JP2004226161A - Squid nondestructive inspection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a SQUID (Superconducting Quantum Interference Device) nondestructive inspection apparatus which is compact, reliable in operation, and has a simple and convenient structure. <P>SOLUTION: The nondestructive inspection apparatus includes a compact refrigerator 1 provided with a cold storage type refrigerator main body 2, a compressor 3, a low- and high-pressure changeover means 6, and a low- and high-pressure difference control means 7 and having an operating fluid piping system 5 for connecting 2 to 3; a vacuum container 8 having a tube body 9 and a lid 10 made of a nonmagnetic material; a SQUID sensor 11 closely opposed to a bottom wall part of the lid 10 at a location at an interval to a cooling stage 4, arranged in the vacuum container 8, and thermally insulated and supported at the container 8; a heat transfer wire 12 made of a nonmagnetic material and interposed between the cooling stage 4 and the SQUID sensor 11 in the vacuum container 8 for thermally coupling 4 and 11; a vacuum maintaining adsorptive sheet 13 made of a nonmagnetic material and wound on the cooling stage 4; and a radiation shield film 14 made of a nonmagnetic material and provided along the inner side of the lid 10 in such a way as to surround the SQUID sensor 11. The refrigerator main body 2 is airtightly inserted in the vacuum container 8, and the inside vacuum of the vacuum container 8 is maintained. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a SQUID non-destructive inspection device, and more particularly, to a SQUID (Superconducting Quantum Interference Device) that is in a superconducting state at a cryogenic level by using a nonmagnetic material from a test object. The present invention relates to a SQUID nondestructive inspection apparatus suitable for nondestructively inspecting a defect such as a flaw or a crack generated inside an object to be inspected by measuring a slight leakage magnetic flux density.
[0002]
[Prior art]
Examples of the nondestructive inspection include an ultrasonic inspection test and a radiation transmission test. Devices using a superconducting SQUID as a sensor have been proposed (for example, “Nondestructive evaluation using SQUID”, Naoko Kasai theory, “ Engineering Vol.31 No.2 (1996) ").
The SQUID as one application of the superconductor in this case can measure a very weak magnetic field. That is, nondestructive inspection is possible by detecting a defect or a crack in a material by measuring a change or change in a weak magnetic field using the SQUID.
[0003]
The conventional SQUID nondestructive inspection apparatus uses a low-temperature refrigerant such as liquid nitrogen (77K) or liquid helium (4.2K) as a cooling means for the SQUID. In this case, since the low-temperature refrigerant evaporates gradually due to heat intrusion from the room temperature part, it is necessary to periodically replenish the low-temperature refrigerant.
[0004]
Conventionally, there are many SQUID nondestructive inspection apparatuses using a small refrigerator as a means for cooling the SQUID (for example, see Patent Document 1).
Further, in order to prevent the vibration of the small refrigerator from entering the SQUID, there has been proposed a method of cooling the small refrigerator with a JT refrigerator having a precooling system (for example, see Patent Document 2).
[0005]
On the other hand, as another example, a low-temperature refrigerant such as liquid nitrogen (77K) or liquid helium (4.2K) is used as a cooling means, but heat intrusion is prevented by a small refrigerator, evaporation of the low-temperature refrigerant is reduced, and the replenishment interval is reduced. Has been invented as an example of lengthening (see, for example, Patent Documents 3 and 4).
Furthermore, there is an invention proposed as an example in which the evaporative gas of a low-temperature refrigerant is reliquefied to eliminate the need for replenishment (for example, see Patent Documents 5 and 6).
[0006]
[Patent Document 1]
JP-A-6-11554 (page 3, paragraph [0011], FIG. 1)
[Patent Document 2]
JP-A-2-302680 (page 4, upper left column, line 5 to upper right column, line 15, FIG. 2)
[Patent Document 3]
JP 2001-66354 A (pages 4 [0021] to [0023], FIG. 1)
[Patent Document 4]
JP-A-2002-2322029 (page 4 [0016] to page 5 [0024], FIG. 1)
[Patent Document 5]
Japanese Patent No. 3084046 (page 3, left column, line 8 to right column, line 26, FIG. 1)
[Patent Document 6]
JP-A-5-297092 (pages [0008] to [0010], FIG. 1)
[0007]
In the prior art of Patent Document 1, there is a problem that large inspection noise is generated because vibration of the small refrigerator is directly transmitted to the SQUID. Further, even in the prior art of Patent Document 2, the influence of vibration transmitted from the small refrigerator cannot be avoided.
On the other hand, in the examples of Patent Literatures 3 and 4, the replenishment interval can be lengthened, but the labor of replenishment cannot be eliminated yet. In the examples of Patent Literatures 5 and 6, the labor of replenishment can be eliminated. However, there is a problem that it cannot be easily used.
[0008]
[Problems to be solved by the invention]
As described above, in the prior art described in each of the conventional patent documents, the present invention has been made in view of the fact that each of them has a problem in practical use. A structure in which a low-temperature refrigerant (cryogenic liquefied gas) is not used as a means for directly cooling, and vibration from a small refrigerator is not transmitted to the SQUID sensor and magnetic noise to the SQUID sensor can be reduced. Accordingly, an object of the present invention is to provide a SQUID non-destructive inspection device having a small size, high operation reliability and a simple structure.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, a SQUID nondestructive inspection apparatus according to the present invention has the following configuration.
That is, the first aspect of the present invention provides a regenerative refrigerator main unit 2 having a cooling stage 4 made of a non-magnetic material at its end, a compressor 3, and a high pressure for switching between a pressurized flow of a compressed working fluid and a reflux of a decompressed working fluid. A small refrigerator comprising a low-pressure pressure switching means 6 and a high-low pressure difference control means 7 for controlling an operating pressure for temperature control, and comprising a working fluid piping system 5 connecting the regenerative refrigerator body 2 and the compressor 3. 1, a cylindrical body 9 and a lid 10 made of a non-magnetic material airtightly connected to the cylindrical body 9, the regenerative refrigerator main body 2 is hermetically inserted into the cylindrical body 9, and the inside is kept at a vacuum. The vacuum vessel 8 is disposed in the vacuum vessel 8 at a position spaced from the cooling stage 4 so as to be close to and opposed to the bottom wall of the lid 10 serving as a detection end. SQUID sensor 11 supported by A heat transfer wire 12 of a non-magnetic material inserted between the cooling stage 4 and the SQUID sensor 11 in the vessel 8 to perform thermal coupling between the two, 4 and 11, and a vacuum vessel 8 surrounding the cooling stage 4. A SQUID, comprising: a non-magnetic material vacuum maintenance suction sheet 13 provided therein; and a non-magnetic material radiation shielding film 14 provided inside the lid 10 so as to surround the SQUID sensor 11. It is a non-destructive inspection device.
[0010]
According to a second aspect of the present invention, there is provided a SQUID non-destructive inspection apparatus according to the first aspect, wherein the regenerative refrigerator main body 2 is a pulse tube refrigerator. I do.
[0011]
According to a third aspect of the present invention, there is provided a SQUID non-destructive inspection apparatus according to the first or second aspect, wherein the high / low pressure differential pressure control means 6 includes a high pressure A pipe 24 connected between the pipe 21 and the low-pressure pipe 22, a pressure difference control valve 25 interposed in the pipe 24, and a temperature difference S detected by the cooling stage 4 or the SQUID sensor 11. It is characterized by including a valve control means 28 for adjusting the temperature of the SQUID sensor 11 by feeding back to the control valve 25 and adjusting the valve opening.
[0012]
According to a fourth aspect of the present invention, there is provided a SQUID non-destructive inspection apparatus according to the first, second, or third aspect, wherein the radiation shield film has a reflection surface on one side. It is characterized in that it is formed in a two-layered film, and is provided inside the lid 10 with the reflection surface facing inward facing the SQUID sensor 11.
[0013]
According to the first aspect of the present invention, the temperature of the SQUID sensor 11 via the cooling stage 4 is adjusted by the high / low pressure difference control means 7 on the working fluid piping system 5 side near the compressor 3. Since the temperature control operation in the vicinity of the SQUID sensor 11 is not performed, measurement noise accompanying the temperature control can be eliminated.
Furthermore, for the cold transfer between the cooling stage 4 and the SQUID sensor 11, the heat transfer wire 12 made of a non-magnetic material having a vibration absorbing ability and a high heat transfer ability is used. Can be prevented from affecting the heat transfer wire 12 and the measurement accuracy of the SQUID sensor 11 can be further improved.
[0014]
Further, according to the first aspect of the present invention, since all the constituent elements between the cooling stage 4 and the SQUID sensor 11 are made of non-magnetic material, magnetic noise to the SQUID sensor 11 can be greatly reduced and measurement can be performed. Accuracy can be further increased. Further, by providing the vacuum maintenance suction sheet 13 around the cooling stage 4, it is possible to reliably and easily maintain the vacuum inside the vacuum vessel 8, and to further surround the SQUID sensor 11 and cover the SQUID sensor 11. Since the radiation shield film 14 is provided inside the SQUID sensor 11, the radiation heat entering the SQUID sensor 11 from the room temperature portion of the vacuum vessel 8 can be reduced, and the SQUID sensor 11 can be stably maintained at a low temperature.
[0015]
On the other hand, according to the second aspect of the present invention, since the regenerative refrigerator main body 2 is a pulse tube refrigerator, the refrigerator main body 2 as a cooling means has a structure with lower vibration. The influence of vibration can be further reduced.
[0016]
Further, according to the third aspect of the present invention, the constant temperature control of the SQUID sensor 11 can be easily and reliably performed by adjusting the valve opening by the feedback of the pressure difference control valve 25.
[0017]
According to the fourth aspect of the present invention, the radiation shield film 14 formed as a two-layer film is provided inside the lid 10 with the reflection surface facing inward facing the SQUID sensor 11. Accordingly, the radiant heat entering the SQUID sensor 11 from the room temperature portion can be more effectively reduced, and the SQUID sensor 11 can be maintained at a lower temperature.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the SQUID nondestructive inspection apparatus according to the present invention will be described with reference to the drawings.
FIG. 1 is an overall system diagram of a SQUID non-destructive inspection device according to an embodiment of the present invention, and FIG. 2 is a front view showing a main part structure of the SQUID non-destructive inspection device shown in FIG. FIG. 3 and FIG. 3 show enlarged front views of the broken portion in FIG. 2, respectively.
[0019]
The illustrated SQUID non-destructive inspection apparatus includes a small refrigerator 1, a vacuum vessel 8, a SQUID sensor 11, a heat transfer wire 12, a vacuum maintenance suction sheet 13, and a radiation shield film 14 as main constituent members. The entire device is configured.
[0020]
The small refrigerator 1 includes a regenerative refrigerator main body 2 that can perform cooling in a low temperature range of 150 K to 4 K using a gas such as helium gas as a working fluid, a compressor 3, and an operation for connecting the two 2 and 3. And a fluid piping system 5.
The regenerative refrigerator main body 2 forms a regenerative refrigerating cycle using gas as a working fluid, which is achieved by three elements: a room temperature part, an expansion part, and a regenerator that thermally separates the two parts. In the case of the present embodiment, a pulse tube refrigerator among various regenerative refrigerators is applied. The pulse tube refrigerator has the advantage that it does not require a low-temperature movable part (expander) and has an advantage in terms of low vibration, and is used as fulfilling the purpose of the present invention. The regenerative refrigerator main body 2 composed of a tube refrigerator has a structure in which a cooling stage 4 formed of a non-magnetic material is provided at an end contacting a lower end of a pulse tube extending vertically.
[0021]
The working fluid piping system 5 includes a high / low pressure switching means 6 which includes an electric switching valve as an element member and switches between a pressurized flow of a compressed working fluid and a reflux of a reduced pressure working fluid, and a pressure difference control valve 25 provided therebetween. A high / low pressure difference control means 7 for controlling an operating pressure for temperature adjustment by providing a pipe 24 as an element member is provided in the piping system, and a discharge port of the compressor 3 and a high / low pressure switching means 6 are provided. The high pressure port is connected by a high pressure pipe 21, the suction port of the compressor 3 and the low pressure port of the high / low pressure switching means 6 are connected by a low pressure pipe 22, and the switching port of the high / low pressure switching means 6 is connected to the regenerator 2 The working fluid piping port 27 is connected by the connecting pipe 23, and the pipe 24 is connected to the high-pressure pipe 21 and the low-pressure pipe 22 to form a predetermined piping system.
[0022]
The pressure difference control valve 25 in the high / low pressure difference control means 7 may be a valve for adjusting the valve opening manually, but in the illustrated embodiment, the valve opening is adjusted based on a feedback control method. The temperature signal S detected by the cooling stage 4 or the SQUID sensor 11 described later is returned to the valve control means 28 as a feedback signal, and the valve of the pressure difference control valve 25 is controlled by the control output from the means 28. Automatic control is performed to open or close.
[0023]
In such a small refrigerator 1, the compressor 3 is driven, the pressure difference control valve 25 is throttled, and the high / low pressure switching means 6 is switched to operate, so that the connecting pipe 23 is alternately switched between the high pressure pipe 21 and the low pressure pipe 22. The switching communication is repeatedly performed to cause the pulse tube refrigerator as the regenerative refrigerator main body 2 to repeatedly perform the pressurized flow of the compressed working fluid and the recirculation of the depressurized working fluid, thereby continuing the low-temperature cooling operation. As a result, the cooling stage 4 is maintained at a predetermined low temperature within a low temperature range of 150K to 4K. In this case, the cooling stage is automatically controlled by the operation of the valve control means 28 so that the valve of the pressure difference control valve 25 is throttled when the temperature rises and vice versa. 4 is maintained at a constant low temperature.
[0024]
Next, referring to FIGS. 2 and 3, the vacuum vessel 8 vacuum-evacuates the pulse tube and the cooling stage 4 of the pulse tube refrigerator as the regenerative refrigerator main body 2, the SQUID sensor 11 described later, and the heat transfer wire 12 similarly. An airtight container for holding under holding, comprising a metal cylindrical body 9 and a bottomed cylindrical non-magnetic material lid 10 having the same diameter as the cylindrical body 9, for example, an alumite surface. A desired vacuum vessel 8 is formed by coaxially and airtightly coupling the treated aluminum cylinder 9 and the acrylic resin lid 10 coaxially. The vacuum container 8 is provided immediately above the container after the pulse tube of the regenerative refrigerator main body 2 and the cooling stage 4 are inserted therein and the above-mentioned other members are accommodated and assembled by airtight coupling. The inside of the vessel is maintained at a high vacuum by bleeding air from the vacuum evacuation port 20.
[0025]
The illustrated tubular body 9 has a ring-shaped inner flange integrally formed on an inner wall portion slightly retracted from a coupling end portion with the lid 10, and has substantially thermal insulation properties with respect to an outer surface portion of the inner flange. A ring 26 of the same shape is fixed by bonding or the like, and a support rod 17 made of a non-magnetic material having thermal insulation and vibration absorbing properties, for example, made of glass epoxy resin, is provided at an appropriate position of the ring 26. Projecting in parallel with the axis of the shaft.
[0026]
2 and 3, a member indicated by reference numeral 16 is a sample stage for supporting a SQUID sensor 11, which will be described later. The sample stage 16 is a nonmagnetic material having a high heat transfer ability, for example, a block made of copper, It is disposed in the vacuum vessel 8 at a position near the bottom wall of the lid 10 as a detection end, and is supported and fixed to the lower end of the support rod 17. A member indicated by reference numeral 18 is a wire anchor for fixing one end of a heat transfer wire 12 described later. The wire anchor 18 is a block made of a nonmagnetic material having a high heat transfer ability, for example, a copper block. 4 are integrally fixed to the lower end surface by bonding.
[0027]
The SQUID sensor 11 includes a superconducting thin film of an oxide superconductor YBaCuO formed as a grain boundary Josephson junction formed on a bonding surface of a bicrystal substrate, and a direct coupling type magnetic field detecting coil provided surrounding the thin film. And a chip structure provided in an element member. The chip structure is disposed in the vacuum vessel 8 at a position spaced from the cooling stage 4 so as to be close to and opposed to the bottom wall of the lid 10 as a detection end. At the same time, it is fixed in close contact with the lower surface of the sample stage 16. The SQUID sensor 11 provided in this manner is fixed at a predetermined position in the vacuum vessel 8 while being supported by the vessel 8 in a thermally insulating manner.
[0028]
The heat transfer wire 12 is made of a non-magnetic material having a high heat transfer ability, for example, a silver-coated copper wire, bundles a large number of these copper wires, and bends them in a zigzag shape to have a vibration absorbing ability. A wire configured to be held is used. One end of the heat transfer wire 12 is fixed to a wire anchor 18, and the other end is fixed to a sample stage 16 via a thermal anchor 15 made of a small plate made of a nonmagnetic material having a high heat transfer capability, for example, a copper plate. It is arranged in the container 8. Such a heat transfer wire 12 is provided between the cooling stage 4 and the SQUID sensor 11 in the vacuum vessel 8 and is provided as a member that plays a role of performing thermal coupling between the two 4 and 11. . The member indicated by reference numeral 19 is a fixing screw made of a non-magnetic material.
[0029]
The vacuum maintenance adsorption sheet 13 is formed of an adsorption sheet of a non-magnetic material, for example, an activated carbon sheet, and is provided in the vacuum vessel 8 around the cooling stage 4. The suction sheet 13 may cause a slight outgas generated from a member in the vacuum vessel 8 or a slight permeated gas permeating the cylinder 9 or the lid 10 and entering the vacuum vessel 8 to cause a decrease in the degree of vacuum. Based on what is considered, there is an advantage that a high degree of vacuum can be maintained for a long period of time by adsorbing the outgas or permeated gas on the adsorption sheet 13 and the running cost can be reduced.
[0030]
The radiation shield film 14 is formed from a thin sheet of a non-magnetic material, and is disposed along the inside of the lid 10 so as to surround the SQUID sensor 11. The radiation shield film 14 performs heat radiation movement in the vacuum vessel 8 based on a temperature difference between the surface of the lid 10 in contact with room temperature and the surface of the SQUID sensor 11 and the sample stage 16 at a lower temperature than the surface. Since this may lead to an increase in the load on the regenerative refrigerator 2, it is provided to prevent such heat radiation transfer. The radiation shield film 14 is a two-layer film having a reflection surface on one side such as an aluminum mirror film formed on one side of a polyester film by an aluminum vapor deposition method. It is a preferred embodiment to attach the inside of the lid 10 to the inside facing the 11, and it is clear that the radiation shielding effect is further enhanced.
[0031]
The SQUID non-destructive inspection apparatus configured as described above uses the heat transfer wire 12 that is used for transmitting the cold between the cooling stage 4 and the SQUID sensor 11 by the minute vibration generated from the regenerative refrigerator main body 2. Since the vibration is not directly transmitted to the SQUID sensor 11 by the vibration absorbing function, vibration noise can be greatly reduced.
[0032]
Further, since all the members between the cooling stage 4 and the SQUID sensor 11 are made of a non-magnetic material, magnetic noise to the SQUID sensor 11 can be reduced. Furthermore, since the vacuum maintenance adsorption sheet 13 is provided so as to surround the cooling stage 4, a reduction in the degree of vacuum due to the influence of outgas or permeated gas can be suppressed. In order to ensure that the vacuum maintaining action of the vacuum maintaining suction sheet 13 can function sufficiently, the number of the heat transfer wires 12 is adjusted so that the temperature of the cooling stage 4 is lower than that of the SQUID sensor 11 by, for example, 5 to 20 K. What is necessary is just to set.
[0033]
Further, by providing the radiation shield film 14 so as to be surrounded by the SQUID sensor 11 and along the inside of the lid 10, radiant heat entering the SQUID sensor 11 from the room temperature portion of the vacuum vessel 8 can be significantly reduced.
[0034]
【The invention's effect】
According to the present invention, the temperature control operation in the vicinity of the SQUID sensor is prevented from being performed, so that measurement noise accompanying the temperature control can be eliminated. Further, since the heat transfer wire made of a non-magnetic material having a vibration absorbing capability is used for the cold transmission to the SQUID sensor, a small vibration generated on the cold storage type refrigerator main body side is not applied to the heat transfer wire. It is possible to further increase the measurement accuracy of the SQUID sensor.
[0035]
Further, according to the present invention, since all the component members between the cooling stage and the SQUID sensor are made of non-magnetic material, magnetic noise to the SQUID sensor can be greatly reduced, and the measurement accuracy can be further improved. Furthermore, it is possible to reliably and easily maintain the vacuum inside the vacuum vessel by providing a vacuum maintenance suction sheet around the cooling stage, and furthermore, a radiation shield is provided inside the lid by surrounding the SQUID sensor. Since the film is provided, radiant heat entering the SQUID sensor from the room temperature portion of the vacuum vessel can be reduced, and the SQUID sensor can be stably maintained at a low temperature.
[0036]
According to the second aspect of the present invention, since the regenerative refrigerator main body is a pulse tube refrigerator, the refrigerator main body as the cooling means has a lower vibration structure, and the influence of vibration on the SQUID sensor is obtained. Can be further reduced.
[0037]
According to the third aspect of the present invention, the constant temperature control of the SQUID sensor can be easily and reliably performed by adjusting the valve opening by feedback of the pressure difference control valve. Furthermore, according to the fourth aspect of the present invention, the radiation shield film formed in the two-layer film is provided inside the lid with the reflection surface facing inward facing the SQUID sensor, The radiant heat entering the SQUID sensor from the room temperature portion can be more effectively reduced, and the SQUID sensor can be maintained at a lower temperature.
[Brief description of the drawings]
FIG. 1 is an overall system diagram of a SQUID nondestructive inspection apparatus according to an embodiment of the present invention.
FIG. 2 is a front view showing a main part structure of the SQUID nondestructive inspection device shown in FIG.
FIG. 3 is an enlarged front view of a broken portion in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Small refrigerator 2 ... Regenerative refrigerator main body 3 ... Compressor 4 ... Cooling stage 5 ... Working fluid piping system 6 ... High-low pressure switching means 7 ... High-low pressure difference control means 8 ... Vacuum container 9 ... Cylindrical body 10 ... lid 11 ... SQUID sensor 12 ... heat transfer wire 13 ... vacuum maintenance adsorption sheet 14 ... radiation shielding film 21 ... high pressure pipe 22 ... low pressure pipe 24 ... pipe 25 ... pressure difference control valve 28 ... valve control means S ... detection temperature signal arrangement Number IWP030102 Page (1/3)

Claims (4)

A regenerative refrigerator body (2) having a cooling stage (4) of non-magnetic material at the end, a compressor (3), and a high-low pressure switching means for switching between a pressurized flow of a compressed working fluid and a reflux of a reduced-pressure working fluid ( 6) and a working fluid piping system (5) for connecting the regenerative refrigerator main body (2) and the compressor (3) with high / low pressure difference control means (7) for controlling the operating pressure for temperature adjustment. A small refrigerator (1) consisting of
It has a cylinder (9) and a lid (10) of a non-magnetic material that is airtightly connected to the cylinder (9), and the regenerative refrigerator main body (2) is hermetically inserted into the cylinder (9), And a vacuum container (8) whose inside is kept in a vacuum,
At a position spaced from the cooling stage (4), the lid (10) as a detection end is disposed in the vacuum vessel (8) in close proximity to and facing the bottom wall, and heat is applied to the vessel (8). An insulated SQUID sensor (11);
It has a vibration absorbing ability and a high heat transfer ability, and is interposed between the cooling stage (4) and the SQUID sensor (11) in the vacuum vessel (8) to perform thermal coupling between the two (4, 11). A non-magnetic heat transfer wire (12);
A non-magnetic material vacuum-maintaining suction sheet (13) provided in a vacuum vessel (8) surrounding the cooling stage (4);
A non-destructive SQUID inspection device comprising: a radiation shield film (14) of a non-magnetic material, which is provided inside the lid (10) so as to surround the SQUID sensor (11). The SQUID nondestructive inspection device according to claim 1, wherein the regenerative refrigerator main body (2) is a pulse tube refrigerator. A high-low pressure difference control means (6) is connected to a high-pressure pipe (21) and a low-pressure pipe (22) of the compressor (3). Feedback of the temperature difference signal (S) from the interposed pressure difference control valve (25) and the cooling stage (4) or the SQUID sensor (11) to the pressure difference control valve (25) to adjust the valve opening. The SQUID nondestructive inspection device according to claim 1 or 2, further comprising a valve control means (28) for controlling the temperature of the SQUID sensor (11) by the following. A radiation shield film (14) is formed as a two-layer film having a reflection surface on one side, and is provided inside the lid (10) with the reflection surface facing inward facing the SQUID sensor (11). The SQUID nondestructive inspection device according to claim 1, 2 or 3.

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