JP3770886B2 - Pressure tube dismantling method for the new converter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of disassembling an advanced conversion reactor (ATR) that has entered into decommissioning, and more particularly to a method of chopping a pressure tube assembly removed from a reactor body.
[0002]
[Prior art]
The new conversion reactor is a pressure tube nuclear reactor that uses heavy water as a moderator and light water as a coolant. Is shown in The Fugen Power Station has already been determined to end operation soon, and will be demolished after a predetermined decommissioning preparation period. The nuclear reactor is activated even when the fuel is taken out, and various technological developments and preparations are required for its decommissioning. This invention was especially studied for dismantling the pressure tube assembly. is there.
[0003]
FIG. 7 is a conceptual diagram showing a reactor main body portion of the new conversion reactor. In FIG. 7, a large number of pipes (Calandria pipes) 3 for passing the pressure pipe assembly 2 are arranged in a lattice between upper and lower tube plates of a cylindrical moderator container (Calandria tank) 1. The tank 1 is filled with heavy water as a moderator. The upper and lower surfaces and side surfaces of the calandria tank 1 are covered with an iron water shielding body 4. The pressure pipe assembly 2 is composed of a pressure pipe (main body) 5 and pressure pipe extension pipes 6 and 7 joined to the upper and lower sides thereof. The pressure pipe 5 is accommodated in the calandria pipe 3, and the upper and lower extension pipes 6 and 7 are It penetrates the iron water shielding body 4.
[0004]
A fuel assembly is housed in the pressure pipe 5, and primary coolant pipes 8 and 9 are connected to the upper and lower extension pipes 6 and 7. Although not shown, the upper and lower extension pipes 6 and 7 are fitted with shielding plugs that allow primary coolant to pass but prevent streaming of radiation, and the lower ends of the lower extension pipes 7 are closed by seal plugs that seal the primary cooling water. Yes. The lower shielding plug and the seal plug are coupled to the lower extension pipe 7 by a ball latch mechanism so that they can be attached and detached by a fuel changer (not shown), and the lower shielding plug and the fuel assembly are coupled by a collet mechanism. Has been. The cooling water (light water) flowing into the pressure pipe assembly 2 from the lower cooling pipe 9 is heated by the pressure pipe 5 to become steam, and is supplied from the upper cooling pipe 8 to the turbine. This reactor main body portion is stored in a reactor containment vessel (not shown).
[0005]
FIG. 8 is a longitudinal sectional view showing only the tube of the pressure tube assembly 2 in three parts. As described above, the pressure pipe assembly 2 is composed of the pressure pipe 5 and the upper extension pipe 6 and the lower extension pipe 7 joined to the upper and lower ends thereof by the roll joint method. The inlet pipe nozzle 10 and the seal leak system nozzle 11 protrude. The length of each part is about 5 m for the pressure pipe 5, about 2 m for the upper extension pipe 6, about 3 m for the lower extension pipe 7, and about 10 m in total length. The outer diameter of the pressure pipe 5 is about 130 mm, and the maximum diameter is about 190 mm at the lowermost end of the lower extension pipe 7.
[0006]
[Non-Patent Document 1]
Mechanical Engineering Handbook edited by the Japan Society of Mechanical Engineers Engineering First edition 4th edition 1997 Japan Society of Mechanical Engineers p. C7-78-83
[0007]
[Problems to be solved by the invention]
Now, since the pressure tube assembly 2 has been activated by long-term operation, it is necessary to perform a remote operation or shielding to perform the shredding process. In that case, it is conceivable to perform the shredding operation of the pressure tube assembly 2 in the containment vessel, for example, directly under the reactor main body. FIG. 7 shows such an example. That is, in FIG. 7, a nozzle part cutting machine 12 that cuts the inlet pipe nozzle part and a pressure pipe cutting machine 13 that shreds the pressure pipe assembly 2 are installed below the reactor main body. After the pressure pipe assembly 2 is cut off from the primary coolant pipe 9 at the inlet pipe nozzle portion, it is suspended by the pressure pipe chopping machine 13 through the protective cylinder 15 by the pressure pipe suspending machine 14 to an appropriate length. Shredded. The shredded pressure tube assembly 2 is collected in the waste material storage device 16 and transferred to the next process.
[0008]
However, the shredding process in the containment vessel has the following problems.
(1) If shredding work is performed in a containment vessel, the radioactivity level of the surrounding atmosphere increases, and other work cannot be performed in parallel. Incidentally, there are a large number (224) of pressure tube assemblies, and it takes a long time for the shredding work and the transporting work after shredding, and as a result, the critical construction period of the reactor demolition work becomes longer.
(2) Since the pressure tube shredder is a newly manufactured device, after the reactor is dismantled, the device itself becomes waste and secondary waste increases.
(3) Since the shredding operation is performed in the air, the amount of material required for shielding the device increases.
[0009]
An object of the present invention is to rationally proceed with the pressure tube disassembly work associated with the decommissioning of the new conversion furnace, to shorten the construction period, reduce dismantling waste, simplify the shielding treatment, and the like.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a fuel transfer device, a fuel transfer device including a fuel change pool, a fuel change pool, and a transfer chute. Is used to transport to the spent fuel storage pool, and this pressure tube assembly is shredded within the pool (claim 1).
[0011]
Considering that the pressure tube assembly is cylindrical and has a large number, the handling operation can be a simple repetitive operation. Therefore, if this transfer operation is performed by using a fuel handling facility that originally handles the fuel underwater, the effect of automation and labor saving is great. In addition, since the pressure tube assembly can be shredded in the pool water, the shielding effect by water can be used and other operations in the containment vessel are not hindered. Furthermore, the dismantling waste can be reduced as compared with the case where a pressure pipe assembly cutting / transferring device is installed after the fuel handling facility is removed.
[0012]
As described above, the pressure tube assembly is approximately 10 m long, and the cooling water inlet tube nozzle protrudes laterally. Therefore, it is necessary to cut the pressure tube assembly to an appropriate length that is easy to handle before transportation, and to cut off the inlet tube nozzle and the like. Therefore, a pressure tube assembly cutting device is installed at the head of the fuel exchange device, and the pressure tube assembly is cut into a shape and size that can be easily handled by the cutting device and then transported. Good (claim 2).
[0013]
By the way, the pressure tube assembly originally designed to accommodate the fuel assembly has a larger diameter than the fuel assembly, and there is a neck in the maximum passage diameter in the transfer path of the fuel handling equipment. First, the pressure tube assembly cannot be accommodated in the magazine tube of the fuel changer. Therefore, for the fuel exchange device, it is preferable to abolish the magazine unit and newly install a guide tube capable of accommodating the maximum diameter of the pressure tube assembly. Thereby, the passage maximum diameter of the fuel changer can be increased (claim 3).
[0014]
Also, the transfer container of the transfer chute cannot accommodate most of the diameter of the pressure tube assembly. In view of this, it is preferable that the transfer chute is replaced with a new container that can accommodate the maximum diameter of the pressure tube assembly to increase the maximum passing diameter.
[0015]
On the other hand, the pressure tube assembly transported to the spent fuel storage pool is temporarily placed in a temporary rack in the pool and then shredded (Claim 5). Thereby, the removal / transfer operation of the pressure tube assembly from the reactor main body can proceed independently of the shredding operation.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 3 is an overall configuration diagram of the fuel handling facility. In FIG. 3, the fuel handling facility includes a fuel exchange device 17 for loading and unloading the fuel assembly from the pressure tube assembly, and a fuel transfer device for transferring the fuel assembly between the containment vessel 18 and the fuel storage pool 19. It consists of twenty. The fuel changer 17 is movably disposed below the reactor main body configured in the calandria tank 1, takes out the fuel assembly in the pressure tube assembly from the lower part of the reactor at the time of fuel replacement, and Move down. The fuel assembly in the fuel changer 17 is pulled up by the fuel inlet / outlet machine 23 via the transfer port 22 and then discharged to the fuel storage pool 19 outside the containment vessel through the upper swing device 24 and the transfer chute 25. This fuel assembly is lifted by the fuel transfer machine 27 via the lower swing device 26 and is transported to the spent fuel rack. The new fuel is carried into the containment vessel 18 in the reverse order as described above, and is loaded into the pressure tube assembly by the fuel changer 17.
[0017]
1 and 2 show a flow of disassembling the pressure pipe assembly that is performed by modifying the existing fuel handling equipment with some modifications , at the time of decommissioning of the reactor equipment. It is sectional drawing which follows the II-II line. The fuel handling equipment originally handles the fuel assembly stored in the pressure tube assembly, and the pressure tube assembly is naturally larger in size than the fuel assembly. Therefore, there is a part that cannot handle the pressure pipe assembly as it is because of the maximum passage diameter in the fuel handling equipment, and it is necessary to modify this part. Hereinafter, the processing flow shown in FIGS. 1 and 2 including this modification will be described in accordance with the procedures (1) to (8) . In addition, the same code | symbol shall be used for the part corresponding to a prior art example.
[0018]
(1) First, the fuel changer 17 is positioned in the lower part of the furnace, and the pressure pipe assembly 2 is received. At that time, the inlet pipe nozzle 10 and the seal leak diameter nozzle 11 (see FIG. 8) protrude from the side and are cut off because they interfere with handling. Further, since the pressure tube assembly 2 is too long as it is, it is cut into an appropriate length, for example, 1/3 to 1/4. These cuttings are performed by a pressure tube cutting device 28 installed at the head of the fuel changer 17 as a preceding operation.
[0019]
FIG. 4 shows an example of the pressure tube cutting device 28. In FIG. 4, a pair of front and rear metal saw type cutting mechanisms 31, 32 are supported on a water-sealed lift / swivel drive unit 29 via a front / rear drive unit 30, and the right metal saw 33 in FIG. In addition, the left metal saw 33 is mounted horizontally. The illustrated pressure tube cutting device 28 is attached to the trace where the snout provided for watertightly coupling the pressure tube 5 and the fuel change device 17 during the fuel change is removed. In order to cut the pressure tube assembly 2, the nozzle portion is cut by the cutting mechanism 31 while the pressure tube assembly 2 is suspended and supported by the pressure tube suspension machine 14 (FIG. 1) having the same structure as the overhead crane. Then, the tube part is cut by the cutting mechanism 32. As the pressure tube cutting device 28, other methods such as a plasma cutting method and an abrasive cutting method can be adopted.
[0020]
On the other hand, a magazine unit is provided in the pressure vessel of the fuel changer 17, and four magazine tubes each containing fuel assemblies are installed in the magazine support cylinder so as to sequentially rotate and move to the center of the snout. It is supported. However, the pressure tube assembly cannot be accommodated in the magazine tube whose inner diameter is as it is. Therefore, the magazine tube is replaced with one having a larger inner diameter, or the magazine unit is removed and a new guide tube is installed, so that the pressure tube assembly can be accommodated. The pressure changer assembly 2 cut by the cutting mechanism 32 as described above is lowered and accommodated in the refueling device 17 thus modified. The fuel changer 17 is filled with water, and the pressure pipe assembly 2 is shielded with this water.
[0021]
(2) When the pressure pipe assembly 2 is accommodated in the fuel changer 17, the fuel changer 17 is moved by the traversing carriage and positioned with respect to the transfer port 22.
[0022]
(3) The pressure pipe assembly 2 is gripped by the fuel loading / unloading machine 23 and suspended from the fuel exchange pool 21. Here, the original gripper 34 of the fuel loading / unloading machine 23 has a structure for gripping the fuel assembly from the outside, but the gripper 34 cannot be used for the pressure tube assembly 2. Therefore, the gripper 34 is modified so that the pressure pipe assembly 2 whose inner peripheral surface is exposed by ring cutting is gripped from the inside.
[0023]
5 and 6 show a configuration example of a gripper that holds the pressure tube assembly 2. (A) of each figure is the state which suspended the gripper in the pressure tube assembly, (B) is the state which hold | gripped the pressure tube assembly. FIG. 5 shows a structure in which the raising / lowering operation of the camshaft 35 is changed to an operation of moving the claw 36 in and out. After the insertion into the pressure tube assembly 2, the claw 36 is extended to the outer peripheral side to Gripping with friction. FIG. 6 shows a structure in which an annular balloon (air picker) 37 is inflated with air pressure and gripped in the same manner.
[0024]
(4) The fuel inlet / outlet machine 23 is moved, and the pressure tube assembly 2 is set in the upper swing device 24.
[0025]
(5) The pressure pipe assembly 2 is transferred to the fuel delivery pool 38 by the transfer chute 25. At this time, since the pressure tube assembly alone is difficult to handle, it is necessary to store it in a storage cylinder such as a transfer container, but the original transfer container is made to have an inner diameter that does not rattle the fuel assembly. Therefore, replace it with a new transfer container with an enlarged inner diameter.
[0026]
(6) The pressure pipe assembly 2 is lifted from the lower swing device 26 by the fuel transfer device 27. The fuel transfer device 27 also uses the same gripper as that of the fuel input / output device 23.
[0027]
(7) The pressure tube assembly 2 is transferred to the spent fuel storage pool 19 and the pressure tube assembly 2 is temporarily placed in the pressure tube temporary rack 39. The pressure tube temporary rack 39 is installed on the trace where the spent fuel rack is removed.
[0028]
(8) The pressure tube assembly 2 is transferred from the pressure tube temporary rack 39 to the spent fuel carry-out chamber 40 by the fuel transfer device 27, and the pressure tube assembly 2 is shredded by the pressure tube shredding device 41 installed there. To do. The shredded waste material is transferred to another space and stored in a waste container.
[0029]
The following advantages are assumed for the transfer and shredding of the pressure pipe assembly using the fuel handling facility described above.
(1) Most handling operations can be performed underwater and remotely. Therefore, exposure associated with the dismantling work can be minimized.
(2) Visual monitoring of work is possible by installing the treatment equipment in water. Moreover, scattering of chips and dross generated at the time of cutting is suppressed, and a secondary waste recovery policy is easy.
(3) Since the chopping operation can be performed after the pressure tube assembly is carried out of the containment vessel, the high-dose operation in the containment vessel can be reduced.
(4) By temporarily placing the pressure tube assembly in the spent fuel storage pool, the removal and transfer of the pressure tube assembly from the reactor body and subsequent shredding / containment in a waste container can be performed independently. The pressure tube assembly can be removed and transferred without waiting for the shredding process, and the process margin of the work in the containment vessel is increased. As a result, the influence on other work processes in the containment vessel is reduced.
(5) Since the pressure tube assembly can be transferred using the existing transfer chute, a new passage for penetrating the containment vessel is unnecessary.
(6) Effective use of existing equipment will reduce the generation of new waste such as equipment dedicated to decommissioning work. As a result, the cost for dismantling can be reduced.
[0030]
【The invention's effect】
As described above, according to the present invention, the pressure tube assembly removed from the reactor main body is transported to the spent fuel storage pool by the fuel transfer device and the fuel transfer device including the fuel replacement pool and the transfer chute , By slicing the pipe assembly in the pool, it is possible to reduce the exposure during shredding shredding using the shielding effect of the pool water and to make the existing equipment effective by simply modifying a part of the existing equipment. Reduction of demolition waste by use can be achieved.
[Brief description of the drawings]
FIG. 1 is a transfer flow diagram of a pressure tube assembly showing an embodiment of the present invention.
2 is a cross-sectional view taken along line II-II in FIG.
FIG. 3 is a diagram illustrating an overall configuration of a fuel handling facility.
FIG. 4 is a side view showing a schematic configuration of a pressure tube cutting device.
FIGS. 5A and 5B show a configuration of a gripper of a fuel loading / unloading machine, where FIG. 5A shows an open state and FIG. 5B shows a gripping state.
6A and 6B show different configurations of the gripper of the fuel loading / unloading machine, where FIG. 6A shows an open state and FIG. 6B shows a gripping state.
FIG. 7 is a view showing a method of dismantling and shredding a pressure tube assembly in a reactor containment vessel.
FIG. 8 is a longitudinal sectional view showing a pressure tube assembly in three parts.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Calandria tank 2 Pressure pipe assembly 17 Fuel change device 19 Fuel storage pool 20 Fuel transfer device 21 Fuel change pool 22 Transfer port 23 Fuel inlet / outlet machine 24 Upper swing device 25 Transfer chute 26 Lower swing device 27 Fuel transfer device 28 Pressure tube Cutting device 38 Fuel delivery pool 39 Pressure tube temporary rack 40 Spent fuel delivery chamber 41 Pressure tube shredding device

Claims (5)

The pressure tube assembly removed from the reactor body of the new conversion reactor that has been decommissioned is transported to the spent fuel storage pool using a fuel transfer device and a fuel transfer device including a fuel change pool and a transfer chute. A pressure tube disassembling method for a new conversion furnace, wherein the pressure tube assembly is shredded in the pool. The pressure tube assembly cutting device is installed at the head of the fuel exchange device, and the pressure tube assembly is cut into a shape and size that can be easily handled by the cutting device, and then transported. Item 4. A pressure tube dismantling method for a new type conversion furnace according to Item 1. 2. A guide pipe capable of accommodating the maximum diameter of the pressure tube assembly is newly installed in place of the magazine unit of the fuel exchange apparatus, and the maximum passage diameter of the fuel exchange apparatus is expanded. Pressure tube dismantling method for the new type of conversion furnace. Wherein the transfer container transfer chute and replaced with a new container maximum diameter that can be accommodated in the pressure tube assembly, the new converter reactor of claim 1, wherein enlarging the maximum diameter passing the transfer chute Pressure tube disassembly method. 2. The pressure tube dismantling method for a new conversion furnace according to claim 1, wherein the pressure tube assembly transported to the spent fuel storage pool is temporarily placed in a temporary rack in the pool and then shredded. .

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