JPS6156477B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel assembly curvature correction device for correcting the overall curvature of a fuel assembly for, for example, a nuclear reactor underwater in a fuel pool.

The fuel assembly that makes up the core of the pressurized water type light water reactor currently in use is columnar as a whole, and is made up of a large number of fuel rods assembled into bundles at predetermined intervals. After inspection, it was reinstalled inside the furnace. Incidentally, when this fuel assembly is removed from the core, it may bend as a whole due to the release of thermal strain, etc., and such a fuel assembly cannot be reloaded into the reactor and loses its value as fuel. I had lost it.
Since it is extremely uneconomical to store or discard such fuel assemblies in an unusable state, it has been desired to develop a device for correcting the overall curvature of the fuel assemblies.

This invention was made in view of the above circumstances,
By moving the columnar fuel assembly in an easy-to-handle upright position and changing its set position, bending in each direction can be easily corrected.
Moreover, it is an object of the present invention to provide a fuel assembly bend correction device whose structure is extremely simple.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

Reference numeral 1 in the figure indicates a frame, and this frame 1
is provided in the water in the fuel pool P along the vertical direction by being suspended and supported by an upper frame 2 fixed to the upper part of the periphery of the fuel pool P. This frame 1 has three grid support plates 3, 4, and 5 at the top and bottom that simultaneously oppose the upper, middle, and lower sides of the vertical columnar fuel assembly F that is to be bent. It is installed offset in the direction. This fuel assembly F is for a pressurized water type light water reactor, and has an upper nozzle and a lower nozzle attached to its upper and lower parts, as well as a plurality of supports offset in the length direction and at positions including the middle part. It is fitted with a lattice and is shaped like a rectangular prism with a total height of about 4m. Fuel assembly F at each grid support plate 3, 4, 5
Recesses 6, 7, and 8 are provided on the side faces 3a, 4a, and 5a facing each other, and are laterally shifted from each other by about the width of the fuel assembly F. The width of each of the recesses 6, 7, and 8 is such that the upper, middle, and lower parts of the corresponding fuel assembly F can be fitted therein. In this embodiment, recesses 7, 8, and 6 are sequentially provided from the left to the right in FIG. A substantially L-shaped support is provided on the left side of the frame 1 located to the left of the middle grid support plate 4 and on the right side of the frame 1 located to the right of the upper and lower grid support plates 35, respectively. Bodies 9, 10, 11 are provided. Grid push arms 15, 16, 17 are rotatably attached to the tips of the supports 9, 10, 11 via vertical rotation shafts 12, 13, 14, respectively. A pad 18 facing the corresponding recess 7 is attached to the grid push arm 15 at the intermediate position, and a pad 19 facing the corresponding recess 6 and side surface 3a is attached to the grid push arm 16 at the upper position. , 20 are attached, and the grid push arm 17 in the lower position
Pads 21 and 22 are attached to the corresponding recess 8 and opposing pads 21 and 22 on the side surface 5a. Upper frame 2
A first shaft 23 along the vertical direction is rotatably supported between the left flange portion 2a and the support body 9 at an intermediate position, and the upper end 23a of the shaft 23 is manually operated by a wrench (not shown). The lower end 23b is connected to the rotating shaft 1 via the sprocket 24, chain 25, and sprocket 26.
It is connected to 2. Similarly, the upper frame 2
Second and third shafts 27 and 28 are supported between the right flange portion 2b and the supports 10 and 11, and by manually operating the upper ends 27a and 28a using a wrench (not shown), The lower ends 27b, 28b are configured to rotate around corresponding rotation shafts 13, 14 via sprockets and chains (not shown). Further, on the right flange portion 2b of the upper frame 2, second and third shafts 2 are attached.
A locking mechanism 29 is provided for locking 7 and 28 in appropriate rotational positions. This locking mechanism 29 is, for example, the second and third shafts 27 and 28.
A locking action is performed by inserting a locking pin provided on the upper frame 2 side into the collars attached to the upper ends 27a, 28a side. Each of these grid push arms 15, 16, 17 and pads 18, 19, 2
0, 21, 22 and the rotation operation system for each grid push arm 15, 16, 17, etc., press the upper, middle, and lower parts of the fuel assembly F toward the opposing recesses 6, 7, and 8. A pressing mechanism 30 is configured. In addition, 31 in the figure is a positioning plate for positioning the lower side of the frame 1 on the inner wall surface side of the pool P. Reference numeral 32 in FIG. 2a indicates a moving mechanism for moving the fuel assembly F in an upright suspended state, and is constituted by, for example, a bridge crane having a hanging tool 33.

Next, the operation of the above-mentioned component device will be explained.

First, when correcting the bending of a fuel assembly F whose middle portion is bent to the right in the figure as shown by the imaginary line in FIG. Move each grid support plate 3, 4, 5 to a position where they face each other on the left side in FIG. 3a and 5a. Thereafter, by manually operating the upper end 23a of the first shaft 23, the corresponding grid push arm 15 is pressed against the side surface of the middle part of the fuel assembly F through the pad 18, and this middle part is pushed into the recess 7. The bend is corrected by forcibly displacing it.

Next, when correcting the bending of the fuel assembly F whose lower part is bent to the right in the figure as shown by the imaginary line in Fig. 2b, each grid support is The plates 3, 4, and 5 are moved to opposing positions in the center in FIG. Then, by manually operating the upper end 27a of the second shaft 27, the corresponding grid push arm 16 is pressed against the upper side surface of the fuel assembly F via the pad 20, and in this pressed state, the second shaft 27 lock. Thereafter, the upper end 28 of the third shaft 28
The bend is corrected by manually operating part a to press the corresponding grid push arm 17 against the lower side surface of the fuel assembly F via the pad 21, and forcibly displacing this lower part into the recess 8. do.

Next, when correcting the bending of the fuel assembly F whose upper part is bent to the right in the figure as shown by the imaginary line in Figure 2c, the fuel assembly F should be kept upright and each grid support Move the plates 3, 4, and 5 to opposite positions on the right side in FIG. Then, by manually operating the upper end 28a of the third shaft 28, the corresponding grid push arm 17 is pressed against the lower side surface of the fuel assembly F via the pad 22, and in this pressed state, the third shaft 28 lock. Then, the upper end 27 of the second shaft 27
The bend is corrected by manually operating the part a to press the corresponding grid push arm 16 against the upper side surface of the fuel assembly F via the pad 19, and forcibly displacing this upper part into the recess 6. do.

In each of these bending correction operations, the amount of forced displacement of the upper, middle, and lower portions of the fuel assembly F is calculated based on the depth of each recess 6, 7, and 8, and the depth of each shaft, taking into account the amount of restoration after the forced displacement. 23, 27,
Adjustments are made using the operating force of 28, and each bending correction work is performed while being confirmed by an underwater camera (not shown) in the pool P. Further, during the repair work, the fuel assembly F is suspended and held by a hanging tool 33.

Further, by rotating the fuel assembly F and changing the side facing the present bending correction device, it is possible to correct various bends in the upper, middle, and lower portions of the fuel assembly F.

Note that the pressing mechanism 30 is not limited to the above-mentioned manual type configuration, and the design can be changed as appropriate, such as a drive type configuration using various cylinders, and each pad 18, 1
If the pads 9, 20, 21, and 22 are swingably provided on the grid push arms 15, 16, and 17, these pads can be brought into contact with the side surface of the fuel assembly F in a well-balanced manner, and the bending correction force can be applied. It is possible to make it work extremely properly, and if the intermediate grid support plate 4 is configured to be able to move up and down, it is possible to correct the bending of the fuel assembly F, which is complicatedly bent.

As explained above, according to the fuel assembly bending correcting device according to the present invention, bending in each direction can be corrected by moving the columnar fuel assembly while maintaining it in an easy-to-handle upright position and changing its setting position. can be easily carried out, and the structure of the device itself is extremely simple.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of the present invention, and FIGS. 2a, 2b, and 2c are longitudinal sectional views shown to explain the operation thereof. F... Fuel assembly, 1... Frame, 3, 4,
5... Grid support plate, 6, 7, 8...
... recess, 30 ... pressing mechanism, 32 ... moving mechanism.

Claims (1)

[Claims] 1. A frame provided along the vertical direction, three grid support plates provided on the frame and facing the upper, middle, and lower sides of the columnar fuel assembly in an upright state, and each of the grid supports. recesses provided in each of the portions of the plate facing the fuel assembly and positioned horizontally offset from each other; and a moving mechanism for moving the fuel assembly to a position facing the grid support plate while maintaining the fuel assembly in an upright state. and a pressing mechanism that presses a portion of the fuel assembly that faces the recess toward the recess.