KR100704752B1 - Standard rod and exchange jig for measuring of oxide thickness by eddy current test - Google Patents

Abstract

The present invention relates to an eddy current flaw standard rod and replacement jig for calibration of thickness measuring equipment of a fuel cladding oxide layer, in which only a fuel cladding tube with a standard film is inserted into a hot cell, and a standard rod change jig and By using a remote controller, the fuel cladding tube with the end-of-life standard film can be replaced and reused, thereby reducing the use of expensive fuel cladding tubes and reducing the amount of non-combustible radioactive waste. By precisely calibrating the thickness measuring equipment, the thickness measurement value of the oxide layer formed on the spent fuel cladding can be measured accurately and reliably.The non-destructive method measures the thickness of the oxide layer of the spent fuel rod to evaluate the integrity of the spent fuel rod. And destructive testing materials It is intended to provide eddy current flaw standard rods and replacement jigs for calibration of thickness measuring equipment of fuel cladding oxide layer, which can be utilized as well as contribute to the design and investigation behavior of fuel rods. A standard consisting of a nuclear fuel cladding tube, a core rod penetrating inside the nuclear fuel cladding tube and having male threads formed at both ends thereof, and coupled to both ends of the core rods and having a female thread formed at one end thereof. Rods; And a stop plate provided at one side end portion, a fixing plate fixed at one side of the upper surface, and a guide plate installed at the other side thereof, wherein the replacement jig is formed at the longitudinal position thereof; Characterized in that comprises a.

Nuclear fuel, cladding, oxide layer, standard rod, replacement jig, guide rod, plate

Description

Standard rod and exchange jig for measuring of oxide thickness by eddy current test

1 is a view schematically showing an eddy current flaw detection standard rod for calibration of thickness measurement equipment for the oxide layer of the nuclear fuel cladding according to the present invention;

2 is an exploded view schematically showing an eddy current flaw standard rod for calibration of thickness measurement equipment for an oxide layer of a nuclear fuel cladding tube according to the present invention;

3 is a plan view schematically illustrating a replacement jig for replacing a fuel cladding tube of an eddy current flaw detection standard rod for calibration of thickness measuring equipment of a fuel cladding tube oxide layer according to the present invention;

4 is a front view schematically showing a replacement jig for replacing a fuel cladding tube of an eddy current flaw standard rod for calibration of thickness measuring equipment of a fuel cladding tube oxide layer according to the present invention;

FIG. 5 is a side view schematically showing a replacement jig for replacing a fuel cladding tube of an eddy current flaw standard rod for calibration of thickness measuring equipment of a fuel cladding tube oxide layer according to the present invention; FIG.

6 is a schematic view showing a tool that can be remotely operated to replace the fuel cladding of the eddy current flaw standard rod for calibration of the thickness measuring equipment of the fuel cladding oxide layer according to the present invention;

FIG. 7 is a schematic view of a remotely operable tool for assembling and disassembling a replacement jig for replacing a fuel cladding of an eddy current flaw standard rod for calibration of thickness measuring equipment of a fuel cladding oxide layer according to the present invention; FIG.

8 is a plan view schematically illustrating a state in which a eddy current flaw detection standard rod for calibrating a thickness measuring device of an oxide layer of a nuclear fuel cladding tube according to the present invention is installed on a replacement jig;

9 is a front view schematically showing a state in which an eddy current flaw standard rod for calibration of thickness measurement equipment for the oxide layer of a nuclear fuel cladding tube according to the present invention is installed on a replacement jig;

FIG. 10 is a side view schematically showing a state in which an eddy current flaw standard rod for calibrating a thickness measuring device of an oxide layer of a nuclear fuel cladding tube according to the present invention is installed on a replacement jig;

** Explanation of symbols for main parts of the drawing **

10: standard rod, 11: fuel cladding tube,

11a: standard film, 13: mandrel,

13a, 13b: male thread part, 15: upper guide rod,

15a: upper groove, 15b: female thread,

17: lower guide rod, 17a: driver groove,

17b: female thread portion, 18: ring plate,

18a: groove, 18b: bolt,

18c: nut, 18d: through hole,

19: separation tool, 30: replacement jig,

31: stop plate, 31a: bolt,

31b: fastening hole, 33: fixed plate,

33a, 33a ': fixing bolt, 33b, 33b': fixing hole,

33c: open groove, 35, 35 ': guide plate,

35a, 35a ': Fixing bolt, 35b, 35b': Fixing hole,

35c: open groove, 37: V block,

39: disassembly tool.

The present invention relates to an eddy current flaw standard rod and replacement jig for calibration of the thickness measurement equipment of the fuel cladding oxide layer. By using rod replacement jigs and remote controls, the fuel cladding with the end-of-life standard film can be replaced and reused, thus reducing the use of expensive fuel cladding and reducing the amount of non-combustible radioactive waste. Eddy current flaw standard rod for calibration of the thickness measurement equipment of the oxide coating layer, which can accurately and reliably measure the thickness measurement value of the oxide layer formed on the spent fuel coating tube by more precisely calibrating the thickness measurement equipment of the oxide coating layer of the fuel coating tube. About the replacement jig .

In general, non-destructive methods using eddy current inspection can measure the oxide layer thickness over the entire length of spent fuel cladding by measuring the thickness of the oxide layer continuously and precisely. In addition to being used as data for soundness assessment and destructive testing, it is also used for the design and investigation of fuel cladding.

The standard rod is used to precisely calibrate the measuring equipment for measuring the oxide layer thickness of the spent fuel cladding by using the eddy current flaw detection. The process of calibrating the measuring equipment with the standard rod is performed on the spent fuel cladding. One of the most important to obtain accurate and reliable measurement of oxide layer thickness.

Here, as a method of fabricating a standard rod for calibrating the oxide layer thickness measuring equipment of spent fuel cladding using eddy current flaw detection, a method of using an artificial oxide cladding tube artificially oxidized into a nuclear fuel cladding tube and an oxide layer on a long fuel cladding tube It is divided into the method of bonding the standard film for measurement for measuring the thickness of the.

The fabrication of artificial oxidized cladding tube artificially oxidized in order to be coupled to a standard rod for calibrating the measuring equipment of the above-described methods is characterized by the uniformity of the oxide layer due to the homogeneity of the material of the fuel cladding tube, the surface condition and the heterogeneous temperature distribution in the furnace. There was a problem that it is difficult to form.

In other words, when measuring the thickness of the oxide layer using eddy current flaw, the measurement probe makes point contact with the specimen, so that each time the calibration probe is calibrated due to the non-uniform thickness of the artificial oxide layer, it is difficult to obtain a constant and reliable measurement value. There was a problem.

On the other hand, when the standard film for measuring the oxide layer thickness is attached to a long nuclear fuel cladding tube, when the standard film is damaged and damaged by radiation, the standard film cannot be replaced remotely using a remote controller, and due to radioactive contamination Disposing of the entire standard rod, making the standard rod again, and bringing it into a hot cell causes a problem of wasting expensive fuel cladding and increasing the amount of non-flammable radioactive waste.

The present invention has been made in order to solve the above problems, the standard of the end of the life using a standard rod replacement jig and a remote controller after only the fuel coating tube with a standard film attached to the fuel cell tube oxide layer thickness eddy current test standard rod in the hot cell By reusing the fuel cladding with the film attached, it is possible to reduce the use of expensive fuel cladding, as well as to reduce the amount of non-combustible radioactive waste, and to more precisely calibrate the thickness measuring equipment of the cladding oxide layer. It is possible to measure the thickness measurement value of oxide layer formed on spent fuel cladding pipe accurately and reliably, and to measure the thickness of oxide layer of spent fuel rod by non-destructive method, and to use it as a material for evaluating the integrity of spent fuel rod and breaking test data. In addition, the theory of nuclear fuel rods And the irradiation behavior for its object to provide a substantial contribution thickness measurement of the fuel cladding oxidation equipment to the eddy current flaw detection for the calibration standard rods and replacing fixture for the study.

In order to achieve the object as described above, the present invention, the nuclear fuel cladding tube is attached to the standard film, the core rod is installed through the inside of the nuclear fuel cladding tube, the male thread is formed at both ends and coupled to both ends of the mandrel, Standard rod consisting of upper and lower guide rods are formed with female threads at one end thereof; And a stop plate provided at one side end portion, a fixing plate fixed at one side of the upper surface, and a guide plate installed at the other side thereof, wherein the replacement jig is formed at the longitudinal position thereof; Characterized in that comprises a.

Preferably, a conical upper groove is formed at one end of the upper end of the upper guide rod of the standard rod.

Alternatively, a driver groove is formed at the end of the lower guide rod.

Here, it is coupled to a driver groove formed at the end of the lower guide rod of the standard rod to separate the core rod and the lower guide rod, the separation tool further comprises a remote control.

On the other hand, in place of the lower guide rod is provided with a cylindrical plate-shaped ring plate formed in the center of the through-hole in close contact with the lower guide of the spent fuel rod non-destructive testing equipment, the movement of the standard rod in the outer peripheral position of the ring plate And grooves that can be grasped by the remote control's tongs when the spent fuel rods are installed on NDEs.

Preferably, one end portion of the ring plate is bolted to form a groove for fixing the ring plate to the lower guide rod, the nut is provided on both sides thereof.

In addition, the mandrel is made of a non-conductor.

On the other hand, while a predetermined length of the end of the male screw portion formed on both ends of the mandrel is formed parallel to the diameter of the bone diameter of the male screw portion, it is made to be easily coupled to the female screw portion of the upper, lower guide rod.

Here, the stop plate is a plate-shaped body, the fastening holes are formed in each of both sides of the through-holes are fastened by bolts to one end portion in the longitudinal direction of the replacement jig.

In addition, the fixing plate and each guide plate is a plate-shaped body, the fixing holes having fixing bolts on both sides of the place is respectively formed through, the fixing bolt for passing through a predetermined portion of any one of the fixing holes. An open groove of the cut shape is formed.

Preferably, the fixing plate coupled to the fixing bolt for fixing the guide plate and each guide plate is separated from the fixed plate fastening to the replacement jig and each guide plate, the disassembly tool further comprises a remote operation is further included. .

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view schematically showing the eddy current flaw detection standard rod for calibration of the thickness measuring equipment of the nuclear fuel cladding tube oxide layer according to the present invention, Figure 2 is a schematic of the eddy current flaw detection standard rod for calibration of the thickness measurement equipment of the oxide fuel coating tube oxide layer according to the present invention 3 is a plan view schematically showing a replacement jig for replacing the fuel cladding of the eddy current flaw standard rod for calibration of the thickness measuring equipment of the nuclear fuel cladding oxide layer according to the present invention, and FIG. 4 is a view of the fuel cladding oxide layer according to the present invention. 5 is a front view schematically illustrating a replacement jig for replacing a fuel cladding tube of a thickness measuring device calibration eddy current flaw standard rod, and FIG. 5 is a view for replacing a fuel cladding tube of a thickness measuring device calibration eddy current flaw standard rod of a fuel cladding tube oxide layer according to the present invention. Schematically show replacement jig It is a side view.

As shown in the drawings, the eddy current flaw standard rod for calibration of the thickness measuring equipment of the nuclear fuel cladding tube oxide layer according to the present invention includes a fuel cladding tube 11 and a fuel cladding tube 11 having a standard film 11a attached thereto. 11) penetrated in the interior of the end, and is coupled to both ends of the mandrel 13 and the mandrel 13, the male threaded portion (13a, 13b) having a thread on the outer periphery of both ends are formed, each end is a mandrel The upper and lower guide rods 15 and 17 are formed to have female threaded portions 15b and 17b for screwing into male threaded portions 13a and 13b formed at both ends of (13).

Here, the upper one end of the upper guide rod 15 is formed with a conical upper groove (15a) to be coupled to the lower end of the spent fuel rod, the end of the lower guide rod 17 is made remotely operable Driver grooves 17a are formed to be coupled to a driver and the like to be separated and combined.

On the other hand, in place of the lower guide rod 17 is provided with a ring plate 18 in close contact with the lower guide of the spent fuel rod non-destructive testing equipment, the ring plate 18 has a through hole (18d) in the center thereof It is formed of a cylindrical body having, the through hole (18d) is made to correspond to the lower diameter of the lower guide bar (17).

Here, a groove 18a is formed in one end portion of the ring plate 18 to be fixed to the lower guide rod 17, and the bolt 18b is fastened to the groove 18a to lower the guide rod 17. The ring plate 18 fastened to is fixed. That is, the groove 18a is penetrated at one end portion of the ring plate 18, and the bolt 18b is fastened by a driver that is remotely operable to the groove 18a, and the groove 18a is provided. The end of the bolt (18b) fastened to the outer peripheral edge of the lower guide rod 17 is fixed to the ring plate 18 fastened to the lower guide rod 17.

Meanwhile, nuts 18c are provided at both sides of the ring plate 18, and the ring plate 18 is more firmly coupled to the lower guide rod 17 by the nuts 18c, respectively. The ring plate 18 is prevented from coming off and moving.

Here, the mandrel 13 is made of a non-conductor, the predetermined length of the end of the male screw portion (13a, 13b) formed at both ends of the mandrel 13 is the diameter of the bone diameter of the male screw portion (13a, 13b) The parallel parts are arranged to be equal to the female threads 15b and 17b of the upper and lower guide rods 15 and 17 in the hot cell.

Meanwhile, the replacement jig 30 for replacing the fuel cladding tube 11 attached to the eddy current flaw detection standard rod 10 for calibrating the thickness measuring equipment of the fuel cladding tube oxide layer according to the present invention has a standard rod 10 at one side end thereof. It is in close contact with the top of the upper guide rod 15 of the stop plate 31 for positioning the upper guide rod 15 uniformly and the fixing plate for fixing the upper guide rod 15 in one end portion of the upper surface 33 ) And the V block 37 for supporting the standard rod 10 and the lower guide rod 17 of the standard rod 10, and the position thereof is fixed when the lower guide rod 17 is rotated. It is configured to include a plurality of guide plates (35, 35 ') provided at the other end portion of the upper surface in order to maintain.

Here, the stop plate 31 is a plate-shaped body, is fastened with a bolt 31a at one end of the longitudinal side of the replacement jig 30, for this purpose, the stop plate 31 is bolted in place on both sides thereof. Fastening holes 31b for fastening the 31a are respectively formed through.

On the other hand, the fixing plate 33 and the guide plate (35, 35 ') is a plate-shaped body, is fastened with fixing bolts (33a, 33a', 35a, 35a ') in place of the replacement jig 30, In order to fasten the fixing bolts 33a and 35a for fastening the fixing bolts 33a and 35a to one side of the fixing plate 33 and the guide plates 35 and 35 ', the fixing bolts are formed at the other side of the fixing plate 33 and the guide plates 35 and 35'. Fixing holes 33b 'and 35b' through which fixing holes 33a 'and 35a' are fastened, and opening grooves 33c and 35c formed to be opened in a predetermined portion to pass through the threaded portions of the fixing bolts 33a and 35a. ) Are formed respectively.

That is, the fixing bolts 33a, 33a ', 35a, and 35a' are fastened to both sides of the fixing plate 33 and the guide plates 35 and 35 'to be coupled to the upper surface of the replacement jig 30. Fixing holes 33b, 33b ', 35b, and 35b' are respectively formed through the fixing holes 33b, 33b ', 35b, and 35b'. The opening grooves 33c and 35c which are opened in predetermined portions so that the plates 33 and 35 are rotated about the other fixing holes 33b 'and 35b' by the loosening of the 33a and 35a are provided.

The fixing plate 33 and the guide plates 35 and 35 'are fixed to the replacement jig 30 with fixing bolts 33a, 33a', 35a, and 35a 'by the shape and structure as described above. (33) and fixing holes 33b having open grooves 33c and 35c without releasing all of the fixing bolts 33a, 33a ', 35a, and 35a' respectively fastened to the guide plates 35 and 35 '. After releasing a predetermined portion of the fixing bolts 33a and 35a fastened to 35b) and rotating in a predetermined direction, the standard rod 10 installed on the replacement jig 30 may be removed and replaced, as well. After releasing a predetermined portion of the fixing bolts 33a and 35a fastened to the fixing holes 33b and 35b having the opening grooves 33c and 35c, they are rotated in a predetermined direction, and then the standard rod 10 is attached to the replacement jig 30. ) Can be installed.

This facilitates the installation and release of the standard rod 10 to the replacement jig 30, as well as the replacement of another standard rod for replacing the fuel cladding tube 11.

On the other hand, in order to secure the lower guide bar 17 of the standard rod 10, the guide plates (35, 35 ') installed in one place on the replacement jig 30 is the replacement of the jig 30 It is preferable that the upper surface is provided in two places, but if it is easy to fix the lower guide rod 17 of the standard rod 10, the guide plates 35 and 35 'may be made of more or less number. In addition, the number of the fixing plate 33 may also be provided with one or more.

Here, as shown in Figure 6, the separation tool made remotely operable to replace the nuclear fuel cladding 11 of the eddy current flaw detection standard rod 10 for calibration of the thickness measuring equipment of the nuclear fuel cladding tube oxide layer according to the present invention ( 19 is further included, the separation tool 19 is coupled to the driver groove (17a) formed in the lower guide rod 17 of the standard rod 10 is made to rotate by replacing the lower guide rod (17) .

The separation tool 19 is preferably made of a screwdriver having a straight shape in order to be coupled to the driver groove 17a of the lower guide rod 17, it is made of a structure that is easy to handle using a remote controller or the like. desirable.

On the other hand, as shown in Figure 7, assembling and disassembling the replacement jig 30 for replacing the nuclear fuel cladding tube 11 of the eddy current flaw detection standard rod 10 for calibration of the thickness measuring equipment of the nuclear fuel cladding tube oxide layer according to the present invention The disassembly tool 39 is further included, and the disassembling tool 39 rotates fixing bolts 33a, 33a ', 35a, and 35a' which are fastened to fix each plate of the replacement jig 30. To be assembled and disassembled.

The disassembly tool 39 is a bolt having a hexagonal groove for engaging the fixing bolts 33a, 33a ', 35a, 35a' which are fastened to fix the plates 33, 35 of the replacement jig 30. It is preferably made of a wrench, preferably made of a structure that is easy to handle using a remote controller or the like.

Hereinafter, a process of installing a standard rod for calibrating an oxide layer thickness measuring equipment of a spent fuel cladding tube using eddy current flaw detection in a replacement jig will be described with reference to FIGS. 9 and 10.

First, fixing bolts 33a and 33a installed in the fixing plate 33 installed on the upper surface of the replacement jig 30 and the fixing holes 33b, 33b ', 35b and 35b' of the guide plates 35 and 35 '. ', 35a and 35a' are rotated to release the fixed portions 33 and the guide plates 35 and 35 'fixed to the replacement jig 30.

At this time, each of the fixing bolts that are fastened to the fixing plate 33 and the fixing holes 33b, 33b ', 35b, 35b' of the guide plate 35 and 35 'installed on the upper surface of the replacement jig 30. Each plate fixed by the fixing bolts 33a and 35a to any one of the fixing holes 33b and 35b having the open grooves 33c and 35c after releasing a predetermined portion of the fastening of the portions 33a, 33a ', 35a and 35a'. The ends of (33, 35, 35 ') are rotated in a predetermined direction.

Meanwhile, fixing bolts 33a, 33a ', and 35a fastened to fixing holes 33b, 33b', 35b, and 35b 'of the plates 33, 35, and 35' installed on the upper surface of the replacement jig 30. , 35a ') disengages a predetermined portion from the replacement jig 30 by using a disassembly tool 39 in the form of a hexagonal groove bolt wrench that is remotely operable.

As described above, one side of the fixing plate 33 and each guide plate 35, 35 ′ installed on the upper surface of the replacement jig 30 is rotated 90 ° in a counterclockwise direction, and then the replacement of the replacement jig 30 is removed. The standard rod 10 is installed in the V block 37.

At this time, the end of the upper guide rod 15 of the standard rod 10 is brought into close contact with the stop plate 31 installed on one side of the replacement jig 30 and then to the upper surface of the replacement jig 30. Fixing bolts 33a, 33a ', 35a, which are fastened to the plates 33, 35, and 35' by rotating one end of the fixing plate 33 and each guide plate 35, 35 'to be installed in a predetermined direction, Tighten 35a ') to fix the standard rod 10 installed in the replacement jig 30.

That is, the standard rod 10 is installed on the V block 37 of the replacement jig 30, and then installed on the upper surface of the replacement jig 30, and the fixing plate 33 and each rotated in a predetermined direction. One end of the guide plates 35 and 35 'is rotated again in a predetermined direction so that the opening grooves 33c and 35c of the fixing holes 33b and 35b formed in the plates 33, 35 and 35' are respectively fixed bolts. After positioning it so as to abut on the threaded portion of the 33a, 35a, tighten the fixing bolts 33a, 35a fastened to the fixing holes 33b, 35b of each plate 33, 35, 35 'to the replacement jig 30. Fix the installed standard rod (10).

As described above, when the standard rod 10 is installed on the replacement jig 30, the upper guide rod 15 of the standard rod 10 is fixed to the replacement jig 30 by the fixing plate 33.

On the other hand, the lower guide rod 17 is installed while maintaining a constant gap between each guide plate (35, 35 ') and the V block 37, the separation tool (a) in the driver groove (17a) of the lower guide rod (17) 19) When the coupling of the lower guide rod 17 in the core rod 13 to release the coupling, the lower guide rod 17 is easy to rotate the screw coupling of the core rod 13 and the lower guide rod 17 Can be released more easily.

In this way, the lower guide rod 17 is released from the mandrel 13, and the fuel cladding tube 11 installed on the outer circumference of the mandrel 13 can be separated and replaced with a new fuel cladding tube.

While the exemplary embodiments of the present invention have been described above by way of example, the scope of the present invention is not limited to the specific embodiments, and those skilled in the art are appropriate within the scope described in the claims of the present invention. It will be possible to change.

As described above, the present invention having the configuration as described above is a standard of which the life span using the standard rod replacement jig and the remote controller after only the fuel cladding tube with the standard film is inserted into the hot cell among the fuel cladding tube oxide layer thickness eddy current test standard rods. By reusing the film-covered fuel cladding to make it reusable, it not only reduces the use of expensive fuel cladding, but also reduces the amount of non-combustible radioactive waste, and more precisely calibrates the thickness measurement equipment of the cladding oxide layer. The thickness measurement value of the oxide layer formed on the spent fuel cladding can be measured accurately and reliably, and the thickness of the oxide layer of the spent fuel rod can be measured in a non-destructive way, and can be used as a test for the integrity and destruction test of the spent fuel rod. No fuel rods This can be a significant contribution to the design and investigation behavior research.

Claims (11)

A nuclear fuel cladding tube 11 to which a standard film 11a is attached, a core rod 13 penetrating inside the nuclear fuel cladding tube 11, and having male threads 13a and 13b formed at both ends thereof, and the core rod ( 13) is coupled to both ends of the standard rod (10) consisting of upper and lower guide rods (15, 17) formed with female threaded portions (15b, 17b) at one end thereof; And It consists of a stop plate 31 provided at one side end portion, a fixed plate 33 fixed to one side of the upper surface, and each guide plate 35, 35 'installed at the other side thereof, A replacement jig 30 in which a V block 37 is formed; Eddy current inspection standard rod and replacement jig for calibration of the thickness measurement equipment of the oxide layer of the nuclear fuel cladding tube, characterized in that comprises a. The method of claim 1, Conical eddy current test standard rod and replacement jig for measuring the thickness of the fuel cladding tube oxide layer characterized in that the upper groove (15a) of the conical shape is formed at one end of the upper guide rod (15) of the standard rod (10). The method of claim 1, Driver groove (17a) is formed at the end of the lower guide rod (17), eddy current flaw detection standard rod and replacement jig for measuring the thickness of the oxide coating layer of the nuclear fuel cladding. The method of claim 3, The separation tool 19 coupled to the driver groove 17a formed at the end of the lower guide rod 17 of the standard rod 10 to separate the core rod 13 and the lower guide rod 17, and remotely operable. Eddy current inspection standard rod and replacement jig for calibration of thickness measurement equipment of the oxide layer of the nuclear fuel cladding tube, characterized in that it further comprises). The method of claim 1, In place of the lower guide rod 17 is provided with a ring-shaped plate 18 having a cylindrical shape in which a through hole 18d is formed at the center thereof to be in close contact with the lower guide of the spent fuel rod NDE. A nuclear fuel cladding tube is formed in the outer circumferential position of the plate 18 so that a groove 18a is formed to be grasped by a tong of a remote controller when the standard rod 10 is moved and installed on a spent fuel rod non-destructive test equipment. Eddy current inspection standard rod and replacement jig for calibration of thickness measuring equipment of oxide layer. The method of claim 5, At one end of the ring plate 18, a bolt 18b is fastened to form a groove 18a for fixing the ring plate 18 to the lower guide rod 17, and nuts 18c on both sides thereof. Eddy current inspection standard rod and replacement jig for calibration of thickness measurement equipment of the oxide layer of the nuclear fuel cladding, characterized in that each provided. The method of claim 1, Eddy current flaw detection standard rod and replacement jig for the thickness measurement equipment of the oxide coating layer of the nuclear fuel cladding, characterized in that the mandrel (13) is made of a non-conductor. The method of claim 1, The parallel portion is formed such that a predetermined length of the ends of the male screw portions 13a and 13b formed at both ends of the mandrel 13 is the same as the diameter of the bone diameter of the male screw portions 13a and 13b, and the upper and lower guide rods 15, 17. An eddy current flaw standard rod and replacement jig for calibration of thickness measurement equipment of a fuel cladding tube oxide layer, characterized in that it is easily coupled to the female screw portions 15b and 17b of 17). The method of claim 1, The stop plate 31 of the replacement jig 30 is a plate-shaped body, the fastening hole 31b is formed through the respective places in both sides of the replacement jig 30 with a bolt 31a at one end in the longitudinal direction of the replacement jig 30. Eddy current inspection standard rod and replacement jig for calibration of thickness measuring equipment of the oxide layer of the nuclear fuel cladding, characterized in that the fastening. The method of claim 1, The fixing plate 33 and the guide plates 35 and 35 'of the replacement jig 30 are plate-shaped bodies, and fixing holes having fixing bolts 33a, 33a', 35a, and 35a 'on both sides thereof. (33b, 33b ', 35b, 35b') are respectively penetrated, and fixing bolts 33a are formed at predetermined portions of the fixing holes 33b, 35b of each of the fixing holes 33b, 33b ', 35b, and 35b'. , 35a) eddy current flaw detection standard rod and replacement jig for measuring the thickness of the fuel cladding oxide layer is formed, characterized in that the opening groove (33c, 35c) of the cut shape for passing through. The method of claim 10, Fixing plate 33 coupled to fixing bolts 33a, 33a ', 35a, 35a' for fixing the fixing plate 33 and each guide plate 35, 35 'and fastened to the replacement jig 30. And a disassembly tool 39 which separates the fastening of each guide plate 35 and 35 ', but which is remotely operable. .

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