Bobbin Type Eddy Current Probe

Abstract

The present invention relates to a bobbin-type eddy current probe for inspecting a heat transfer tube, comprising: a head portion inserted into the interior of the heat transfer tube; a cable portion including a cable that supplies current to the head portion; an elastic deformation portion having one end connected to the head portion and accommodating a part of the cable portion; a shaft portion accommodating another part of the cable portion, connected to the other end of the elastic deformation portion, and capable of deforming in correspondence with the curved shape of the heat transfer tube; and a fluid supply portion that supplies fluid into the interior of the shaft portion.

Description

Technology Field

[0001] The present invention relates to a bobbin-type eddy current probe for inspecting a heat transfer tube. Background Technology

[0002] In the past, to evaluate the integrity of heat transfer tubes in steam generators within nuclear power plants, eddy current inspection probes were used to identify defects such as wear and pitting.

[0003] Conventional steam generator heat transfer tubes consist of straight tubes or U-shaped curved tubes, and in the case of recently constructed nuclear power plants, the maximum length of the heat transfer tubes is about 27m.

[0004] Conventional probes have a straight nylon shaft connected to a probe head equipped with a coil, and this shaft transmits the driving force to insert and withdraw the probe along the length of the heat transfer tube and is used as a connection passage for signal cables.

[0005] However, in recently developed Small Modular Reactors (SMRs), the heat transfer tubes are shaped into spiral or complex forms to increase steam generator efficiency.

[0006] Therefore, as the length of the probe inserted into the inner surface of the heat transfer tube increases, it becomes difficult to insert and withdraw the probe due to continuous friction with the inner surface of the heat transfer tube. Consequently, a problem arises in which it becomes impossible to inspect the entire length of the heat transfer tube and thus cannot perform an evaluation of the integrity of the heat transfer tube. Prior art literature

[0007] Korean Registered Patent No. 10-0881265 (Registered January 22, 2009) The problem to be solved

[0008] The object of the present invention is to provide a bobbin-type eddy current probe for inspecting a heat transfer tube. means of solving the problem

[0009] The present invention relates to a bobbin-type eddy current probe for inspecting a heat transfer tube, comprising: a head portion inserted into the interior of the heat transfer tube; a cable portion including a cable that supplies current to the head portion; an elastic deformation portion having one end connected to the head portion and accommodating a part of the cable portion; a shaft portion accommodating another part of the cable portion, connected to the other end of the elastic deformation portion, and capable of deforming in correspondence with the curved shape of the heat transfer tube; and a fluid supply portion that supplies fluid into the interior of the shaft portion.

[0010] The shaft portion is composed of a plurality of shaft units that are connected in a row and extend long in the direction of connection, and the cross-section of the shaft unit in the direction perpendicular to the direction of connection may be circular.

[0011] The shaft unit comprises: a central part including a central portion and a peripheral portion whose diameter decreases as it moves away from the central portion along the coupling direction; a receiving portion extending from one end of the central part; a coupling portion extending from the other end of the central part; and a fluid passage hole formed in the central part and which discharges fluid supplied from the fluid supply portion to the inner surface of the heat transfer tube; wherein the coupling portion of the shaft unit located at the front end adjacent to the head portion may be received in the receiving portion of the shaft unit located at the rear end spaced apart from the head portion.

[0012] The above fluid supply unit supplies fluid from the rear end of the shaft unit toward the front end, and the passage area of ​​the fluid passage hole formed at the front end of the shaft unit may be larger than the passage area of ​​the fluid passage hole formed at the rear end of the shaft unit.

[0013] The diameter of the above-mentioned joint may increase as it moves away from the other end of the above-mentioned central part.

[0014] The diameter of the above receiving portion decreases as it moves away from one end of the above central part, and the diameter of the end of the connecting portion may be larger than the diameter of the end of the receiving portion.

[0015] The above shaft unit may be made of engineering plastic material.

[0016] The engineering plastic may include at least one of polytetrafluoroethylene, perfluoroalkoxy, and fluorinated ethylene propylene.

[0017] It further includes a tension wire connected from the head portion to the shaft portion, wherein at least a portion of the tension wire may be disposed inside the cable.

[0018] It may further include a connecting support member that connects the elastic deformation part and the shaft part and has a guide wing formed thereon to guide movement within the heat transfer tube. Effects of the invention

[0019] According to the present invention, a bobbin-type eddy current probe for inspecting a heat transfer tube is provided. Brief explanation of the drawing

[0020] FIG. 1 shows a bobbin-type eddy current probe according to an embodiment of the present invention, and Figure 2 is an enlarged view of A in Figure 1, and FIG. 3 shows a cross-sectional view of the shaft portion of a bobbin-type eddy current probe according to an embodiment of the present invention, and FIG. 4 is a perspective view of the shaft portion of a bobbin-type eddy current probe according to an embodiment of the present invention, and FIG. 5 shows the operation of the shaft portion of a bobbin-type eddy current probe according to an embodiment of the present invention. Specific details for implementing the invention

[0021] The present invention will be described in more detail below with reference to the drawings.

[0022] The attached drawings are merely examples illustrated to further explain the technical concept of the present invention, and therefore the concept of the present invention is not limited to the attached drawings. Additionally, the sizes and spacing, etc., in the attached drawings may be exaggerated from reality to explain the relationships between the components.

[0023] FIG. 1 shows a bobbin-type eddy current probe according to an embodiment of the present invention.

[0024] Referring to FIG. 1, the bobbin-type eddy current probe (10) includes a head part (100), a cable part (200), an elastic deformation part (300), a connecting support part (400), a shaft part (500), and a fluid supply part (600).

[0025] The head unit (100) is inserted into the interior of a heat transfer tube (not shown) and includes a body unit (110) and a head unit (120).

[0026] The body unit (110) is composed of a body (111) having a through hole formed inside so that a cable is inserted in a horizontal direction, and may have a protrusion with the through hole extended in both directions for inserting and withdrawing the cable, and may have a separate ridge formed on the outer surface of the protrusion, but is not limited thereto.

[0027] A coil (112) may be attached to the outer surface in a direction perpendicular to the direction in which the through hole of the body (111) is formed, and the coil (112) may be attached to the body (111) in a direction perpendicular to the direction in which the bobbin-type eddy current probe is inserted into the heating tube (not shown).

[0028] The coil (112) is coated with a paint such as polyurethane that reacts with alcohol to bond the coils together, and before joining to the body (111), the paint can be melted with alcohol in a separate external mold to wind the coil, thereby controlling the desired shape, thickness, number of turns, etc.

[0029] The head unit (120) can guide smooth insertion when the bobbin-type eddy current probe (10) is inserted into the heat transfer tube, and can provide flexibility in response to bends inside the heat transfer tube.

[0030] The cable section (200) is connected to the head section (100) and includes a cable (210) and a tension wire (220).

[0031] The cable (210) supplies current to the head unit (100) and transmits a signal transmitted from the head unit (100) to the outside. In this embodiment, the cable (210) simultaneously performs the role of transmitting current to the head unit (100) and transmitting a signal transmitted from the head unit (100) to the outside, but is not limited thereto. In other embodiments, a separate current cable and a signal cable for transmitting a signal may be separated within the cable (210).

[0032] At least a portion of the tension wire (220) is disposed inside the cable (210) and is connected from the head portion (100) to the shaft portion (500) described later. In this embodiment, the tension wire (220) is shown disposed inside the cable (210), but it is not limited thereto, and in other embodiments, the tension wire (220) may be provided separately from the cable (210).

[0033] The tension wire (220) provides a tension force that can restrain the shaft portion (500) and may be made of a metal material to provide the tension force. In particular, the wire may be in the form of thin metals made of spring steel that are twisted (stranded) or braided, but is not limited thereto, and any material may be used as long as it can transmit high pressure and tension force.

[0034] The elastic deformation part (300) is connected to the head part (100) at one end and accommodates a part of the cable part (200).

[0035] Referring to FIG. 1, the elastic deformation part (300) is shown as having a plurality of springs (310) having elastic force surrounding a part of the cable part (200), but is not limited thereto. The external shape of the elastic deformation part (300) can be freely deformed in correspondence with a curved heating tube (not shown) while protecting a part of the cable part (200), and it does not matter what material is used or what shape it is manufactured in.

[0037] The connecting support member (400) connects the elastic deformation member (300) and the shaft member (500), and has a guide wing (410) formed therein to guide movement within the heat transfer tube (not shown).

[0038] The guide wing (410) guides the probe so that it can be easily inserted or discharged by contacting the inner surface of the heat transfer tube when the probe moves inside the curved heat transfer tube.

[0039] The shaft portion (500) is composed of a plurality of shaft units (510a, 510b, ...) that are connected in a row and extend long in the direction of connection, and the cross-section of the shaft units (510a, 510b, ...) in the direction perpendicular to the direction of connection may be circular, but is not limited thereto.

[0040] The shaft units (510a, 510b, ...) all have the same structure, and a specific shaft unit (510a) is described below as an example. However, in other embodiments, the structure and size of the shaft units (510a, 510b, ...) may differ in some respects, and in particular, the number and size of the fluid passage holes (514) may differ.

[0041] The shaft unit (510a) includes a central part (511), a receiving part (512), a connecting part (513), and a fluid passage hole (514).

[0042] The shaft unit (510a) is made of an engineering plastic material, and the engineering plastic may include at least one of polytetrafluoroethylene, perfluoroalkoxy, and fluorinated ethylene propylene.

[0043] The central part (511) includes a center and a peripheral part whose diameter decreases as it moves away from the center along the direction of connection.

[0044] Referring to FIGS. 2 to 4, the central part (511) is shown with a convex outer surface, but is not limited thereto. The shape of the outer surface can be configured to minimize the contact area with the inner surface of the heat transfer tube (not shown).

[0045] The receiving portion (512) extends from one end of the central part (511), and its diameter decreases as it moves away from the one end of the central part (511).

[0046] The connecting part (513) extends from the other end of the central part (511), and as it moves away from the other end of the central part (511), its diameter increases, and the diameter of the end is formed to be larger than the diameter of the end of the receiving part (512).

[0047] The fluid passage hole (514) is formed in the central part (511) and allows the fluid supplied from the fluid supply part (600) to be discharged into the inner surface of the heat transfer tube (not shown).

[0048] Here, the passage area of ​​the fluid passage hole (514) formed in the shaft unit (510a) located at the front end adjacent to the head part (100) is formed to be larger than the passage area of ​​the fluid passage hole (514) formed in the shaft unit (510b) at the rear end spaced apart from the head part (100).

[0049] In order to vary the passage area, the number of fluid passage holes (514) of the same size can be varied, or even if the same number is used, the size of the fluid passage holes (514) can be varied.

[0050] Due to the difference in the passage area of ​​the fluid passage hole (514) formed in the front shaft unit (510a) and the rear shaft unit (510b), the reduction in fluid pressure for the supplied fluid can be compensated for as the distance from the fluid supply unit (600) increases.

[0051] The fluid supply unit (600) supplies fluid to the shaft unit (500), and in FIG. 1, it is shown as being located at the rear end of the shaft unit (500), but is not limited thereto. Although not shown, the fluid supply unit (600) may further include a separate supply valve for controlling the amount of fluid supplied.

[0052] Although not shown, a signal processing unit that converts the signal transmitted from the head unit (100) into a digital signal may be further included.

[0053] Next, with reference to FIG. 5, an inspection of a heat transfer tube using a bobbin-type eddy current probe according to the present embodiment will be described.

[0054] FIG. 5 shows the operation of the shaft portion of a bobbin-type eddy current probe according to an embodiment of the present invention.

[0055] In the exploration of a heat transfer tube using a probe (10), while inserting the probe (10) into a heat transfer tube (not shown), fluid is supplied to the inner surface of the heat transfer tube (not shown) through a fluid supply unit (600). The fluid is supplied to the shaft unit (500) and supplied to the inner surface of the heat transfer tube (not shown) through a fluid passage hole (514). Here, a thin fluid layer is formed on the inner surface of the heat transfer tube (not shown) by the supplied fluid, and due to the formed fluid layer, the driving friction of the probe (10) inserted into the heat transfer tube (not shown) is reduced.

[0056] Since the passage area of ​​the fluid passage hole (514) formed in the shaft unit (510a) located at the front end adjacent to the head part (100) is formed to be larger than the passage area of ​​the fluid passage hole (514) formed in the shaft unit (510b) at the rear end spaced apart from the head part (100), the reduction in fluid pressure for the supplied fluid can be compensated for as the distance from the fluid supply part (600) increases.

[0057] Referring to FIG. 5, when the probe (10) passes through a curved section of a heat transfer tube (not shown), the arrangement relationship between individual shaft units (510a, 510b) is deformed, and the shaft section (500) is deformed in correspondence with the shape of the heat transfer tube, and the connection relationship between the front shaft unit (510a) and the rear shaft unit (510b) is stably maintained. During this process, fluid is present through the fluid supply section (600) between the shaft section (500) and the inner surface of the heat transfer tube (not shown), and at this time, the contact area between the convex shaft section (500) and the heat transfer tube (not shown) is minimized by point contact or line contact.

[0058] A tensile force is provided through the tension wire (220) so that the shaft portion (400) can be restrained even if the arrangement relationship between the individual shaft units (410a, 410b) is deformed.

[0059] The embodiments of the present invention described above and illustrated in the drawings should not be interpreted as limiting the technical scope of the present invention. The scope of protection of the present invention is limited only by the matters described in the claims, and a person skilled in the art may modify or change the technical scope of the present invention in various forms. Accordingly, such modifications and changes will fall within the scope of protection of the present invention insofar as they are obvious to a person skilled in the art.

Claims

Claim 1 The present invention relates to a bobbin-type eddy current probe for inspecting a heat transfer tube, comprising: a head portion inserted into the interior of the heat transfer tube; a cable portion including a cable that supplies current to the head portion; an elastic deformation portion having one end connected to the head portion and accommodating a part of the cable portion; a shaft portion accommodating another part of the cable portion, connected to the other end of the elastic deformation portion, and capable of deforming in correspondence with the curved shape of the heat transfer tube; and a fluid supply portion that supplies fluid into the interior of the shaft portion; wherein the shaft portion is composed of a plurality of shaft units that are connected in a row and extend long in the direction of connection, and the cross-section of the shaft unit in the direction perpendicular to the direction of connection is circular, and the shaft unit comprises: a central part including a center portion and a peripheral part whose diameter decreases as it moves away from the center portion along the direction of connection; a receiving portion extending from one end of the central part; and a connecting portion extending from the other end of the central part. A bobbin-type eddy current probe comprising: a fluid passage hole formed in the central part and discharging fluid supplied from the fluid supply part to the inner surface of the heat transfer tube; wherein the coupling part of the shaft unit located at the front end adjacent to the head part is received in the receiving part of the shaft unit located at the rear end spaced apart from the head part. Claim 2 delete Claim 3 delete Claim 4 In claim 1, the fluid supply unit supplies fluid from the rear end of the shaft unit toward the front end, and the bobbin-type eddy current probe has a passage area of ​​the fluid passage hole formed at the front end of the shaft unit that is larger than the passage area of ​​the fluid passage hole formed at the rear end of the shaft unit. Claim 5 In claim 1, the coupling part is a bobbin-type eddy current probe whose diameter increases as it moves away from the other end of the central part. Claim 6 A bobbin-type eddy current probe according to claim 1, wherein the diameter of the receiving portion decreases as it moves away from one end of the central part, and the diameter of the end of the connecting portion is larger than the diameter of the end of the receiving portion. Claim 7 In claim 1, the shaft unit is a bobbin-type eddy current probe made of engineering plastic material. Claim 8 In claim 7, the engineering plastic comprises at least one of polytetrafluoroethylene, perfluoroalkoxy, and fluorinated ethylene propylene, forming a bobbin-type eddy current probe. Claim 9 The bobbin-type eddy current probe of claim 1, further comprising a tension wire connected from the head portion to the shaft portion, wherein at least a portion of the tension wire is disposed inside the cable. Claim 10 A bobbin-type eddy current probe according to claim 1, further comprising a connecting support member having a guide wing formed thereon that connects the elastic deformation part and the shaft part and guides movement within the heat transfer tube.

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