JP3086871B2 - Hermetic sealing device for neutron detector - Google Patents

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. 8 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 100.
The cable portion 102 of the neutron detector is hermetically inserted through the inside of the neutron detector hermetic sealing device 100 and is isolated from the sensor portion.

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.

[0005] 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 significantly 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.

[0007]

However, as shown in FIG. 8, in the conventional hermetic sealing device for a neutron detector,
Cylindrical insulated connecting member 103 and pipe-shaped metal member 10
4 and 105, the fitting surfaces of the joints thereof are formed in parallel with the axial direction of the through hole 106. Therefore, for example, when a 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 104,
There has been a problem that the fitting connection with the joint 105 is easily released, and the air-tightness of the joint is reduced.

[0008] 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 greatly different coefficients of thermal expansion, the two members have a large difference in the coefficient of thermal expansion. 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. The large difference between the thermal expansion coefficient of the brazing material used for joining the two and that of the ceramic material also causes the thermal stress. Becomes

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.

[0011]

In order to achieve the above object, an airtight sealing device for a neutron detector according to the present invention comprises an insulating connection made of a ceramic material having a through hole formed therein for inserting a cable of the neutron detector. Member, a pipe-shaped metal member fitted and connected to each end of the insulated connection member, the connection fitting surface of the insulated connection member, from the tapered surface inclined with respect to the axial direction of the through hole Between the connection fitting surface and the fitting surface of the pipe-shaped metal member.
A soft metal layer having a thickness of 1 mm or more and 2 mm or less is provided.

The connection fitting surface of the insulating connection member is formed on an inner peripheral surface.

The connection fitting surface of the insulating connection member is formed on an outer peripheral surface.

The tapered surface is a tapered surface that tapers toward the tip.

The tapered surface is a tapered surface that tapers inward.

The ceramic material is silicon nitride, silicon carbide, aluminum nitride, sialon, alumina or spinel.

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

The joint thickness between the fitting surfaces of the insulated connecting member, the soft metal layer, and the pipe-shaped metal member is 0.1 mm.
It is characterized by being joined by a brazing material of 1 μm or more and 30 μm or less.

The brazing material comprises Ti as the active metal,
It is a brazing material containing at least one of Zr and Hf.

[0020] The brazing material is characterized in that it is pressurized in a vacuum of 0.1 mpa or less and heated and joined.

The surface roughness of the connection fitting surface of the insulated connection member does not exceed 5 μm in Ra.

[0022]

[0023]

[0024]

[0025]

[0026]

In the above-mentioned invention, since the connection fitting surface of the insulated connecting member is formed of a tapered surface inclined with respect to the axial direction of the through hole, a part of the force acting in the axial direction is partially connected to the connection fitting surface. By acting in the direction in which the adhesiveness with the fitting surface increases, 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.

[0029]

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 hermetic sealing device 1 for a neutron detector includes a cylindrical drum-shaped insulating connection member 2 made of a ceramic material, and pipe-shaped metal members 4 and 5 fitted and connected to respective ends of the insulating connection 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. 8, the sensor part of the LPRM neutron detector (not shown) is connected to one side 101 of the neutron detector hermetic seal device 1, and the neutron detector cable part 102 is connected to the 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.

Here, the ceramic material constituting the insulating connection member 2 is silicon nitride, silicon carbide, aluminum nitride, sialon, alumina or spinel. 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 and 5a of the pipe-shaped metal members 4 and 5 are formed such that the insulating connection member 2 is inserted inside the pipe-shaped metal members 4 and 5 and fitted with the connection fitting surfaces 2a and 2b. I have.

As shown in FIG. 1, the insulated connecting member 2 may have a cylindrical drum-like shape whose diameter is increased symmetrically from both ends toward the center in the longitudinal direction with an increasing degree. It may have a cylindrical drum shape whose diameter increases at different increments from both ends toward the center as shown in FIG. 2, or as shown in FIG. A portion parallel to the axis of the through hole 6 may be formed.

The operation of this embodiment will be described with reference to FIG.

In FIG. 7, a part of the force 9 of the vertical pressing (uniaxial pressing from above and below) acting in the direction of the arrow is converted into a force 9a acting vertically on the connection fitting surfaces 2a, 4a in the fitting portion 7. You. Thereby, the conventional insulated connecting member 10 shown in FIG.
As can be seen from comparison with 3, the pressure is transmitted in the direction in which the joints of the fitting portions 7 are brought into close contact. The same applies to the fitting portion 8. As a result, a good fitting connection can be maintained between the insulated connection member 2 and the pipe-shaped metal members 4, 5.

Next, a second embodiment of the present invention will be described with reference to FIG.

In the hermetic sealing device 1 for a neutron detector shown in FIG. 4, an insulating connecting member 2 made of a ceramic material is used.
Has a truncated cone shape. In the fitting portion 7, as in the case shown in FIG. 1, the connection fitting surface 2a of the insulating connection member 2 is formed on the outer peripheral surface, and the end is fitted into the inside of the pipe-shaped metal member 4. On the other hand, in the fitting portion 8, the end of the pipe-shaped metal member 5 is fitted into a concave portion formed at one end of the insulating connection member 2, and the connection fitting surface 2 b of the insulating connection member 2 is formed.
Is formed on the inner peripheral surface of the recess formed at one end.

The connection fitting surface 2a of the insulating connection member 2 is formed as a tapered surface that tapers toward the distal end with respect to the axial direction of the through hole 6, and the connection fitting surface 2b is formed in the axial direction of the through hole 6. Is formed as a tapered surface that tapers inwardly of the insulating connection member 2. Pipe-shaped metal member 4,
5 are connected to the connection fitting surfaces 2a, 5a, respectively.
2b.

According to the configuration of the embodiment shown in FIG.
As can be understood from the above description with reference to FIG. 7, the pressure is also transmitted to the fitting portion 8 in the direction in which the bonding is brought into close contact, similarly to the case of the fitting portion 7. As a result, a good fitting connection can be maintained between the insulated connection member 2 and the pipe-shaped metal members 4, 5.

Next, FIG. 5 shows a modification of the hermetic sealing device 1 for a neutron detector shown in FIG. In FIG. 5, the insulating connection member 2 is composed of a cylindrical portion and a truncated cone. The fitting part 7 is the same as the example shown in FIG. 4, but the fitting part 8 is different from the example shown in FIG. In FIG.
Connection fitting surface 5a of pipe-shaped metal member 5 in fitting portion 8
The portion to be fitted into the concave portion formed at the end of the insulated connecting member 2 is composed of a cylindrical portion and a truncated cone portion following the tip of the cylindrical portion. Correspondingly, the concave portion formed at the end of the insulated connecting member 2 has a connection fitting surface 2c formed on the cylindrical inner peripheral surface, and further inward from the tip of the cylindrical inner peripheral surface. And a connection fitting surface 2b formed on a conical inner peripheral surface of which the radius decreases gradually.

According to the configuration of the embodiment shown in FIG.
As in the example shown in FIG. 7, pressure is also transmitted to the fitting portion 8 in the direction in which the bonding is brought into close contact, as in the case of the fitting portion 7. As a result, the insulated connecting member 2 and the pipe-shaped metal member 4,
5 can be maintained with a good fitting connection.

In the fitting portion 8 shown in FIG. 5, since the cylindrical connection fitting surface 2c having no taper is formed in the concave portion, the connection can be made without excessively increasing the pipe diameter of the pipe-shaped metal member 5. It is possible to ensure the required angle of inclination of the tapered surface of the fitting surface 2b.

Next, a third embodiment of the present invention will be described.

As shown in FIG. 6, 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, 4b 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 or less.

The connection fitting surfaces 2 a and 2 b of the insulating connection member 2 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.

FIGS. 6 (a), 6 (b) and 6 (c) respectively show the connection 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.

FIG. 6A 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.

FIG. 6B shows a brazing material comprising 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.

FIG. 6 (c) shows the connection between the connection fitting surfaces 2a and 2b 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.

6 (a), 6 (b) and 6 (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 different from that of 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.

If the thickness of the soft metal layer 20 is too large, the stress generated by itself increases, and if it is too thin, 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 reducing thermal stress at the time of joining, it also has an effect of reducing stress generated in a 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, the metal members constituting the pipe-shaped metal members 4 and 5 are made of a low thermal expansion coefficient alloy. 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.

When 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 to 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 can be made smaller, reducing the generation of thermal stress from brazing material,
A highly reliable hermetic sealing device for a neutron detector can be provided.

The thickness of the brazing material, excluding the volume of the pores in the brazing material, is 200 μm or less and 0.01 μm or less.
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.

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 metallizing the ceramic material in advance and using ordinary brazing. The joining may be performed using a material such as a silver braze, a copper braze, a nickel braze, an aluminum braze, or a solder. This metallization is applied to oxide ceramics by applying a paste containing Mo, W, Mn powder or the like, which is generally called the Moriman method, to the ceramic joint surface in advance, and humidifying atmosphere for 1400 mm.
A method in which a ceramic surface is metallized by performing a high-temperature heat treatment at a temperature of not less than ° C. and then Ni plating is applied, but basically the metallization 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 filler metal 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.

Examples of the type of ceramic material constituting the insulating connection member 2 include dense and chemically stable ceramics such as silicon nitride, silicon carbide, aluminum nitride, sialon, alumina, and spinel. From the viewpoint of heat stress resistance, those having high strength of the ceramic itself are desirable, and impurities and sintering aids (SiO ₂ , MgO, Y ₂ O ₃ ,
High-strength ceramics with little Al ₂ O ₃ free Si) are more desirable. Also, if the surface roughness of the ceramics is large, the surface roughness of the surface to be bonded to the metal is at least 10 μm or less in Ra when the surface roughness of the ceramics tends to be a crack generation source of the bonding material.
Desirably, it does not exceed 5 μm.

The contents described in the third embodiment of the present invention are preferably applied in combination with the structure of the first embodiment or the second embodiment.

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

In the following first or second embodiment, the insulating connecting member 2 is formed so as to have a shape corresponding to the hermetic seal shown in FIGS. 1 to 5, and a soft metal layer for relaxing thermal stress. 20 is inserted as an intermediate layer, and the fitting connection with the pipe-shaped metal members 4, 5 is performed by brazing or bonding using an active metal brazing material.

It is important how the embodiments 1 and 2 can form a more airtight joint as compared with the case where the shape of the conventional ceramic material as shown in FIG. 8 is employed.

For ceramics having a relatively large thermal expansion coefficient, such as alumina, by using a metal having a low thermal expansion coefficient for the pipe-shaped metal members 4 and 5, good results can be obtained without the insertion of the soft metal layer 20 as an intermediate layer. And excellent sealing characteristics.

(1) Comparison of Example 1 with Comparative Examples 1 and 2 Table 1 shows Example 1, Table 2 shows Comparative Example 1, and Table 3 shows Comparative Example 2.

In Tables 1 to 3, the item of ceramics indicates the type of ceramic material constituting the insulated connecting member 2, and all types indicate that any of the configurations shown in FIG. 6 may be used. The term “metal” indicates the type of metal material forming the pipe-shaped metal members 4 and 5. The term “intermediate layer” indicates the type and thickness of the metal material constituting the soft metal layer 20 as the intermediate layer. The brazing material section indicates the composition of the brazing material, and the thickness of the brazing material was set to 0.1 to 30 μm. The term "joining temperature" indicates the temperature at which the brazing material is joined, and the term "airtightness" indicates the degree of airtightness obtained from these results.

In the first embodiment, the shape of the insulating connection member 2 made of a ceramic material is changed to the shape shown in FIGS. 1 to 5, and the soft metal layer 20 is used as an intermediate layer. On the other hand, in Comparative Example 1, the shape of the insulated connecting member made of a ceramic material was merely changed to the shape shown in FIGS.
The case where the soft metal layer 20 is not adopted as the intermediate layer is shown.
Comparative Example 2 shows a case where only the soft metal layer 20 is used as the intermediate layer, and the shape of the insulated connecting member is the conventional shape shown in FIG.

In Example 1 or Comparative Example 1, the insulating connecting member 2 was formed into a shape as shown in FIGS. 1 to 5 and alumina (various in purity from 92 to 99%), sialon, silicon nitride (sintering aid) was used. Any of Y ₂ O _3, Al ₂ O ₃ , MgO, etc., containing one or more of them, atmospheric pressure sintering, hot pressing material), silicon carbide (reaction sintering, hot pressing material) or any of these The pipe-shaped metal members 4 and 5 were composed of SUS304 and a component made of 42% Ni-Fe which is a low thermal expansion coefficient alloy. SUS3
For 04, a stress relaxation layer made of pure copper or pure Ni and having a thickness of 0.05 to 3 mm was inserted in the middle. These parts were joined directly by the active metal method, or in the case of alumina or sialon, after the surface was metallized by the Moriman method, and then joined using a normal brazing material.

In Comparative Example 2, the insulated connecting member was formed in the conventional shape shown in FIG. 8, and bonding was performed by the same method in all the configurations shown in FIG.

In the joining by the active metal method, the joining was carried out in a high vacuum on the order of mpa or in an argon atmosphere, and the ordinary brazing was carried out in a vacuum or a forming gas containing hydrogen. The airtightness of the joint was evaluated by a He leak test for all the joining materials. As the brazing material, an alloy brazing material, a powder mixture of a metal constituting the brazing material, or a laminate of thin layers was used, but the results were the same. The amount of the active metal varies depending on the type of the metal to be combined.
Performed at about 50%. The element indicated as Act in Tables 1 to 3 is an active metal or at least one of Ti, Zr, and Hf.

[0076]

[Table 1]

[0077]

[Table 2]

[0078]

As can be seen by comparing Example 1 and Comparative Example 1, it is recognized that the provision of the soft metal layer 20 improves the airtightness.

Further, as can be seen from a comparison between Example 1 and Comparative Example 2, it is recognized that the hermeticity is improved by making the shape of the insulating connection member 2 into the shape shown in FIGS. Can be

(2) Example 2 Example 2 is a result of verifying the effect of the thickness of the brazing material and the effect of the type of the brazing material. Details are shown in Table 4.

In the second embodiment, the insulating connecting member 2 is formed in the shape shown in FIGS.
%, Sialon, silicon nitride (sintering aid Y ₂
O ₃ Others as Al ₂ O ₃ and various those containing one or more of such MgO, pressureless sintering, hot pressing member), silicon carbide (reaction sintering is configured using a hot pressed material) component SUS304 as the pipe-shaped metal members 4 and 5
It is configured using For SUS304, a stress relaxation layer having a thickness of 0.1 to 2 mm or less made of pure copper or pure Ni was inserted in the middle. These parts can be obtained directly by the active metal method, or for alumina and sialon,
After the surface was metallized by the Moriman method, it was joined using a brazing filler metal. In the joining by the active metal method, the joining was performed in a high vacuum on the order of mpa, and the normal brazing was performed in a vacuum or a forming gas containing hydrogen. The airtightness of the joint was evaluated by a He leak test for all the joining materials. Otherwise, the method is the same as in the first embodiment.

[0082]

As can be seen from Example 2, it is recognized that the thickness of the brazing material affects the airtightness, and that the airtightness is improved by setting the thickness of the brazing material to 0.1 to 30 μm.

When the surface roughness exceeds 11 μm in Ra, it is recognized that the airtightness is slightly lowered. Therefore, it can be said that reducing the surface roughness is effective for improving the airtightness.

As described above, according to the embodiment of the present invention, the insulating connecting member 2 and the pipe-like metal members 4, 5 are formed by forming the shape of the insulating connecting member 2 as shown in FIGS. Are fitted and connected to each other, so that the joints can be satisfactorily adhered to each other, and highly airtight joining can be performed by using a minimum necessary brazing material layer. Further, when stainless steel parts having high corrosion resistance are used as metal parts, the soft metal layer 2 is used as an intermediate layer.
By inserting 0, thermal stress can be relieved, and a stress relieving effect can be obtained even when a stress is generated during use. Therefore, the occurrence of cracks in the insulating connecting member 2 made of a ceramic material can be suppressed, and the amount of brazing material can be reduced. The synergistic effect of being kept to a minimum can be obtained, and a highly reliable hermetic seal device for an LPRM neutron detector in which the hermeticity of the joint is good and crack generation is suppressed can be provided.

In the above description, the insulating connecting member 2 is made of a ceramic material. However, the present invention is not limited to this. The insulating connecting member 2 may be made of another member as long as it has electrical insulation.

[0086]

As described above, according to the present invention,
Since the connection fitting surface of the insulated connection member is formed of a tapered surface inclined with respect to the axial direction of the through hole, the insulated connection member and the pipe-shaped metal member can be fitted and connected with high airtightness,
A highly reliable hermetic sealing device for a neutron detector can be provided.

Further, by providing the soft metal layer between the connection fitting surface and the fitting surface of the pipe-shaped metal member, it is possible to provide a more reliable airtight sealing device for a neutron detector.

[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 sectional view showing a modification of the shape of the insulated connecting member in FIG. 1;

FIG. 3 is a sectional view showing another modified example of the shape of the insulated connecting member in FIG. 1;

FIG. 4 is a sectional view showing a second embodiment of the hermetic sealing device for a neutron detector according to the present invention.

FIG. 5 is a sectional view showing a modification of the shape of the insulating connection member in FIG. 4;

FIG. 6 is a cross-sectional view showing a third embodiment of the hermetic sealing device for a neutron detector according to the present invention, showing examples in which the front and back of a soft metal layer are joined in various configurations.

FIG. 7 is a diagram showing that a force acting perpendicular to the connection fitting surface in the fitting portion is generated in the case of the shape of the insulated connection member in FIG. 1;

FIG. 8 is a sectional view showing a conventional airtight sealing device for a neutron detector, and shows that a force acting on a connection fitting surface is in an axial direction of a through hole.

[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 part 8 Fitting part 9 Vertical pressure 20 Soft metal layer 101 Sensor part side 102 Cable

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuo Morishima 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Inside the Yokohama office of Toshiba Corporation (72) Inventor Mikio Izumi Toshiba-cho, Koyuki-ku, Kawasaki-shi, Kanagawa 1 Toshiba R & D Center (72) Inventor Toshiaki Ito 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Toshiba Corporation Yokohama Office (72) Inventor Eiji Seki 1385 Shimoishigami, Otawara-shi, Tochigi Co., Ltd. Toshiba Nasu Electron Tube Factory (72) Inventor Koji Fukutani 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Pref. Toshiba Corporation Yokohama Office (56) References JP-A-57-118078 (JP, A) 3-174370 (JP, A) JP-A-11-295476 (JP, A) JP-A-7-33545 (JP, A) JP-A-62-167041 (JP, A) JP-A-56-1981 41879 (JP, A) JP-A-52-145420 (JP, A) Takuya Otani "Development of a New Hermetic Sealing Part for BWR Neutron Detector", Thermal Nuclear Power, Vol. 50, No. 4, p. 444-450 (1999). (58) Field surveyed (Int. Cl. ⁷ , DB name) G21C 17/10-17/12 C04B 37/02 G01T 3/00, 7/00 JICST file (JOIS)

Claims (11)

(57) [Claims] An insulated connecting member made of a ceramic material having a through hole formed therein through which a cable of a neutron detector is inserted, a pipe-shaped metal member fitted and connected to each end of the insulated connecting member. A connection fitting surface of the insulated connection member is formed of a tapered surface inclined with respect to an axial direction of the through-hole; and 0 between the connection fitting surface and the fitting surface of the pipe-shaped metal member. An airtight seal device for a neutron detector, wherein a soft metal layer having a thickness of 1 mm or more and 2 mm or less is provided. 2. The hermetic sealing device for a neutron detector according to claim 1, wherein said connection fitting surface of said insulating connection member is formed on an inner peripheral surface. 3. The hermetic sealing device for a neutron detector according to claim 1, wherein the connection fitting surface of the insulating connection member is formed on an outer peripheral surface. 4. The hermetic sealing device for a neutron detector according to claim 1, wherein said tapered surface is a tapered surface tapering toward a tip. 5. The hermetic sealing device for a neutron detector according to claim 1, wherein said tapered surface is a tapered surface tapering inward. 6. The hermetic sealing device for a neutron detector according to claim 1, wherein said ceramic material is silicon nitride, silicon carbide, aluminum nitride, sialon, alumina or spinel. 7. 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. 8. A joint thickness between each of the fitting surfaces of the insulated connecting member, the soft metal layer, and the pipe-shaped metal member is set to 0.1.
The hermetic sealing device for a neutron detector according to claim 1, wherein the airtight sealing device is joined by a brazing material having a size of 1 m to 30 m. 9. The brazing material according to claim 1, wherein the active metal is Ti,
The hermetic sealing device for a neutron detector according to claim 8, wherein the brazing material contains at least one of Zr and Hf. 10. The brazing material is pressurized in a vacuum of 0.1 mpa or less and heated and joined.
An airtight sealing device for a neutron detector according to the above. 11. The hermetic sealing device for a 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.