JPS5975131A - Method and device for measuring spring force of support grating elastic support part of fuel assembly - Google Patents

Abstract

PURPOSE:To measure spring force directly by positioning a measuring sensor between the rigid support part and elastic support part of a support grating and measuring a variation in the resistance of a strain gauge when the plate member of this sensor is deformed by the force of the elastic support part. CONSTITUTION:The deformation bar which has the recessed part 44 where a leaf spring part 43 and the strain gauge 45 are stuck and the measuring sensor consisting of an expanded tube 39 and an tube expanding rod 40 are positioned right over the center of the support grating 5 having a dimple 10 and a spring part 11 and then the lower end part of the expanded tube 39 is positioned in the center of the spring part 11. The tube expanding rod 40 is lifted to expand the lower part of the expanded tube 39. At this time, the lower part of the rod 40 is so formed that the diameter of the tube 39 is equal to the diameter of a fuel rod, so the variation in the resistance value of the strain gauge 45 is recorded to measure the spring force directly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for measuring spring force of an elastic support section of a support grid of a fuel assembly for a nuclear reactor.

The fuel assemblies loaded in the pressurized water light water reactor 1 currently in use are configured as shown in Figures 1 to 4. An upper nozzle 1 and a lower nozzle 2 arranged therebetween, and a plurality of support grids 5 arranged at predetermined intervals and having grid spaces 4 formed by straps 3;
This is inserted into the grid space 4 of the support grid 5 at a predetermined interval, and the fixed part of the support grid 5 is fixed.
Furthermore, a control rod guide 6 is connected to the upper and lower ends of the upper nozzle 1 and the lower nozzle 2, and the cladding tube 7 contains a large number of sealed fuel pellets 8 and a presser spring 9,
A large number of fuel rods 12 are inserted at predetermined locations in the lattice space 4 of the support grid 5 (the rigid support portions (dimples) 10 and the elastic support portions (spring portions) of the support grid 5 are inserted through the lattice space 4).
It is composed of -C.

The holding force at the contact portion 1 in each lattice space 4 of the support lattice 5 that supports the fuel rods 12 is determined by thermal expansion of the cladding tube 7 and the support lattice 5, irradiation growth, and irradiation (due to the spring force of the elastic support portion). Low temperature (also called relaxation), coolant flow,
It is set taking into consideration various factors such as flow velocity. If this holding force is excessive, when assembling the fuel assembly (this
When the fuel rod 121 is inserted into the fuel rod 121, it is easily damaged and the fuel rod 12 is easily bent during combustion. On the contrary, if this holding force is too small, the relaxation of the elastic support part 11 due to irradiation will cause the fuel rod to
Due to the cooling water flow, the holding force for the fuel rod 2 is insufficient, and homogeneous movement occurs between the contact area between the fuel rod 2 and the support grid 5 and between the fuel rods, resulting in so-called fretting wear and damage to the coating. The lifespan of tube 7 is shortened by one.

As described above, the holding force of the fuel rods 12 in the support grid 5 is an important factor that affects the performance of the fuel assembly. However, it is only possible to measure the pushing force of the simulated fuel rods etc. onto the support grid 5 and indirectly estimate the holding force (also called restraint force) for the actual fuel rods from this pushing force. Ta.

This invention was made in view of the above-mentioned article 1, and provides a support grid elastic support for a fuel assembly that can directly determine the spring force in the substantially horizontal and orthogonal direction of the elastic support portion of the support grid. The object of the present invention is to provide a method and device for measuring spring force in parts.

Hereinafter, this invention will be explained in detail based on FIGS. 5 to 9.

First, an embodiment of the apparatus of the present invention used in the method of the present invention will be explained in detail. In this embodiment, the same parts as in the conventional example are given the same reference numerals and the explanation thereof will be omitted. 21 in the figures and FIG. 6 is a main body, and this main body 21 consists of a base 22, a columnar part 23, and a head 24.

A base 22 (here a table 25 is provided).

This table 25 is composed of an
A Y table 27 is placed on the Y table 26 and moves horizontally in a direction perpendicular to the moving direction of the X axis table 26, and a rotating table 28 is mounted on the Yl!l table 27 and rotates horizontally It consists of

In addition, X-suke table 26. The Y-axis table 27 is driven by a pulse motor 1 according to commands from a microcomputer (CPU) 30, allowing accurate positioning.

Furthermore, the X-axis table 26 and Y[l! [1
1 X-axis origin sensor 26 provided on one side of the table 27
a.

The stopping position is reconfirmed by the action of the Y-axis origin sensor 27a. Further, the rotary table 28 is rotated by a rotation angle of 90° by a motor 29 provided on one side thereof, and then stopped. In addition, X-suke table 26. The Y-axis table 27 and rotation table 28 are each connected to a microcomputer (CPU) 30.

A predetermined location on this rotary table 28 (moss fixing jig 3
A support grid 5 is fixed via 1.

Further, a measurement sensor mounting body 33 is attached to the main body 21 so as to be located above the table 25. This measurement sensor mounting body 33 (this means that the measurement sensor 32 is in the vertical state)
It is removably attached. Measurement sensor mounting body 33 (main feed motor 34. Balance weight 3
A vertical movement mechanism 36 having a vertical movement mechanism 36, etc., is connected thereto, and the measurement sensor mounting body 33 can be moved vertically through this vertical movement mechanism 364 so as to freely adjust the vertical movement position.

The measurement sensor mounting body 33 has a hanging fitting 37, and the hanging fitting 37 (an arm 37a1 provided on the hanging fitting 37) has the same number of measurement sensors 32 as the number of grid spaces 4 in one row of the support grid 5 as shown in FIG. One row is arranged at the same pitch as the grid space 4, and one removable one is attached.

This measurement sensor 32 is constructed as shown in FIG. In the deformable bar 38, one side of a rectangular cylindrical portion 41 is extended downward to form a plate-shaped portion (plate member) 42.A particularly thin wall is formed at the approximate center of the plate-shaped portion 42 to form a plate spring. A concave portion 44 is formed in the lower outer surface of the plate-like portion 42. Four portions 44 (this includes two gauges 45 and 45 spaced apart vertically)
〇 Deformed bar 38 (shingled plate-like part 42 (an enlarged diameter tube 39 is attached along this
1 (the plate-shaped portion 42i is fixed by being fitted into the plate).

Further, the lower half of the enlarged diameter tube 39 is divided into a plurality of vertical division cuts (n7) provided at intervals in the circumferential direction.
5.45 center) is located here.

A tube expansion rod 40 is inserted into the diameter expansion tube 39, and the lower end of the tube expansion rod 40 (first tapered portion 46, first short cylindrical portion 47. A second tapered portion 48 t'!=' 2 short cylindrical portion 49 is formed.The upper part of the tube expansion rod 40 is fitted into a flanged bush 50, and a nut 51 is screwed therein.Flanged bush 50 is fitted into the rectangular cylindrical part 41 and its flange is engaged with the upper surface of the rectangular cylindrical part 41.Thereby, the tube expansion rod 40 is suspended from the deformed bar 38i. The expanded diameter tube 39 and expanded tube rod 40 constitute an operating rod.

The measurement sensor mounting body 331 is provided with a measurement sensor lifting mechanism 53 having a child feed motor 52. The shaft 5 of the child feed motor 52 of this measurement sensor pulling mechanism 53
4 (here, the upper ends of the expansion rods 40 of the measurement sensor 32 are connected to each other.

In addition, the strain gauge 45.45ζ of the measurement sensor 32 is connected to a dynamic strain gauge 56 provided with a measurement board 551 as shown in FIG. A data processing system 59 consisting of a disk drive 57, a CRT display 58, etc. is connected to it.In response to commands from the microcomputer 30, the horizontal movement mechanism, vertical movement mechanism 36° measurement sensor is pulled up via the drive control system 60. The mechanism 53 etc. are operated automatically).

In addition, a total of 6111 sensors 32 are connected between the rigid support section 102 and the elastic support section 11 of the single support grid 5, as shown in FIG.
These can be inserted without touching them (this is done).

Next, the method of the present invention is carried out using a device (H
This will be explained along with the effect of

(1) Set the fixing jig 31 on the rotary table 28 at the origin position of the main body 21.

(2) Attach this fixing jig and support grid 5.

(3) Enter the specified items on the CRT display 581,
X-axis table 26. The Y-axis table 27 is driven to position the lower end of each measurement sensor 32 on the support grid 5 in FIG. When this position (this measurement sensor 32 is located), these measurement sensors 32 are
The stopping position force 1 (
Safety against rAhd jamming and malfunction is ensured (Fig. 8(a)). 33, the measurement sensor 32 is lowered. When the lower end of the expanded diameter tube 39 of the measurement sensor 32 is positioned at the center of the spring part 11 of the support grid 5, the parent feed motor 34 is stopped and the measurement sensor 32 is lowered. Stop. (Fig. 8 (
b)) At this time, the measurement sensor 32 is inserted between the dimple 10° spring portion 11 (without touching it).

(5) Next, rotate the child feed motor 52 to operate the measurement sensor lifting mechanism 53, and! 11154 to raise the tube expansion rod 40. Then, the first tapered portion 4
6. First short cylindrical portion 47. Second tapered portion 48. The second cylindrical part 49 expands the diameter of the lower part of the expanded diameter tube 39, and the expanded diameter tube 39
While pressing the lower edge of the spring part 11, the plate-shaped part 42)
This is pressed to deform this plate-like portion 42. Then, the second short cylindrical part 49 is button rusted, and the lower end of the 39 is sieved at the 1st position.
1, the lower end of the measurement sensor 32 (FIG. 8(d))
Kokeru dimples 10. The width 32a between the spring parts 11 is approximately the same as the outer diameter of the fuel rod 12. (Figure 8(C),
(d) )kot'1. From f, upper and lower plot gauge 4
5.45 resistance changes, and this change in resistance value is transmitted to the dynamic strain meter 56] and is sent to the central processing unit f (CP
The input spring force is compared with the calibrated spring force value and recorded as a spring force. (Fig. 9) (6) Next, rotate the child feed motor 52 in the reverse direction to operate the measurement sensor pull-up 4-shaft mechanism 53, and 'a@'+! The tube expanding rod 40 is lowered through the tube 54 to release the engagement between the dimple 10 and the plate-like portion 42 and the engagement between the spring portion 11 and the diameter expanding tube 39. (Fig. 8(e)) (7) Next, the main feed motor 34 is operated in reverse, the vertical movement mechanism 36 is operated, and the measurement sensor 32 is moved together with the measurement sensor mounting body 33 to the initial position above the support grid 5. Raise it to the position. (FIG. 8(f)) (8) Next, the Y-axis table 27 is moved in the direction of the arrow in FIG. 6 by one grid space pitch.

When the Y-axis table 27 moves by one grid space pitch in this way, the Y-axis table 27 is stopped by the microcomputer 30, but the Y-axis light sensor 27a also confirms whether it is in the stopped position, ensuring safety against malfunction. Ru.

(9) Next meeting, above (3) to (8) (from this support grid 5
The spring force of the inner spring portion 11 in the horizontal direction (X-axis direction) in FIG.

00) Next (Here, drive the motor 29 to rotate the rotary table 28 by 90 degrees.

αD Next, according to (3) to (9) above, (
The spring force in the Y-axis direction is sequentially measured.

C13 simulated leaf spring inside [Daily inspection jig 61 provided with this
By inserting the measurement sensor once a day, the spring force F m
ll Compare with the specified setting and confirm that there is no abnormality in the sensor.

In the embodiment described in Xi, the tube expansion rod 401 has a first tapered portion 46. First short cylindrical portion 47. Second taber portion 48. Although the second short cylindrical portion 49 is provided, the tube expansion rod is not limited to this, and the tube expansion rod may be a straight ruler, and a tapered hole portion and a circular hole portion whose diameter decreases downwardly at the lower end of the diameter expansion tube may be provided. Good too. However, in this case, the lower end of the tube expansion rod is initially positioned above the tapered portion of the diameter expansion tube, and by lowering the tube expansion rod, the diameter of the diameter expansion tube is expanded, and from this point, the plate-shaped portion 42 is expanded. It will be transformed.

In the above embodiment, the measurement sensor mounting body 33
Although one row of many measurement sensors 32 is attached to the hanging fitting 37, the present invention is not limited to this, for example, multiple rows of measurement sensors 32 may be attached, or only one measurement sensor 32 may be attached to each. Good too. However, simply 1
When only 5 measurement sensors 32 are installed, the X-axis table 26 and Yi child table 7 are installed in order
In Figures 1 and 6, it must be moved left and right.

Further, in the embodiment, the measurement sensor mounting body 33
is moved only in the vertical direction, and the table 25 is moved horizontally; however, this is not limited to this, and at least one of the measurement sensor mounting body 33 and the table 25 may be horizontally movable. At least one of 33 and table 25 may be movable up and down.

Further, in the above embodiment, the operating rod is composed of the diameter-expanding tube 39 and the tube-expanding rod 40. Any other configuration of the operating rod may be used as long as it deforms the plate-shaped portion 42.

As explained above, according to the present invention, the support grid is fixed at a predetermined location, the measurement sensor is positioned on the center of the grid space of the support grid, and the measurement sensor is lowered so that its lower end is connected to the support grid. A part of the operating rod of the measurement sensor is moved up or down between the rigid support part and the elastic support part of the rigid support part. Since the plate members are pressed against each other and the plate members are deformed, and the resistance change of the gauge attached to this plate member is measured using a strain meter, the spring force in the substantially horizontal and orthogonal direction of the elastic support part of the support grid can be directly measured. The main body is equipped with a table and a measurement sensor mounting body (a support grid and a measurement sensor are respectively attached thereto, and at least one of the table and measurement sensor mounting body is horizontally moved, By moving at least one of them up and down and activating the measurement sensor pulling mechanism provided on the measurement sensor mounting body, the spring force of the elastic support portion of the support grid can be measured very easily and quickly. If a microcomputer is connected to control the table, measurement sensor mounting body, and measurement sensor lifting mechanism, the spring force of the elastic support part of the support grid can be controlled automatically (and more quickly). can be measured.

[Brief explanation of the drawing]

Figure 1 is a partially cutaway cross-sectional view showing an example of a nuclear reactor fuel combination; Figure 2 is a cross-sectional view taken along line ■-1 in Figure 1; Enlarged sectional view, Figure 4 is the tv in Figure 3.
5 is a front view showing one embodiment of the device of the present invention, FIG. 6 is a side view thereof, FIG. 7 is a vertical sectional view of the measurement sensor, and FIG. ) to (f) are schematic sectional views for explaining the measurement method of the present invention, and Figure @9 is a block diagram for explaining the spring force measurement system of the present invention.0 4... Lattice space , 5...Support grid, 1
0... Rigid support part (dimple), 11...
...Elastic support part (spring part), 21... Main body, 2
5...Table, 26...XIII
Table, 27...YIII11] Table,
28...Rotary table, 32...Measurement sensor, 33...Measurement sensor mounting body, 36
... Vertical movement mechanism, 38 ... Deformation bar, 3
9...Expanding tube, 40...Expanding rod, 4
2... Plate portion (plate member), 45... Strain gauge, 53... Measurement sensor lifting mechanism, 5
6...Dynamic strain meter. Figure 1

Claims (2)

[Claims] (1) A support grid having a rigid support part and an elastic support part is fixed at a predetermined location, and a part of the elastic plate member extending in the vertical direction and having a strain gauge attached to the lower end is fixed above the support grid. A measuring sensor provided with an operating rod having means for deforming the plate member is vertically moved, and the measuring sensor is moved vertically relative to the support grid. Move the measurement sensor horizontally to the center of the grid space of the support grid (
the measurement sensor is lowered to position the lower end of the measurement sensor between the rigid support part and the elastic support part of the support grid, and a part of the actuation rod is moved upward or downward. The plate member, the elastic support part 1, and the operating rod are pressed against the rigid support part to deform the plate member, and change the resistance of the attached gauge. A method for measuring a spring force of an elastic support portion of a support grid of a fuel assembly, characterized in that the spring force is measured from the i4 angle. (2) A main body, and a top surface of the main body (with a table fixed thereon and a supporting grid that can be freely removed) and a table that is located above the table with a top surface that is (This is the lower end of the extension (This is one side of the elastic plate member to which the strain gauge is attached.) is vertically removable (a measurement sensor mounting body attached thereto, and at least one of the table and the measurement sensor attachment body (this is provided,
A horizontal movement mechanism for horizontally moving these tables and the measurement sensor mounting body; a vertical movement mechanism (A) that is provided on the measurement sensor mounting body and that moves a part of the operating rod of the measurement sensor up and down, and a strain gauge that is connected to the strain gauge. A spring force measuring device for a support grid elastic support portion of a fuel assembly, comprising: