JPH035557B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an apparatus for inspecting the spacing of grid portions of spacers in a fuel assembly.

[Technical background of the invention and its problems]

Generally, in a fuel assembly for a nuclear reactor, nuclear fuel spacers are provided at multiple locations in the longitudinal direction to correct curvature of the nuclear fuel rods and to suppress vibrations of the fuel rods due to the flow of coolant.

That is, FIG. 1 is a longitudinal cross-sectional view of the fuel assembly for the above-mentioned nuclear reactor, and in the fuel channel 1,
A plurality of fuel rods 4 and water rods 5 are installed in an array, the upper and lower ends of which are supported by an upper tie plate 2 and a lower tie plate 3, respectively. A plurality of spacers 6 are provided in the axial direction of the fuel rods 4 for restraining vibration and ensuring a flow path for the coolant.

The spacer 6 has a square band 7 as shown in FIG. 2 and FIG. cells 12
is formed. Further, at each intersection of the bars 8 and 9, a leaf spring portion 1 protruding outward on each side is provided.
A lantern spring 13 having a lantern spring 3a is attached to the fuel rod 4 inserted into each cell 12.
from the corner of the cell 12 to the divider 10,
It is configured to elastically press against S-bends 10a and 11a formed in 11.

However, if the positions of the cells of the spacer 6, that is, the intervals between the lattice parts, are not manufactured to the correct dimensions, there will be problems such as the intervals between the fuel rods inserted into each cell will not be as designed.

Therefore, conventionally, the intervals between the lattice parts of each spacer are strictly inspected to prevent the above-mentioned problems from occurring.

However, in the conventional interval inspection,
Arrange the two spacers in parallel at regular intervals so that the axes of both grid positions are in a straight line, insert the same number of pin gauges as the spacer grid into each grid part, and insert all the two adjacent A thickness gauge was inserted between the pin gauges to check whether the distance between each pin gauge was within a predetermined value. Therefore,
The above inspection involves a lot of repetitive manual work.
There were problems such as the work was troublesome and the inspection required a long time.

[Purpose of the invention]

In view of these points, the present invention has been devised to provide an interval between the lattice portions of spacers in a fuel assembly, which eliminates the need for repeated manual work and repeated inspections, and allows inspection of each lattice interval at the same time. The purpose is to obtain inspection equipment.

[Summary of the invention]

The present invention provides a pin gauge holding plate having the same center axis spacing as a predetermined center axis spacing of each cell in a spacer and having the same number of pin gauge holding holes as each cell, mounted above a substrate, and standing upright from the substrate. The installed pin gauges are made to pass through each pin gauge holding hole of the pin gauge holding plate so as to be movable in a horizontal direction to some extent, and the pin gauges can be respectively inserted into guide pins set upright from the pin gauge holding plate. A punching plate and a holding plate each having the same number of holes are slidably and removably attached, and the tip of each pin gauge can be inserted into a position that matches the axis of each pin gauge held at a predetermined interval. The present invention is characterized in that an inspection gauge plate having small holes is attached to the guide pin in a slidable and detachable manner.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 4 and 5.

In FIG. 4, reference numeral 20 is a board, and a pin gauge holding plate 21 is attached to the upper part of the board 20 with bolts 22 at a predetermined distance from the board. A guide pin 23 is erected at each.

The pin gauge holding plate 21 is provided with the same number of pin gauge holding holes 24 in a lattice pattern corresponding to each cell of the spacer S. It is made equal to the predetermined center axis spacing of the cells.
Further, on the substrate 20, pin gauges 25 of the same number as the cells are arranged in a grid pattern in correspondence with each cell of the spacer S. are connected to each other.

The pin gauge 25 is formed to have the same diameter as the fuel rod, and has a small diameter projection 2 on its top end on its central axis.
5a is formed, the pin gauge 25 is made to penetrate the pin gauge holding hole 24 of the pin gauge holding plate 21 and protrude upward, and the pin gauge holding hole 24 is made slightly larger than the pin gauge 25,
The pin gauge 25 is configured to be able to move horizontally to some extent within the pin gauge holding hole 24. Further, a large diameter portion 25b having a larger diameter than the pin gauge holding hole 24 is formed at the base of the pin gauge 25, and the lower end surface and the upper end surface of the large diameter portion 25b form the upper surface of the substrate 20 and the pin gauge holding plate 21, respectively. The pin gauge 25 is in sliding contact with the lower surface of the pin gauge 25, and serves as a guide for the horizontal movement of the pin gauge 25 in the vertical state.
5 is prevented from slipping out upwards.

Further, the guide pin 23 includes each pin gauge 2.
A punching plate 26 and a holding plate 27, which have holes 26a and 27a each having an inner diameter slightly larger than the diameter of the pin gauge 25 at positions corresponding to 5, are inserted and engaged from their top ends, and are horizontally moved along the guide pin 23. It is possible to move up and down depending on the situation. The guide pin 23 is further provided with an inspection gauge plate 28 which is removably provided with small holes 28a arranged at the same pitch p so as to be able to fit into the small diameter protrusions 25a of the pin gauges 25 arranged at predetermined positions. It is mounted so that it can be moved vertically along the guide pin 23 while maintaining a horizontal state.

Therefore, when inspecting the spacing between the lattice portions of the spacer S, the holding plate 27 and the inspection gauge plate 28 are removed from the guide pin 23, and the spacer S is lowered from above the pin gauge 25 to inside each cell of the spacer S. The pin gauge 25 corresponding to the spacer S is inserted, and the holding plate 27 is then engaged with the guide pin 23 and lowered along the guide pin 23 until the lower end surface of the spacer S comes into contact with the upper surface of the punching plate 26. position.

Therefore, the inspection gauge plate 28 is engaged with the guide pin 23 and the inspection gauge plate 28 is attached to the guide pin 23.
When the lattice spacing of the spacer S is as specified and the pitch between the center axes of each pin gauge 25 inserted through the spacer is a predetermined value, each small part of the inspection gauge plate 28 Hole 28
Small diameter portion 25a at the tip of the pin gauge 25 corresponding to a
It can be detected that all of the spacers S are inserted smoothly and that the spacer S is manufactured according to the specifications.

On the other hand, if the lattice spacing of the spacer is different from the design specification value, use the pin gauge 2
5, each pin gauge 25 moves in the horizontal direction accordingly, thereby causing the pitch between the center axes of each pin gauge 25 to deviate from the design specification value. Therefore, when the inspection gauge plate 28 is lowered as described above, the inspection gauge plate 2
The tip of the pin gauge 25 contacts or butts against the edge of the small hole 28a of No. 8, and the insertion load in the downward direction of the inspection gauge plate 28 increases or the insertion becomes impossible, making it impossible to detect that the spacer is a defective product. Moreover, it is also possible to detect grid portions that deviate from the design specifications by recognizing their abutting positions and the like.

Also, when taking out the spacer S,
The spacer S can be removed from the pin gauge 25 by pulling out the inspection gauge plate 28 and the holding plate 27 upward and moving the punching plate 26 upward.

〔Effect of the invention〕

As explained above, in the present invention, a pin gauge holding plate having the same number of pin gauge holding holes as each cell, the center axis interval of which is equal to the predetermined center axis interval of each cell in the spacer, is mounted above the substrate. At the same time, a pin gauge erected from the substrate is passed through each pin gauge holding hole of the pin gauge holding plate so as to be movable to some extent in the horizontal direction, and a guide pin erected from the pin gauge holding plate,
A punching plate and a holding plate each having the same number of holes as the pin gauges through which the pin gauges can be inserted are slidably and removably mounted, and furthermore, at positions that match the axes of the pin gauges held at predetermined intervals, An inspection gauge plate with a small hole into which the tip of each pin gauge can be inserted was attached to the guide pin in a slidable and removable manner. The suitability of the spacer can be determined simply by lowering the spacer along the guide pin.In addition to inserting multiple pin gauges into the spacer cells one after another as in the past, it is also possible to There is no need to repeatedly insert a thickness gauge, and as described above, the intervals between all the lattice parts of the spacer can be inspected by simply operating one inspection gauge plate, making inspection extremely easy. Not only is this possible, but the time required can be significantly shortened.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of the fuel assembly, FIG. 2 is a plan view of the spacer, FIG. 3 is a sectional view taken along the - line in FIG. 2, and FIG. 4 is a partial longitudinal sectional side view of the inspection device of the present invention. FIG. 5 is a partially cross-sectional plan view of the same as above. 20... Board, 21... Pin gauge holding plate, 2
3...Guide pin, 25...Pin gauge, 26...
...Bunching plate, 27... Holding plate, 28... Inspection gauge plate, S... Spacer.

Claims (1)

[Scope of Claims] 1. A pin gauge holding plate having the same number of pin gauge holding holes as each cell in the spacer is mounted above the substrate, and the center axis spacing is equal to the predetermined center axis spacing of each cell in the spacer. The pin gauges standing up from the board are inserted into each pin gauge holding hole of the pin gauge holding plate so as to be movable to some extent in the horizontal direction, and the pin gauges are respectively inserted into the guide pins standing up from the pin gauge holding plate. A punching plate and a holding plate each having the same number of holes as the pin gauges to be obtained are each slidably and removably attached, and the tip of each pin gauge is placed at a position that coincides with the axis of each pin gauge held at a predetermined interval. 1. An apparatus for inspecting the interval of a lattice portion of a spacer in a fuel assembly, characterized in that an inspection gauge plate having a small hole into which it can be inserted is slidably and detachably attached to the guide pin. 2. An apparatus for inspecting the spacing of a grid portion of a spacer in a fuel assembly according to claim 1, wherein the bases of each pin gauge are connected to each other by a spring. 3. Each pin gauge has a large diameter portion at its base, and both upper and lower surfaces of the large diameter portion are in sliding contact with the pin gauge holding plate and the substrate, respectively, and the vertical state thereof is maintained. An apparatus for inspecting the spacing of a lattice portion of a spacer in a fuel assembly according to item 1.