JP2660049B2 - Inspection device for control rod drive mechanism housing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to various inspections such as an ultrasonic inspection test and a helium leak test of a control rod drive mechanism housing during a periodic inspection of a boiling water reactor. The present invention relates to an apparatus for inspecting a control rod drive mechanism housing used for a test.

(Conventional technology) A control rod drive mechanism housing (C) containing a control rod drive mechanism (CRD) is located at the bottom of the reactor pressure vessel of a boiling water reactor.
RD housing). The CRD housing penetrates vertically through the bottom of the reactor pressure vessel, and is fixedly welded to the bottom of the reactor pressure vessel via a stub tube provided on the outer periphery thereof.

The weld between the CRD housing and the stub tube
In-service tests (ISIs) are conducted periodically to become the boundary between the primary cooling water of the reactor and the atmosphere. This service test is performed from the inside or outside of the GRD housing. Ultrasonic testing (UT), liquid penetration testing (PT), electromagnetic wave testing (ET), helium leak test (He test), appearance test ( VT).

(Problems to be Solved by the Invention) Conventionally, service tests have been carefully performed before actual operation, but at the time of periodic inspection after actual operation, since the CRD housing is in cooling water, these tests are performed. Was not done.

However, regular inspections of the CRD housing at the time of periodic inspections have been required from the viewpoint of enhancing the safety of the reactor. Therefore, it is desired to develop an inspection device that assists inspection by preventing cooling water from entering the CRD housing and preventing He from leaking out of the control rod drive mechanism housing in the He test. .

The present invention has been made in consideration of the above circumstances, and can be handled by a control rod guide tube gripper, an automatic control rod exchange machine, and the like, so that the control rod drive mechanism housing can be inspected efficiently and in a short time. It is an object of the present invention to provide an apparatus for inspecting a control rod drive mechanism housing which can be remotely operated and thereby prevent work exposure.

[Configuration of the invention]

(Means for Solving the Problems) The present invention includes a seal plug having a grip portion that can be handled by a control rod guide tube gripper, and a model control rod drive mechanism simulating a control rod drive mechanism. Has a large-diameter portion that is substantially the same diameter as the control rod guide tube and can be held by the core support plate, and a shaft portion that contacts and seals the upper end of the control rod drive mechanism housing. The mechanism is a model piston tube that advances and retreats in the control rod drive mechanism housing, a drive mechanism that drives this model piston tube, and the model piston tube is pushed up to abut the upper end flange of the control rod drive mechanism housing from inside. It has a seal flange for hermetically sealing and a gas supply hole for supplying a gas for inspection into the control rod mechanism housing. .

(Operation) At the time of the periodic inspection, the fuel is moved from the core and the control rod and the control rod guide tube are pulled out. Next, a seal plug is hung from the fuel exchange platform with a control rod guide tube gripper, passed down through the upper lattice plate and the core support plate, and further lowered, and the shaft abuts on the upper end of the control rod drive mechanism housing. And the large diameter portion is held by a core support plate. Thereafter, the control rod drive mechanism is pulled out by the control rod drive mechanism automatic exchange. Then, various tests and inspections are performed from inside and outside of the control rod drive mechanism housing. In this case, since the upper end of the control rod drive mechanism housing is sealed by the shaft of the seal plug, the cooling water is prevented from flowing into the control rod drive mechanism housing.

Then, the model control rod drive mechanism is installed in the control rod drive mechanism housing using the control rod drive mechanism exchanger, the model piston tube is pushed up by the drive mechanism, and the seal flange is applied to the upper end flange of the control rod drive mechanism housing from inside. Contact and seal hermetically. Then, a gas for inspection is supplied from the gas supply hole, and a leak test is performed. In this case, since the upper flange of the control rod drive mechanism housing is hermetically sealed by the seal flange, the gas for inspection is prevented from leaking from the upper opening of the control rod drive mechanism housing.

(Embodiment) An embodiment of an apparatus for inspecting a control rod drive mechanism housing according to the present invention will be described with reference to the accompanying drawings.

In FIG. 2, a control rod drive mechanism housing (CRD housing) 2 is provided at the bottom of the reactor pressure vessel 1 so as to penetrate vertically. The CRD housing 2 is fixed to the reactor pressure vessel 1 by a weld 4 via a stub tube 3 provided on the outer periphery thereof.

Control rod drive mechanism (CRD) from below in CRD housing 2
5 is inserted into the lower flange 6 of the CRD housing 2.
The flange 7 is bolted. The CRD 5 has an outer tube 9 in the CRD housing 2.
A piston tube 10 is provided so as to be able to reciprocate up and down in the inside. Piston tube 10 is a tube on a long hollow cylinder
10a and a piston 10 provided at a lower end of the tube 10a.
b. In the piston tube 10, an indicator 11 indicating the position at which the control rod is moved up and down is housed. A ring flange 12 is provided at the lower end of the CRD 5, and is fastened by a nut 13. The lower end of the indicator 11 is a position pointing device 14
Connected to. Reference numeral 15 indicates a cover. CRD flange 7
A water passage 17 is formed therein, and the water passage 17 is supplied with pressurized water for control rod insertion / extraction from a water pipe 18 connected to the lower end flange 6.

An upper end flange 20 is provided at the upper end of the CRD housing 2, and a conical seat 20 a is formed on the inner peripheral side of the upper end flange 20. The lower end of the control rod guide tube 21 is fitted to the upper end flange 20, and the conical seat portion 21a of the control rod guide tube 21 is seated on the conical seat 20a. The control rod 22 is inside the control rod guide tube 21.
Are reciprocally accommodated.

When inspecting the CRD housing 2 configured as described above, the control rod 22, the control rod guide tube 21 and the CRD 5
Is removed, and an inspection device as shown in FIG. 1 is mounted. That is, a seal plug 24 that can be handled by the control rod guide tube grip 23 is mounted from above the CRD housing 2, and a model control rod drive mechanism (model CRD) 25 simulating the CRD 5 is mounted from below the CRD housing 2. Is done. The seal plug 24 has a large diameter portion 27 having substantially the same diameter as the control rod guide tube 21 and capable of being held by the core support plate 26 so that it can be handled by the control rod guide tube grip 23. A grip 28 that can be handled by the control rod guide tube grip 23 is provided. Reference numeral 29 denotes a gripper stud of the control rod guide tube gripper 23, and a gripper arm 30 is provided below the gripper stud 29.
Is provided. A pin 32 is provided at the tip of the gripper arm 30 and protrudes outward by a gripper air cylinder 31 and can be engaged with the gripper 28. The grip portion 28 is, for example, a large diameter portion 27
Is composed of a plurality of holes formed in the outer peripheral portion. The shape of the grip portion 28 is formed in substantially the same shape as the hole for the control rod guide tube gripping tool 23 provided in the control rod guide tube 21. The gripping stud 29 is formed so as to be connectable to the tip of a wire rope extending from an auxiliary hoist (not shown).

At the lower part of the large diameter part 27, the upper end flange 2 of the CRD housing 2
A shaft portion 34 is provided to abut against and seal with zero. The shaft portion 34 extends in the up-down direction, and a contact portion 35 is provided at a lower end portion of the shaft portion 34 so as to be in contact with and seal with the conical seat 20a of the upper end flange. Contact part 35
For example, a seal rubber or the like is provided between and the conical seat 20a. A guide 36 is provided on the outer periphery of the shaft portion 34, and the guide 36
A vent hole 37 is formed between the shaft 36 and the shaft portion 34. Reference numeral 38 denotes a drain hole provided below the large diameter portion 27.

The model CRD25 attached to the CRD housing 2 has the same outer shape and length as CRD5. Model CRD of Model CRD25
The flange 40 is fixed to the lower end flange 6 of the CRD housing 2 with bolts or the like, and a blind plug 42 is provided in the model waterway 41 to airtightly partition the water pipe 18. Model CRD flange 4
From 0, a model outer tube 43 extends upward, and a model piston tube 44 is provided in the model outer tube 43 so as to be able to reciprocate. An end plate 45 is provided at the upper end of the model outer tube 43, and a hole through which the model tube 44a penetrates is formed at the center of the end plate 45. The upper end of the model tube 44a is provided with a seal flange 46 that abuts against the upper end flange 20 of the CRD housing 2 from inside and hermetically seals. This seal flange
For example, a seal rubber is provided on the outer peripheral portion of 46.

A flange 48 is fixed to a lower portion of the model CRD flange 40, and the flange 48 is provided with a cover 49 and a cylinder flange.
A hydraulic jack 51 as a drive mechanism is attached via 50. The hydraulic jack 51 moves the piston using, for example, hydraulic pressure or the like, and houses a spring for automatic return inside. The extension shaft of the piston of the hydraulic jack 51 is connected to the model piston 44b of the model piston tube 44 by a nut 52. The model CRD flange 40
Is provided with a gas supply hole 53 for supplying a helium (He) gas for inspection in the CRD housing 2. This gas supply hole is communicated with the model waterway 41, and the CRD
He gas is supplied into the housing 2.

 Next, the operation of the above embodiment will be described.

At the time of the periodic inspection, the control rod 22, the control rod guide tube 21, the fuel (not shown), and the like are removed, and the seal plug 24 gripped by the control rod guide tube grip 23 is suspended from the platform by the auxiliary hoist. It is lowered through the gap of the support plate 26, and the contact part 35 of the shaft part 34 is
A large diameter portion 27 of the core support plate 26.
Is held. After attaching the seal plug 24, the control rod guide tube gripper 23 is disengaged, and the control rod guide tube gripper 23 is released.
Hoist only with the auxiliary hoist. The seal plug 24 has its own weight on the upper end flange 20, and the contact weight
A seal is provided between 35 and the conical seat 20a.

After that, CRD5 is pulled out from CRD housing 2 by CRD exchanger, and ultrasonic inspection (UT), liquid penetration inspection (PT), electromagnetic wave inspection (ET), and appearance test (VT) are performed from inside CRD housing 2. Do. Also,
An appearance test of the CRD housing 2 is performed by suspending a television camera or the like from above the core.

Next, the model CRD 25 is inserted and mounted from below the CRD housing 2 using a CRD exchanger. And the liquid jack 51
The model piston tube 44 is pushed up by this, and the seal flange 46 is brought into contact with the upper end flange 20 from the inside to hermetically seal. After sealing, helium leak test (He test) by supplying He gas from the gas supply hole into the CRD housing 2
Perform If there is a leak in the CRD housing 2, the He gas leaks to the upper surface of the reactor core or below the reactor pressure vessel 1, so that a defective portion of the CRD housing 2 can be confirmed.

As described above, according to the above-described embodiment, the inside of the CRD housing 2 can be kept airtight by using the seal plug 24 that can be handled by the control rod guide tube grip 23 and the model CRD 25 that can be handled by the CRD exchanger. Therefore, the CRD housing 2 can be inspected from the inside or outside of the CRD housing 2, and the work can be efficiently performed in a short time by using the control rod guide tube gripper 23 and the CRD exchanger. Exposure to work can be prevented by performing the operation.

FIG. 3 shows another embodiment of the present invention.
Are fixed to the upper end flange 20 by fixing bolts 55. The fixing bolt 55 is attached from inside the CRD housing 2 after the CRD 5 is removed from the CRD housing 2. According to this embodiment, even if an earthquake or the like occurs during the inspection work of the CRD housing 2,
The contact portion 35 can be prevented from coming off the upper end flange 20, and the cooling water can be prevented from leaking outside through the inside of the CRD housing 2.

〔The invention's effect〕

The present invention includes a seal plug having a grip portion that can be handled by a control rod guide tube gripper, and a model control rod drive mechanism simulating a control rod drive mechanism, wherein the seal plug has substantially the same diameter as the control rod guide tube. A large-diameter portion that can be held by the core support plate, and a shaft portion that abuts on and seals the upper end of the control rod drive mechanism housing. A model piston tube that moves forward and backward, a drive mechanism that drives the model piston tube, a seal flange that abuts from the inside to the upper end flange of the control rod drive mechanism housing when the model piston tube is pushed up, and hermetically seals; A gas supply hole for supplying a gas for inspection within the rod mechanism housing; Using a dynamic mechanism exchanger, the inside of the control rod drive mechanism housing is kept airtight by the seal plug and the model control rod drive mechanism, and the inspection work of the control rod drive mechanism housing can be performed efficiently and in a short time. By performing the remote control, it is possible to prevent work exposure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing an embodiment of an apparatus for inspecting a control rod drive mechanism housing according to the present invention, and FIG. 2 is a control rod drive mechanism and a control rod mounted on the control rod drive mechanism housing. FIG. 3 is a sectional view showing a state where the guide tube is mounted, and FIG. 3 is a sectional view showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Reactor pressure vessel, 2 ... Control rod drive mechanism housing, 3 ... Stub tube, 4 ... Welded part, 5 ... Control rod drive mechanism, 20 ... Top flange, 21 ... Control rod guide tube , 22 ... Control rod, 23 ... Control rod guide tube gripper, 24 ...
… Seal plug, 25 …… Model control rod drive mechanism, 26 ……
Core support plate, 27 large diameter part, 28 grip part, 34 shaft part, 35 contact part, 40 model control rod drive mechanism flange, 44 model piston tube, 46 Seal flange, 51 ... Hydraulic jack, 53 ... Gas supply hole.

Claims (1)

(57) [Claims] 1. A control rod guide tube comprising: a seal plug having a grip portion that can be handled by a control rod guide tube gripper; and a model control rod drive mechanism simulating a control rod drive mechanism, wherein the seal plug is substantially the same as the control rod guide tube. A large diameter portion that can be held by the core support plate with a diameter, and a shaft portion that abuts on and seals the upper end of the control rod drive mechanism housing. A model piston tube that moves forward and backward, a drive mechanism that drives this model piston tube, and a seal flange that abuts from the inside to the upper end flange of the control rod drive mechanism housing when the model piston tube is pushed up to hermetically seal it, A control rod drive mechanism housing having a gas supply hole for supplying a gas for inspection in a control rod mechanism housing. Inspection apparatus of grayed.