JPH0328703A - Method for inspecting fuel assembly - Google Patents

Abstract

PURPOSE:To take measurements regarding inspection items required for the fuel assembly through remote operation and to reduce radiation exposure, shorten a measurement time, and improve the measurement accuracy by photodetecting transmitted light and measuring various sizes of the fuel assembly while rotating the fuel assembly and moving up and down a laser measuring instrument. CONSTITUTION:The laser measuring instrument 19 consists of reference position members 17 and 18 and a laser light source and a photodetection part which are arranged on both sides of the fuel assembly 10 opposite each other. The laser light source and photodetection member are provided with plural laser light sources and plural photodetecting elements in array on the same plane. Then while the fuel assembly 10 is rotated and the measuring instrument 19 is moved up and down, the transmitted light is photodetected. Consequently, the distances between the respective reference position members and the outside of the fuel assembly 10 at respective height positions corresponding to respective angles of rotation of the fuel assembly 10 are measured. All the required inspection items can be inspected at a time from the respective measured values and the constant reference position member distance to the overall circumference and overall length of the fuel assembly 10.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the inspection of the final shape of fuel assemblies used in nuclear reactors, and in particular the inspection of the total length of cylindrical fuel assemblies with complex shapes,
This invention relates to a method for automatically inspecting outer diameter, bending, torsion, fuel element spacing, spacer mounting position, etc.

``Prior Art'' Fuel assemblies used in nuclear reactors are assembled with fuel elements in cylindrical, square, or hexagonal shapes, but a cylindrical fuel assembly with a complex shape will be explained as an example.

The twelfth scale is a diagram showing a cylindrical fuel paddy aggregate, and FIG. 13 is a diagram showing the B B' cross section marked 4 in FIG. 12. In the figure,
1 is an upper tie plate, 2 is a lower tie plate, 3 is a fuel element, and 4 is a spacer.

In the figure - C1 fuel assembly has fuel elements 3, for example 28
The upper S and lower parts are fixed with the upper tie plate 1 and the -1 part tie plate 2, respectively, and the middle part is fixed with a plurality of bee-shaped spacers 4 at equal intervals. is kept constant to form a multiple circular shape.

When the fuel assembly burns in the reactor, cooling water flows along each fuel element 3 from the lower tie plate 2 to the L section tie plate 1 to remove the generated heat, and cools each part of the fuel assembly. Cooling. In order to ensure the flow path of this cooling water, the fuel assembly is regulated by the 11 method over the narrow FjlS.Therefore, the fully assembled fuel assembly has a total length of 'I-1' as shown in the figure. Spacer inquiry {j position tT+
h;+distance between fuel elements A1. A, , twist-to △C
' or -△C' and +iii of lower tie plate 2
i F of the upper tie plate 1 from the f points. =:
:． Inspections are being conducted to see if the L between the parts is manufactured according to the design method or not.

Conventionally, when inspecting a completed fuel assembly, the location and overall length of the spacer 4 was measured by suspending the fuel assembly with a crane and measuring the dimensions with a tape measure, thereby measuring the fuel element spacing. To measure bending and torsion, insert a thickness gauge into the gap along the entire circumference and entire length, and measure bending and torsion by attaching the fuel assembly to a mount, installing a plumb bob, and reading the distance between the plumb bob and the plumb bob using a tranny 7. In order to carry out these measurements, the rice burnt aggregates are moved to multiple locations using cranes, and all measurements are carried out manually.

[Problem to be solved by the invention]

Such conventional manual inspection methods have the following problems in terms of safety, quality control, and inspection efficiency.

When measuring the total length of the fuel assembly or supporting the lower part of the suspended rice paddy assembly to prevent it from swinging during movement, the workpiece spends a lot of time in contact with the fuel assembly, increasing the risk of radiation exposure to the human body. In particular, if more plutonium, fuel assemblies and highly enriched uranium fuel assemblies are handled in the future, exposure to radiation will become a problem.

11. When lowering or lifting the fuel assembly into the pit or moving it from the focus to the frame, contact with the edge of the pit or other equipment may cause damage or deformation to the fuel assembly. People have the potential to grow.

In addition, a plurality of skilled persons are required to read the transint, and furthermore, the fuel element spacing at more than 200 locations is manually measured, resulting in extremely low inspection efficiency.

The present invention is intended to solve the above-mentioned problems, and aims to reduce radiation exposure, shorten measurement time, and improve measurement accuracy by automatically measuring inspection items required for fuel assemblies by remote control. It is an object of the present invention to provide a method and apparatus for inspecting a fuel assembly.

[Means to solve the problem]

To this end, the present invention rotatably supports a fuel assembly with reference position members disposed on both sides, and is movable up and down to illuminate the reference position member and the fuel assembly with laser light and receive the transmitted light. The fuel assembly is rotated and the measuring means is moved downward by -12 while receiving the transmitted light, thereby measuring the various types of fuel assemblies.
It is characterized by measuring the law.

[Effect]

The present invention supports a fuel assembly having reference position members arranged on both sides so as to be rotatable, irradiates the reference position member and the fuel assembly with laser light, and receives the transmitted light.1-. A measuring means that can be moved downward is provided, and by rotating the fuel assembly and receiving transmitted light while lowering the measuring means -L, each height position at each rotation angle of the fuel diagonal assembly is determined. The distance between each reference position and the outside of the fuel assembly is measured, and all the inspection mounds required over the entire circumference and length of the fuel assembly are measured from each measured value and the constant distance between the reference position members. ['' is 1. This can be done by testing 1'i"i.

〔Example〕

1. An embodiment will be described below with reference to the drawings.

Fig. 1 is a diagram showing an embodiment of the fuel assembly inspection device according to the present invention in which a cylindrical fuel assembly is attached, Fig. 2 is a diagram showing a cross section taken along line E-E' in Fig. 1, and Fig. 13 is a diagram showing a fuel assembly inspection device according to the present invention. FIG. 4 is an explanatory diagram of the principle of calculating center coordinates of elements, and is an explanatory diagram of bending measurement. In the figure, the same numbers as in FIG. 12 indicate the same contents. In addition, 10 is a fuel assembly, 11 is a lower chuck, 12
13 is the right arm, 14 is the support column,
15 is a rotating station, 16 is a direction detector, 17.1.8
19 is a reference position member, 19 is a laser measuring device, 20 is a station, 2l is a laser light source, 22 is a laser receiver, and 23 is an upper chuck.

The fuel assembly inspection according to the present invention has the following structure.

The lower chuck 11 is mounted on an M rotation station 15 set in a horizontally installed frame at a ratio of 1:3, and is driven by -r[01 rotation. The support column 14 is provided perpendicularly to the pedestal 13, and
An arm l2 with a -L section chanter is provided on the upper end side of the switch 4. The respective center lines of the upper chunk 23 and the lower chianok l1 provided in the upper chaseok-7-1 and 12 are -
It is on straight line 2 and perpendicular to the frame 1:3. The fuel assembly 10 has an upper tie plate (2) and a lower tie plate (2) each fixed by an upper T yank 23 and an F section chunk 1l, and a lower tie plate (2). Rotating stage 1 through '7 Ku 11
Rotationally driven by 5.

Further, the rotating station 15 has a built-in drive mechanism for rotating the fuel assembly 10, a rotation angle indicator for the fuel assembly 10, or a transmission mechanism for transmitting the rotation angle as an electrical signal. Orientation detection for detecting the orientation mark of the fuel assembly 10 (usually a V-groove is engraved as a physical landmark) which is engraved on the lower tie plate 2 to detect the reference position of the rotation angle of the fuel assembly 10 A container 16 is provided on the pedestal 13.

The reference position members 17 and 18 are provided perpendicularly to the pedestal 13 on both sides of the fuel assembly 10 within a plane containing the center line of rotation of the fuel assembly 10.

Furthermore, the upper F stage 20 for moving the laser measuring device 19 to the upper stage is mounted on the support l4 in a water-mounted manner, and moves along the support.
Move to C-L. As shown in FIG. 2, the laser measuring device 19 is composed of reference position parts Ig' l 7 and 18, a laser light source 2l and a light receiving part 22, which are arranged facing each other on both sides of the fuel assembly 10. In each of the laser light source 2l and the light receiving section 22, a plurality of I/- sensor light sources and a plurality of light receiving elements j'- are provided in a row in the same plane. Also,"
The upper and lower stages 20 have built-in drive mechanisms for moving the lower stainless steel 20 by two inches, and a transmitting mechanism for transmitting the lower moving position (light receiving position) as an electrical signal. , Since it has such a structure, the laser measuring device 19
is the reference mounting member 17J at an arbitrary height using a laser beam.
3 and 18 and the fuel assembly 10, and the laser beam that has passed through without being blocked by these is received by the receiver 111122,
At this time, it is possible to detect the height position of the laser beam, the reference positions 17 and 18, and the shape of the fuel assembly 10.

Although it is not shown in the figure, there is an overnight processing device that receives measurement data from the operation panel that imitates each drive mechanism and each transmission mechanism, and performs arithmetic processing. It is provided.

Next, regarding the inspection required for the cylindrical fuel assembly, (1) Prepare the fuel assembly 10 with the lower chuck 1 and the upper chuck. , the fuel assembly 10 is rotated by the inspection device using the -L part chuck 23 of 12, the orientation mark engraved on the lower tie plate 2 is detected by the orientation detector 16, and the fuel assembly 10 is rotated at that position. stop.

This angle is used as a reference for measuring the rotation angle of the fuel assembly 10.

Next, the laser measuring device 1 set on the upper and lower spacers 20
9, and stopped at the boundary between the lower tie plate 2 and the east of the rice burning element, that is, point D on the L surface of the lower tie plate 2, set the height setting value of the lower tie plate 20 to 0, and measured the height. Use as a standard.

(2) Outer diameter measurement The outer diameter of the fuel is as shown in Figure 2 at the reference position paulownia 1.
7 and 18 and the fuel assembly 10 with a laser beam, the light is received by the light receiving section 22, and the respective intervals a and a' between the reference position parts 4A17 and 18 and the fuel assembly 10 are measured, and the reference position member is It can be determined from the distance L between 17 and l8.

11 That is, I, is known and constant, and the outer diameter d (11 ·
θ) is d (h, θ) = [−. −[ a (h,
θ) + a ′(h, θ)]. Maximum outer diameter at any height/i゛iJ. The fuel assembly 10 is 1. 8 0
Pass by degree. This is the maximum value obtained when measuring the eye roll 0', and the maximum outer diameter of the fuel assembly 10 is the maximum value of the two values.

Note that this measurement excludes the location of the sveza.

(3) Total length and width measurement {t a) 'y position measurement The laser measuring device 19 that measures the outer diameter is mounted on the -L lower station 20, and the upper and lower stages 2 () move up and down while detecting the height position. do.

The laser measuring device 19 ascends while measuring the outer diameter, detects a plurality of subareas having larger outer diameters from the east of the fuel element, and finally detects a point D' on the lower surface of the -L section tie plate 1.

Therefore, the four positions of the spacer 4 are the positions h1, hz, h0, etc. where the outer diameter changes as shown in Fig. 12, and 1
It is determined from the height position value of the second lower station 20. In this case, since the spacers have a width, strictly speaking, the upper and lower ends of each spacer may be detected and the height position of the center may be determined from the average value thereof.

In addition, the installation interval of each spacer is h, -hh1-h,
, -h, -h, . You can ask for it.

The total length H is determined by determining the position where the laser measuring device 19 detects point D' downward of the upper tie plate 1 from the height position values of the upper and lower stages 20, and calculating the distance H between the upper and lower tie plates 1 and 2.
' is the height H1 and H of the upper and lower tie plates 1 and 2. It can be found by adding.

II-H'ten+T. , +-t I, H. ,．． I-1. is the individual height information (numeric value) measured on 11J.

(4) Fuel element spacing measurement The fuel element spacing at any height h is
The center coordinates of each of the plurality of fuel elements constituting the outer layer of the fuel element can be sequentially determined and calculated from the center coordinates of adjacent fuel elements.

That is, the coordinate origin is the center of the fuel assembly, and the intervals in the horizontal section are A, . (X,
．． Y. ,) (X,+,.Y,,...) then Atn = (X,,-X,,++)'' (Y,
-Yh. +)2-2r...(1). r is the nominal radius of the fuel element (tolerance number 1 inch)
It is. FIG. 3 shows the relationship between the fuel element and the reference position paulownia when measuring the fuel element spacing at an arbitrary height h.

Looking at the fuel assembly rotating between the reference position members 17 and 18, the two reference position members 17 and 18 rotate around the fixed fuel assembly, forming two circles with different radii. It is considered that M'OJ6 and N are drawn.

Since the distances between the two reference position members and the fuel assembly are not necessarily equal, there are two closed circles for the reference position members.

If the center coordinates are (X,, Y,,), (Xh.l Y., +.
) is the angle between the diameter '1' of the circle M and the X-axis, which is obtained by dropping a perpendicular line from the center of the circle to the outer tangent P that touches the adjacent fuel element, and the angle α1 is J. ．． ;
The distance between the circle M and the tangent P with l and t is aα1, and the angle α.
{-1. 8 (If the distance between the circle M and the outer tangent of the adjacent fuel element at 1° is a'α1, then the radius R of the circle M (YoR- (a α 1 td α l +a
′ at ) / 2 ...{2). Here, dα1 is the outer diameter of the fuel assembly at angle α1. aα1 and a′α1 can be determined by the reference position member 17, and dα can be determined by the outer diameter measuring method described in (2) above, and as a result, the radius R can be determined. Also,
The radius of circle N can be found in the same way.

In order to determine the fuel element spacing, it is necessary to determine the center coordinates of each fuel element that makes up the outer layer of the fuel assembly. Here, when the reference position member 17 rotates while drawing a circle M around the fixed fuel assembly, at a certain -1 rotation angle θ - α1, it contacts two adjacent fuel elements in a direction orthogonal thereto. If the laser beam is irradiating the fuel element as shown in FIG.
R-aα+)X COSα+ } -1- (
R-a a1') Slnα+ -=-(3), and the equation of the tangent Q to the fuel element when the rotation angle θ-α2 is y---(COSα2/Slnα2) {×-(R-aα
2) x COS α2} + (R-a α2) sin
α2. ．． ．． ．． ．． ．． (4) becomes. aα2 is the distance between the circle M and the tangent Q at the angle α2.

Here, the tangent line P and the tangent line Q are each at the center coordinates (X.Y.
) adjacent center coordinates (X..,,Y) on both sides of the fuel element
．． , +1) and (X..., Y, -.), then the tangent P and the center coordinates (X., Y.,
) is the coordinate of the outer contact point of the fuel element (x1, −l− r
coSal, Yn4-r sinα1)
And, the coordinates of the point of contact between the tangent Q and the outside of this fuel element are (X, +r cos α2, Yll+r Sl
nα2).

Therefore, the coordinates of the contact point when θ-α1, θ-α2 are (3
) and (4), Y, −1−rsinα 16 (COSα1/ Slnα1) (X +1+ r
COSα1)→ (1/sinα,) (
R − a a +)−−・−(5)Y, +r
sinα2 (COSα2/S1nα2) (Xn1-rCOSα2)
-I- (1/s+nα2) (R-a
a2)・・・・・・(6), and X according to equations (5) and (6). , Yo is determined by X, = I/s
in (a2-α.) H((R-r-aα+) si
nα2<R-r-aa2)sinα+]Y. =I/sin(α2-α,>・((R-r-aα,:l cosα2(R-r-aα
2) cosαl). R is the value of formula (2). Similarly, find the center coordinates (X., ., Y, ..) of adjacent fuel elements,
Furthermore, by sequentially finding the center coordinates of the fuel elements, we find that the interval A. ,A2...A. , can be found. Here, the rotation angle θ is the rotation stage portion l5
angle detection data is used.

In addition, in the actual calculation, in order to eliminate measurement errors, α is (
αI+1) degrees and α2 are (α2−1) degrees.

In this way, the spacing between fuel elements can be determined at predetermined intervals over the entire length of the fuel assembly.

(5) Measurement of bending The bending of the fuel assembly is determined by measuring the −C bending of each fuel element constituting the outer layer, and taking the maximum value.

The bending of one fuel element is determined by measuring the distance between the fuel element and a straight line connecting the upper and lower parts of the fuel element.

In Fig. 4, the value of the distance a from the reference position member obtained by outer diameter measurement for the entire length of a certain fuel element n is collected, and the value of a when the height of the lowest part of the fuel element H is h min. a.

(hmin), top height hma. ■ Curve at a certain height h from the value of a at x (h max). (h) is obtained by the following formula.

1. , (h) one[: (a. (hmax)-a.
(hmin)) / (hmax - hmin)
] X (h-hmin)+ah(hmin)-afi
(h) Here, a, , (h) is the distance between the reference position paulownia and the outside of the fuel element H at the height h.

When the value of 1.0 is maximum, this is the maximum bending of the fuel element n, and the maximum value of each fuel element constituting the outer layer is the bending of the fuel assembly.

(6) Torsion measurement For a certain paddy element n, the value of a when the lowest height h min obtained by outer diameter measurement and the highest height I]ma
The rotation angle at which the value of a becomes the minimum when x is determined is determined, but if there is no twist in the fuel assembly, the rotation angle will have the same value.

If there is a twist in the fuel assembly, the height of the lowest part h
It is necessary to further rotate the fuel assembly in order to measure the minimum value of a when the height of the F-most part is h max with respect to the rotation angle at which the minimum value of a was measured when the height was h max.

If this rotated angle θ is the twist angle ((1/
2) The twist can be determined from sin θ. Here, d is the outer diameter of the fuel assembly at the top height hmax.

The torsion of the fuel assembly is measured for each fuel element constituting the outside, and the maximum value is taken as the torsion of the fuel assembly.

(7) Measurement of spacer inclination The inclination of the spacer is determined by calculation from the data of the spacer blade attachment position in two orthogonal directions or three directions at 60° obtained when measuring the outer diameter.

If you want to find the inclination of a certain spacer H from the height values in 3 directions of 60°, measure 3 degrees counterclockwise from the direction mark.
The heights at 0°, 90°, and 150' positions are hn (30
), hn (90”), hn (150°)
and the side 180° opposite to the measurement is 11'n (3 0')
, +1'n (90°) and h'n (150°), the slope in the three directions is h Tl (30°) - h'n (30°).
゜〉hn(90')-h'n(90゜)h n
(1.50°) -h' n (150"). Also, the inclination angle δ is δ- sin-1 ((hn-h' n) /Z)
becomes. Here, 2 is the diameter of the spacer.
20 describes the inspection of cylindrical fuel assemblies, but square and hexagonal fuel assemblies can also be inspected for the following items:

Fig. 5 is a diagram showing an embodiment of the fuel assembly inspection device according to the present invention in which a square fuel assembly is attached, Fig. 6 is a diagram showing a sectional view taken along the line FF' in Fig. 5, and Fig. 7 { 5th '3/IJ
Figure 8 is an enlarged view of part K in Figure 5, where (A) is an explanatory diagram of the squareness, Figure 8 (opening) is a diagram showing the measurement points of the squareness, and Figure 8 is an enlarged view of part K in Figure 5, showing the first factor. The same number as E#1 indicates the content. In addition, 30 is a fuel assembly, 31 is a fuel element, and 32
33 is an upper tie plate, 34 is a spring, and 35 is a spacer.

In the figure, the fuel element 31 of the square-shaped fuel rice aggregate 30 is supported by a plurality of spacers 35 at the middle part, a lower tie plate 33 at the lower part, and an upper tie plate 33 at the upper part so as not to receive stress due to the difference in thermal expansion. It is attached via a plate 32 and a spring 34.

The rectangular fuel assembly 30 is placed in an inspection device in the same manner as the cylindrical fuel assembly described above.

(1) The overall length, spacer position, spacer inclination, splinter length, etc. are the same as for cylindrical fuel assemblies.
It is determined by the change rate of the stage 20 and the outer diameter.

(2) Measuring the outer diameter of the fuel assemblies and spacers In FIG. 6, the distance between the two faces id and the diagonal distance nd' are measured at any height of the fuel assembly 30 in which the fuel elements 31 are arranged in a square shape. . Fuel assembly 30 and reference position members 17 and 1
When the distances a and a' between 8 have the maximum value, D = -
(a+a') is the distance d between facing faces, and a and a' indicate the minimum value (,), then L-(a-+-a') is the distance d between diagonals.
′. The heights of the upper and lower stages 20 are changed and their maximum values are determined. In addition, IF-1 measurements are also performed on the spacer.

(3) Measurement of twist Torsion is measured on four sides. For a certain surface, the rotation angle of the fuel assembly at which the gap with the reference position member 17 or 18 is the maximum value is measured at the positions of the upper surface of the F part tie plate 33 and the lower surface of the upper tie plate 32, respectively, and the rotation angle difference is determined. becomes torsion horn disease. If the rotation angle is O degrees,
There will be no misfortune. This is also measured on the other three surfaces, and the maximum value is taken as the maximum value of the twist of the fuel assembly.

(4) Curvature measurement Each surface and reference position member] Find the maximum distance between 7 or 18 from the bottom of the fuel assembly to 12 parts, and calculate the obtained value using the equation for bending of a cylindrical fuel assembly, The maximum value is taken as the maximum value of the bending of the burnt rice aggregate.

(5) Squareness For square fuel assemblies, measure the squareness between the lower surface of the upper tie plate 32 and the fuel element.

As shown in FIG. 7(a), the reference position member 17 or 18
The gaps between the upper tie plate 32 and the outer surface of the fuel element are defined as b and b', respectively. As shown in Fig. 7 (opening), b is from the lower surface of the tie plate 32 to h'
At a distance of , two places b 1b 2 with a distance of l1 apart.
, and at two locations b. at the same distance <11' from the bottom surface of the upper tie plate 32 and at the same distance h. ′, b′ and find the squareness using the following formula.

23 90° + jan' { (b2 -b+
)/h}→one jan−' ((b2 ′ b+
')/h) In order to reduce the influence of bending of the fuel element, etc., h' and h are set to short distances.

(6) Gasometry measurement between the spacer corner and the fuel element In Fig. 8, the distances e and f between the reference position member 17° or 18 at an arbitrary height and the outer surface of the spacer corner and the outer surface of the fuel element are calculated. Each is measured and determined from the difference fe between them. Also, measure other spades corners.

(7) Measurement of minimum spacing between fuel elements The spacing A between each fuel element shown in FIG. By sequentially measuring the width of the laser beam, the minimum spacing between fuel elements in two orthogonal directions is determined.

FIG. 9 is a diagram showing an embodiment of the fuel assembly inspection device according to the present invention, which uses a hexagonal fuel assembly, and FIG. The same numbers as in Figure 1 indicate the same contents. In addition, 24 40 is a fuel assembly, 41 is a pad, 42 is an upper hardware, 4
3 is the lower hardware.

In the figure, a hexagonal fuel assembly 40 has a fuel element placed in a hexagonal tube, and a part and a lower part of the hexagonal fuel assembly 40 have respective metal fittings 42.
and 43.

Regarding the outer diameter, etc. of the hexagonal fuel assembly 40, including the total length, bending, twisting, band position, and face-to-face distance g shown in FIG. The rate can be measured using the upper and lower stays 20 in the same way as for a cylindrical fuel assembly.

Furthermore, the outer diameter and bending of control rods, round rods, etc. can also be measured in the same way as for cylindrical fuel assemblies.

In the description of this inspection device described above, a plurality of laser light sources and light receiving elements are arranged in a row on the same plane, but
Using one laser light source, the outer diameter of the fuel assembly 10 is also measured by sequentially irradiating the reference position members 17 and 18 and the fuel assembly 0 with laser light, and receiving the light with a plurality of light receiving elements. This is town Noh. In this case, a horizontal distribution mechanism for the laser light source is provided on the upper and lower stages 20.

In addition, the two reference position portions 17 and 18 are located within the 1L plane that includes the center line connecting the lower chucks 23 and 11 (FIG. 1), that is, the center line of rotation of the fuel assembly 10. However, since this inspection device measures the influence of the laser beam on any rotation angle of the fuel assembly 10, the reference position part 17 is installed as shown in FIG. and 18 are located on both sides of the fuel assembly 10, respectively, and may be provided within two parallel planes U and U' parallel to the center line T of rotation of the fuel assembly 10, even if they are oblique. , Therefore, the center line T of rotation and the reference position members 17 and 18 do not need to be located in the same plane.

〔Effect of the invention〕

As described above, according to the present invention, the external shape of a fuel assembly, etc. is automatically and continuously measured over the entire circumference and length, and especially for cylindrical fuel assemblies, it is possible to perform all required inspections. This can significantly improve inspection efficiency.

Furthermore, since data is collected over the entire circumference and length in one measurement, necessary data can be arbitrarily selected, which is effective for quality control.

Since this inspection method does not make contact with the fuel assembly, it does not cause damage or deformation to the fuel assembly, and the effects of radiation on the human body can be extremely reduced.

Furthermore, since the calibration of the measuring instrument is automatically performed using a dummy, there is no need for skilled operators, and data collection with high measurement accuracy and reproducibility can be achieved with just one tool.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an embodiment of the fuel assembly inspection device according to the present invention in which a cylindrical fuel assembly is attached, Fig. 2 is a diagram showing cross sections F and E' in Fig. 1, and Fig. 3 is a diagram showing the fuel assembly inspection device according to the present invention. FIG. 4 is an explanatory diagram of the principle of calculating the center coordinates of elements; FIG. 4 is an explanatory diagram of bending measurement; FIG. Figure 6 is a cross-sectional view taken along line FF' in Figure 5, and Figure 7 is an enlarged view of section J in Figure 5.
A) is an explanatory diagram of the perpendicularity, the figure (opening) is a diagram showing the measurement points of the perpendicularity, Fig. 8 is an enlarged view of part K in Fig. 5, and Fig. 9 is a book with the hexagonal fuel assembly attached. A diagram showing an embodiment of the fuel assembly inspection device according to the invention, FIG. 10 is c-c of FIG.
Figure 11 is a diagram showing the setting of the reference position member, Figure 12 is a diagram showing a cylindrical fuel assembly, and Figure 3 is a diagram showing the BB' cross section in Figure 12. be. 1. Upper tie plate, 2. F section tie plate,
3. Fuel element, 4. Spacer, 10. Fuel assembly, 11. Lower chuck, 12.・・・
Rotating digital unit, l6...direction detector, 17.18...X
Semi-positioning member, 19... Laser measuring device, 20...'' two lower stages, 21... Laser emitting section, 22... Laser receiving section, 23... 10... Department Jack. Applicant: Power Reactor and Nuclear Fuel Development Corporation (1 other person)

Claims (8)

[Claims] (1) A fuel assembly with reference position members arranged on both sides is rotatably supported, and a vertically movable measuring means is provided that irradiates the reference position member and the fuel assembly with laser light and receives the transmitted light. and rotate the fuel assembly,
A method for inspecting a fuel assembly, comprising measuring various dimensions of the fuel assembly by moving the measuring means up and down and receiving transmitted light. (2) Measure the distance between each reference position member and the fuel assembly,
Inspection of a fuel assembly according to claim 1, characterized in that the outer diameter of the fuel assembly at each height position is determined by subtracting the distance between each reference position member and the fuel assembly from the distance between the reference position members. Method. (3) The method for inspecting a fuel assembly according to claim 2, characterized in that the height position of the spacer is measured from the height of the measuring means when the change in the outer diameter is detected. (4) The distance between the upper and lower tie plates is calculated from the height position of the measuring means using the change in the outer diameter, and the fuel assembly is performed by adding the height information (value) of the upper and lower tie plates. 3. The method for inspecting a fuel assembly according to claim 2, further comprising measuring the total length of the fuel assembly. (5) Detecting the irradiation light contacting the two adjacent fuel assembly elements at two different rotation angles for three sequentially adjacent fuel elements of the fuel assembly, and comparing the rotation angle, the reference position member, and the center of the fuel assembly. 2. The method for inspecting a fuel assembly according to claim 1, further comprising determining the center position of the fuel assembly element from the distance and determining the spacing between each fuel element. (6) The method for inspecting a fuel assembly according to claim 1, characterized in that the distance between the reference position member and the fuel element is measured over the entire length, and bending of the fuel element is measured. (7) Detecting the rotation angle at which the distance between the upper and lower ends of the fuel element and the reference position member is maximum or minimum, and determining the twist from the difference between the rotation angles at the upper and lower ends and the outer diameter of the fuel assembly. The method for inspecting a fuel assembly according to claim 1, characterized in that: (8) The method for inspecting a fuel assembly according to claim 1, characterized in that the height position of the spacer on the opposite side by 180 degrees is measured, and the inclination of the spacer is determined from the ratio of the difference between the two measured values and the diameter of the spacer. .