. Figure 2 shows the state after the filling step (S1), showing that the calandria container 200 is completely submerged in water. The concrete bolt 100 is closed off by the RM-deck (Reactivity-Mechanism deck) 10 covering the top.

[0031] In the opening step (S2), the RM-deck 10 is dismantled and the concrete bolts 100 are opened. Since the concrete bolts 100 are opened after the inside of the concrete bolts 100 are filled with water, the radioactive contaminants inside the concrete bolts 100 do not spread, and the exposure of workers to radiation can be reduced.

[0032] After the RM-deck 10 is dismantled in the opening step (S2), a vertical reactivity structure dismantling step (S6) can be performed to dismantle the vertical reactivity structure, which includes a vertical reactivity controller 20 that is inserted into the protruding lugs 210 of the calandria vessel 200 and extends to the RM-deck 10.

[0033] In the installation step (S3) following the opening step (S2), the operating device 400 is installed in the calandria container 200. As shown in Figure 3, in this embodiment, rail sections 220 are provided at both ends of the calandria container 200. More specifically, the rail sections 220 may be provided on auxiliary cells 201 which are at both ends of the calandria container 200. Thus, in the installation step (S3), the operating device 400 is installed on the rail section 220, and thereafter, in the upper dismantling step (S4) and the lower dismantling step (S5), the operating device 400 is movable along the rail section 220 in the circumferential direction of the calandria container 200.

[0034] In this embodiment, the rail section 220 is expandable because it is a double rail. As shown in Figure 4, the rail section 220 is provided on the upper side of the calandria container 200 and is expandable toward the lower side of the calandria container 200. This allows the operating device 400 to move not only to the upper side but also to the lower side of the calandria container 200, and various types of devices attached to the operating device 400 can be used to safely dismantle the calandria container 200 and fuel pipes 300 in an underwater environment while reducing worker exposure to radiation.

[0035] The detailed structure of the operating device 400 will be examined with reference to Figure 5. The operating device 400 includes a main body 410 provided on the rail section 220 so as to traverse the longitudinal direction of the calandria container 200, and a pair of movable parts 420a and 420b provided on the main body 410 so as to be movable along the longitudinal direction, each having a first extending part 421 extending in one direction along the circumferential direction of the calandria container 200 and a second extending part 422 extending in the other direction.

[0036] The first extension 421 is provided with a first mounting portion 430 to which the first cutting device 500 is attached, and the second extension 422 is provided with a second mounting portion 440 to which the second cutting device 600 is attached. Figure 6 shows the first mounting portion 430 without the first cutting device 500 attached, and Figure 9 shows the second mounting portion 440 without the second cutting device 600 attached.

[0037] Subsequently, the calandria container 200 and the fuel pipes 300 located inside it are dismantled. First, an upper dismantling step (S4) is performed in which the upper part of the calandria container 200 and the fuel pipes 300 located inside the upper part of the calandria container 200 are cut and dismantled using an operating device 400. Then, a lower dismantling step (S5) is performed in which the lower part of the calandria container 200 and the fuel pipes 300 located inside the lower part of the calandria container 200 are cut and dismantled using an operating device 400.

[0038] Specifically, the upper dismantling step (S4) includes a first container dismantling step (S4-1) in which the upper part of the calandria container 200 is cut using a first cutting device 500 and a second cutting device 600 attached to the operating device 400, and a first fuel pipe dismantling step (S4-2) in which both ends of the fuel pipe 300 located inside the upper part of the calandria container 200 that is exposed after the first container dismantling step (S4-1) are cut using a second cutting device 600 attached to the operating device 400.

[0039] When dismantling the upper part of the calandria container 200, the fuel pipe 300 is located inside the calandria container 200, and because the calandria container 200 has a cylindrical shape, the fuel pipe 300 cannot be dismantled due to interference unless the calandria container 200 is dismantled first.

[0040] Prior to the first container dismantling step (S4-1), an attachment step (S7) is performed in which the first cutting device 500 and the second cutting device 600 are attached to the operating device 400. At this time, it is desirable that the pair of first cutting devices 500 are attached so as to be spaced apart from each other in the circumferential and longitudinal directions of the calandria container 200, and the pair of second cutting devices 600 are attached so as to be spaced apart from each other in the circumferential and longitudinal directions of the calandria container 200. That is, as shown in Figure 5, when cutting the calandria container 200, the pair of first cutting devices 500 and the pair of second cutting devices 600 may both be arranged intersecting (diagonally).

[0041] For this reason, when cutting the calandria container 200, the first mounting portion 430 and the second mounting portion 440 of the pair of movable portions 420a and 420b are arranged parallel to each other in the longitudinal direction. That is, the first mounting portion 430 and the second mounting portion 440 are arranged parallel to each other in both area A, which is one side of the main body portion 410, and area B, which is the other side. With this arrangement, the calandria container 200 can be cut effectively.

[0042] For example, while moving the movable part 420a longitudinally relative to the main body 410, the calandria container 200 can be cut longitudinally using the first cutting device 500 of area A attached to the first mounting part 430 of the movable part 420a. Then, while moving the entire operating device 400 circumferentially along the rail part 220, the calandria container 200 can be cut circumferentially using the second cutting device 600 of area A attached to the second mounting part 440 of the movable part 420b. After that, while moving the movable part 420b longitudinally relative to the main body 410, the calandria container 200 can be cut longitudinally using the first cutting device 500 of area B attached to the first mounting part 430 of the movable part 420b. Then, while moving the entire operating device 400 circumferentially along the rail part 220, the calandria container 200 can be cut circumferentially using the second cutting device 600 of area B attached to the second mounting part 440 of the movable part 420a.

[0043] The upper part of the cut calandria container 200 may be lifted by a separate lifting device such as a crane and transported outside the concrete bolt 100.

[0044] In the first container dismantling step (S4-1), the upper part of the calandria container 200 may be cut all at once, or it may be cut in multiple pieces.

[0045] However, the invention is not limited to this, and if necessary, when cutting the calandria container 200, one first mounting portion 430 of the pair of movable portions 420a, 420b and the other first mounting portion 430, and one second mounting portion 440 and the other second mounting portion 440 may be arranged parallel to each other in the longitudinal direction.

[0046] As shown by the arrows in Figures 5 and 7, the first cutting device 500 is movable longitudinally relative to the first mounting portion 430 and vertically relative to the calandria container 200, either closer to or further away from it. This allows the first cutting device 500 to be moved upward when not in use to avoid interference with the calandria container 200 or the fuel pipe 300.

[0047] As indicated by the arrows in Figures 5 and 8, the second mounting portion 440 is movable along the circumferential direction on the second extension portion 422. The second cutting device 600 also includes a second wheel saw 610, which is vertically movable within the second cutting device 600 to move closer to or further away from the calandria container 200. This allows the second cutting device 600 to be moved upward to avoid interference with the calandria container 200 or the fuel pipe 300 when not in use. However, in some cases, instead of the second wheel saw 610 moving vertically within the second cutting device 600, the second cutting device 600 may be vertically movable relative to the second mounting portion 440.

[0048] In this embodiment, both the calandria container 200 and the fuel pipe 300 are cut by a mechanical cutting method. Thus, the first cutting device 500 includes a first wheel saw 510, and the second cutting device 600 includes a second wheel saw 610. In this case, the diameter of the second wheel saw 610 is larger than the diameter of the first wheel saw 510. This is because the second wheel saw 610 must cut the fuel pipe 300, as will be described later, and the fuel pipe 300 is a double pipe including a calandria pipe and a pressure pipe located inside the calandria pipe. For example, the first wheel saw 510 may be a disc wheel saw, and the second wheel saw 610 may be a diamond wheel saw.

[0049] The calandria vessel 200 is made of stainless steel and needs to be worked from RM-deck 10 to a depth of 15m. The fuel tube 300 is made of Zircaloy alloy, so its brittleness is increased by neutrons, and a mechanical cutting method that can be operated at a low speed can be applied.

[0050] In the first fuel pipe dismantling step (S4-2), it is desirable that both ends of the fuel pipe 300 be simultaneously cut by a pair of second cutting devices 600 mounted on the operating device 400, which are parallel to each other and facing each other in the longitudinal direction of the calandria container 200.

[0051] For this purpose, after the first container dismantling step (S4-1) and before the first fuel pipe dismantling step (S4-2), a first swapping step (S8) can be performed to swap the arrangement of the pair of first cutting devices 500 and the pair of second cutting devices 600 so that the pair of second cutting devices 600 are mounted on the operating device 400 in a longitudinal direction, facing each other and parallel to one another.

[0052] Each of the movable parts 420a and 420b is detachably attached to the main body 410. Specifically, each of the movable parts 420a and 420b can be separated from the end of the main body 410, and by rotating them in the opposite direction and reattaching them, the installation direction of the movable parts 420a and 420b can be easily adjusted.

[0053] In the first replacement step (S8), the installation direction of one of the pair of movable parts 420a and 420b is reversed so that the first mounting part 430 of one of the pair of movable parts 420a and 420b and the first mounting part 430 of the other, as well as the second mounting part 440 of one and the second mounting part 440 of the other, are arranged parallel to each other in the longitudinal direction. That is, only the first mounting part 430 is arranged in one of the two regions of the main body 410, region A and region B, and only the second mounting part 440 is arranged in the other region. With this arrangement, the fuel pipe 300 can be cut effectively.

[0054] In the first fuel pipe dismantling step (S4-2), the fuel pipes 300 may be cut one by one. The cut fuel pipes 300 may be lifted by a separate lifting device such as a crane and transported outside the concrete bolts 100.

[0055] Figure 9 shows the state after the first fuel pipe dismantling step (S4-2) and before the second fuel pipe dismantling step (S5-1).

[0056] The lower section dismantling step (S5) includes a second fuel pipe dismantling step (S5-1) in which both ends of the fuel pipe 300 located inside the lower section of the calandria container 200 are cut using a second cutting device 600 attached to the operating device 400, and a second container dismantling step (S5-2) in which the lower section of the calandria container 200 is cut using a first cutting device 500 and a second cutting device 600 attached to the operating device 400.

[0057] When dismantling the lower part of the calandria container 200, the fuel pipes 300 do not interfere with the calandria container 200, and the lower part of the calandria container 200 cannot be dismantled unless the fuel pipes 300 are completely dismantled. Therefore, the calandria container 200 is dismantled after the fuel pipes 300 have been dismantled.

[0058] Similarly, in the second fuel pipe dismantling step (S5-1), it is desirable that both ends of the fuel pipe 300 be simultaneously cut by a pair of second cutting devices 600 mounted on the actuator 400 in a longitudinal direction, parallel to each other. Therefore, there is no need to change the arrangement of the pair of first cutting devices 500 and the pair of second cutting devices 600 after the first fuel pipe dismantling step (S4-2) and before the second fuel pipe dismantling step (S5-1). In other words, after the upper fuel pipe 300 is dismantled, all fuel pipes 300 down to the lower fuel pipe 300 are dismantled in succession.

[0059] However, if necessary, a longer second cutting device 600 may be used when cutting the lower fuel pipe 300.

[0060] After the second fuel pipe dismantling step (S5-1) and before the second container dismantling step (S5-2), a second swapping step (S9) can be performed to swap the arrangement of the pair of first cutting devices 500 and the pair of second cutting devices 600 so that the pair of first cutting devices 500 are mounted on the operating device 400 so that they are spaced apart from each other in the circumferential and longitudinal directions of the calandria container 200, and the pair of second cutting devices 600 are mounted so that they are spaced apart from each other in the circumferential and longitudinal directions of the calandria container 200.

[0061] However, in some cases, if the lower part of the calandria container 200 is dismantled all at once rather than in multiple pieces, the pair of first cutting devices 500 may not be used in the second container dismantling step (S5-2), and the second replacement step (S9) may not be performed.

[0062] After the lower section demolition step (S5), a drainage step (S10) is performed to drain the inside of the concrete bolt 100. Subsequently, steps to demolish other structures within the concrete bolt 100 can be performed, such as a feeder / end fitting demolition step (S11) to demolish the feeder and end fitting, and a horizontal reactivity structure demolition step (S12) to demolish the horizontal reactivity structure.

[0063] To lift and install the operating device 400, the first cutting device 500, and the second cutting device 600 using a crane, or to disassemble them outside the concrete bolt 100, the main body 410, the first cutting device 500, and the second cutting device 600 may each be provided with lugs 700 for crane lifting.

[0064] The present invention is not limited to the specific embodiments and descriptions described above, and various modifications can be carried out by a person with ordinary skill in the art to which the present invention belongs without departing from the gist of the invention claimed in the claims, and such modifications are within the scope of protection of the present invention. [Explanation of Symbols]

[0065] S1: Water filling step S2: Release step S3: Installation step S4: Upper section dismantling step S4-1: First container dismantling step S4-2: First fuel line dismantling step S5: Lower section dismantling step S5-1: Second fuel pipe dismantling step S5-2: Second container dismantling step S6: Vertical reactivity structure dismantling step S7: Installation step S8: First replacement step S9: Second replacement step S10: Drainage step S11: Feeder / End Fitting Disassembly Step S12: Horizontal Reactivity Structure Demolition Step 10: RM-deck 20: Vertical reactivity controller 100: Concrete bolts 200: Calandria containers 201: Auxiliary cell 210: Protruding lug 220: Rail section 300: Fuel pipe 400: Operating device 410: Main unit 420a, 420b: Moving part 421: First extension part 422: Second extension section 430: First mounting section 440: Second mounting section 500: First cutting device 510: First wheel saw 600: Second cutting device 610: Second wheel saw 700: Lug

Claims

1. A filling step involves filling the inside of a concrete vault equipped with a calandria container with water, An opening step to dismantle the RM-deck (Reactivity-Mechanism deck) and release the concrete bolts, Installation step of installing the operating device in the aforementioned calandria container, Using the aforementioned operating device, the upper part dismantling step involves cutting and dismantling the upper part of the calandria container and the fuel pipes located inside the upper part of the calandria container, A method for dismantling a calandria container underwater, comprising: a lower dismantling step of using the operating device to cut and dismantle the lower part of the calandria container and the fuel pipes located inside the lower part of the calandria container.

2. The method for dismantling a calandria container underwater according to claim 1, wherein the operating device in the installation step is provided on rails provided at both ends of the calandria container, and the operating device in the upper dismantling step and the lower dismantling step is movable along the rails in the circumferential direction of the calandria container.

3. The aforementioned upper part dismantling step is, A first container dismantling step involves cutting the upper part of the calandria container using a first cutting device and a second cutting device attached to the aforementioned operating device, A method for dismantling a calandria container underwater according to claim 2, comprising: a first fuel pipe dismantling step of cutting both ends of the fuel pipes located inside the upper part of the calandria container using a second cutting device attached to the operating device.

4. The aforementioned lower part dismantling step is, A second fuel pipe dismantling step involves using a second cutting device attached to the aforementioned operating device to cut both ends of the fuel pipe located inside the lower part of the calandria container, A method for dismantling a calandria container underwater according to claim 3, comprising a second container dismantling step of cutting the lower part of the calandria container using a first cutting device and a second cutting device attached to the operating device.

5. The method for dismantling a calandria container underwater according to claim 4, further comprising, before the first container dismantling step, a mounting step of mounting a pair of first cutting devices to the operating device so as to be spaced apart from each other in the circumferential and longitudinal directions of the calandria container, and a pair of second cutting devices so as to be spaced apart from each other in the circumferential and longitudinal directions of the calandria container.

6. A method for dismantling a calandria container underwater according to claim 5, further comprising a first swapping step of swapping the arrangement of the pair of first cutting devices and the pair of second cutting devices so that, after the first container dismantling step and before the first fuel pipe dismantling step, the pair of second cutting devices are mounted on the operating device parallel to each other and facing each other in the longitudinal direction of the calandria container.

7. A method for dismantling a calandria container underwater according to claim 6, further comprising a second swapping step of swapping the arrangement of the pair of first cutting devices and the pair of second cutting devices such that, after the second fuel pipe dismantling step and before the second container dismantling step, the pair of first cutting devices are mounted on the operating device so as to be spaced apart from each other in the circumferential and longitudinal directions of the calandria container, and the pair of second cutting devices are mounted so as to be spaced apart from each other in the circumferential and longitudinal directions of the calandria container.

8. The method for dismantling a calandria container underwater according to any one of claims 4 to 7, wherein in the first fuel pipe dismantling step and the second fuel pipe dismantling step, both ends of the fuel pipe are simultaneously cut by a pair of second cutting devices mounted on the operating device parallel to each other and facing each other in the longitudinal direction of the calandria container.

9. Rail sections provided at both ends of a calandria container placed inside a concrete bolt, An operating device provided on the rail section, A first cutting device attached to the operating machine for cutting the calandria container, A calandria dismantling apparatus for an underwater calandria vessel, comprising the calandria vessel and a second cutting device attached to the actuator for cutting fuel pipes located inside the calandria vessel.

10. The underwater dismantling apparatus for a calandria container according to claim 9, wherein the rail section is a double rail, is provided on the upper side of the calandria container, and is expandable toward the lower side of the calandria container.

11. The aforementioned operating device is The main body portion is provided on the rail portion so as to traverse the longitudinal direction of the aforementioned calandria container, The main body includes a pair of movable parts that are movable along the longitudinal direction and each has a first extending part extending in one direction along the circumferential direction of the calandria container and a second extending part extending in the other direction, The underwater dismantling apparatus for a calandria container according to claim 9, wherein the first extension portion is provided with a first mounting portion to which the first cutting device is attached, and the second extension portion is provided with a second mounting portion to which the second cutting device is attached.

12. The underwater dismantling apparatus for a calandria container according to claim 11, wherein the first cutting device is movable in the longitudinal direction relative to the first mounting portion and in a vertical direction toward or away from the calandria container.

13. The underwater dismantling apparatus for a calandria container according to claim 11, wherein the second mounting portion is movable along the circumferential direction on the second extending portion.

14. The underwater dismantling apparatus for a calandria container according to claim 13, wherein the second cutting device includes a second wheel saw, the second wheel saw is movable vertically within the second cutting device toward or away from the calandria container.

15. Each of the aforementioned movable parts is detachably attached to the main body, When cutting the calandria container, the first mounting portion of one of the pair of movable parts and the second mounting portion of the other are arranged parallel to each other in the longitudinal direction. The underwater dismantling apparatus for a calandria container according to any one of claims 11 to 14, wherein when the fuel pipe is cut, the second mounting portion of one of the pair of movable parts and the second mounting portion of the other are arranged parallel to each other and facing each other in the longitudinal direction.

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