JP2005300301A - Bend measuring method and instrument for rod-like body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure bends in a plurality of rod-like bodies. <P>SOLUTION: A probe 9, arranged facing a pair of electrostatic sensors 14, is inserted between two fuel rods 4, 4 adjacent in the X-axis direction and Y-axis-direction, in primary measuring processing, as the large number of fuel rods 4 in a fuel assembly, and pieces of distance information up to the facing fuel rods 4 are thereby output, respectively as ridge-shaped waveforms. Total ridge-shaped waveforms are obtained based thereon by an output waveform totalizing means 31, and the area of the each ridge-shaped waveform is partitioned by a imaginary line, with an equal distance to both sides from the center line thereof. The distance between a bisector in the each area and the X-axis or the Y-axis is calculated by a control means 33. A position of the each fuel rod 4 is measured along the longitudinal direction of the fuel rod, to detect the bending. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and an apparatus for measuring the bending of a rod-shaped body that measures the bending of a rod-shaped body such as a number of fuel rods held in a fuel assembly.

Conventionally, a fuel assembly for a nuclear reactor is fixed by inserting a plurality of control rod guide tubes through a plurality of support grids arranged at predetermined intervals, and a lower nozzle and an upper nozzle at the lower portion of the control rod guide tube, respectively. It is installed. A large number of fuel rods are supported and arranged in an inserted state in the lattice space of each support lattice. When a fuel assembly having such a configuration is used in a nuclear reactor, cooling water flows through a flow path composed of a large number of fuel rods and control rod guide tubes to transmit heat.
In order to effectively transmit heat by passing cooling water between the fuel rods or the like, the gaps between the fuel rods or between the fuel rods and the control rod guide pipes must be maintained at predetermined dimensions. Therefore, it is necessary to accurately measure whether the gaps between the fuel rods and between the fuel rods and the control rod guide tube are within the allowable dimension range before using the fuel assembly.

By the way, what was described in the following patent documents 1 and 2, for example as a space | interval measuring apparatus which measures space | intervals between fuel rods etc. is proposed. These interval measuring devices employ an interval measuring probe that is inserted between fuel rods to measure the interval. The interval measuring probe has a probe tip that protrudes on both sides in the vicinity of the tip of a long elastic plate, and A strain gauge is provided in the vicinity to provide a strain sensor. Then, an interval measurement probe is inserted between the fuel rods of the fuel assembly, and when the probe tip is deformed by contacting the fuel rods on both sides, the amount of deformation is measured with a strain gauge. The interval is calculated.
Japanese Examined Patent Publication No. 2-61681 Japanese Examined Patent Publication No. 2-61682

However, in the above-described interval measuring device, the interval between fuel rods and the like can be measured, but the bending of the fuel rod cannot be measured. Since the fuel rods usually have a length of about 4 m, they were easy to bend even if they were supported by a support grid. Also, since the fuel assembly is longer than the fuel rod and is heavier, the fuel assembly itself is likely to bend even if it is raised using a lifting tool, which causes the fuel rod to bend. There was also the possibility of making it bend or bend.
However, in the conventional interval measuring device, even if the interval between the fuel rods can be measured, it is impossible to grasp the state in which the fuel rods are bent and face each other. For this reason, when using the fuel assembly in the nuclear reactor, it has not been possible to estimate that an abnormal decrease in the channel (cooling water flow path) occurs after the operation of the nuclear reactor. In addition, when the interval measurement probe is bent or inclined and enters between two fuel rods, there is a problem that the measurement accuracy is not stable even in the interval measurement.
In particular, the periodic inspection after operating the fuel assembly in the nuclear reactor for one cycle observes the interval and bending of the fuel rods on the outer peripheral side with images, so when comparing and judging the data after the operation, The initial bend is particularly important. Considering that the inner fuel rods are spaced by the outer fuel rods, the initial bending of the outer fuel rods is measured to estimate the inner fuel rod bending that cannot be observed directly after operation. It is important to keep it.

  In view of such a situation, an object of the present invention is to provide a bending measuring method and a bending measuring apparatus for a rod-like body that can measure the bending of a plurality of rod-like bodies.

The bending measurement method of the rod-like body according to the present invention is a bending measurement method of a plurality of rod-like bodies arranged in the X-axis direction and the Y-axis direction intersecting each other, and is adjacent to each other in the X-axis direction and the Y-axis direction. A distance measurement probe including an electrostatic sensor is inserted between the bodies, and distance information from the electrostatic sensor to the opposing rod-shaped body is output as a chevron waveform, and the center of the total chevron waveform is the sum of these two chevron waveforms A line is obtained, and the area of each chevron corrugation is partitioned in a range of a certain width from both sides of the center line, and two bar shapes from the X-axis or Y-axis are obtained by bisectors that bisect the area of each chevron waveform. The primary measurement processing for obtaining the distance to the body is performed, and the primary measurement processing is performed at one or a plurality of positions along the longitudinal direction of the rod-shaped body, thereby measuring the bending of the plurality of rod-shaped bodies arranged. Do
Further, the bending measurement apparatus for a rod-shaped body according to the present invention is a bending measurement apparatus for a plurality of rod-shaped bodies arranged in the X-axis direction and the Y-axis direction intersecting each other, and is adjacent to each other in the X-axis direction and the Y-axis direction A distance measuring probe including a pair of electrostatic sensors that are inserted between two rod-shaped bodies and output distance information to each of the opposing rod-shaped bodies as a mountain-shaped waveform, and the center line of the total mountain-shaped waveform summing up the two mountain-shaped waveforms A primary measurement process to determine the distance from the X-axis or Y-axis to the two rod-like bodies by dividing the area of each chevron waveform into a fixed width range on both sides from the X-axis or the bisecting line that bisects the area of each chevron waveform And measuring the bending of each rod-shaped body by determining the distance from the X-axis or Y-axis to the two rod-shaped bodies at one or a plurality of positions along the longitudinal direction of the rod-shaped body. To do.

According to the present invention, at one or a plurality of appropriate positions along the longitudinal direction of the rod-shaped body, a distance measuring probe including an electrostatic sensor is sequentially entered between two rod-shaped bodies adjacent to each other in the X-axis direction. Measure the distance from. Similarly, in the Y-axis direction, a distance measuring probe including an electrostatic sensor is sequentially entered between two adjacent rod-shaped bodies to measure the distance from the Y-axis. As a result, the position (x, y) of each fuel rod relative to the X axis and Y axis can be detected. The bending of each rod-shaped body can be measured by measuring the position (x, y) of each fuel rod with respect to the X-axis and the Y-axis at a plurality of positions along the length direction of the rod-shaped body. Further, even when the position (x, y) of each rod-like body is measured at one position along the length direction of the rod-like body, the known rod-like body position (x, y) such as a design value or a specification value is used as a reference. The bend can be measured in the same way.
In the primary measurement process, the area of each chevron waveform is preferably set in a region partitioned by two imaginary lines set at equal intervals from the center line of the total chevron waveform.

In addition, the bending measurement method of the rod-shaped body according to the present invention provides the distance information to the rod-shaped bodies arranged on the outer peripheral side by running the outer sensor along the X axis and the Y axis outside the plurality of arranged rod bodies. Output as a chevron waveform, and perform secondary measurement processing to obtain the distance from the X-axis and Y-axis to the rod-shaped body on the outer periphery side based on the peak value of the chevron-shaped waveform. By performing the measurement process, the bending of the plurality of rod-shaped bodies arranged is measured.
According to the present invention, it is possible to measure the distance of the rod-like bodies arranged on the outer peripheral side along the X-axis direction and the Y-axis direction by the secondary measurement process using the outer sensor with the X-axis or the Y-axis as the reference axis.
Further, in the secondary measurement process, the movement distance along the X axis and the Y axis of the outer sensor may be measured at the position of the peak value of the mountain waveform obtained by the outer sensor.
In this case, since the position of the outer peripheral rod-shaped body along the reference axis can be measured from the distance information from the reference axis to the peak value, the outer peripheral rod-shaped body obtained in the primary measurement process in the X-axis and Y-axis directions can be measured. The accuracy of distance information can be verified. The position (x, y) can be measured in relation to the distance from the reference axis to the rod-shaped body at the peak value described above.
Thereby, the measurement accuracy of the position (x, y) and the bending of the rod-shaped body measured in the primary measurement process can be verified. This means that when measuring the bending of each fuel rod during periodic inspections after the reactor operation, only the outer fuel rod can be measured, and the bending and spacing of the inner fuel rods can be estimated by the bending of the outer fuel rod. In order to avoid this, it is particularly important to compare the initial bend measured for the outer peripheral fuel rod with the bend at the periodic inspection after the operation of the reactor.

In addition, the bending measuring apparatus for a rod-shaped body according to the present invention outputs distance information to the rod-shaped bodies arranged on the outer peripheral side by running along the X axis and the Y axis outside the plurality of arranged rod-shaped bodies as a mountain waveform. The outer sensor to be used, and the peak value of the chevron waveform obtained by the outer sensor to obtain the distance from the X axis and the Y axis to the rod-like body on the outer peripheral side, and the travel of each outer sensor to the peak value along the X axis and the Y axis. Secondary measurement processing means for measuring the distance, and measuring the bending of each rod-shaped body by performing measurement processing by the outer sensor and the secondary measurement means at one or a plurality of positions along the longitudinal direction of the rod-shaped body. It is characterized by that.
According to the present invention, the distance of the rod-like bodies arranged on the outer peripheral side along the X-axis direction and the Y-axis direction by the secondary measurement process using the outer sensor is further measured using the X-axis or the Y-axis as the reference axis. A position (x, y) is obtained. Thereby, the measurement accuracy of the position (x, y) and the bending of the rod-shaped body measured in the primary measurement process can be verified. In particular, it is possible to verify the bending of the rods on the outer circumferential side by measuring the distance from the reference axis of the rods on the outer circumferential side in the X-axis and Y-axis directions at a plurality of positions along the length direction of the rod-shaped body. Moreover, even when the distance between the fuel bodies on the outer circumference side is measured at one position along the length direction of the rod-shaped body, the bending similarly occurs based on the distance of the known rod-shaped body such as the design value and the specification value. Can be verified.

Further, the rod-shaped body is a fuel rod supported by a plurality of support grids arranged at a predetermined interval in the fuel assembly, and the fuel grid has a position near the support grid and an intermediate position between two adjacent support grids. It is preferable to perform a measurement process for each.
In this case, each fuel rod position (x, y) measured at the position near the supporting grid is detected from each fuel rod position (x, y) measured at the intermediate position, thereby detecting each fuel. The presence / absence of the bending of the bar, the degree of bending, etc. can be detected. The supporting grid vicinity position may be either one of the supporting grid vicinity positions or two supporting grid vicinity positions.
Alternatively, the rod-shaped body is a fuel rod supported by a plurality of support grids arranged at a predetermined interval in the fuel assembly, and the measurement processing is performed on each of the fuel rods at an intermediate position between two adjacent support grids. May be.
Since the fuel rods in the vicinity of the support grid are gripped by the support grid and are not bent, inclined, or misaligned, the design values and specification values can be substituted, and the positions of the fuel rods measured at the intermediate positions (x, y ) And the design value, specification value, etc., it is possible to detect the presence or absence of the bending of each fuel rod, the degree of bending, etc., improving the measurement and detection speed and increasing the inspection efficiency.

  According to the method and apparatus for measuring the bending of a rod-like body according to the present invention, the bending of each rod-like body can be measured for a plurality of rod-like bodies. In particular, even if the distance measuring probe is bent or inclined with respect to the X axis and Y axis which are the reference axes and enters between the rod-shaped bodies, or even if the distance measuring probe is biased toward one side of the two rod-shaped bodies, the distance with a predetermined accuracy Can be measured.

Next, an embodiment of the present invention will be described with reference to FIGS.
1 to 10 show a bending measuring device according to an embodiment, FIG. 1 is a schematic configuration diagram of the bending measuring device, FIG. 2 is a diagram showing a relationship between a fuel assembly and a measuring block, and FIG. 3 is a fuel rod. FIG. 4 is a view showing the relationship between the fuel rod, the probe, and the advance / retreat mechanism, (a) is a state before the probe is inserted, (b) is a state where the probe is inserted, and (c) is a view FIG. 5 is a cross-sectional view of the tip portion of the probe, FIG. 6 is a main part configuration diagram of a bending measuring device having a probe and an outer sensor, and FIGS. The figure which shows the state which inserted the probe between the rods, and the measured angle waveform, FIG. 10 (a) is the output waveform figure of the electrostatic capacitance which measures the distance of the X-axis and fuel rod by the outer sensor in a support grid vicinity position, (B) is the same figure as (a) in an intermediate position. A.
1 to 3, the bending measuring device 1 according to the present embodiment measures the spacing and bending of adjacent fuel rods 4, 4, fuel rods 4, and control rod guide tubes 4 </ b> S arranged in the fuel assembly 2. Is for. The fuel assembly 2 is fixed by inserting control rod guide tubes 4S through a plurality of support grids 3 arranged at predetermined intervals in the vertical direction (see FIG. 4), and upper and lower ends of the control rod guide tubes 4S. The nozzle 2a and the lower nozzle 2b are connected to each other. A large number of fuel rods 4 are elastically supported by each support grid 3 in an inserted state.
An imaginary line parallel to one outer peripheral surface (side) perpendicular to each other of the fuel assembly 2 having a substantially square shape in a plan view of FIG. 2 is an X axis, and an imaginary line parallel to the other outer peripheral surface (side) is a Y axis. In this case, the X axis and the Y axis are orthogonal to each other, and a plurality of fuel rods 4 and control rod guide tubes 4S (hereinafter referred to as fuel rods 4 etc.) are arranged in the X axis and Y axis directions.
Then, a pair of measuring units 5 and 5 of the bending measuring device 1 are arranged in the X-axis and Y-axis directions adjacent to the fuel assembly 2, and at a position facing the measuring unit 5 across the fuel assembly 2. An inspection stand 6 is erected.

Each measuring unit 5 is supported by an inspection stand 6 and can move up and down, and is provided on the top of the saddle 8 and enters a gap between the fuel rods 4 and 4 of the fuel assembly 2 to be adjacent to each other. A distance measuring probe (hereinafter simply referred to as a probe) 9 for measuring the distance between the fuel rods 4, 4 and the like and an advance / retreat mechanism 10 thereof are provided (see FIG. 2). As shown in FIG. 2, the probe 9 and the advancing / retreating mechanism 10 are respectively arranged in one or more sets (two sets in the figure) in a direction substantially orthogonal to the surfaces of the fuel assembly 2 in the X-axis direction and the Y-axis direction, In the example shown in FIG. 2, movement between the fuel rods 4 and 4 is possible by moving in the X-axis direction and the Y-axis direction.
A center detection sensor 11 (positioning member) for detecting the center in the width direction of the fuel assembly 2 in the X-axis or Y-axis direction is provided on the outer peripheral surface of the fuel assembly 2. From the detected center position in the width direction of the fuel assembly 2, the center position between the fuel rods 4 and 4 arranged in the X-axis and Y-axis directions is calculated, and positioning before inserting the probe 9 is performed. Alternatively, the center detection sensor 11 may directly detect the center position of the gap between the adjacent fuel rods 4 and 4.

Next, the probe 9 and its advance / retreat mechanism 10 will be described with reference to FIGS. The probe 9 is composed of an insulator 12 having a base 9a having a cross-sectional plate shape and extending long, and the outer peripheral surface of the insulator 12 is sandwiched between two surfaces by a thin stainless steel sheet 13 having rigidity. This reinforces the base 9a of the probe 9 to ensure rigidity and protect the sensor 14 and the insulator 12. Moreover, the base portion 9a has flexibility, and can escape and bend when contacting the control rod guide tube 4S having a diameter larger than that of the fuel rod 4 when inserted into the fuel assembly 2.
Near the tip of the probe 9, the two stainless steel sheets 13 are cut off, and the electrostatic sensors 14 and 14 are embedded in the insulator 12 without contact with the sheet 13. Each electrostatic sensor 14 detects the capacitance according to the distance from the fuel rod 4 or the control rod guide tube 4S facing the sensor 14, and the output can be obtained as a mountain waveform (output waveform) ( See FIGS. Since the peak value of this chevron waveform corresponds to the distance between the electrostatic sensor 14 and the fuel rod 4 or the control rod guide tube 4S, the correlation between the electrostatic sensor 14 and the fuel rod 4 or the control rod guide tube 4S depends on the correlation. Distance can be measured and calculated.

The front end of the base 9 a is formed in a roof shape and easily enters between the fuel rods 4 and 4. The base end portion of the base portion 9a is fixed to a pedestal block 15, and this pedestal block 15 is supported on a slide guide 17 extending in a direction orthogonal to the base portion 9a and can reciprocate with a small load. A fixing portion 15a protrudes rearward of the base block 15 on the further proximal end side, and the fixing portion 15a can be held by a grip portion 18 including two arm portions 18a and 18b.
The grip portion 18 moves the probe 9 to the center position between the fuel rods 4 and 4 detected by the above-described center detection sensor 11 by holding the fixed portion 15a with the probe 9 retracted from between the fuel rods 4 and 4. (See FIG. 4 (a)), and then the fixing portion 15a is released to hold the arm portions 18a, 18b at an equal interval (see FIG. 4 (b)). When the probe 9 enters between the fuel rods 4 and 4 and contacts the control rod guide tube 4S, the probe 9 moves along the slide guide 17 in a separating direction (see FIG. 4C). At that time, the arm portions 18 a and 18 b in the opened state of the grip portion 18 regulate the movement range of the fixing portion 15 a of the probe 9.
When the probe 9 enters between the fuel rods 4 and 4 by an advancing / retreating member (not shown), the advancing / retreating mechanism 10 also moves together.

The base portion 9a is formed with a thin probe thickness d (for example, d = about 0.5 mm or less) over the entire length from the distal end portion to the fixed block 15, and the distance between the electrostatic sensors 14 and 14 is dt. . By making d = 0.5 mm or less, the wear (friction resistance) due to contact when the probe 9 is inserted between the fuel rods 4 and 4 or between the fuel rod 4 and the control rod guide tube 4S is reduced, and the life is improved. And variation in measured values can be reduced. Moreover, even if the probe 9 comes into contact with the control rod guide tube 4S, the probe 9 is allowed to enter without expanding the gap.
In FIG. 4, a ground wire 20 is connected to the stainless steel sheet 13 provided on both surfaces of the probe 9. Even if the stainless steel sheet 13 comes into contact with or rubs against the fuel rod 4 or the control rod guide tube 4S, the static electricity is discharged through the ground wire 20 to eliminate the potential difference. Stabilize.

Next, in FIG. 6, in the fuel assembly 2, the fuel rods 4 on the outer peripheral side along the X axis (identified by reference numerals 4 a, 4 b, 4 c,... In the drawing for convenience) extend along the Y axis. The fuel rods 4 on the outer peripheral side (also identified by reference numerals 4a, 4d, 4g,... For convenience) are arranged. In the X-axis direction, an outer sensor 22 for scanning along the X-axis and measuring the distance to the fuel rods 4a, 4b, 4c,... Is arranged. An outer sensor 23 for measuring the distance from the fuel rods 4a, 4d, 4g,. These outer sensors 22 and 23 are constituted by electrostatic sensors similarly to the probe 9, but may be laser sensors or the like. The outer sensors 22 and 23 and the probes 9 and 9 are connected to the measurement processing means 25.
The outer sensors 22 and 23 start scanning from the Y axis and the X axis, respectively, along the X axis and the Y axis, detect capacitances corresponding to the distances from the fuel rods 4, and measure the measurement signals to the measurement processing means 25. Are output as waveform waveforms (output waveforms) to the waveform output means 27a and 27b of the secondary measurement processing means 26, and the calculation means 28 calculates distance information from the peak value of each peak waveform. In the distance information, the X axis and the Y axis are the reference axes. Further, it is preferable that the outer sensors 22 and 23 simultaneously detect the distance from the starting point to the peak value when detecting the peak value of each mountain-shaped waveform. Thereby, the distances in the X-axis direction and the Y-axis direction can be measured, respectively, and the position (x, y) is obtained.

6 and 7, the electrostatic sensors 14, 14 of each probe 9 are connected to the waveform output means 30a, 30b, 30c, 30d of the primary measurement processing means 29, respectively. Capacitances corresponding to the distances are detected and angle waveforms ha and hd are output, the angle waveforms are summed by the output waveform summing means 31 and 32 for each probe 9, and the center line Mx is determined from the total angle waveform had. . Then, the control means 33 takes the virtual lines Ma and Ma having the same width on both sides from the center line Mx of the total peak waveform had and partitions each peak waveform and bisects the area into two bisectors Pix (i = a , B, c,...) Are calculated, and distance information between the bisector Pix and the Y or X axis is calculated. The bisector Pix passes through the center of each fuel rod 4 or a position closer to the center.
Even when one or both of the two fuel rods 4 and 4 into which the probe 9 is inserted are bent or displaced, the reference axis (X axis, Y axis) with the bisector Pix as the approximate center line of each fuel rod 4 ).

The bending measuring apparatus 1 according to the present embodiment has the above-described configuration. Next, a bending measuring method for the fuel rod 4 and the like using the bending measuring apparatus 1 will be described with reference to FIGS.
First, as a first bending measurement method, a primary measurement processing method using the probe 9 will be described with reference to FIGS.
In FIG. 1 and FIG. 2, a pair of measuring units 5, 5 arranged to face the fuel assembly 2 supported by the inspection stand 6 is composed of a lowermost support lattice 3 and a second support lattice 3. The saddles 8 are stopped so as to sequentially measure the gaps between the plurality of rows of fuel rods 4 arranged between them (this is called a primary measurement region).
In this state, the bending of the fuel rod 4 in the primary measurement region is measured. As shown in FIG. 3, the measurement positions are assumed to be support grid vicinity positions S1 and S2 and a center position (intermediate position) S3 between the two support grids 3 and 3. Note that the position S3 need not be in the center, but may be in the middle between the positions S1 and S2.

As a primary measurement processing step, first, as shown in FIG. 4A, the fuel rod 4 detected by the center detection sensor 11 directly or indirectly by holding the fixed portion 15a of the probe 9 with the grip portion 18 of the advance / retreat mechanism 10. 4 is moved horizontally so that the probe 9 is located in the center between the four (see FIG. 4A). And the grip part 18 is spaced apart to an open position (refer FIG.4 (b)).
In FIG. 6, the probe 9 is entered from the center between the fuel rods 4a and 4d on the outer peripheral side so as to be orthogonal to the Y axis, for example, and a pair of electrostatic sensors 14 and 14 are respectively positioned at positions facing the fuel rods 4a and 4d. The electrostatic sensor 14 detects the capacitance up to the fuel rods 4a, 4d. Then, since the probe 9 enters approximately the center between the fuel rods 4a and 4d substantially parallel to the X axis, the distance between each electrostatic sensor 14 and the fuel rods 4a and 4d as shown in FIG. Corresponding capacitance chevron waveforms ha and hd are obtained by the waveform output means 30a and 30b. When the output waveform summing means 31 sums up the mountain-shaped waveforms ha and hd, a total mountain-shaped waveform had shown in FIG.
In the case of FIG. 7A, since the fuel rods 4a and 4d are not bent or displaced, the center line Mx in the width direction of the total mountain waveform had is a line that bisects the waveform, and at the same time, each mountain waveform ha, hd The peak values Pa and Pd coincide with each other. Then, in FIG. 7B, virtual lines Ma and Ma of equal distances a and a are drawn in parallel to Mx on both sides of the center line Mx, and the intersections with the respective mountain-shaped waveforms ha and hd are L and M, respectively. When a line parallel to the X axis (reference axis) is drawn at the intersections L and M, they intersect each other (because the waveforms ha and hd are symmetrical with respect to Pa and Pd), and become a line LM. When bisectors Pax and Pdx perpendicular to the X axis that bisect the areas HA and HD enclosed by the waveforms ha and hd and the line LM are drawn, the bisectors Pax and Pdx, peak values Pa and Pd, and the center line Mx matches.
Since the peak values Pa and Pd of each mountain-shaped waveform correspond to the distance between each electrostatic sensor 14 and the fuel rods 4a and 4d, the fuel rod 4a, The distance between 4d can be measured and calculated.
The distances from the Y axis to the bisectors Pax and Pdx can be roughly measured as the distances Ax and Dx in the X axis direction from the Y axis to the centers of the fuel rods 4a and 4d.

Further, in the case of FIG. 8A, the fuel rods 4a and 4d are displaced from each other on the opposite side in the X-axis direction due to bending, and the probe 9 enters while swinging. They are displaced from each other in the X-axis direction and deformed asymmetrically. The peak values Pa and Pd of the chevron waveforms ha and hd are similarly shifted.
Also in this case, the total peak waveform had is taken in FIG. 8B and the center line Mx in the width direction is taken. Then, in FIG. 8B, virtual lines Ma and Ma of equal distances a and a are drawn on both sides of the center line Mx in parallel with Mx, and the intersections with the mountain-shaped waveforms ha and hd are L and M, respectively. The intersections L and M are shifted in the direction of the center line Mx, and if a line parallel to the X axis (reference axis) is drawn in any of them, the waveforms ha and hd intersect at the intersection K. Draw bisectors Pax and Pdx perpendicular to the X axis that bisect the areas HA and HD enclosed by the waveforms ha and hd and the lines MK and LK. When the distances between the bisectors Pax and Pdx thus obtained and the Y axis are measured, distances Ax and Dx in the X axis direction from the Y axis to the centers of the fuel rods 4a and 4d are obtained.
In the case of FIG. 9A, the fuel rods 4a and 4d are bent and deviated from each other in the X-axis direction, and the probe 9 approaches the one fuel rod 4d and is substantially parallel to the X-axis. Enter between 4d. The chevron waveforms ha and hd are shifted from each other in the X-axis direction, and the peak values Pa and Pd are also shifted in the same manner. However, the chevron waveforms ha and hd are symmetrical with respect to the lines of the peak values Pa and Pd. It is. Then, the total peak waveform had, its center line Pad, the area of each peak waveform ha, hd, and the bisectors Pax and Pdx are obtained by the same procedure as in FIGS. The distances between the bisectors Pax and Pdx and the Y axis are obtained as the distances Ax and Dx in the X axis direction from the Y axis to the centers of the fuel rods 4a and 4d.

In this way, in the primary measurement process, the distance from the X axis or the Y axis to the center of each fuel rod 4 regardless of the bending or displacement of each fuel rod 4 shown in FIGS. Can be obtained with substantially constant accuracy.
Then, the measurement of the distance from the Y axis of each fuel rod 4 in the row of fuel rods 4a and 4d is sequentially performed while the probe 9 is inserted, and when completed, the probe 9 is pulled out and inserted between the fuel rods 4d and 4g. The same measurement is sequentially performed. The probe 9 is inserted between the fuel rods 4 and 4 which are adjacent to each other perpendicularly to the Y axis and measured by the electrostatic sensors 14 and 14, so that each fuel rod 4 is from the Y axis to the center of each fuel rod 4. Can be obtained sequentially. Further, the probe 9 is inserted between the adjacent fuel rods 4 and 4 so as to be orthogonal to the X axis, and similarly, the distance from the X axis to the center of each fuel rod 4 can be obtained.
When the distance of each fuel rod 4 from the X-axis and Y-axis is measured at the support grid vicinity positions S1, S2 and the central position S3 in the primary measurement region in this way, the position of each fuel rod 4 (x, y) can be measured. For example, if the positions (x, y) of the fuel rods 4 at the positions S2 and S3 are compared with the position (x, y) of the fuel rods 4 at the position S1 near the support grid as a reference, this region The bending of all the fuel rods 4 can be obtained.
Similarly, for the secondary measurement region between the next support grids 3 and 3 and the fuel rods 4 in each measurement region above the same, the X axis and the Y axis at three positions of the support grid vicinity positions S1, S2 and the central position S3. Is used as a reference to measure the position (x, y) of each fuel rod 4... And the bending of each fuel rod 4 can be measured.

  As described above, according to the present embodiment, the positions of the fuel rods 4 (x, x) at the three positions of the supporting grid vicinity positions S1, S2 and the central position S3 by the probes 9, 9 having the electrostatic sensors 14, 14. By obtaining y), the bending of each fuel rod 4 can be measured. Further, the interval between the fuel rods can be inspected from the data of the positions (x, y) of these fuel rods. In particular, according to the present embodiment, even if the probe 9 enters between the fuel rods 4 and 4 while swinging with respect to the X axis and the Y axis as the reference axes, the probe 9 also moves to one side of the two fuel rods 4 and 4. You can measure distances and bends with a certain degree of accuracy even if you approach with a bias.

Next, the secondary measurement process using the outer sensors 22 and 23 will be described.
After measuring the bending of each fuel rod 4 by the primary measurement process described above, the fuel rods 4 on the outer circumferential side along the X-axis and Y-axis directions with respect to the fuel assembly 2 are arranged on the outer circumferential side with the X-axis and Y-axis as reference axes. It is preferable to measure the distance for each fuel rod 4 with the outer sensors 22 and 23.
In this case, the position (x, y) of the outer peripheral fuel rod 4 can be measured by the outer sensors 22 and 23 based on the distance information from the reference X axis and Y axis to the outer peripheral fuel rod 4, so that the primary measurement process The accuracy of the distance information in the X-axis and Y-axis directions of the obtained outer peripheral fuel rod 4 can be verified. This is because when measuring the bending of each fuel rod 4 during periodic inspection after the operation of the reactor, only the fuel rod 4 on the outer peripheral side can be measured, and the bending of the fuel rod 4 on the inner side due to the bending of the fuel rod 4 on the outer peripheral side. Therefore, it is particularly important to compare the initial bend measured for the outer peripheral fuel rod with the bend at the periodic inspection after the reactor operation. Therefore, it is preferable to verify the measurement accuracy of the initial bending of the outer peripheral fuel rod 4.

Such a measuring method will be described below as a second embodiment of the present invention.
After performing the primary measurement processing method described in the first embodiment and measuring the bending of each fuel rod 4, the secondary measurement processing is performed.
In the secondary measurement processing step, measurement is performed at the supporting grid vicinity positions S1 and S2. First, in FIG. 6, the outer sensor 22 is scanned along the X axis with the Y axis as a starting point, and the outer sensor 22 and each fuel rod 4 are positioned at positions facing the fuel rods 4 (4a, 4b, 4c,...). Measure distance. In the measurement, the electrostatic capacitance corresponding to the distance between the outer sensor 22 and each fuel rod 4 is detected, and the waveform output means 27b in the secondary measurement processing means 26 uses the waveform waveforms ha, hb, Get hc, ... Then, the distance in the Y-axis direction between the X axis (outer sensor 22) and each outer peripheral fuel rod 4 is obtained by calculating from the peak values Pa, Pb, Pc,. If the radius of the fuel rod 4 is added to each measured distance, distances Ay, By, Cy..., Ax, Dx, Gx... From the X axis and Y axis to the center of each outer peripheral fuel rod 4 are obtained.
In this case, since each fuel rod 4 is held by the support grid 3, the fuel rod 4 at the positions S1 and S2 in the vicinity of the support grid is hardly bent, and the chevron waveform shown in FIG. ha, hb, hc,... have substantially the same shape, and the distance between the outer sensor 22 and the fuel rod 4 also measures substantially the same value.

Further, when the outer sensor 22 is scanned along the X-axis in order to measure the distance in the Y-axis direction to the outer peripheral fuel rods 4a, 4b, 4c,..., The peak value of each chevron waveform ha, hb, hc,. Each travel distance from the Y axis at a position where Pa, Pb, Pc,... Are detected may be detected. The position (x) can be obtained by comparing whether or not each traveling distance in the X-axis direction matches the positions Ax, Bx, Cx... Measured by the other outer sensor 23 or the probe 9.
By these, the position (x, y) of the outer peripheral fuel rod 4 can be measured. By comparing this with the position (x, y) of the outer peripheral fuel rod 4 in the primary measurement process, the measurement data can be verified.
Similarly, the outer sensor 23 similarly obtains the travel distance of each peak value and measures the position (x, y) of the outer peripheral fuel rod 4 to measure the position (x, y) of the outer peripheral fuel rod 4 by the primary measurement process. ) And can be verified.

Next, the outer sensors 22 and 23 are moved to the center position S3, and similarly, the position (x, y) of the outer peripheral fuel rod 4 is measured by secondary measurement processing by scanning along the X axis and Y axis. .
In this measurement, a mountain-shaped waveform is obtained by each waveform output means 27b, 27a of the secondary measurement processing means 26. In FIG. 6, the fuel rod 4b is deformed and curved inward (fuel rod 4e side) as shown by a one-dot chain line, and the other fuel rods 4 are hardly deformed. Therefore, in the X-axis direction, the chevron waveform hb ′ shown in FIG. 10B appears as a peak value Pb ′ lower than the other chevron waveforms ha ′ and hc ′, and the fuel rod 4 b obtained by the computing means 28 is reached. Is longer than the distance between the fuel rods 4a and 4c. Similarly in the Y-axis direction, the distance to each fuel rod 4 (4a, 4d, 4g,...) Is also measured from the peak value of the chevron waveform. If the radius of the fuel rod 4 is added to each measured distance, the distances Ay, By ′, Cy,... From the X axis to the center of each fuel rod 4, and the distance from the Y axis to the center of each fuel rod 4 Ax, Dx, Gx,... Are obtained.
At the same time, the distance in the X-axis direction can also be measured by the travel distance of the outer sensor 22 to the position of the peak values Pa ′, Pb ′, Pc ′ of each mountain-shaped waveform. Similarly, the outer sensor 23 is caused to travel to obtain the traveling distance in the Y-axis direction up to the peak value of each chevron waveform. In this manner, the position (x, y) of the outer peripheral fuel rod 4 by the outer sensors 22 and 23 is measured.
And it verifies by comparing with the measurement position (x, y) of the outer peripheral fuel rod 4 at the center position S3 by the primary measurement process.

Next, a simple measuring method will be described as a measuring method according to the third embodiment.
In each of the above-described embodiments, the outer sensors 22 and 23 and the probe 9 are located at three positions S1, S2 and S3 in the longitudinal direction of the fuel rod 4 for the plurality of fuel rods 4 supported by the adjacent support grids 3 and 3. 9, the position (x, y) of each fuel rod 4 was measured. However, since the fuel rods 4 are close to the positions fixed to the support grid 3 at the upper and lower support grid vicinity positions S 1 and S 2, Hard to occur.
Therefore, in the primary and secondary measurement methods, the position (x, y) of each fuel rod 4 in the supporting grid vicinity positions S1 and S2 is substituted with the design value or the specification value without measuring, and the above-described only at the central position S3. The primary and secondary measurement methods are performed, and the position (x, y) of each fuel rod 4 is measured. Thus, the bending of each fuel rod 4 can be easily measured, and the outer peripheral fuel rod 4 can be easily verified.
If this measurement method is employed, the bending of each fuel rod 4 can be measured more easily, and the bending measurement value of the outer peripheral fuel rod 4 can be verified.
Further, the primary and / or secondary measurement at the support grid vicinity position S1 on the lower nozzle 2b side or one support grid vicinity position S2 on the upper nozzle 2a side may be omitted.

In this embodiment, when the primary measurement process is performed using the probe 9, the measurement is performed by inserting the probe 9 between all the fuel rods 4 and 4 in the Y-axis direction and the X-axis direction. However, the measurement may be performed by inserting the probes 9 every other row. As a result, the inspection time can be further reduced and an efficient inspection can be performed.
Further, the present invention is not limited to the measurement of the bend between the fuel rods 4 and 4 of the fuel assembly 2 and between the fuel rod 4 and the control rod guide tube 4S, but also any rod-like body including other appropriate objects to be measured. It can be used as an apparatus or a method for measuring the bending of.

It is a side view which shows the structure of the bending measuring apparatus by embodiment of this invention. It is a top view which shows the relationship between a fuel assembly and a measurement block. It is a figure which shows the bending measurement position of the fuel rod hold | maintained between the upper and lower support grids. It is a figure which shows the relationship between a fuel rod, a probe, and an advance / retreat mechanism, (a) is the state before inserting the probe, (b) is the state where the probe is inserted, (c) is the state where the probe has passed the control rod guide tube is there. It is sectional drawing of the front-end | tip part of a probe. It is a principal part top view of the bending measurement state which shows a fuel rod and a measurement process means. (A) is a plan view of a state in which the distance between two adjacent fuel rods is measured by a probe, and a diagram showing a chevron waveform obtained by each electrostatic sensor, and (b) is a chevron waveform obtained by each electrostatic sensor. FIG. It is a figure similar to FIG. 7 of the state which the probe has approached while swinging. FIG. 8 is a view similar to FIG. 7 with the probe biased to one fuel rod. (A) is the output waveform figure of the electrostatic capacitance which measures the distance of the X-axis and fuel rod by the outer side sensor in the position near a support grid, (b) is the same output waveform figure by the outer side sensor in a center position.

Explanation of symbols

1 Bend measuring device 2 Fuel assembly 4 Fuel rod (rod-like body)
4a Control rod guide tube (bar-shaped body)
9 Distance measurement probe (probe)
14 Electrostatic sensors 22, 23 Outside sensor 25 Measurement processing means 26 Secondary measurement processing means 28 Calculation means 29 Primary measurement processing means 31, 32 Output waveform summing means ha, hd Yamagata waveform had Total Yamagata waveform 33 Control means

Claims (7)

A method for measuring the bending of a plurality of rod-shaped bodies arranged in the X-axis direction and the Y-axis direction intersecting each other,
A distance measuring probe including an electrostatic sensor is inserted between two rod-shaped bodies adjacent to each other in the X-axis direction and the Y-axis direction, and distance information from the electrostatic sensor to the opposing rod-shaped body is output as a mountain waveform. Then, the central line of the total chevron waveform obtained by summing up these two chevron waveforms is obtained, and the area of each chevron waveform is divided within a certain range on both sides from the center line, and the area of each chevron waveform is divided into two equal parts. Performing a primary measurement process to obtain a distance from the X-axis or Y-axis to the two rod-like bodies by a bisector
A bending measurement method for a rod-shaped body, wherein the bending of the plurality of arranged rod-shaped bodies is measured by performing the primary measurement process at one or a plurality of positions along the longitudinal direction of the rod-shaped body. Outside the plurality of arranged rod-shaped bodies, an outer sensor is run along the X-axis and the Y-axis, and distance information to the rod-shaped bodies arranged on the outer peripheral side is output as a mountain waveform, and the peak value of the mountain waveform To perform a secondary measurement process for obtaining the distance from the X axis and the Y axis to the rod-like body on the outer peripheral side,
2. The bar shape according to claim 1, wherein the bending of the plurality of arranged bar-shaped bodies is measured by performing the secondary measurement process at one or a plurality of positions along the longitudinal direction of the bar-shaped body. Body bending measurement method.   3. The bending measurement of the rod-shaped body according to claim 2, wherein in the secondary measurement process, the movement distance along the X axis and the Y axis of the outer sensor is measured at the position of the peak value of the mountain waveform obtained by the outer sensor. Method.   The rod-shaped body is a fuel rod supported by a plurality of support grids arranged at a predetermined interval in the fuel assembly, and each of the fuel rods at a position near the support grid and an intermediate position between two adjacent support grids. The method for measuring bending of a rod-shaped body according to any one of claims 1 to 3, wherein measurement processing is performed.   The rod-shaped body is a fuel rod supported by a plurality of support grids arranged at predetermined intervals in the fuel assembly, and the measurement processing is performed at an intermediate position between two adjacent support grids for the fuel rod. The bending measurement method of the rod-shaped body according to any one of claims 1 to 3. A bending measuring device for a rod-shaped body arranged in a plurality of X-axis and Y-axis directions intersecting each other,
A distance measuring probe including a pair of electrostatic sensors, each of which is inserted between two rod-like bodies adjacent to each other in the X-axis direction and the Y-axis direction and outputs distance information to each of the opposing rod-like bodies as a mountain waveform;
The area of each chevron waveform is partitioned in a range of a certain width on both sides from the center line of the total chevron waveform obtained by summing up the two chevron waveforms, and the X axis or the bisection that bisects the area of each chevron waveform respectively. Primary measurement processing means for obtaining a distance from the Y axis to the two rod-shaped bodies,
A bar shape characterized in that the bending of each bar-shaped body is measured by measuring the distance from the X-axis or the Y-axis to the two bar-shaped bodies at one or a plurality of positions along the longitudinal direction of the bar-shaped body. Body bending measuring device. An outer sensor that travels along the X-axis and the Y-axis outside the plurality of arranged rod-shaped bodies and outputs distance information to the rod-shaped bodies arranged on the outer peripheral side as a chevron waveform;
The distance from the X axis and the Y axis to the rod-shaped body on the outer peripheral side is obtained from the peak value of the mountain waveform obtained by the outer sensor, and the travel distance of each outer sensor to the peak value along the X axis and the Y axis is measured. A secondary measurement processing means,
The bending of each rod-shaped body is measured by performing measurement by the outer sensor and secondary measurement processing means at one or a plurality of positions along the longitudinal direction of the rod-shaped body. Measuring device for bending of rod-shaped body.

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