JP4018299B2 - Jet pump maintenance equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a jet pump maintenance device for preventing and repairing a welded portion of a riser pipe of a jet pump installed between a reactor pressure vessel and a core shroud in a boiling water reactor.
[0002]
[Prior art]
In a boiling water reactor as a light water reactor, as shown in FIG. 5, a reactor core 2 is accommodated in a reactor pressure vessel 1, and the reactor core 2 is immersed in reactor water, that is, a coolant 3. The core 2 is configured by arranging a large number of fuel assemblies and control rods (none of which are shown) in a cylindrical core shroud 4.
[0003]
The coolant 3 in the reactor pressure vessel 1 flows from the lower core plenum 9 upward in the core 2. When the coolant 3 moves up in the core 2, it receives a nuclear reaction heat and is heated up and pressured to be in a two-phase flow state of water and steam. The coolant 3 that has become a gas-liquid two-phase flow flows into the steam / water separator 5 installed above the core 2, and is separated into water and steam by the steam / water separator 5.
[0004]
The vapor that has been subjected to gas-liquid separation is introduced into a vapor dryer 6 installed above the vapor-water separator 5, where it is dried to become dry vapor. This dry steam becomes main steam and is sent to a steam turbine (not shown) through a main steam pipe 7 connected to the reactor pressure vessel 1 for power generation.
[0005]
On the other hand, the gas-liquid separated water is guided to a downcomer portion 8 formed in a torus shape or a sleeve shape between the core shroud 4 and the reactor pressure vessel 1, and descends the downcomer portion 8 to lower the core lower portion. Guided to Plenum 9. A plurality of jet pumps 10 are installed at equal intervals on the outer periphery of the core shroud 4 in the downcomer portion 8.
[0006]
On the other hand, a control rod guide tube 11 is installed in the core lower plenum 9 below the core 2, and a control rod drive mechanism is installed below the control rod guide tube 11. The control rod drive mechanism controls the output of the nuclear reactor by inserting or extracting a control rod (not shown) through the control rod guide tube 11 into the core 2.
[0007]
Two reactor recirculation systems equipped with a reactor recirculation pump (not shown) are installed outside the reactor pressure vessel 1, and the reactor recirculation system is operated by the recirculation pump operation. Reactor water in the reactor pressure vessel 1 is returned from the cooler recirculation water outlet nozzle 12 to the reactor pressure vessel 1 through the reactor recirculation system (not shown) and jetted through the recirculation water inlet nozzle 13. Guided to pump 10.
[0008]
In this jet pump 10, the surrounding reactor water is entrained and fed to the lower core plenum 9. That is, the driving water supplied from the nuclear reactor recirculation pump to the jet pump 10 causes the jet pump 10 to forcibly circulate the coolant 3 into the core 2 through the core lower plenum 9.
[0009]
On the other hand, the reactor pressure vessel 1 is provided with a core spray system 15 constituting an emergency cooling system for the reactor. The reactor recirculation system is composed of the reactor recirculation pump and the jet pump 10 and the reactor recirculation pipe connecting the two. That is, the jet pump 10 forcibly circulates the coolant 3 in the core 2 by the driving water supplied to the jet pump 10 by the nuclear reactor recirculation pump.
[0010]
As shown in FIGS. 6 and 7, the jet pump 10 includes a riser pipe 12 at the center. The riser pipe 12 recycles the coolant 3 supplied from the reactor recirculation pump to the reactor pressure vessel 1. It introduces through the circulation inlet nozzle 13.
[0011]
A pair of left and right elbows 15a and 15b are connected to the upper portion of the riser pipe 12 via a transition piece 14, and inlet throats 17a and 17b are connected to the elbows 15a and 15b via mixing nozzles 16a and 16b, respectively. Has been. Diffusers 18a and 18b are connected to the lower portions of these inlet throats 17a and 17b, respectively.
[0012]
When the coolant 3 is injected from the upper mixing nozzles 16a and 16b, the reactor water is drawn from the surroundings. The injected coolant 3 and the entrained reactor water are mixed in the inlet throats 17a and 17b, and then the hydrostatic head is recovered by the diffusers 18a and 18b.
[0013]
In the jet pump 10, fluid vibration is generated by the flow of the coolant 3 fed from the reactor recirculation pump. To cope with this, the lower end of the riser pipe 12 is welded to the recirculation inlet nozzle 13. The upper end is fixed to the reactor pressure vessel 1 through a riser brace 19.
[0014]
The inflow water pressure of the driving water supplied through the riser pipe 12 acts on the elbows 15 a and 15 b at the upper end of the jet pump 10. Since this inflow water pressure is ejected from the nozzle (not shown) connected to the other ends of the elbows 15a and 15b into the inlet throats 17a and 17b and the diffusers 18a and 18b, the reaction pressure such as the ejection water pressure of the drive water The force acts upward.
[0015]
The inlet throats 17a and 17b are mechanically connected to the transition piece 14 via mixing nozzles 16a and 16b and elbows 15a and 15b, and the lower ends are inserted into the upper ends of the diffusers 18a and 18b. The lower ends of the diffusers 18a and 18b are fixed to a shroud support 20 welded to the reactor pressure vessel 1, and the lower end of the riser pipe 12 is welded to a riser elbow 21 as shown in FIGS. Has been.
[0016]
The riser elbow 21 is welded to the thermal sleeve 22, and the thermal sleeve 22 is connected to a recirculation inlet nozzle 13 fixed to the reactor pressure vessel 1. The inlet throats 17 a and 17 b are attached to a riser bracket 23 fixed to the riser pipe 12. This prevents the riser pipe 12 and the inlet throats 17a and 17b from vibrating.
[0017]
As shown in FIG. 8, the riser brace 19 has a pad 24 formed on the inner wall of the reactor pressure vessel 1, and four thin plate riser brackets 23 are welded to the pad 24. The four thin plate riser brackets 23 have a thickness of about 10 mm.
[0018]
The ends of the four thin plate riser brackets 23 are welded to the inside of the block. Therefore, the riser brace 19 suppresses fluid vibration generated during the operation of the reactor generated in the riser pipe 12.
[0019]
The riser brace 19 absorbs a difference in thermal expansion between the reactor pressure vessel 1 made of carbon steel and the riser tube 12 made of austenitic stainless steel. For this reason, during the operation of the reactor, it is in a deformed state as a state where the thermal expansion difference is absorbed.
[0020]
[Problems to be solved by the invention]
The jet pump 10 flows the coolant from the recirculation inlet nozzle 13 into the riser pipe 12, sucks the coolant around the riser pipe 12, pressurizes the coolant, and pressurizes the pressurized coolant into the core 2 In order to circulate inside, it is operated under harsh conditions compared to other in-furnace equipment. Therefore, a large load acts on each component of the jet pump 10, and a large stress is applied.
[0021]
For example, if an excessive load is applied to the jet pump 10 due to the external piping such as the reactor recirculation piping being broken, or if rust is generated on the inner surface of the riser pipe 12 due to some cause, this develops into a crack or the like. There is a case.
[0022]
Since the austenitic stainless steel pipe is mainly used as the material of the riser pipe 12, if the three conditions of stress, corrosive environment, and material (generation of chromium-deficient layer) are satisfied, stress corrosion cracking (Stress Corrosion Cracking) It is assumed that the riser tube 12 is damaged due to the occurrence of the above. The stress corrosion cracking phenomenon does not occur if any one of the above three conditions is missing, so various measures must be taken to prevent this stress corrosion cracking.
[0023]
In addition, when rust or cracks are generated on the surface of the jet pump 10 for any reason, the cracks may progress and the jet pump 10 may be cracked if left untreated. Therefore, the jet pump 10 that controls the output of the nuclear reactor is in such a state, which may adversely affect other structures, which is undesirable.
[0024]
The present invention has been made to solve the above problems, and can be installed at a predetermined position on the outer peripheral surface of a riser pipe of a jet pump installed in a reactor pressure vessel. Surface modification of the jet pump, laser desensitization treatment It is an object of the present invention to provide a maintenance device for a jet pump that can perform underwater remote control.
[0025]
The present invention also provides a jet pump maintenance device capable of effectively and effectively performing preventive repairs and preventive maintenance using a laser beam, and greatly improving the soundness and reliability of piping in the core of the jet pump and the like. There is to do.
[0026]
[Means for Solving the Problems]
The invention according to claim 1 is a one-side opening housing having an upper plate and a lower plate installed between a jet pump and a riser pipe installed between a reactor pressure vessel and a core shroud, and provided in the housing. Laser head, a laser optical system case in contact with the lower part of the laser head, a nozzle provided on the laser irradiation side of the optical system case, a linear guide for mounting the laser optical system case, and the linear guide A pair of upper and lower plates, a half ring having a gear on a side surface inserted between the pair of upper and lower plates, a rotational drive mechanism meshing with the gear of the half ring, and the pair of upper and lower plates It is characterized by comprising a vertical movement drive mechanism to be moved.
[0027]
According to the present invention, the laser optical system case of the laser head is mounted on the transition piece portion of the jet pump under water during periodic inspection of the reactor, and the rotation and vertical movement drive device is operated to operate against the outer peripheral surface of the jet pump. Then, laser desensitization treatment can be performed by irradiating laser from the laser head.
[0028]
According to a second aspect of the present invention, a hood seal material that is in airtight contact with the outer surface of the riser pipe is provided at the tip of the nozzle.
According to the present invention, the purge gas is sent into the laser optical system case to expand the hood seal, and the riser tube and the laser optical system case can be sealed in a watertight manner, so that the repair work is facilitated.
[0029]
The invention of claim 3 is characterized in that a foldable handle is attached to the upper surface of the upper plate via a rod. According to this invention, the handle can be suspended, the upper plate can be seated on the transition piece opening at the top of the riser tube, and the opening can be sealed by the sealing member.
[0030]
According to a fourth aspect of the present invention, the rotational drive mechanism has a drive motor attached to the pair of upper and lower plates, a first gear is attached to the rotation shaft of the drive motor, and a second gear meshing with the first gear is provided. A first pulley is attached to the attached first rotary shaft, and a second rotary shaft having a second pulley that rotates through the belt is provided on the first pulley and the pair of upper and lower plates, The rotary shaft is provided with a third gear. According to this invention, the laser head and the laser optical system case in the invention of claim 1 can be easily rotated.
[0031]
According to a fifth aspect of the present invention, the vertical movement drive mechanism is provided with a lower bearing on the lower plate, a screw is rotatably attached to the lower bearing, and the upper ends of the screws are connected to the lower surfaces of the pair of plates via the upper bearing. A rotary gear is attached to the lower end of the screw, and a vertical movement drive motor is provided for rotating the rotary gear. According to this invention, the laser head and the laser optical system case in the invention of claim 1 can be moved up and down easily.
[0032]
The invention according to claim 6 is characterized in that a lens and a mirror are provided in the laser optical system case, and an underwater camera and an underwater illumination tool are provided in the vicinity of the laser optical system case.
[0033]
According to this invention, after passing the laser beam through the lens, the laser beam path is bent and irradiated by the mirror, so that the total length of the laser head and the laser optical system case can be shortened, and the narrow portion is also irradiated with the laser beam. Can do. In addition, the underwater camera and the underwater illumination device facilitate inspection and monitoring in the vicinity of the laser irradiation unit.
[0034]
The invention of claim 7 is characterized in that at least one of an ultrasonic flaw detection test apparatus and a polishing apparatus is provided in the vicinity of the laser head. According to the present invention, it is possible to simultaneously perform an ultrasonic flaw detection test or polishing on the entire outer surface of the jet pump along with the laser desensitization treatment.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of a maintenance device for a jet pump according to the present invention will be described with reference to FIGS.
Note that the jet pump maintenance apparatus according to the present embodiment targets the 14 transition parts of the jet pump 10 installed between the reactor pressure vessel 1 and the core shroud 4 shown in FIG. This equipment is used for surface modification of the weld metal structure, preventive repair of welds, and preventive maintenance work.
[0036]
That is, the maintenance device 25 of the jet pump according to the present embodiment is a transition piece attached to the riser pipe 12 of the jet pump 10 installed between the reactor pressure vessel 1 and the core shroud 4 of the boiling water reactor. FIG. 1 shows an application example thereof, FIG. 2 shows an enlarged view of the maintenance device 25 of FIG. 1, FIG. 3 shows a state in which the device of FIG. 4 shows a plan view seen from above in FIG. Since the overall structure of the reactor pressure vessel 1 has already been described with reference to FIGS. 5 to 6, the same parts are denoted by the same reference numerals and description thereof is omitted.
[0037]
As shown in FIG. 1, the jet pump maintenance device 25 according to the present embodiment is installed and fixed at a maintenance target location in the reactor pressure vessel 1 or in the vicinity thereof. The maintenance target location is a welded portion 49 between the riser pipe 12 and the transition piece 14 of the jet pump 10, and the maintenance device 25 according to the present embodiment is an inlet throat 17a, 17b of the jet pump 10 in the reactor pressure vessel 1. After the removal, the riser tube 12 and the transition piece 14 are attached.
[0038]
That is, in the maintenance device 25 according to the present embodiment, as shown in FIGS. 1 to 4, one side is opened and the U-shaped upper plate 26 and the U-shaped lower plate 27 are integrally connected by a connecting body. The U-shaped housing 28 configured as described above is mainly used, and the upper plate 26 of the U-shaped housing 28 is seated on the upper opening surface of the transition piece 14. A seal member 29 is incorporated in the lower surface of the upper plate 26 to seal the opening of the transition piece 14.
[0039]
A handle portion 30 that can be folded right and left is provided above the upper plate 26, and the upper plate 26 and the handle portion 30 are connected by a rotatable rod 31. A handle plate 32 is assembled below the handle portion 30, and the plate 32 engages with the groove portion 14a of the transition piece 14 and can be fixed as shown in FIG.
[0040]
The handle 30 is suspended from the wire of the refueling machine on the operation floor. At the time of hanging and lifting, the handle portion 30 is in a vertical direction, and below that, the handle portion 30 is arbitrarily laid down.
[0041]
Between the upper plate 26 and the lower plate 27, plates 33 and 33a composed of double plates which are movable up and down are incorporated. The plates 33 and 33a are provided with screws 34 attached to the lower plate 27 and attached to the lower plate 27. It is possible to move up and down by rotating one drive motor 35. The U-shaped portion of the upper plate 26 has an opening large enough to insert / remove the upper outer surface of the transition piece 14, and the U-shaped portion of the lower plate 27 is large enough to insert / remove the outer surface of the riser tube 12. Has an opening.
[0042]
The upper end portion of the screw 34 is rotatably attached to the lower surface of the plate 33a via the upper bearing 53, and the lower end portion is screwed into the tightening nut 55 via the lower bearing 54. A rotating gear 56 is attached to the tightening nut 55, and the rotating gear 56 meshes with a gear (not shown) attached to the drive motor 35 for vertical movement. The screw 34 is rotated up and down while rotating, and the plates 33 and 33a are moved. Move up and down.
[0043]
A half ring 36 having a U-shaped longitudinal section is provided between the plates 33 and 33 a via a key 57. The half ring 36 is rotatable through a first gear 38 attached to a rotating shaft 37 a of the rotation drive motor 37 and a second gear 39 meshing with the first gear 38. A first pulley 51 is attached to the rotary shaft 50 to which the second gear 39 is attached. The rotation drive motor 37 is attached to the plate 33 a, and the rotation shaft 37 a projects from the plate 33.
[0044]
A linear guide 41 is provided on the plate 33, and the laser head 40 is incorporated on the linear guide 41. A linear guide 41 is incorporated below the laser head 40 and is adjusted so that the gap between the laser head 40 and the riser tube 12 is always constant. A lens 45 and a mirror 46 are arranged in a vertical direction in a laser optical system case 40a provided at the lower part of the laser head 40, and a nozzle 47 is attached to a tip portion in the horizontal direction.
[0045]
The rotation of the half ring 36 is transmitted to the second gear 39 by the first gear 38 rotated by the second drive motor 37, and the third gear 43 is rotated by the belt 42 to be processed into the half ring 36. The half ring 36 is rotatable by being transmitted to the gear 44.
[0046]
As shown in FIG. 4, the third gear 43 is provided between the plates 33 and 33 a extending to the vicinity of the core shroud 4 via a rotating shaft 58. A second pulley 52 is attached to the lower portion of the rotating shaft 58, and a belt 42 is stretched between the second pulley 52 and the first pulley 51.
[0047]
The laser head 40 has a structure in which laser light transmitted from a laser oscillator (not shown) through an optical fiber cable is passed through a lens 45, the light diameter is reduced, bent at a mirror 46 portion, and irradiated from a nozzle 47. Yes. A hood seal 48 is incorporated in the outer periphery of the nozzle 47 portion, and by feeding purge gas into the laser optical system case 40a to expand the hood seal 48, it is possible to prevent water from entering from outside. .
[0048]
Next, the operation of the maintenance device 25 for the jet pump will be described.
The maintenance device 25 of the jet pump is suspended in the reactor pressure vessel 1 by an operator operating from a fuel exchanger (not shown) or the like, and above the downcomer portion 8 between the reactor pressure vessel 1 and the core shroud 4. Suspended by. The maintenance device 25 of the jet pump suspended from the downcomer 8 is seated and fixed on the upper part of the transition piece 14 of the jet pump 10. In this state, the height of the laser irradiation part of the laser head 40 is adjusted by driving the first drive motor 35. Next, the laser head 40 is driven by the second drive motor 37 to perform laser desensitization processing.
[0049]
Sensitization refers to a portion where the amount of Cr is reduced near the grain boundary and the corrosion resistance is reduced because carbon (C) in the austenitic stainless steel forms carbide with chromium (Cr) in the vicinity of the grain boundary. The laser desensitization treatment is to melt a material sensitized by laser energy and to make the Cr amount uniform again.
[0050]
A pressure fluid, such as purge helium gas, is sent inside the hood seal 48 to expand the hood seal 48 to provide a water-tight seal, creating an air environment, and laser desensitization treatment by remote control Department maintenance work is performed. By this laser desensitization treatment, the surface modification of the jet pump welded portion is performed, and the preventive repair and preventive maintenance of the jet pump are performed, and the soundness and reliability of the jet pump can be improved.
[0051]
In the above embodiment, an underwater camera and an underwater illumination tool can be provided in the vicinity of the laser optical system case 40a. Further, an ultrasonic flaw detection test device or a polishing device can be provided in the vicinity of the laser head 40. The polishing apparatus is a polishing apparatus with a built-in brush that gives gloss.
[0052]
【The invention's effect】
According to the present invention, the laser desensitization processing means can be installed at a predetermined position on the outer peripheral surface of the jet pump or riser tube in the nuclear reactor, and the laser light from the laser desensitization processing means is spread over the entire outer circumference of the jet pump. Irradiation, surface modification of the jet pump and laser desensitization treatment can be performed, and preventive repair and preventive maintenance by laser light can be performed efficiently and effectively. Therefore, the soundness and reliability of the in-core piping such as a jet pump can be greatly improved.
[0053]
In addition, surface modification and laser desensitization treatment by laser desensitization treatment means can be performed in water by remote operation, so it can be a simple maintenance work and the possibility of radiation exposure of workers. It can be greatly reduced.
[Brief description of the drawings]
FIG. 1 is an elevational view showing a partial cross section for explaining a first embodiment of a maintenance device for a jet pump according to the present invention.
FIG. 2 is an elevational view showing a principal part of FIG.
FIG. 3 is an elevational view showing a partial cross section of FIG. 1 viewed from a direction rotated by 90 °.
4 is a plan view partially shown in cross section in FIG. 1. FIG.
FIG. 5 is a longitudinal sectional view showing a partial side view for explaining a boiling water nuclear reactor.
6 is a perspective view with a partial cross section for explaining the jet pump in FIG. 5. FIG.
7 is a partially cutaway front view of the jet pump in FIG. 6. FIG.
8 is a perspective view partially showing a cross section of the main part of the jet pump in FIG. 6. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Reactor pressure vessel, 2 ... Core, 3 Coolant, 4 ... Core shroud, 5 ... Steam separator, 6 ... Steam dryer, 7 ... Main steam pipe, 8 ... Downcomer part, 9 ... Lower plenum, 10 ... Jet pump, 11 ... Control rod guide tube, 12 ... Riser tube, 13 ... Recirculation inlet nozzle, 14 ... Transition piece, 15a, 15b ... Elbow, 16a, 16b ... Mixing nozzle, 17a, 17b ... Inlet throat, 18a , 18b ... Diffuser, 19 ... Riser brace, 20 ... Shroud support, 21 ... Riser elbow, 22 ... Thermal sleeve, 23 ... Riser bracket, 24 ... Pad, 25 ... Jet pump maintenance device, 26 ... Upper plate, 27 ... Lower plate 28 ... Case, 29 ... Seal member, 30 ... Handle, 31 ... Rod, 32 ... Handle plate, 33,33a ... Plate, 34 ... Screw, 35 ... Vertical drive motor, 36 ... Semi-ring, 37 ... Drive motor for rotation, 3 7a ... rotating shaft 38 ... first gear 39 ... second gear 40 ... laser head 40a ... laser optical system case 41 ... linear guide 42 ... belt 43 ... gear 44 ... gear 45 ... Lens, 46 ... Mirror, 47 ... Nozzle, 48 ... Hood seal, 49 ... Welded part, 50 ... First rotating shaft, 51 ... First pulley, 52 ... Second pulley, 53 ... Upper bearing, 54 ... Lower Bearing, 55 ... clamping nut, 56 ... rotating gear, 57 ... key, 58 ... second rotating shaft.

Claims (7)

A one-sided opening housing having an upper plate and a lower plate installed between a jet pump and a riser tube installed between a reactor pressure vessel and a core shroud, a laser head provided in the housing, and the laser A laser optical system case in contact with the lower part of the head, a nozzle provided on the laser irradiation side of the optical system case, a linear guide for placing the laser optical system case, and a pair of upper and lower parts for placing the linear guide A plate, a half ring having a gear on a side surface inserted between the pair of upper and lower plates, a rotation drive mechanism meshing with the gear of the half ring, and a vertical movement drive mechanism for moving the pair of upper and lower plates up and down An apparatus for maintaining a jet pump, comprising: 2. The maintenance device for a jet pump according to claim 1, wherein a hood seal material that is in airtight contact with the outer surface of the riser pipe is provided at the tip of the nozzle. 2. The maintenance device for a jet pump according to claim 1, wherein a foldable handle is attached to the upper surface of the upper plate via a rod. The rotary drive mechanism has a drive motor mounted on the pair of upper and lower plates, a first gear mounted on a rotary shaft of the drive motor, and a first rotary shaft mounted with a second gear meshing with the first gear. A first pulley is attached to the first pulley, and a second rotating shaft having a second pulley rotating on the first pulley via a belt is provided on the pair of upper and lower plates, and a third rotating shaft is provided on the second rotating shaft. 2. The maintenance device for a jet pump according to claim 1, wherein the maintenance device comprises a gear. The vertical drive mechanism is provided with a lower bearing on the lower plate, a screw is rotatably attached to the lower bearing, an upper end portion of the screw is rotatably attached to the lower surfaces of the pair of plates via the upper bearing, 2. The maintenance device for a jet pump according to claim 1, wherein a rotary gear is attached to a lower end portion of the screw, and a vertical movement drive motor for rotating the rotary gear is provided. 2. The jet pump maintenance device according to claim 1, wherein a lens and a mirror are provided in the laser optical system case, and an underwater camera and an underwater illumination tool are provided in the vicinity of the laser optical system case. The jet pump maintenance apparatus according to claim 1, wherein at least one of an ultrasonic flaw detection test apparatus and a polishing apparatus is provided in the vicinity of the laser head.

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