JP2809899B2 - Incore tightening nut handling tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-core fastening nut for fixing a neutron instrumentation tube in a boiling water reactor having a motor driven control rod drive mechanism (hereinafter referred to as FMCRD). And a tool for handling an in-core tightening nut.

[0002]

2. Description of the Related Art Since the output of a nuclear reactor such as a boiling water reactor is proportional to the neutron flux, the reactor is provided with a neutron flux detector (neutron flux monitor) for monitoring the neutron flux. The output of the reactor, the evaluation of the burnup, and the like are performed based on the detection output of the neutron flux monitor. The neutron flux detector includes an activation area monitor (hereinafter, referred to as SRNM) and an output area monitor (hereinafter, LPRM, APRM).
, Etc.), and a plurality of these monitors are installed in the reactor core. SRNM measures neutron multiplication factor during critical approach and neutron flux measurement during reactor power increase.

As schematically shown in FIGS. 4 and 5, S
A neutron instrumentation tube 1 containing a neutron flux detector such as an RNM is installed in a reactor core 3 in a reactor pressure vessel 2. FIG. 4 shows the inside of the reactor pressure vessel 2, and FIG. 5 shows a state where the neutron instrumentation tube 1 is attached to the reactor core 3. That is,
In FIG. 4, a reactor core 3 indicated by a broken line in the figure is accommodated in a reactor pressure vessel 2, and the reactor core 3 is surrounded by a reactor core support plate 4, an upper lattice plate 5 and a shroud 6. Although only one neutron instrumentation tube 1 is shown for simplicity of illustration, a plurality of neutron instrumentation tubes 1 are actually installed with their tips inserted into the core 3. .

The neutron instrumentation tube 1 is formed in an elongated tubular shape, and its upper end is elastically supported by a supporting recess 5a formed on the lower surface of the upper lattice plate 5, as shown in FIG. Protrudes downward from the lower surface of the reactor pressure vessel 2 via an incore guide tube 8 and an incore housing 9 which concentrically surround the neutron instrumentation tube 1. The lower end of the neutron instrumentation tube 1 is supported in contact with the in-core flange 10. In addition, the lower end of the neutron instrumentation tube 1 is
Is fixed by an in-core tightening nut 11. The in-core flange 10 is fixed to a flange 7 provided at a lower end of the in-core housing 9 by a tightening bolt 12.

[0005] In order to attach the neutron instrumentation tube 1 to the reactor core 3 in the reactor pressure vessel 2, work is performed in the following procedure. First, the neutron instrumentation tube 1 is suspended from above the core 3, and the lower end thereof is inserted into the in-core guide tube 8. Next, the suspension was further advanced, and the lower end of the neutron instrumentation tube 1 was moved to the position shown in FIG.
As shown in (1), the in-core flange 10 is brought into contact with and supported by the tapered receiving surface 10a. As is apparent from FIG. 5, a plunger 13 is slidably provided on the upper part of the neutron instrumentation tube 1, and a spring force upward is applied to the plunger 13 by a coil spring 14. . Therefore, after the suspension is performed as described above, the distal end 13a of the plunger 13 is fitted into the supporting concave portion 5a while pushing down the plunger 13 against the spring force, and the neutron instrumentation tube 1 is elastically mounted. can do. Finally, the incore tightening nut 11 is tightened to fix the lower end of the neutron instrumentation tube 1 to the incore flange 10 to complete the installation.

On the other hand, in order to detach the neutron instrumentation tube 1 from the reactor core 3, a procedure reverse to the above-mentioned procedure may be taken. That is, first, the in-core tightening nut 11 fixing the lower end is removed, and then, while the plunger 13 is pressed down against the elasticity of the coil spring 14, its tip 13 a is held in the supporting recess 5 a.
, And use a suitable handling tool (not shown)
13b is gripped and lifted, and detached from the core 3.

The lower end of the neutron instrumentation tube 1 is shown in FIG.
As shown in the figure, the sensor cable 15 is connected, this sensor cable 15 is inserted into the cable guide 16,
A signal cable is connected to the terminal via cable connector 17.
18 is connected. Signal cable 18 is a cable guide
The neutron detection signal is guided to the control room (not shown) from the end of 16 and transmitted to the control room. The cable guide 16 is screwed to the lower end of the neutron instrumentation tube 1, and the cable connector 17 is protected from water leakage by a seal 19 provided therein. In FIG. 6, reference numeral 20 denotes a drain hole provided on the side surface of the cable guide 16.

[0008]

In a boiling water reactor, as shown in FIG. 7, a large number of control rod drive mechanisms (hereinafter, referred to as CRDs) 21 are formed in a group below a reactor pressure vessel 2. A large number of CRD housings 22 are disposed around the incore housing 9 which is suspended and protrudes downward from the bottom of the reactor pressure vessel 2. Some boiling water reactors, such as an improved boiling water reactor, are planning a motor-driven control rod drive mechanism (hereinafter, referred to as FMCRD). In this FMCRD, an elongated motor section 23 is attached to a lower portion of the CRD housing. The space between adjacent motor sections 23 is remarkable and high. Therefore, when attaching / detaching the in-core tightening nut 11 for fixing the neutron instrumentation tube 1 to the in-core flange 10, the operator needs to
Cannot enter the space between 23 and tightening nut 11
Operation cannot be performed directly by hand.

The attachment and detachment work of the in-core tightening nut 11 is performed by LP
The replacement is performed when the neutron instrumentation tubes 1 such as RM and SRNM are replaced, and the replacement is performed at a time of periodic inspection of the reactor, for example, a plurality of tubes such as 10 tubes. When replacing the neutron instrumentation tubes 1, it is necessary to remove the CRD motor section 23 around the in-core housing 9 before replacing each neutron instrumentation tube, and it takes several hours to remove and install this CRD motor 23. And

Therefore, the replacement work of the neutron instrumentation tube 1 performed at the time of the periodic inspection of the reactor requires an extremely long time, and as a result, there is a problem that the periodical inspection time is lengthened and the radiation exposure of the workers is increased. is there.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and improves the workability of neutron instrumentation tube replacement work, shortens the time required for periodic inspection of a nuclear reactor, and reduces the radiation exposure of workers. An object of the present invention is to provide an in-core tightening nut handling tool which can be reduced.

[0012]

According to the present invention, there is provided a cylindrical operating pole having a socket at the upper end into which an in-core tightening nut is fitted and a small-diameter pipe at the lower end , and an inner operating pole support for inserting the small-diameter pipe. An outer operating pole support surrounding the inner operating pole support via a bearing, a cylindrical mount provided outside the outer operating pole support, and an outer cylindrical body for fixing the mount.
And the lower part of the outer operation pole support is
A double cylindrical fixing stand having an inner cylinder to be inserted between the cylindrical body, a spring interposed between the inner cylinder of the fixing base and said outer manipulation pole support, provided in the small diameter tube And a torque wrench engaging portion.

[0013]

In a state where the operation pole and the gantry are combined, the operation is automatically performed by a control rod drive mechanism (CRD) exchange machine, that is, a CRD exchange platform, a CRD bolt removal machine, or the like. As a result, the positioning is performed just below the in-core to be removed or attached. Thereafter, the lift truck rises and approaches the in-core tightening nut. Next, the torque wrench is engaged with the wrench engaging portion of the operation pole, the operation pole is rotated, and the in-core tightening nut is tightened or loosened to mount or remove the nut.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an in-core tightening nut handling tool according to the present invention will be described with reference to FIGS. FIG.
Reference numeral 24 denotes an operation pole, and the operation pole 24 is connected to a socket 25 having a regular hexagonal hole formed at an upper end thereof, into which the in-core tightening nut 11 is inserted, and is connected to a lower end of the operation pole 24. It consists of a body. A wrench engaging portion 27 is provided on the outer surface of the small diameter tube 26. A drain hole 28 is provided on the lower side surface of the socket 25, and a water receiving device 29 is attached to the socket 25 via a support 30 so as to surround the outside of the socket 25.
Liquid-tight. Reference numeral 31 denotes a cylindrical inner operation pole support into which the small-diameter tube 26 is inserted. Outside the inner operation pole support 31, upper and lower bearings 32 and 33 are provided with a large-diameter cylindrical outer operation pole support 34. ing. These inner and outer operating pole supports 31, 34
The operation pole 24 is supported by. A handle having an operating rod 35a on the outer surface of the lower end of the outer operating pole support 34
35 is installed. A large-diameter cylindrical mount 36 is provided so as to slide on the outer surface of the outer operation pole support 34, and the mount 36 is connected to a fixed base 37 by bolts 40 with flanges 38 and 39. Fixing base 37 is an inner cylindrical body
41 and from the center of circle cylindrical double cylinder having an outer cylindrical body 42
It is, operating rod 35a of the handle 35 to the outer cylindrical body 42
There is formed a slit-shaped handle guide hole 43 in which the upper and lower sides move vertically . Outside operation between the inner cylinder 41 and the outer cylinder 42
The lower part of the pole support 34 is inserted , a spring 44 is inserted between the inner cylindrical body 41 and the outer operation pole support 34, and a spring retainer 45 is formed on the inner surface of the outer operation pole support 34, It comes into contact with the upper end. The fixing base 37 is mounted on a bolt detacher 47 via an adapter 46. In the figure, reference numeral 48 denotes a drain pipe connected to the lower part of the inner operation pole support 31.
Is connected to a drain hose 49. Reference numeral 50 denotes a cover which covers the upper ends of the inner and outer operation pole supports 31, 34 and the outer side of the gantry 36. Wrench engaging part
A torque wrench 51 is attached to 27. The in-core tightening nut 11 coupled to the thread portion 52 of the in-core flange 10 is inserted into the socket 25. Reference numeral 53 indicates a nose piece projecting from the in-core flange 10.

Next, an example of use of the in-core tightening nut handling tool having the above configuration will be described with reference to FIGS. FIG. 2 shows an example of a CRD exchanger installed at a lower portion of the reactor pressure vessel 2, and FIG. 3 shows a use state of an in-core tightening nut handling tool. In FIG. 3, the worker 54 is located on a platform 55 of the CRD exchange, and is mounted on a bolt detacher 57 gripped by a lift truck 56 with the operation pole 24 connected to a gantry 36, and tightened with an incore. Nut 11
2 shows a state in which the unit is set. The operator 54 operates the torque wrench 51 to apply a rotational force to the operation pole 24. In FIG. 2, reference numeral 58 denotes an adapter storage for the bolt detacher 57, reference numeral 59 denotes a storage case for the bolt remover 57, reference numeral 60 denotes a pedestal, reference numeral 61 denotes an internal pump, and reference numeral 62 in FIG.
RD (improved electric control rod drive) cables are shown, respectively , and the bolt detacher shown in FIGS. 2 and 3 is shown.
57 and the bolt detacher 47 shown in FIG.
But the same . The platform 55 rotates in the circumferential direction (reverse rotation is also possible), and the lifting carriage 56 allows vertical movement. Positioning to the corresponding incore is performed by inputting the address data of the incore to the computer. The ascending after the positioning is performed by further inputting the ascending level data to the computer.

Next, a tightening operation method will be described. The in-core tightening nut handling tool is an in-core tightening nut 11 for fixing the neutron instrumentation tube 1 to the in-core flange 10.
Used to tighten or loosen The neutron instrumentation tube 1 seated on the in-core flange 10 has the screw portion 52 and the nose piece 53 as the lower end portions thereof protruding from the in-core flange 10 so that the in-core tightening nut 11 is tightened to the screw portion 52. The adapter 46 is used for mounting the in-core tightening nut handling tool on the bolt detacher 47. The fixing base 37 is used to attach the in-core tightening nut handling tool to the adapter 46. The in-core tightening nut handler moves below the neutron instrumentation tube 1 which is to be accessed by the platform 55 and the CRD exchanger. The bolt remover 47 is used to move the in-core tightening nut handling tool upward. The nosepiece is the in-core tightening nut inserted into the hexagonal socket 25
When the screw 52 is raised to the screw 52 while being guided by the screw 53, the screw having the inner diameter of the in-core tightening nut 11 comes into contact with the screw 52. When the bolt removal machine 47 rises, the mount
36 rises, but since the screw part 52 and the screw of the inside diameter of the in-core tightening nut 11 are in contact, the operation pole 24, the spring presser 45, the handle 35, and the inner and outer operation port support
The spring 44 contracts without raising 31 and 34. Since the handle guide hole 43 is provided in the fixed base 37, the handle 35 that rises with the fixed base 37 appears to descend to the lower end of the handle guide hole 43. When the torque wrench 51 is rotated, since the bearings 32 and 33 are provided, the fixed base 37 does not rotate, and only the operation pole 24 and the operation pole supports 31 and 34 rotate, and the in-core tightening nut 11 rotates the torque wrench 51. It rises as much as you do. When the in-core tightening nut 11 for fixing reaches the in-core flange 10, torque wrench
Tighten with the specified torque at 51. If water leaks from the in-core flange 10 during the above operation, the water is received by the water receiving device 29, and the water passes through the drain hole 28, drains through the inside of the operation pole 24, the small diameter pipe 26, the drain pipe 48, and the drain hose 49. Is done. The support 30 supports the water receiving device 29. The handle 35 to which the in-core tightening nut 11 is tightened is lowered, and the handle 35 is set to the lower side of the handle guide hole 43, and then the bolt detacher 47 is lowered.

In the above-mentioned tightening operation method, when the bolt detacher 47 rises and the in-core tightening nut 11 approaches the threaded portion 52 of the neutron instrumentation tube 1, the bolt remover 47 is stopped from moving up. The operator lifts the handle 35 manually. As a result, the resilient force of the spring 44 is urged to raise the operation pole 24, and the in-core tightening nut 11 in the socket 25 is screwed into the in-core tightening nut screw portion.

In this state, another worker 54 confirms that the socket 25 is engaged with the target in-core tightening nut, and the torque wrench 51 is
To rotate the operation pole 24 to tighten the in-core tightening nut. When the in-core tightening nut is detached, the same procedure as described above is adopted. However, it goes without saying that the rotation direction of the operation pole 24 by the torque wrench is opposite to the above. Operation pole 24 is adjacent to FM
The neutron instrumentation tube 1 is approached so as to be inserted between the CRDs, but in the narrow gap, as shown in FIG.
However, according to the above-described embodiment, the in-core tightening nut in a position with poor workability where the operator 54 is difficult to enter can be easily operated by remote control. Can be attached and detached.

The present invention is not limited to the above embodiment. For example, the wrench engaging portion and the socket are hexagonal, but may be of any other appropriate shape. . In addition, if drain water is not generated during the in-core tightening nut attaching / detaching operation, a water receiving device, a drainage channel, and a drain hose are not required, and a more compact handling tool can be provided.

[0020]

According to the present invention, the tightening of the in-core tightening nut can be performed by remote control in a significantly shorter time and with a smaller number of people than in the prior art. Therefore, the period required for the periodic inspection of the reactor can be shortened, and the radiation exposure of the workers can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view partially showing a side view of an embodiment of an in-core tightening nut handling tool according to the present invention.

FIG. 2 is a perspective view of the pedestal for handling the in-core tightening nut handling tool in FIG.

FIG. 3 is an external view showing a use state of the in-core tightening nut handling tool in FIG. 2;

FIG. 4 is a longitudinal sectional view schematically showing a state in which a neutron instrumentation tube is installed in the reactor.

FIG. 5 is a longitudinal sectional view showing in detail a mounting state of the neutron instrumentation tube in FIG. 4;

FIG. 6 is a longitudinal sectional view showing a lower structure of the neutron instrumentation tube in FIG. 4;

FIG. 7 is a schematic diagram showing a state where the FMCRD is attached to the nuclear reactor in FIG.

[Explanation of symbols]

1: neutron instrumentation tube, 2: reactor pressure vessel, 3: core, 4
... core support plate, 5 ... upper grid plate, 6 ... shroud, 7 ...
Flange, 8: In-core guide tube, 9: In-core housing, 10: In-core flange, 11: In-core tightening nut,
12… Tightening bolt, 13… Plunger, 14… Coil spring, 15
... Sensor cable, 16 ... Cable guide, 17 ... Cable connector, 18 ... Signal cable, 19 ... Seal, 20 ... Water drain hole, 21 ... Control rod drive mechanism, 22 ... CRD housing, 23 ...
Motor part, 24 ... Operation pole, 25 ... Socket, 26 ... Small diameter pipe, 27 ... Wrench engaging part, 28 ... Drain hole, 29 ... Water receiving device,
30 ... Support, 31 ... Inner operation pole support, 32, 33 ...
Bearing, 34 ... Outside operation pole support, 35 ... Handle, 36 ... Stand, 37 ... Fixed stand, 38, 39 ... Flange, 40 ...
Bolt, 41… Inner cylinder, 42… Outer cylinder, 43… Handle guide hole, 44… Spring, 45… Spring presser, 46
... Adapter, 47 ... Bolt remover, 48 ... Drain tube, 49 ... Drain hose, 50 ... Cover, 51 ... Torque wrench, 52 ... Screw, 53 ... Nose piece, 54 ... Worker, 55 ... Platform, 56 ... Dolly, 57 ... bolt detacher, 58 ... adapter storage stand, 59 ... storage case, 60 ... pedestal, 61 ... internal pump, 62 ... FMCRD cable.

Claims (1)

(57) [Claims] 1. A cylindrical operating pole having a socket for fitting an in-core tightening nut at an upper end thereof and having a small-diameter pipe at a lower end, an inner operating pole support for inserting the small-diameter pipe, and an inner operating pole support. An outer operation pole support surrounding the outer side and provided via a bearing, a cylindrical mount provided outside the outer operation pole support , and an outer cylindrical body for fixing the mount ; and Outside operation
Insert the lower part of the pole support between the outer cylindrical body
A double cylindrical fixing stand having an inner cylinder that, with interposed spring between said inner cylinder of the fixing base and said outer manipulation pole support, and the torque wrench engagement portion the provided on the small diameter tube An in-core tightening nut handling tool comprising: