JPS5949522B2 - Fuel channel box strain measurement device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel channel box distortion measuring device for inspecting an activated fuel channel box used in a nuclear reactor of a nuclear power plant.

In general, a fuel channel box in a nuclear reactor is affected by thermal stress caused by a nuclear fission reaction of a fuel body inside the fuel channel box, which may cause distortion or the like in the fuel channel box.

On the other hand, in a large number of fuel channel boxes housed in a nuclear reactor, a certain gap is provided between one fuel channel box and another fuel channel box.

The control rods that control the nuclear fission reaction slide through this fixed gap to be withdrawn or inserted. For this reason, if the fuel channel box is highly distorted, the movement of withdrawing and inserting the control rods will not be smooth, which may impede the control of the nuclear fission reaction by the control rods. Conventionally, to inspect the distortion of this fuel channel box,
All the fuel rods and other items stored inside the fuel channel box were removed to ensure that there was no risk of exposure to radiation from the used fuel, and then they were inspected.

The strain in this empty fuel channel box was measured using an instrument using a dial gauge, and the degree of distortion was determined based on the readings from the dial gauge. These measurements are performed underwater in the fuel pool to avoid exposure to radiation, so they are very time-consuming and require reading dial gauges using an underwater television. was. For this reason, it is currently possible to measure strain in the fuel channel box at only three or four locations out of the total length of the fuel channel box.

Furthermore, after measuring one measurement surface of the fuel channel box, the same procedure was repeated to measure the strain on the surface of 900 rotations, and it took a lot of time to measure the strain on one fuel channel box. .

Furthermore, since measurements using a dial gauge are carried out individually for each measurement location, it has been extremely difficult to determine the strain associated with the method of determining the standard value of strain.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a strain measuring device that can easily and accurately measure strain over the entire length of a fuel channel box. In other words, the present invention includes a cylindrical outer frame installed underwater, a guide provided at the top of the outer frame and shaped to open upward, and a movable guide provided at the bottom of the outer frame so as to be movable in the horizontal direction. a frame, a measuring device protruding inside the movable frame to measure the dimensions of the fuel channel box that passes through the movable frame, and a measuring device connected to the measuring device to transmit the measured dimension signals on the water surface. the fuel channel box and the measuring device; and a driving amount measuring means for measuring the driving amount of the vertical driving means. This is a strain measurement device for fuel channel boxes.

An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIGS. 1 and 2, the reactor well 10 and the fuel pool 11 communicate through a canal 16. A fuel assembly 24 is housed inside the reactor well 10.
Above the reactor well 10 and fuel pool 11, a fuel exchange platform 12 for operating a fuel channel box 21 is provided on a moving rail 12A and can be moved as desired. A fuel cask 13 for storing used fuel is provided inside the fuel pool 11. As shown in FIGS. 3 and 4, a fuel channel box strain measuring device mount 14 is provided at the upper corner of the fuel cask 13, and a fuel channel box strain measuring device 15 is provided at the center of this mount. As shown in FIG. 5, the fuel channel box strain measuring device 15 has four guides 52 attached to the upper part of a polygonal cylindrical outer frame 51, and an upper guide support 53 and a lower guide support 54 installed inside the outer frame 51. The fuel channel box 21 is configured to be easily guided to the strain measurement section. Furthermore, a movable frame 55A is suspended by several wires 60 from a fixed frame 55 fixed to the lower side inside the outer frame 51, and the upper guide support 55A is suspended by several wires 60.
3 and the lower guide support 54, it has play to freely move relative to the fuel channel box 21 which is positioned and inserted. At least one mounting plate 56A is attached to the movable frame 55A, and a spring 56 is attached to the mounting plate 56A, which sensitively responds to irregularities caused by distortion on the surface of the fuel channel box 21 when the fuel channel box 21 is inserted. is installed. Furthermore, this spring 56
A wire strain gauge 57 for sensing the movement of the spring is attached to the back surface of the spring 56.

A waterproof cable 59 is installed to transmit the amount of strain sensed by the wire strain gauge 57 to a measuring device. On the other hand, the movable frame has fuel channel box 2.
A fixing support 58 is provided for sliding while fixing the opposite surface of the channel box to the measurement surface when the channel box 1 is inserted. The movable frame 55A is designed to have play in moving freely relative to the inserted fuel channel box 21 and to absorb the lateral movement of the fuel channel box 21, and is suspended from the fixed frame 55 by a wire 60. A head support 61 is fixed to the outer frame 51 in order to prevent the measurement head set from falling if the wire 60 is damaged. FIG. 6 shows the planar arrangement of the fixed support 58, spring 56, and wire strain gauge 57 during strain measurement of the fuel channel box 21.

As shown, the fuel channel box 21
For example, the strain measurement is performed using a fixed support 5 in the X2-X2 direction.
8, a spring 56, and a wire strain gauge 57, and strain can be measured simultaneously in the Y2-Y2 direction and the Z1-Z1 direction.

The amount of strain sensed by the wire strain gauge 57 is transmitted through a waterproof cable 59 and input to a fuel channel box strain measuring device 70 shown in FIG.

As shown in FIG. 7, this fuel channel box strain measuring device 70 is comprised of a prisge head 71, a strain measuring device 72, a data recorder 73, a synchroscope 74, and a recorder 75 as shown. On the other hand, the measuring device also receives the signal of a hoist linear displacement meter 25 attached to the hoist 22 of the refueling platform 12 in order to monitor the insertion position of the fuel channel. Note that, although not shown in the figure, a non-contact type displacement meter using eddy current may be used as a detector for sensing the unevenness of strain on the surface of the fuel channel box, instead of the spring 56 and wire strain gauge 57. You can also do it. Next, the operation of the fuel channel box strain measuring device constructed as described above will be explained. As shown in Figure 2, water is filled in the reactor well 10, canal 16, and fuel pool 11 during periodic inspections of the reactor to prevent exposure to radiation from used or spent fuel when replacing reactor fuel, etc. That's what I do. In order to measure the distortion of the spent fuel channel box, the fuel assembly 2
4, grab any fuel channel box 21 with the grip at the tip of the mast 22 of the fuel exchange platform 12, lift it up, and lift it from the water in the reactor well 10 to the canal 16.
and then into the water of the fuel pool 11. Thereafter, it is moved to a position directly above the fuel channel box distortion measuring device 15 provided above the fuel cask 13 in the fuel pool 11. From that position, the mast 22 of the refueling platform 12 is gradually extended to lower the fuel channel box 21 to the position of the guide 52 of the fuel channel box strain measuring device 15. As shown in FIG. 5, the fuel channel box 21 is connected to the guide 5
2, along the upper guide support until the lower guide support 54 is inserted. At this time, the fuel channel box 21 is ready for strain measurement. From this state, the fuel channel box 21 is further inserted downward. As the fuel channel box 21 is inserted between the fixed support 58 and the spring 56, the spring 56 responds sensitively to the distortion of the unevenness of the measurement surface of the fuel channel box 21. Since a wire strain gauge 57 is attached to this spring, the response to the distortion of the unevenness of the spring 56 is measured by the wire strain gauge 57.
It is sensed as a distortion amount of 7. Therefore, strain measurement can be started from the tip of the fuel channel box 21 and can be continuously measured until the end of the fuel channel box 21. Moreover, instead of the spring 56 and the wire strain gauge 57 as means for measuring strain, a non-contact type displacement meter using eddy current can be used. The procedure described above is a measurement procedure for a pair of surfaces of the fuel channel box 21, but as shown in FIG.
If the pairs of springs 56 and 56 are provided in three radial directions, the X2-X2 direction, the Y2-Y2 direction, and the Z1-Z1
Strain can be measured continuously from the starting end to the ending end in three radial directions of the fuel channel box 21.

Of course, the fixed support 58, the spring 56, and the wire strain gauge 57 are further paired, and
-X3 direction, Y1-Y1 direction, Y3-Y3 direction, Z2-
It is also possible to measure strain at multiple points simultaneously, such as in the Z2 direction. When the amount of strain sensed by the wire strain gauge 57 is inputted to the plug head 71 of the fuel channel box strain measuring device 70 through the waterproof cable 59, the amount of strain is converted into an electrical signal by the strain measuring device 72 and collected by the data recorder 73. be done.

Furthermore, a distortion amount signal is sent from the distortion measuring device 72 to a synchroscope 74, and the amount of distortion is displayed. On the other hand, in order to measure continuously from the start end to the end end of the fuel channel box 21, a signal from a hoist linear displacement meter 25 attached to the hoist 23 part is also used to determine the expansion/contraction position of the mast 22 of the fuel exchange platform 12. , are simultaneously input to the synchroscope 74 and data recorder 73.

An electrical signal from the data recorder 73 or the strain measuring device 72 is recorded in the graphical recorder 75. Here, a curve of strain measurements versus longitudinal position of the fuel channel is obtained, as shown in one illustrative example in FIG. In the example shown in this figure, a predetermined reference value of the amount of fuel channel box distortion and an allowable value of the amount of fuel channel box distortion are shown simultaneously. This tolerance value uses the measured value obtained as a result of experimental strain measurement using a calibration fuel channel box made to allowable dimensions prior to actual fuel channel box strain measurement. . Therefore, if the actual distortion value of the fuel channel box 21 is between the standard value and the allowable value, the amount of distortion of the fuel channel box 21 is within the specified range, but the measured value exceeds the allowable value. is determined to be an abnormal amount of distortion. If this abnormal distortion occurs, it is determined that it is unsuitable to put it back into the fuel assembly 24 in the nuclear reactor and use it. As explained above, according to the fuel channel box distortion measuring device of the present invention, it is possible to determine whether or not the distortion of the activated fuel channel box used in a nuclear reactor is within the allowable range. This can be easily done by remote control continuously over the entire length of the end.

[Brief explanation of drawings]

FIG. 1 is a plan view of a structure in which a reactor well in which a fuel channel box strain measuring device of the present invention is installed and a fuel pool are communicated with each other through a canal, and FIG. 3 is a detailed view of part A in FIG. 1, and FIG. 4 is a side view showing a combination of a fuel channel box measuring instrument mount and a fuel channel box strain measuring instrument, as seen from the - arrow direction in FIG. 3. FIG. 5 is a sectional view showing the main body of the fuel channel box strain measuring device according to the present invention, and FIG.
7 is a block diagram showing an embodiment of the fuel channel box strain measuring device of the present invention, and FIG.
The figure is a strain measurement diagram recorded on a recorder according to the present invention.〇14...Fuel channel box measuring instrument mount, 15...Fuel channel box strain measuring instrument, 70... ...Fuel channel box distortion measuring device.

Claims (1)

[Claims] 1. A cylindrical outer frame installed underwater, a guide provided at the top of the outer frame and shaped to open upward, and a movable frame provided at the bottom of the outer frame so as to be movable in the horizontal direction; A measuring device that is provided protruding inside the movable frame and measures the dimensions of the fuel channel box that passes inside the movable frame, and a display device that is connected to this measuring device and is provided on the water surface to display the measured dimension signal. a display means for displaying on the fuel channel box; a vertical driving means for driving the fuel channel box and the measuring device relative to each other; and a driving amount measuring means for measuring the driving amount of the vertical driving means. Channel box distortion measurement device.