JP2007163346A - Inspection tool of fuel assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection tool of a fuel assembly that can reduce the number of insertion times of the inspection tool and efficiently inspect the fuel rod interval. <P>SOLUTION: The inspection tool 9 of the fuel assembly for inspecting the fuel rod intervals (d) of the fuel assembly 1 comprises a plurality of thickness gauges 10 having a thickness dimension (t) of a predetermined clearance reference value, and a gauge fixing section 11 for arranging the plurality of thickness gauges 10 in the thickness direction and fixing and supporting them so that the plurality of thickness gauges 10 can be inserted into a plurality of rows of fuel rod intervals (d). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel assembly inspection jig for inspecting a fuel rod gap of a fuel assembly.

  For example, a fuel assembly for a boiling water reactor includes a number of fuel rods in which fuel pellets made of fissile material are sealed in a cladding tube made of, for example, zirconium, at least one water rod that is a neutron moderating rod, A plurality of fuel spacers that bundle a plurality of fuel rods and water rods in the axial direction to form a fuel bundle, an upper tie plate and a lower tie plate that respectively support the upper and lower portions of the fuel bundle, and a fuel assembly surrounding the fuel bundle And a substantially rectangular tube-shaped channel box forming the outer wall of the body. In this fuel assembly, the gap size between adjacent fuel rods and water rods is important in terms of performance, and a minimum value is defined.

  Therefore, conventionally, for example, a pair of non-curved gap gauge pieces projecting in one plane so as to be spaced apart from each other in the width direction from the one end side of the operation base end portion and have substantially the same length, and these non-curved gap gauges A required number of (having a length extending between the non-curved gap gauge pieces and disposed between the pieces, projecting in parallel in the same plane as the non-curved gap gauge pieces from the base end portion for operation. An inspection jig including a (curved) gap gauge piece is disclosed (for example, see Patent Document 1). The non-curved gap gauge piece is formed with a thickness of the gap reference value in the line-of-sight direction of the inspection object, and the curved gap gauge piece has a gap reference value thickness that is not in the line-of-sight direction of the inspection object at the tip. It is composed of a short gauge part, and a bendable long connecting part that extends to the base end part for operation in the longitudinal direction of the short gauge part and is thinner than the short gauge part and has flexibility. ing.

  In this prior art, even if the gap between the water rod and the fuel rod is not in the line-of-sight direction from the outside, the short gauge portion enters while the long gauge portion of the curved gap gauge is bent, and the short gauge portion is inserted. We are going to check pass / fail. Further, a gap in the line-of-sight direction, such as a gap between fuel rods, is subjected to pass / fail inspection by whether or not a non-curved gap gauge is inserted. Then, by one insertion operation of this inspection jig, both the gap not in the line-of-sight direction (the gap between the water rod and the fuel rod) and the gap in the line-of-sight direction (the gap between the fuel rod and the fuel rod) are inspected. In addition, a plurality of positions in the longitudinal direction of these gaps are inspected.

Japanese Patent Laid-Open No. 8-43003

However, there are the following problems in the above-described prior art.
That is, the inspection jig has a structure in which a pair of non-curved gap gauge pieces and a required number of curved gap gauge pieces spaced apart in the width direction are provided in substantially the same plane. The fuel rod-to-fuel rod gap (hereinafter referred to as fuel rod gap) that can be inspected by the insertion operation is only one line in the line-of-sight direction. For example, in the inspection of the fuel assembly in which the fuel rods are arranged in a square grid of 9 rows × 9 rows, between the fuel spacer and the fuel spacer (or between the upper tie plate and the lower tie plate and the fuel spacer). In addition, it is necessary to inspect the fuel rod gap of 8 rows × 8 rows, and the number of insertions of the inspection jig is 16 to 32 times (the number of insertions varies depending on the number of water rods and their arrangement). Therefore, there is room for improvement in terms of working efficiency.

  An object of the present invention is to provide a fuel assembly inspection jig that can reduce the number of insertions of the inspection jig and can efficiently inspect the fuel rod gap.

  (1) In order to achieve the above object, the present invention provides a fuel assembly inspection jig for inspecting a fuel rod gap of a fuel assembly, a plurality of gap gauges having a predetermined gap reference value thickness dimension, And a gauge fixing portion that fixes and supports the plurality of gap gauges in parallel in the thickness direction so that the plurality of gap gauges can be inserted into the plurality of rows of the fuel rod gaps.

  In the present invention, when the inspector performs the operation of inserting the inspection jig from one direction of the fuel bundle, a plurality of gap gauges are inserted into the plurality of rows of fuel rods. At this time, whether or not the fuel rod gap is larger than a predetermined gap reference value is determined based on whether or not each gap gauge (in the thickness direction) is inserted into the fuel rod gap. That is, when a plurality of gap gauges are inserted through the fuel rod gaps, it is determined that the plurality of rows of fuel rod gaps are larger than a predetermined gap reference value, and any of the plurality of gap gauges does not pass through the fuel rod gaps. In this case, it is determined that any one of the plurality of rows of fuel rod gaps is smaller than a predetermined gap reference value. In this way, since a plurality of gap gauges inserted into a plurality of rows of fuel rod gaps are determined to be acceptable, a plurality of rows of fuel rod gaps can be inspected simultaneously by a single insertion operation of the inspection jig. . Therefore, the number of insertions of the inspection jig can be reduced, and the fuel rod gap can be inspected efficiently.

  (2) In the above (1), preferably, it further includes adjusting means for adjusting the insertion lengths of the plurality of gap gauges that can be inserted into the fuel rod gaps.

  Generally, a fuel assembly for a boiling water reactor is provided with at least one water rod having a diameter larger than that of the fuel rod. For this reason, for example, if the insertion lengths of a plurality of gap gauges are all fixed to the same length, the gap gauge inserted into the fuel rod gap in the water rod direction can only be inserted to the near side of the water rod, and at the same time, other than the water rod direction. The gap gauge inserted in the fuel rod gap can only be inserted up to the distance on the near side of the water rod, although it does not interfere with the water rod. Therefore, in the present invention, the insertion lengths of the plurality of gap gauges are adjusted by the adjusting means of the inspection jig, for example, the insertion length of the gap gauge inserted into the fuel rod gap in the water rod direction does not interfere with the water rod. Thus, the insertion length of the gap gauge inserted into the fuel rod gap other than the water rod direction can be made relatively long. That is, the number of insertions of the inspection jig can be reduced by adjusting the insertion lengths of the plurality of gap gauges according to the arrangement of the water rod of the fuel assembly and the insertion position of the inspection jig. Therefore, even in a fuel assembly for a boiling water reactor equipped with a water rod, the fuel rod gap can be efficiently inspected.

  (3) In the above (1) or (2), preferably, a gripping means that can be gripped by an inspector is further provided.

  (4) In any one of the above (1) to (3), preferably, the gap gauge is provided in the same number as the number of rows of the fuel rod gaps in the fuel assembly.

  According to the present invention, when the inspector performs the operation of inserting the inspection jig from one direction of the fuel bundle, the plurality of gap gauges are inserted into the plurality of rows of fuel rod gaps, respectively. Thereby, a plurality of rows of fuel rods can be simultaneously inspected by one insertion operation of the inspection jig. Therefore, the number of insertions of the inspection jig can be reduced, and the fuel rod gap can be inspected efficiently.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 2 is a perspective view showing the entire structure of a fuel assembly for a boiling water reactor to be inspected according to the present invention, and FIG. 3 is a horizontal sectional view of a fuel bundle described later.

  2 and 3, a fuel assembly 1 for a boiling water reactor is a plurality of fuel rods 2 in which fuel pellets made of fissile material are sealed in a cladding tube made of, for example, zirconium, and a neutron moderating rod. For example, two water rods 3, a plurality of fuel spacers 5 that bundle a plurality of axial positions of these fuel rods 2 and water rods 3 to form a fuel bundle 4, and an upper type that supports the upper and lower portions of the fuel bundle 4, respectively. A rate 6 and a lower tie plate 7, and a channel box 8 having a substantially rectangular tube shape surrounding the fuel bundle 4 and forming the outer wall of the fuel assembly 1 are provided.

  The fuel rods 2 are arranged in a substantially square lattice pattern (n rows × n rows, in this embodiment, 9 rows × 9 rows) at equal intervals p, and the water rods 3 are arranged near the center thereof. As shown in the figure, the outer width W of the fuel bundle 4 is the same in both the vertical and horizontal directions, and a fuel rod gap d of 8 rows × 8 rows is formed.

  The minimum value of the fuel rod gap d is defined in terms of the performance of the fuel assembly 1. Therefore, in assembling and manufacturing the fuel assembly 1, before the channel box 8 is attached, every time between the fuel spacer 5 and the fuel spacer 5 (or between the upper tie plate 6 and the lower tie plate 7 and the fuel spacer 5), It must be checked whether the fuel rod gaps d in all rows (eight rows and eight rows) are larger than the specified minimum value. The fuel assembly inspection jig of the present invention used for such inspection will be described in detail.

  FIG. 1A is a plan view showing the overall structure of an embodiment of a fuel assembly inspection jig according to the present invention, and FIG. 1B is a side view.

  1A and 1B, the fuel assembly inspection jig 9 according to the present embodiment includes, for example, eight gap gauges 10 that are the same as the number of rows of fuel rod gaps d of the fuel assembly 1, A gauge fixing portion 11 is provided for fixing and supporting these gap gauges 10 in parallel in the thickness direction of the gap gauge 10 (left and right direction in FIG. 1A) at substantially the same interval as the fuel rod interval p.

  The gap gauge 10 is made of nylon, for example, so as not to be damaged when coming into contact with the cladding tube of the fuel rod 2, and is provided on the tip side (the upper side in FIGS. 1A and 1B). An inspection part 10a whose thickness dimension t is a predetermined gap reference value (the above-mentioned specified minimum value of the fuel rod gap d or a value slightly larger than this), and a base end side (FIG. 1 (a) and It extends to the lower side in FIG. 1 (b), and is composed of a support portion 10b having a thickness dimension of t or less.

  In the gauge fixing part 11, eight openings 12a in which the gap gauge 10 is slidable in the longitudinal direction (vertical direction in FIGS. 1A and 1B) are formed at substantially the same interval as the fuel rod interval p. The fixing member 12 and a substantially U-shaped frame member 13 fixed to the fixing member 12. Screw holes 12b communicating with the openings 12a are formed in the upper portion (left side in FIG. 2) of the fixing member 12, and fixing screws 14 are screwed into the screw holes 12b.

  And when the front end side (right side in FIG.1 (b)) of the screwed fixing screw 14 does not protrude in the opening part 12a of the fixing member 12, the clearance gauge 10 slides on the opening part 12a, and is fixed The length L from the member 12 to the tip side of the gap gauge 10 (hereinafter referred to as the insertion length of the gap gauge 10) L can be adjusted. At this time, the maximum dimension of the insertion length L of the gap gauge 10 is, for example, larger than the outer width W of the fuel bundle 4. Further, when the front end side of the screwed fixing screw 14 projects into the opening 12 a of the fixing member 12, the fixing screw 14 comes into contact with the support portion 10 b of the gap gauge 10 and the support portion 10 b of the gap gauge 10 is moved. It is designed to be pressed and fixed.

  The substantially U-shaped frame member 13 secures a space of the above-mentioned maximum dimension on the proximal end side of the gap gauge 10 so that the gap gauge 10 can move in the longitudinal direction. The frame member 13 is provided with, for example, a substantially cylindrical handle 15 that can be gripped by an inspector.

  In the above, the fixing member 12 and the fixing screw 14 constitute adjusting means for adjusting the insertion lengths of the plurality of gap gauges that can be inserted into the fuel rod gaps described in the claims, and the handle 15 is claimed. The gripping means that can be gripped by the inspector described in the above range is configured.

  Next, the detailed procedure of the inspection method of the fuel assembly 1 using the inspection jig 9 according to the present embodiment will be described.

  FIG. 4A is a diagram illustrating a preparation state in which the inspection jig 9 is inserted from one direction (A surface side) of the fuel bundle 4, and FIG. 4B is a diagram illustrating a state after the insertion. 5 (a) is a diagram showing a preparation state in which the inspection jig 9 is inserted from the other direction (B surface side) of the fuel bundle 4, and FIG. 5 (b) is a state after the insertion. FIG.

  4 (a), 4 (b), 5 (a), and 5 (b), first, the fuel bundle 4 is erected, and the A surface side of the fuel bundle 4 (FIG. 4 (a)). Keep the middle and lower side facing the examiner.

  For example, if the insertion length L of the gap gauge 10 of the inspection jig 9 is made the same length and inserted into the fuel rod gap d, the four gap gauges 10 inserted in the direction of the water rod 3 interfere with the water rod 3. Therefore, the eight gap gauges 10 can be inserted only up to the front side of the water rod 3 (the lower side in FIGS. 4A and 4B). Therefore, the inspector adjusts the insertion length L of the four clearance gauges 10 on the inner side of the inspection jig 9 to the front side of the water rod 3 according to the arrangement of the water rods 3, and The insertion length L of the gap gauge 10 (two on the left side and two on the right side in detail) is adjusted to the maximum dimension.

  The inspector holds the handle 15 of the inspection jig 9 and inserts eight gap gauges 10 into the eight rows of fuel rod gaps d from the A surface side of the fuel bundle 4. At this time, depending on whether the thickness dimension t of each gap gauge 10 is inserted into the fuel rod gap d (in other words, whether the gap gauge 10 can be inserted without resistance), the fuel rod gap d is greater than a predetermined gap reference value. Determine if it is larger. For example, when the eight gap gauges 10 are inserted into the fuel rod gaps d, it is determined that the eight rows of fuel rod gaps d from the A surface side are larger than a predetermined gap reference value, and pass. On the other hand, if any of the eight gap gauges 10 does not pass through the fuel rod gap d, it is determined that any of the eight rows of fuel rod gaps d from the A side is smaller than a predetermined gap reference value. Fail.

  Next, the B surface side (the lower side in FIG. 5A) of the fuel bundle is in a state facing the inspector. As in the above procedure, the inspector sets the insertion length L of the four inner clearance gauges 10 of the inspection jig 9 to the maximum while the insertion length L of the outer four clearance gauges 10 of the inspection jig 9 is the maximum dimension. Adjust according to the arrangement of the rod 3. The inspector holds the handle 15 of the inspection jig 9 and inserts eight gap gauges 10 into the eight rows of fuel rod gaps d from the B surface side of the fuel bundle 4. At this time, whether or not each of the gap gauges 10 is inserted into the fuel rod gap d determines whether or not the eight rows of fuel rod gaps d from the B surface side are larger than a predetermined gap reference value, and a pass / fail test is performed.

  Next, although not shown, the C surface side of the fuel bundle is in a state facing the inspector. Since the inspection of the fuel gaps d in the outer four rows (specifically, the left two rows and the right two rows) of the fuel bundle 4 has been completed in the inspection procedure from the A surface side, 9, the insertion length L of the four outer clearance gauges 10 is adjusted to the minimum dimension, and the insertion length L of the four clearance gauges 10 on the inner side of the inspection jig 9 is adjusted according to the arrangement of the water rod 3. The inspector holds the handle 15 of the inspection jig 9 and places the four gap gauges 10 from the C surface side of the fuel bundle 4 in front of the water rod 3 (upper side in FIGS. 4A and 4B). Are inserted into the four rows of fuel rod gaps d. At this time, whether or not each of the gap gauges 10 is inserted into the fuel rod gap d determines whether or not the four rows of fuel rod gaps d from the C plane side are larger than a predetermined gap reference value, and a pass / fail test is performed.

  Next, although not shown, the D surface side of the fuel bundle is in a state facing the inspector. In the inspection procedure from the B surface side, the inspection of the fuel gaps d in the outer four rows (specifically, the left two rows and the right two rows) of the fuel bundle 4 has been completed. Similarly, the insertion length L of the four inner clearance gauges 10 of the inspection jig 9 is set to the minimum dimension while the insertion length L of the inner four clearance gauges 10 of the inspection jig 9 is adjusted to the arrangement of the water rod 3. adjust. The inspector holds the handle 15 of the inspection jig 9 and places the four gap gauges 10 from the D surface side of the fuel bundle 4 in front of the water rod 3 (upper side in FIGS. 5A and 5B). Are inserted into the four rows of fuel rod gaps d. At this time, whether or not each of the gap gauges 10 is inserted into the fuel rod gap d determines whether or not the four rows of fuel rod gaps d from the D surface side are larger than a predetermined gap reference value, and a pass / fail test is performed.

  As described above, in this embodiment, eight (or four) gap gauges 10 are provided in each of the inspection procedures from the A side, B side, C side, and D side of the fuel bundle 4. Since what is inserted into the row (or 4 rows) of fuel rod gaps d is determined to be acceptable, 8 rows (or 4 rows) of fuel rod gaps d are simultaneously inspected by one insertion operation of the inspection jig 9. Can do. That is, in the inspection jig having the conventional structure, only one row of fuel rod gaps d can be inspected by one insertion operation, so that the inspection jig is inserted 24 times in total. The number of insertions of 9 can be greatly reduced to 4 times. In particular, since the inspection must be performed every time between the fuel spacer 5 and the fuel spacer 5 (or between the upper tie plate 6 and the lower tie plate 7 and the fuel spacer 5), the effect becomes more remarkable. Therefore, the number of insertions of the inspection jig 9 can be reduced, and the fuel rod gap d can be inspected efficiently.

  In the above-described embodiment, the fuel assembly for the boiling water reactor has been described as an example of the inspection target. However, the present invention is not limited to this, and for example, the fuel assembly for the pressurized water reactor that does not include a water rod or the like. It may be applied to the body. In this case, the same effect as described above can be obtained.

It is the top view and side view showing the whole structure of one Embodiment of the inspection tool of the fuel assembly of this invention. It is a perspective view showing the whole structure of the fuel assembly for boiling water reactors which becomes the inspection object of the inspection jig of the fuel assembly of the present invention. It is a horizontal sectional view showing the detailed structure of the fuel bundle for boiling water reactors used as the inspection object of the inspection jig of the fuel assembly of the present invention. It is a top view showing the detailed procedure of the inspection method using one embodiment of the inspection jig of the fuel assembly of the present invention, the preparation state to insert the inspection jig from one direction of the fuel bundle, and the state after insertion To express. It is a top view showing the detailed procedure of the inspection method using one embodiment of the inspection jig of the fuel assembly of the present invention, the preparation state to insert the inspection jig from the other direction of the fuel bundle, and the state after insertion To express.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel assembly 2 Fuel rod 9 Inspection jig 10 of a fuel assembly Crevice gauge 11 Gauge fixing part 12 Fixing member (adjustment means)
14 Fixing screw (adjustment means)
15 Handle (gripping means)
d Fuel rod gap L Insertion length t of gap gauge Thickness dimension

Claims (4)

In the fuel assembly inspection jig for inspecting the fuel rod gap of the fuel assembly,
A plurality of gap gauges having a predetermined gap reference value thickness dimension;
A gauge fixing portion for fixing and supporting the plurality of gap gauges in parallel in the thickness direction so that the plurality of gap gauges can be inserted into the plurality of rows of fuel rod gaps. Inspection jig.   2. The fuel assembly inspection jig according to claim 1, further comprising adjusting means for adjusting insertion lengths of the plurality of gap gauges that can be inserted into the fuel rod gaps. jig.   3. The fuel assembly inspection jig according to claim 1, further comprising gripping means that can be gripped by an inspector.   4. The fuel assembly inspection jig according to claim 1, wherein the gap gauge is provided in the same number as the number of rows of the fuel rod gaps in the fuel assembly. 5. Inspection tool for fuel assembly.

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