JPH11295476A - Airtight seal device for neutron detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an airtight seal device for a neutron detector high in reliability having excellent airtightness. SOLUTION: An airtight seal device for a neutron detector is provided with an insulation connection member 2, comprising an insulator in which a through hole 6 inserting a neutron detector cable 102 is formed in the inside and pipe-like metal members 4, 5 connected to the insulation connection member outward fitted to the end of the insulation connection member. The connection fitting faces 2a, 2b of the insulation connection member comprise a taper face tapered toward the end to the axial line direction of the through hole, and inclination faces 41, 42 making an acute angle with the connection fitting face of the insulation connection member is formed on the opening edge part of the tube-like metal member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hermetic sealing device for a local power range monitor (LPRM) neutron detector for monitoring the power in a boiling water reactor (BWR), and more particularly, to a metal and ceramic which are reliable. TECHNICAL FIELD The present invention relates to an airtight sealing device for a neutron detector which is highly bonded.

[0002]

2. Description of the Related Art An LPRM neutron detector comprises a sensor section and a cable section for transmitting a signal detected by the sensor section.

FIG. 14A shows a sensor unit 203 of an LPRM neutron detector 202 disposed inside a reactor core 201 in a reactor pressure vessel 200. As shown in FIG. 14B, the hermetic sealing device 100 for the LPRM neutron detector is located at the tip of the LPRM neutron detector 202.

FIG. 12 shows a conventional hermetic sealing device 100 for an LPRM neutron detector. The sensor part of the LPRM neutron detector (not shown) is a neutron detector hermetic sealing device 10.
0 is connected to one side 101 of the neutron detector.
It is airtightly inserted through the inside of the, and is isolated from the sensor unit.

A hermetic sealing device 100 for a neutron detector is
Since it is necessary to insulate between the anode and the cathode, an insulating connecting member 103 made of a ceramic material having excellent environmental resistance and heat resistance is provided in between in order to connect the anode side and the cathode side while insulating each other; Pipe-shaped metal members 104, 105 fitted and connected to respective ends of the pipe 103
And A through hole 106 through which the cable portion 102 is inserted is formed inside the insulating connection member 103.

Insulated connecting member 10 made of ceramic material
3 and the pipe-shaped metal members 104 and 105 need to be hermetically connected by joining or the like so as to maintain airtightness in order to maintain sealing resistance.

In general, since the chemical or mechanical properties of ceramic materials and metal materials are greatly different, it is not easy to mate and connect the two materials satisfactorily and reliably, and there is room for improvement. . Particularly, a member used in a severe environment such as a seal for an LPRM neutron detector requires a highly reliable fitting connection.

[0008]

However, FIG.
As shown in the figure, in the conventional hermetic sealing device for a neutron detector, a cylindrical insulating connection member 103 and a pipe-shaped metal member 1 are used.
04 and 105, the mating surfaces of the joints are formed with through holes 106.
Are formed in parallel to the axial direction of. Therefore, for example, when vertical pressing (uniaxial pressing from above and below) 107 acts in the direction of the arrow, the insulating connecting member 103 and the pipe-shaped metal member 10
4 and 105, the connection is easily released, and the airtightness of the joint is often deteriorated.

[0009] One of the reasons that this problem occurs is that the brazing material does not sufficiently enter the joint. On the other hand, if the brazing material is supplied excessively so as not to run short, the brazing material adheres to unnecessary portions and adversely affects the insulation properties, and cracks occur in the insulating connecting member 103 made of ceramics due to excessive brazing material accumulation. May occur.

Another important point which is a problem in performing good joining between the ceramic material and the metal material is that since the two materials have significantly different coefficients of thermal expansion, the difference in the coefficients of thermal expansion results in a difference in the two. This means that thermal stress is frequently generated in the portion, and therefore, cracks are easily generated on the ceramics side. This thermal stress is mainly caused by the difference in thermal expansion between the ceramic material and the metal material, but the difference between the thermal expansion coefficient of the brazing material used for joining the two and that of the ceramic material is also large. Becomes

Further, the cylindrical insulated connection member 103 and the pipe-shaped metal members 104 and 105 are formed so that the fitting surfaces of their joints are formed in parallel with the axial direction of the through hole 106, so that the insulated connection member 103 is formed. 13 is joined to the pipe-shaped metal member 104 via a brazing material 110 or the like.
As shown in a partially enlarged view, since the axial center position is not determined in the insulating connection member 103, the brazing material 110 is unevenly distributed, and particularly, a crack is easily generated in a thick portion of the brazing material 110. There is.

When the insulated connection member 103 and the pipe-shaped metal member 104 are fitted and joined together, the insulated connection member 103
End 1 where the pipe and the metal member 104 are fitted
It has been discovered by the present inventors that thermal stresses that cause cracks are easily generated in 03a and 104a. FIG.
In 3, for example, a thermal stress that causes a crack is generated in the region 112. The reason that cracks are likely to occur at the ends 103a and 104a is explained as follows. In FIG. 13, when moving upward along the wall surface of the insulating connection member 103, an end portion 104 a discontinuously in the longitudinal direction appears at the end portion 104 a of the pipe-shaped metal member 104 having a certain thickness. I do. Since the thickness of the pipe-shaped metal member 104 is not negligible and appears discontinuously in the longitudinal direction, the change in the thermal expansion coefficient difference of the pipe-shaped metal member 104 with respect to the insulated connecting member 103 in the longitudinal direction is an end. It becomes maximum near the portions 103a and 104a. For this reason, it is considered that near the ends 103a and 104a, thermal stress which causes a crack is generated in the region 112 on the side of the insulating connection member 103 such as a ceramic material.
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a highly reliable hermetic sealing device for a neutron detector.

[0013]

In order to achieve the above object, a first hermetic sealing device for a neutron detector according to the present invention comprises:
An insulating connection member made of an insulating material having a through-hole formed therein through which a cable of the neutron detector is inserted, and a pipe-shaped metal member externally fitted to an end of the insulating connection member and fitted and connected to the insulating connection member A connection fitting surface of the insulated connection member is formed of a tapered surface that tapers toward a tip end in the axial direction of the through-hole, and the insulated connection member is provided at an opening edge of the pipe-shaped metal member. Wherein an inclined surface that forms an acute angle with the connection fitting surface is formed.

According to a second aspect of the present invention, there is provided an airtight seal device for a neutron detector, comprising: an insulated connecting member made of an insulating material having a through hole formed therein for inserting a cable of the neutron detector; A pipe-shaped metal member externally fitted and fitted and connected to the insulated connection member; and a soft metal layer or a low thermal expansion coefficient metal layer disposed between the insulated connection member and the fitting surface of the pipe-shaped metal member. Comprising an intermediate layer, wherein the connection fitting surface of the insulated connection member is formed of a tapered surface that tapers toward the tip in the axial direction of the through hole,
A layer inclined surface that forms an acute angle with the connection fitting surface of the insulating connection member is formed at an opening edge of the intermediate layer.

Further, the inclination angle of the inclined surface formed at the opening edge of the pipe-shaped metal member is 30 degrees to 60 degrees.

Further, the inclination angle of the inclined surface formed at the opening edge of the pipe-shaped metal member is 30 degrees to 60 degrees.

Further, the inclination angle of the layer inclined surface formed at the opening edge of the intermediate layer is 30 degrees to 60 degrees.

The opening edge of the pipe-shaped metal member may be reduced in thickness to 2 mm or less after the insulated connection member and the pipe-shaped metal member are connected to each other. Features.

Further, the pipe-shaped metal member is made of an alloy having a low coefficient of thermal expansion.

Further, the insulating connecting member is made of a ceramic material.

Further, the pipe-shaped metal member is made of an alloy having a low coefficient of thermal expansion equivalent to that of the ceramic material.

Further, the ceramic material is silicon nitride, silicon carbide, aluminum nitride, sialon, or alumina.

Further, the ceramic material is a non-oxide ceramic, which is characterized in that the ceramic material is a non-oxide ceramic.

Further, the connection fitting surface of the insulating connection member is joined by a brazing material containing an active metal.

Further, the connection fitting surface of the insulated connection member is metallized with a brazing material containing an active metal in advance to form a metallized layer, and then the pipe-shaped metal member or the intermediate member is formed. It is characterized by being bonded to a layer.

The active metal is at least one of Ti and Zr, and the metallized layer is 0.1 mP
a. It is characterized by being formed in a vacuum of not more than a.

The brazing filler metal containing the active metal is used in an amount of 0.1%.
In a vacuum of 1 mPa or less, 0.1 to
It is characterized by being heat-bonded under a pressure of 10 kgf / cm ² .

The metallized layer has a thickness of 0.1 mPa.
It is characterized by being heat-bonded to the pipe-shaped metal member or the soft metal layer under a pressure of 0 to 10 kgf / cm ² with respect to a bonding area in the following vacuum or hydrogen atmosphere.

Further, the surface roughness of the connection fitting surface of the insulating connection member does not exceed 5 μm in Ra.

Further, the thickness of the intermediate layer is 0.1 mm or more and 2 mm or less.

Further, the joining thickness of the brazing material is 0.1 μm.
It is at least 30 μm or less.

Further, a slit is formed in the opening edge of the pipe-shaped metal member in the axial direction.

Further, a slit is formed in the opening edge of the intermediate layer in the axial direction.

Further, the slit has a length of 1/4 to 3/4 of an axial length of the pipe-shaped metal member or the intermediate layer which fits into contact with the edge connection member. And

Further, a plurality of the slits are formed at intervals around the axial direction.

Further, the intermediate layer is made of copper or a composite material containing copper as a main component.

The intermediate layer is heated and joined, and then cooled in a temperature range of 400 ° C. to 600 ° C. in a cooling process.
It is characterized by being maintained for a time of not less than seconds and not more than 180000 seconds.

In the above-mentioned invention, since the connection fitting surface of the insulated connecting member is formed of a tapered surface that tapers toward the tip in the axial direction of the through-hole, the axial relationship between the pipe-shaped metal member and the insulated connecting member is reduced. It is possible to determine uniquely,
The gap formed between the connection fitting surface of the insulated connection member and the connection fitting surface of the pipe-shaped metal member can be maintained uniformly without unevenness, and the soft metal layer or brazing material It can be evenly distributed between the connection fitting surface and the connection fitting surface of the pipe-shaped metal member.

Further, since an inclined surface which forms an acute angle with the connection fitting surface of the insulating connecting member is formed at the opening edge of the pipe-shaped metal member, the insulating connecting member is formed at the opening edge of the soft metal layer. Since a layer inclined surface that forms an acute angle with the connection fitting surface is formed, it is difficult to generate a thermal stress that causes a crack at a fitting connection end portion between the insulating connection member and the pipe-shaped metal member. Can be.

As a result, a part of the force acting in the axial direction is applied in a direction in which the adhesion between the connection fitting surface and the mating connection fitting surface is increased, and the stress at the fitting connection end is relaxed. Thereby, a highly airtight fitting connection can be achieved.

Further, by arranging a soft metal layer between the connection fitting surface and the fitting surface of the pipe-shaped metal member, the stress is relaxed, and the occurrence of cracks or the like in the insulating connection member or the like is avoided. be able to.

[0042]

Preferred embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 shows a hermetic sealing device 1 for a neutron detector according to a first embodiment of the present invention. The neutron detector hermetic sealing device 1 includes a cylindrical drum-shaped insulated connecting member 2 made of a ceramic material, and pipe-shaped metal members 4 and 5 that are externally connected to respective ends of the insulated connecting member 2. .

A through hole 6 through which a cable of a neutron detector (not shown) is inserted is formed in the center of the insulated connecting member 2. The through-hole 6 communicates with the inside of the pipe-shaped metal members 4 and 5. As in the case shown in FIG. 12, the sensor section of the LPRM neutron detector (not shown) is connected to one side 101 of the neutron detector hermetic seal device 1, and the cable section 102 of the neutron detector is a neutron detector hermetic seal. The inside of the device 1 is airtightly inserted and is isolated from the sensor unit.

The insulating connection member 2 and the pipe-shaped metal members 4, 5
The fitting portions 7 and 8 are fitted with connection fitting surfaces 2a and 2b of the insulating connection member 2 and connection fitting surfaces 4a and 5a of the pipe-shaped metal members 4 and 5.

The ceramic material forming the insulating connection member 2 is silicon nitride, silicon carbide, aluminum nitride, sialon, or alumina. The pipe-shaped metal members 4 and 5 are made of an alloy having a low coefficient of thermal expansion.

The connection fitting surfaces 2a, 2b of the insulating connection member 2
Is formed on the outer peripheral surface of the insulating connection member 2, and is formed as a tapered surface tapering toward the distal end with respect to the axial direction of the through hole 6. The connection fitting surfaces 4a, 5a of the pipe-shaped metal members 4, 5 are directly or indirectly fitted to the connection fitting surfaces 2a, 2b when the insulated connection member 2 is inserted inside the pipe-shaped metal members 4, 5. It is formed so that it may fit.

As shown in FIG. 1, a pipe-like shape is formed between the connection fitting surfaces 2a, 2b of the insulating connection member 2 and the fitting ends 40a, 40b of the connection fitting surfaces 4a, 5a of the pipe-shaped metal members 4, 5. At the opening edges of the metal members 4, 5, inclined surfaces 41, 42 forming acute inclination angles θ 1, θ 2 with the connection fitting surfaces 2 a, 2 b of the insulating connection member 2 are formed. Inclined surfaces 41, 42
By forming, the thermal stress generated between the joining surfaces can be reduced as described later.

As shown in FIG. 2, in the example shown in FIG. 1, the fitting between the connection fitting surfaces 2a, 2b of the insulating connection member 2 and the connection fitting surfaces 4a, 5a of the pipe-shaped metal members 4, 5 is performed. The connection is
It is joined by the brazing material 21 as described later.

Next, the operation of the above embodiment will be described.

In FIG. 10 and FIG. 11, a part of the force 9 of the vertical pressing (uniaxial pressing from above and below) acting in the direction of the arrow is the force 9 acting vertically on the connection fitting surfaces 2a and 4a in the fitting portion 7.
is converted to a. Thereby, as can be seen from comparison with the conventional insulated connection member 103 shown in FIGS. 12 and 13, the pressure is transmitted in the direction in which the joint of the fitting portion 7 is brought into close contact. That is, since the connection fitting surface 2a of the insulated connecting member 2 and the tapered surface tapering toward the tip end in the axial direction of the through hole 6, the axial relationship between the pipe-shaped metal member 4 and the insulated connecting member 2 is univocally defined. , And the gap formed between the connection fitting surface 2a of the insulated connection member 2 and the connection fitting surface 4a of the pipe-shaped metal member 4 can be uniformly maintained without unevenness. In addition, the brazing material can be evenly distributed between the connection fitting surface 2a of the insulating connection member 2 and the connection fitting surface 4a of the pipe-shaped metal member 4.

Then, the connection fitting surface 2a and the connection fitting surface 4a
In this way, the brazing material can be uniformly and sufficiently wrapped around, and it is not necessary to supply the brazing material excessively so as not to run out.

As a result, it is possible to prevent phenomena such as the brazing material from adhering to unnecessary portions, adversely affecting the insulation, and the occurrence of cracks in the insulating connecting member due to the generation of excessive brazing material.

Further, by selecting an alloy having a low coefficient of thermal expansion equivalent to that of the insulated connecting member (ceramic material) 2 as the pipe-shaped metal member 4, the joining portion is formed due to the difference in thermal expansion coefficient between the ceramic material and the metal material. Therefore, thermal stress can be suppressed, and the occurrence of cracks on the ceramics side can be prevented.

Further, at the opening edge of the pipe-shaped metal member 4, an acute angle of inclination θ with respect to the connection fitting surface 2a of the insulated connection member 2.
As shown in FIG. 11, as the inclined surface 41 is formed along the wall surface of the insulated connecting member 2 and moves upward (arrow A), the fitting end 40 a has a pipe-like shape in the longitudinal direction. The thickness of the metal member 4 can be made to increase continuously, not discontinuously. By forming the inclined surface 41 forming an acute angle with the connection fitting surface 2a, the thickness t of the pipe-shaped metal member 4 is increased.
Is gradually changed in the longitudinal direction.

On the other hand, generally, the residual stress generated between two members having different thermal expansion coefficients is related to the heat transfer speed in addition to the difference Δα in temperature between the two and the temperature difference ΔT. It is proportional to the distance t between the two. Here, the distance t between the two corresponds to the thickness t of the pipe-shaped metal member 4.

FIG. 8 is a diagram showing an analysis result showing the relationship between the residual stress and the inclination angle of the inclined surface formed at the opening edge of the pipe-shaped metal member 4.

As shown in FIG. 8, by forming an inclined surface 41 that forms an acute angle with the connection fitting surface 2a, the fitting end 40a is formed.
In the above, it is recognized that the residual stress caused by the thermal stress causing the crack can be reduced.

As can be understood from the above, the inclined surface 41 which forms an acute angle with the connection fitting surface 2a of the insulating connection member 2 is formed at the opening edge of the pipe-shaped metal member 4, so that the fitting end 40a is formed. It is possible to make it difficult to generate thermal stress that causes a crack in the insulating connection member 2.

As described above, according to the configuration of the present embodiment, a part of the force acting in the axial direction is applied in a direction in which the adhesion between the connection fitting surface and the mating connection fitting surface increases. By relaxing the stress at the fitting connection end,
A highly airtight fitting connection can be achieved.

Next, another embodiment will be described with reference to FIG.

As shown in FIG. 3, a soft metal layer 20 is provided between the connection fitting surfaces 2a, 2b of the insulating connection member 2 and the connection fitting surfaces 4a, 5a of the pipe-shaped metal members 4, 5. Have been. The thickness of the soft metal layer 20 is 0.1 mm or more and 2 mm
The thickness is as follows. A connection fitting surface 2a of the insulating connection member 2,
2b and the surface of the soft metal layer 20 are joined by a brazing material 21 or the like. The connection between the connection fitting surfaces 4a and 5a of the pipe-shaped metal members 4 and 5 and the surface of the soft metal layer 20 are also preferably joined by a brazing material 22 or the like.

The connection fitting surfaces 2a and 2b of the insulating connection member 2 and the fitting ends 40a and 40b of the connection fitting surfaces 4a and 5a of the pipe-shaped metal members 4 and 5 correspond to the opening edges of the soft metal layer 20. Have layer inclined surfaces 43 and 44 which form acute inclination angles θ1 and θ2 with the connection fitting surfaces 2a and 2b of the insulating connection member 2.

In FIG. 3, as shown in FIG.
Reference numerals 3 and 44 denote cases where the fitting ends 40a and 40b are formed as intermediate layers at the opening edges of the soft metal layer 20. In addition, as shown in FIG.
Also in FIG. 3 (see FIG. 3), by forming the layer inclined surface 44 at the edge of the opening of the soft metal layer 20, the thermal stress generated between the bonding surfaces can be more reliably reduced.

Incidentally, instead of the soft metal layer 20 as the intermediate layer, a low thermal expansion coefficient alloy layer may be provided as the intermediate layer.

As shown in FIG. 4B, the edge of the opening of the soft metal layer 20 is arranged at regular intervals around the axial direction.
A plurality of slits 60 extending in the axial direction are formed. The slit 60 can contribute to stress relaxation by increasing the degree of freedom for dispersing the stress at the opening edge of the intermediate layer where the stress is concentrated.

The length of the slit 60 in the axial direction is set in the range of １ ／ to ／ of the contact length between the insulating connecting member 2 and the soft metal layer 20 as the intermediate layer. The longer the length of the slit 60 is, the greater the effect of relaxing the stress can be. However, on the other hand, the joining area is reduced and the airtightness is affected.

Incidentally, slits may be provided at the opening edges of the pipe-shaped metal members 4, 5 shown in FIG. 1 or FIG.

Next, referring to FIG. 9, a fitting connection for joining between the connecting fitting surfaces 2a, 2b of the insulating connecting member 2 and the connecting fitting surfaces 4a, 5a of the pipe-shaped metal members 4, 5 will be described. Will be described. Note that the connection fitting surfaces 2a,
2b and connection fitting surfaces 4a, 5a of pipe-shaped metal members 4, 5
It is also possible to make a fitting connection between the two and only by fitting without using a brazing material.

FIGS. 9 (a), 9 (b) and 9 (c) respectively show the positions between the connection fitting surfaces 2a and 2b of the insulating connection member 2 and the surface of the soft metal layer 20, and the pipe-like metal members 4 and 5 respectively. Connection mating surface 4
It is a figure which shows the case where various brazing material layers are formed between a, 5a and the surface of the soft metal layer 20, and the joining layers 51, 52, 53 were formed.

FIG. 9A shows a pipe-shaped metal member in which the connection fitting surfaces 2a and 2b of the insulating connection member 2 and the surface of the soft metal layer 20 are joined by a brazing material 21 mixed with an active metal. An example is shown in which the connection fitting surfaces 4a, 5a and the surface of the soft metal layer 20 are joined with a brazing material 22. Here, the brazing material 22 is a simple brazing material or a brazing material mixed with an active metal. The bonding layer 51 is composed of the brazing material 21 and the soft metal layer 2.
0 and a brazing material 22.

FIG. 9B shows a brazing material composed of an active metal layer made of an active metal and a brazing material layer between the connection fitting surfaces 2 a and 2 b of the insulating connecting member 2 and the surface of the soft metal layer 20. 23
And the connection fitting surfaces 4a of the pipe-shaped metal members 4, 5
An example in which an active metal layer made of an active metal and a brazing material 24 made of a brazing material layer are also joined between 5a and the surface of the soft metal layer 20 is shown. The bonding layer 52 includes the brazing material 23 and the soft metal layer 20.
And a brazing material 24.

FIG. 9C shows the connection between the connection fitting surfaces 2 a and 2 b of the insulating connection member 2 and the surface of the soft metal layer 20 with a metallized layer 25 and a brazing material comprising a brazing material layer 26. ,
An example in which the connection fitting surfaces 4a and 5a of the pipe-shaped metal members 4 and 5 and the surface of the soft metal layer 20 are joined with a brazing material 27 is shown.
The bonding layer 53 includes the metallized layer 25, the brazing material layer 26, the soft metal layer 20, and the brazing material 27.

9 (a), 9 (b) and 9 (c), the thermal stress generated due to the difference in thermal expansion coefficient between the insulating connecting member 2 made of ceramics and the pipe-shaped metal members 4 and 5 is reduced by the soft metal layer 20. Has the property of being easily deformed by a load, so that the occurrence of cracks in the insulated connecting member 2 can be reduced, and a highly reliable hermetic sealing device for a neutron detector can be obtained.

FIG. 6 or FIG. 7 shows that the insulating connection member 2 or the pipe-shaped metal members 4 and 5 are preliminarily connected to the joining layer 5 before the fitting connection between the insulated connection member 2 and the pipe-shaped metal members 4 and 5.
An example in which 1, 52, or 53 is formed will be described. In this way, by previously forming the bonding layer 51 or the like on the insulating connection member 2 or the pipe-shaped metal members 4 and 5, the labor for inserting the active metal brazing material into the bonding portions of the members can be omitted,
The joining can be easily performed.

If the thickness of the soft metal layer 20 is too large, the stress generated by itself increases, and if the thickness is too small, the stress buffering effect is reduced.
More preferably, it is more preferably 2 mm or less and 0.1 mm or more.

The material of the soft metal layer 20 is not particularly limited as long as the soft metal is soft.
For example, metals such as copper and nickel can be used.

As a method of inserting between the insulated connecting member 2 and the pipe-shaped metal members 4 and 5, the soft metal layer 20 may be used.
May be machined (machined, discharged, etc.) into a predetermined shape and inserted, or may be deposited at the joint by physical vapor deposition or the like. In this case, the brazing material may be deposited and laminated at the same time, or the pipe-shaped metal members 4 and 5 and the soft metal may be joined in advance, and then joined to the insulating connection member 2. The joining between the pipe-shaped metal members 4 and 5 and the soft metal constituting the soft metal layer 20 may be performed by a normal metal / metal joining method, for example, brazing or diffusion joining.

Although the soft metal layer 20 mainly exerts an effect of relieving thermal stress at the time of joining, it also has an effect of relieving the stress generated in the seal portion when used as an LPRM hermetic seal part. Therefore, a more reliable hermetic seal device for a neutron detector without cracks in the insulating connection member 2 is enabled.

In the above-described embodiment, a low thermal expansion coefficient alloy is used as the metal member forming the pipe-shaped metal members 4 and 5. Here, as the low thermal expansion coefficient alloy, for example, an iron-based alloy, particularly an iron-based alloy such as an invar-based alloy, an elinvar-based alloy, or an Fe-Ni-based alloy or a Fe-Ni-Co-based alloy commonly called 42 alloy or the like. The low coefficient of thermal expansion alloy has a smaller coefficient of thermal expansion than ordinary steel or stainless steel, and is effective in reducing the thermal stress generated at the joint.

It is also effective to use a low thermal expansion coefficient alloy as the metal member constituting the pipe-shaped metal members 4 and 5 and to provide the soft metal layer 20 in combination.
The insertion method in the case of providing the soft metal layer 20 can be performed in the same manner as the case where a normal metal member is used as the metal member constituting the pipe-shaped metal members 4 and 5 instead of a low thermal expansion coefficient alloy.

Further, the insulating connecting member 2 made of a ceramic material and the soft metal layer 20 are joined with a brazing material, or the insulating connecting member 2 made of a ceramic material and the pipe-shaped metal members 4 and 5 are joined with a brazing material. This allows the liquefied brazing material to fill the joint and obtain good airtightness. In this case, if a large amount of brazing material is used, the excess brazing material protrudes from the joining portion and adheres to unnecessary portions to cause insulation failure, or also forms a brazing material pool and acts as a source of thermal stress and is made of a ceramic material. There is a problem that cracks occur in the insulating connection member 2. For this reason, it is desirable that the amount of brazing material used be kept to the minimum necessary for joining.

In the case where cylindrical ceramics are used as described in the section of the prior art, the gap at the joint is likely to be large unless the processing accuracy is strict, so that the gap cannot be filled with a small amount of brazing material. There was a problem. In addition, if the clearance is barely increased by increasing the processing accuracy, a problem has arisen that the brazing material is less likely to enter the joint. On the other hand, in the present invention, as described above, the pressurization from above and below at the time of joining is efficiently converted into the joining portion as described with reference to FIG. The entire surface of the brazing filler metal is pressed evenly, so that even when the minimum necessary brazing material is inserted into the joint, the brazing material can be efficiently supplied to the joint, and the thickness of the brazing material can be reduced. It is possible to provide a highly reliable hermetic sealing device for a neutron detector, which can be reduced in size and can reduce the generation of thermal stress from the brazing material.

The thickness of the brazing material, excluding the volume of the pores in the brazing material, is not more than 200 μm and not more than 0.01 μm.
Although the above-mentioned degree is mentioned, the brazing material thickness of 30 μm or less and 0.1 μm or more is particularly desirable. this is,
If the thickness is too thick, the problem of coagulation of excess brazing material will occur, and if it is too thin, unless the processing of the joining surface is particularly smooth, the amount of brazing material will be small and will be buried in the unevenness of the joining surface. This is because a certain thickness (amount) is required to completely fill the joint portion in consideration of the precision of the mechanical processing.

As described above, the joining of the insulating connection member 2 made of a ceramic material and the soft metal layer 20 or the joining of the pipe-shaped metal members 4 and 5 made of a low-thermal-expansion metal member are performed by previously metallizing the ceramic material. The joining may be performed using a conventional brazing material, for example, a silver brazing material, a copper brazing material, a nickel brazing material, an aluminum brazing material, or a solder. This metallization is applied to oxide ceramics by applying a paste containing Mo, W, Mn powder or the like, commonly called the Moriman method, to the ceramic joint surface in advance and performing a high-temperature heat treatment at 1400 ° C. or more in a humid atmosphere. A method of metallizing the surface and then performing Ni plating may be mentioned, but basically the metallizing method is not particularly limited. In addition, when joining to non-oxide ceramics that are difficult to perform the Moriman method, or when performing direct joining easily without performing metallization in advance, the joining with the ceramic material is performed using a brazing material containing an active metal. Good to do.

In the case of joining using a brazing material containing an active metal, at least one element of the group IVA or VA of the periodic table, such as Ti, Zr, Hf or V, is used as the active metal and the active metal is used. In order to prevent oxidation of the active metal, the joining is preferably performed by applying pressure and heat in a vacuum of 0.1 mPa or less or in an inert atmosphere containing no oxygen using an alloy brazing material. Although the type of the active metal brazing material is not particularly limited, typical active metal brazing materials include Ti-Ag-Cu, Zr-Ag-
Cu-based and Ti-Cu-based brazing materials can be used. By placing these active metal brazing materials in various states such as alloys, foils, film laminates, alloy powders, and powder mixtures on the joints of metal and ceramics, and heating them in vacuum or in an inert atmosphere The metal and ceramics can both be joined well.

As a kind of ceramic material constituting the insulating connection member 2, dense and chemically stable ceramics such as silicon nitride, silicon carbide, aluminum nitride, sialon, alumina, spinel and the like can be mentioned. From the viewpoint of heat stress resistance, it is desirable that the ceramic itself has high strength, and impurities and sintering aids (SiO ₂ , MgO, Y ₂ O ₃ , A
High-strength ceramics with little (such as l ₂ O ₃ free Si) are more desirable. In addition, if the roughness of the bonding surface of the ceramic is large, it tends to be a source of cracks in the bonding material. Therefore, it is desirable that the surface roughness of at least the bonding surface with the metal does not exceed 10 μm or less, preferably 5 μm.

Next, specific examples of the present invention will be described in detail below.

In the following embodiment, as shown in FIG. 1, the inclined edges 41, 42 forming acute inclination angles θ1, θ2 with the connection fitting surfaces 2a, 2b are formed at the opening edges of the pipe-shaped metal members 4, 5, respectively. In the case of inclination, or as shown in FIG. 3, an acute angle of inclination θ1 with the connection fitting surfaces 2a, 2b at the opening edge of the soft metal layer 20,
The stress relaxation effect is compared and verified between the case where the layer inclined surfaces 43 and 44 forming θ2 are formed and the conventional case where the inclined surfaces 41 and 42 and the layer inclined surfaces 43 and 44 are not formed. In addition, a result of comparison between a case where the slit 60 is formed and a case where the slit 60 is not formed is also shown.

[0090] <Example> ceramic member, alumina (various up purity 92-99%) or silicon nitride (Shoyuisukezai Y ₂ 0 ₃ of such other as Al ₂ O ₃ or MgO 1
Material members of various types, normal pressure sintering, hot pressing materials) containing more than one kind were used. Care was taken not to exceed a roughness Ra of 5 μm on the surface of the ceramic member.

In the case corresponding to FIG. 1, without using the intermediate layer (intermediate metal layer), the pipe-shaped metal members 4 and 5 are directly made of 42% Ni--Fe which is a low thermal expansion coefficient alloy and parts made of Kovar. Was. Before joining the seal parts,
42 alloy / active metal brazing material / ceramics / active metal brazing material / 42 alloy.

In the case corresponding to FIG. 3, the intermediate layer (intermediate metal layer) made of pure copper or pure Ni has a thickness of 0.1 to 1 mm.
mm of the stress relaxation layer was inserted. Pipe-shaped metal members 4, 5
Was used as SUS304. The structure of the sealing component before joining is as follows: SUS304 / Cu intermediate layer formed on both surfaces / ceramics / Cu intermediate layer formed on both surfaces / Ti
US304 or SUS304 / active metal brazing material /
Ni intermediate layer / active metal brazing material / ceramics / active metal brazing material / Ni intermediate layer / SUS304.

In both cases corresponding to FIG. 1 and FIG. 3, the members were directly joined in a high vacuum of the order of mPa using a brazing material containing an active metal.

The airtightness of the rejoined portion was evaluated by a He leak test for the joining material having no crack.

The brazing material used is a Ti-Cu alloy brazing material having a thickness of about 0.5 to 5 μm. When the intermediate layer (intermediate metal layer) is Cu, the Ti layer is previously formed on the inner and outer surfaces of the intermediate layer by sputtering. Was formed to a thickness of about 0.1 to 3 μm, and reacted with a part of Cu in the intermediate layer by heating to form a brazing alloy. When the intermediate layer (intermediate metal layer) was Ni, the bonding was performed by inserting 25 to 30 wt% Ti and the balance Cu alloy foil brazing material. Although Zr-Cu was also used as the brazing filler metal, the same result as that of the Ti-Cu type was obtained. The joining temperature is 900 ° C. to 980 ° C., which is several tens of degrees higher than the melting point of the brazing material of about 880 ° C., and the pressure is 0.1 to 10 kgf / cm ^2.
Met.

Further, the case where bonding was performed by the following method was also examined. As a result, the same result as that obtained by the above-described joining method was obtained, but the result obtained by the joining method will also be described.

That is, according to the method, a Ti layer was formed to a thickness of 1 μm by an ion plating method. afterwards,
A Cu layer was formed on the Ti layer to a thickness of 10 μm and 300 μm by plating. They were heated in a high vacuum of the order of mPa at 930 ° C. for 15 minutes to metallize the ceramic joint. In some parts, a 1 μm Ni plating was further applied to the Cu surface. Cu layer is 3
In the case of 00 μm, the end was tapered to 60 degrees by machining. SUS304 / brazing material / taper 60 ° C
u intermediate layer / brazing material / Cu layer Metallized ceramic with a thickness of 10 μm, or SUS304 / brazing material / C
The ceramics metalized with a u layer thickness of 300 μm or the ceramics metalized with a 42 alloy / brazing material / Cu layer thickness of 10 μm are superposed on each other,
The sample was placed in a forming gas furnace or a vacuum furnace containing hydrogen. In addition, as a comparative material, a bonding material similar to the above three types was prepared for the other members except that the contact portion angle of the Cu intermediate layer was 100 degrees or the Cu thickness was 300 μm and metallization was not performed, but the tapering was not performed. As a brazing material, a Cu-36% Mn brazing material was inserted in a foil shape so as to have an average thickness of 300 μm or less. After that, these superimposed products are 0.2 kgf
Under the pressure of / cm ² at the final 960 ° C.
Seal parts were obtained. At the joint with Ni plating, C
The flow of the u-Mn brazing material was superior to that of the unapplied appearance.

Table 1 shows the above results. Regarding the sealing parts produced by the above-mentioned different joining methods, almost the same results were obtained in the airtightness regardless of the joining method.

[0099]

[Table 1] * 1) Conventionally shaped ceramics * 2) Surface roughness Ra of 5 μm or more In Table 1, the case with the best airtightness is indicated by “AA”.
A case of good airtightness is indicated by "A", a case of poor airtightness is indicated by "B", and a case of good airtightness is indicated by "C".

In Table 1, an example in which “metal” is a 42 alloy (0.1-1) corresponds to FIG. 1, in which there is no intermediate layer (intermediate metal layer), 5 shows a case where the inclination angles of the inclined surfaces 41 and 42 formed in FIG. The other case corresponds to FIG. 3 in which there is an intermediate layer (intermediate metal layer) and the inclination angles of the layer inclined surfaces 43 and 44 formed on the soft metal intermediate layer 20 are changed.

As can be seen from the results shown in Table 1, when the taper (inclination angle) is smaller than 80 degrees, the occurrence of cracks in the ceramic at the joint is small, and in particular, the taper (inclination angle) is small.
Is less than 60 degrees, it is recognized that good airtightness can be obtained.

Further, in the case of “with slit”, it is recognized that the state of occurrence of cracks is further improved as compared with the case where there is no slit 60.

On the other hand, when the taper (inclination angle) is as large as 80 °, it is recognized that the crack generation situation is not good.

As described above, according to the embodiment of the present invention,
The insulating connection member 2 made of a ceramic material and the pipe-shaped metal members 4 and 5 can be satisfactorily adhered to each other, and highly airtight joining can be performed using a minimum necessary brazing material layer.
By using the pipe-shaped metal members 4 and 5 formed with 1, 42 and the soft metal intermediate layer 20 formed with the layer inclined surfaces 43 and 44, thermal stress can be satisfactorily relieved, and aging occurs when the sealing parts are used. In addition, the effect of reducing the stress that occurs in the ceramic part can be obtained, so that the occurrence of cracks in the ceramic parts can be suppressed, the synergistic effect that the amount of brazing material is minimized is obtained, and the airtightness of the joint is obtained. It is possible to provide a highly reliable LPRM neutron detector hermetic seal part having good properties and suppressed crack generation.

[0105]

As described above, according to the structure of the present invention, since the opening edge of the pipe-shaped metal member is formed with an inclined surface which forms an acute angle with the connection fitting surface of the insulating connection member,
Alternatively, since a layer inclined surface that forms an acute angle with the connection fitting surface of the insulating connecting member is formed at the opening edge of the intermediate layer made of the soft metal layer or the low thermal expansion coefficient metal layer, the insulating connection at the fitting end is formed. It is possible to make it difficult to generate thermal stress which causes cracks in the member.

Further, since the connection fitting surface of the insulated connecting member is formed as a tapered surface that tapers toward the tip in the axial direction of the through hole, the axial relationship between the pipe-shaped metal member and the insulated connecting member is uniquely determined. It is possible to uniformly and sufficiently wrap the brazing material or the like between the connection fitting surface of the insulating connection member and the connection fitting surface of the pipe-shaped metal member, and cracks occur in the insulation connection member. Can not be.

As a result, a part of the force acting in the axial direction is applied in a direction in which the adhesion between the connection fitting surface and the mating connection fitting surface is increased, and the stress at the fitting connection end is reduced. Thereby, a highly airtight fitting connection can be achieved. In addition, by arranging an intermediate layer made of a soft metal layer or a metal layer having a low coefficient of thermal expansion between the connection fitting surface and the fitting surface of the pipe-shaped metal member, stress relaxation is achieved, and cracks or the like are formed on the insulating connection member. Can be avoided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of a hermetic sealing device for a neutron detector according to the present invention.

FIG. 2 is a partially enlarged view of FIG. 1, showing that a connection fitting surface of an insulating connection member and a connection fitting surface of a pipe-shaped metal member are joined by a brazing material.

FIG. 3 is a sectional view showing a second embodiment of the hermetic sealing device for a neutron detector according to the present invention.

FIGS. 4A and 4B show that a layer inclined surface is formed at an opening edge of a soft metal layer 20 as an intermediate layer in FIG. 3 and a slit that is formed at an opening edge of the soft metal layer 20; .

FIG. 5 is a view showing that a layer inclined surface is formed at an opening edge portion at both ends of the soft metal layer in FIG. 3;

FIG. 6A is a diagram showing that the bonding layer 51 and the like shown in FIG. 9 are formed in advance on the insulating connection member prior to the fitting connection between the insulating connection member and the pipe-shaped metal member; FIG.

FIG. 7 shows a pipe-like metal member having a bonding layer 5 shown in FIG.
The figure which shows forming 1 grade.

FIG. 8 is a diagram showing an analysis result showing a relationship between a residual stress and an inclination angle (taper angle) of an inclined surface formed at an opening edge of a pipe-shaped metal member 4.

FIG. 9 is a cross-sectional view showing an example in which the front and back surfaces of a soft metal layer are joined in various configurations.

FIG. 10 shows the case of the shape of the insulated connecting member in FIG.
The figure which shows that the force which acts perpendicularly to the connection fitting surface in a fitting part is produced | generated.

FIG. 11 is a partially enlarged view of FIG. 10 and illustrates that a force acting perpendicularly to a connection fitting surface in a fitting portion is generated.

FIG. 12 is a cross-sectional view illustrating a conventional hermetic sealing device for a neutron detector, showing that a force acting on a connection fitting surface is in an axial direction of a through hole.

13 is a partially enlarged view of FIG. 12, showing that the axial relationship between the insulating connecting member and the pipe-shaped metal member is not fixed when the force acting on the connection fitting surface is in the axial direction of the through hole. FIG. 5 is a diagram showing that a region where thermal stress causing a crack is generated is generated in an insulated connection member at a fitting end when an inclined surface is not provided at an open end of a pipe-shaped metal member. .

FIG. 14 is a view showing L disposed inside a reactor core in a reactor pressure vessel.
The figure which shows the sensor part 203 of a PRM neutron detector (b)
FIG. 2 is an enlarged view showing a tip of a LPRM neutron detector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Airtight sealing device for neutron detectors 2 Insulated connection member 2a Connection fitting surface 2b Connection fitting surface 3 Insulation connection member 4 Pipe-shaped metal member 4a Connection fitting surface 5 Pipe-shaped metal member 5a Connection fitting surface 6 Through hole 7 Fit Joint 8 Fitting 9 Vertical pressure 20 Soft metal layer 40a Fitting end 40b Fitting end 41, 42 Inclined surface 43, 44 Layer inclined surface 51, 52, 53 Joining layer 60 Slit 101 Sensor side 102 Cable 200 Reactor pressure vessel 201 core 202 LPRM neutron detector 203 sensor unit

[Procedure amendment]

[Submission date] March 18, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0056

[Correction method] Change

[Correction contents]

On the other hand, generally, the residual stress generated between two members having different thermal expansion coefficients is related to the heat transfer speed in addition to the difference Δα in temperature between the two and the temperature difference ΔT. It is proportional to the distance t between the two. Here, the distance t between the two corresponds to the thickness t of the pipe-shaped metal member 4. The wall thickness t of the pipe-shaped metal member 4 is the length of the perpendicular line when the perpendicular line is perpendicularly dropped from each point of the inclined surface 41 to the outer peripheral surface of the insulating connection member 2 with respect to the inclined surface 41. In addition, the length of this perpendicular line when a perpendicular line from the outer peripheral surface to the outer peripheral surface of the insulated connection member 2 is made perpendicular to the outer peripheral surface of the pipe-shaped metal member 4 with respect to the portion excluding the inclined surface 41 is shown. As expected. The same applies to the pipe-shaped metal member 5.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasuo Morishima 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Inside the Toshiba Yokohama Office (72) Inventor Toshiaki Ito Shin-Sugita-cho, Isogo-ku, Yokohama-shi, Kanagawa No. 8 Inside the Toshiba Yokohama office of the Company Limited (72) Inventor Eiji Seki 1385 Shimoishigami, Otawara City, Tochigi Prefecture Inside the Nasu Electron Tube Factory, Toshiba Corporation (72) Inventor Koji Fukutani 8-8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture (72) Inventor Mikio Izumi Inside Toshiba Research & Development Center 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa

Claims (24)

[Claims] An insulated connecting member made of an insulating material having a through hole formed therein through which a cable of a neutron detector is inserted, an outer connecting member fitted to an end of the insulated connecting member and connected to the insulated connecting member. A pipe-shaped metal member, wherein the connection fitting surface of the insulated connection member is formed of a tapered surface that tapers toward the tip in the axial direction of the through-hole, and an opening edge of the pipe-shaped metal member An airtight sealing device for a neutron detector, wherein an inclined surface forming an acute angle with the connection fitting surface of the insulated connection member is formed. 2. An insulated connecting member made of an insulating material having a through-hole formed therein through which a cable of a neutron detector is inserted, an outer connecting member fitted to an end of the insulated connecting member and connected to the insulated connecting member. A pipe-shaped metal member, and an intermediate layer made of a soft metal layer or a low thermal expansion coefficient metal layer disposed between the insulated connection member and the fitting surface of the pipe-shaped metal member. Is formed by a tapered surface that tapers toward the tip of the through hole in the axial direction, and forms an acute angle with the connection fitting surface of the insulating connection member at the opening edge of the intermediate layer. A hermetic sealing device for a neutron detector, wherein a layer inclined surface is formed. 3. The hermetic sealing device for a neutron detector according to claim 1, wherein an inclination angle of the inclined surface formed at an opening edge of the pipe-shaped metal member is 30 degrees to 60 degrees. 4. The hermetic sealing device for a neutron detector according to claim 2, wherein the inclination angle of the layer inclined surface formed at the opening edge of the intermediate layer is 30 degrees to 60 degrees. 5. An opening edge of the pipe-shaped metal member is reduced in thickness to 2 mm or less after fitting connection between the insulated connection member and the pipe-shaped metal member is performed. The hermetic sealing device for a neutron detector according to claim 1, wherein: 6. The hermetic sealing device for a neutron detector according to claim 1, wherein said pipe-shaped metal member is made of an alloy having a low coefficient of thermal expansion. 7. An airtight sealing device for a neutron detector according to claim 1, wherein said insulating connecting member is made of a ceramic material. 8. The hermetic sealing device for a neutron detector according to claim 7, wherein said pipe-shaped metal member is made of an alloy having a low coefficient of thermal expansion equivalent to that of said ceramic material. 9. The hermetic sealing device for a neutron detector according to claim 7, wherein said ceramic material is silicon nitride, silicon carbide, aluminum nitride, sialon, or alumina. 10. The hermetic sealing device for a neutron detector according to claim 7, wherein said ceramic material is a non-oxide ceramic. 11. The connection fitting surface of the insulating connection member,
The hermetic sealing device for a neutron detector according to any one of claims 1 to 10, wherein the hermetic sealing device is joined by a brazing material containing an active metal. 12. The connection fitting surface of the insulating connection member,
The neutron according to claim 11, wherein the neutron is joined to the pipe-shaped metal member or the intermediate layer after metallization is performed in advance by using a brazing material containing an active metal to form a metallized layer and metallized. Airtight sealing device for detector. 13. The neutron according to claim 12, wherein said active metal is at least one of Ti and Zr, and said metallized layer is formed in a vacuum of 0.1 mPa or less. Airtight sealing device for detector. 14. A brazing filler metal containing an active metal is 0.1 m
In a vacuum of Pa or less, 0.1 to 10
under a pressure of kgf / cm ^2, the neutron detector hermetic sealing device according to any one of claims 11 to 12, characterized in that it is heat-bonding. 15. The pipe-like metal member or the intermediate layer under a pressure of 0 to 10 kgf / cm ² in a vacuum of 0.1 mPa or less or in a hydrogen atmosphere under a pressure of 0 to 10 kgf / cm ^2. The hermetic seal device for a neutron detector according to claim 12, wherein the hermetic seal device is heated and joined. 16. The neutron detector according to claim 1, wherein the surface roughness of the connection fitting surface of the insulating connection member does not exceed 5 μm in Ra. Hermetic sealing device. 17. The intermediate layer has a thickness of 0.1 mm or more and 2 mm or more.
The hermetic seal device for a neutron detector according to claim 2, wherein the diameter is not more than mm. 18. The hermetic sealing device for a neutron detector according to claim 11, wherein a joining thickness of said brazing material is 0.1 μm or more and 30 μm or less. 19. An opening edge of said pipe-shaped metal member,
The airtight sealing device for a neutron detector according to claim 1, wherein a slit is formed in an axial direction. 20. The hermetic sealing device for a neutron detector according to claim 2, wherein a slit is formed in an opening edge portion of the intermediate layer in an axial direction. 21. The slit has a length of １ ／ to ／ of an axial length of the pipe-shaped metal member or the intermediate layer which is fitted and in contact with the edge connection member. Any one of claim 20 or claim 21
Airtight sealing device for a neutron detector according to Item. 22. An airtight sealing device for a neutron detector according to claim 20, wherein a plurality of said slits are formed at intervals around an axial direction. . 23. The hermetic sealing device for a neutron detector according to claim 2, wherein said intermediate layer is made of copper or a composite material containing copper as a main component. 24. The method according to claim 23, wherein the intermediate layer is maintained at a temperature in the range of 400 ° C. to 600 ° C. for 60 seconds or more and 180,000 seconds or less in a cooling process after the heat bonding. Hermetic sealing device for neutron detectors.