JP5833904B2 - Fast reactor trumpet tube and its joining method - Google Patents

Description

  The present invention relates to a fast reactor trumpet tube (hereinafter sometimes abbreviated as a trumpet tube), and more particularly to a welded structure of different materials at an open end of a trumpet tube.

  In the fast reactor fuel assembly, a large number of fuel cladding tubes around which spacer wires are wound are loaded into a trumpet tube-shaped trumpet tube. A handling head and an entrance nozzle are joined to the upper and lower portions of the trumpet by welding, respectively.

  In the conventional fast reactor fuel assembly, the trumpet pipe, the handling head, and the entrance nozzle are all made of austenitic stainless steel. However, in recent years, high burnup of fuel has been demanded from the viewpoint of economy and the like, and it has become necessary to apply ferritic stainless steel, which has higher swelling resistance than austenitic stainless steel, as a material for a trumpet tube. .

  To apply a ferritic stainless steel trumpet tube, it is necessary to weld an austenitic stainless steel handling head or entrance nozzle. If a δ ferrite structure is generated in the weld, the reactor is in operation. In addition, there is a high possibility that the welded portion becomes brittle, and there is a problem that the mechanical strength cannot be maintained due to a decrease in impact characteristics.

  Therefore, it is necessary to perform heat treatment to eliminate the δ ferrite structure. However, the length of the trumpet tube to which the handling head and the like are joined is about 4200 mm in the case of the fast reactor “Monju”, and a large heat treatment furnace is required.

  In order to solve the technical problems as described above, a method of providing a joint portion made of austenitic stainless steel in advance on a trumpet tube (see Patent Documents 1 and 2 below), or a mechanical member of an austenitic stainless steel joint member is mechanically provided. A joining method (see Patent Documents 3 and 4 below) has been proposed.

Japanese Patent No. 3572285 JP-A-7-260973 Japanese Patent No. 4229289 Japanese Patent No. 3117285 "Development of dissimilar material welding technology between PNC-FMS steel trumpet pipe and SUS316 steel" Cycle Organization Technical Report No.13, December 2001

  19 and 20 are views for explaining the joint structure between the trumpet pipe and the handling head proposed in Patent Document 3, and FIG. 19 is an exploded perspective view of the upper part of the trumpet pipe, the joint member, and the handling head. FIG. 20 is an enlarged cross-sectional view showing the joining structure of the upper portion of the trumpet tube, the joint member, and the handling head.

  As shown in these drawings, a trumpet pipe 51 made of ferritic stainless steel and a handling head 52 made of austenitic stainless steel are joined via a joint member 53 made of austenitic stainless steel.

  As shown in FIG. 19, the lower end fitting portion 54 of the joint member 53 having the same hexagonal tube shape is fitted inside the upper end opening portion of the hexagonal tube shape of the trumpet tube 51, and is formed on the flat portion of the trumpet tube 51. Then, the screw 57 is inserted and tightened from the screw hole 55 toward the screw hole 56 formed in the flat portion of the joint member 53 to mechanically connect the trumpet pipe 51 and the joint member 53.

  Furthermore, the same hexagonal pipe-shaped handling head 52 is inserted inside the upper end opening of the joint member 53, and TIG welding 58 (see FIG. 20) is used to connect the two joints. The structure is such that the trumpet pipe 51 and the handling head 52 are joined.

The method of providing a joint portion made of austenitic stainless steel in advance on the trumpet tube and the method by mechanical joining have the following technical problems.
(1) Method of providing an austenitic stainless steel joint on a trumpet tube In the normal trumpet tube manufacturing process, a step of welding and heat-treating the joint in the state of a round tube is added, which increases the number of processes. This will lead to price increases for trumpet tubes. It is necessary to suppress the price increase of the trumpet pipe as much as possible.

(2) Method of mechanically joining an austenitic stainless steel joint member to the trumpet pipe The joint strength between the trumpet pipe and the handling head depends on the shear stress of the joint member, but the screws shown in FIGS. 19 and 20 In the case of the tightening structure, even if a predetermined bonding strength is obtained in the vicinity of the screw 57, a sufficient bonding strength cannot be obtained at a place away from the screw 57.

  Furthermore, there is a concern that the screw 57 may be loosened or detached due to deterioration due to radiation or fluid vibration caused by cooling agent sodium, so that the soundness of the joined state cannot be maintained, and sodium leakage from the screw holes 55 and 56 may occur. .

  Welding between tubes is a commonly used technology, but fast reactor trumpet tubes have a special hexagonal shape, so the following technologies can be achieved simply by butt welding the trumpet tube and the joint member. Problems arise.

(1) Since the trumpet tube is manufactured by drawing, its cross-sectional dimension may deviate from a regular hexagon. On the other hand, since the joint member is manufactured by drawing or cutting, its cross-sectional dimension may not match that of the trumpet tube. For this reason, the joint surface of the trumpet pipe and the joint member is not constant, and a step or the like may occur.

  Furthermore, the metal melted by welding may move to the inner surface side, the molten bead shape on the inner and outer surfaces may become unstable, and welding defects such as undercut and poor penetration may occur. In particular, since the trumpet tube is a strength member of the fast reactor fuel assembly, it is not preferable that the thickness of the trumpet tube is reduced due to a welding defect.

(2) Since the trumpet pipe and the joint member are polygonal pipes such as hexagonal pipes, when rotating welding with the center of the polygonal pipe as the central axis, if electron beam welding, the distance from the electron gun, If tungsten-inert gas welding (TIG welding) is used, the distance from the electrode is not constant, and unless the welding conditions are always controlled according to the rotation angle, a stable weld cannot be obtained. Undercuts may occur.

(3) When restraining the trumpet pipe or joint member in order to prevent welding deformation, the wall thickness of the trumpet pipe or joint member is relatively thin (in the case of a trumpet pipe for a fast experimental reactor, for example, the outer facing distance is about 80 mm. On the other hand, the thickness is about 2 mm), it is difficult to fix firmly, and it is difficult to prevent bending after welding.

  An object of the present invention is to solve such problems of the prior art, and to provide a fast reactor trumpet tube and a method for joining the trumpet tube which are less likely to bend after welding and have high reliability.

In order to achieve the above object, the first means of the present invention comprises:
In the fast reactor trumpet tube that welds and integrates the open end of the joint tube to the open end of the trumpet tube,
The trumpet tube has a hexagonal outer shape and is composed of ferritic stainless steel,
The joint pipe has the same hexagonal outer shape as the trumpet pipe and is made of austenitic stainless steel. The abutting surface with which the opening end surface of the trumpet pipe abuts the opening end thereof, and A centering tube portion extending in the axial direction of the trumpet tube continuously from the contact surface;
The open end of the wrapper tube fitted along the centering cylinder portion of the joint tube, the open end of the wrapper tube abutting surface of the joint tube while abutting, of the wrapper tube it is characterized in that the open end faces and welding the abutting surfaces of the joint tube.

According to a second means of the present invention, in the first means,
A thickness t2 in the tube diameter direction of the centering tube portion of the joint tube is thicker than a thickness t1 in the tube diameter direction of the trumpet tube (t2> t1).

A third means of the present invention is the first or second means,
The centering tube portion is formed on the radially inner side of the joint tube body, and the open end portion of the trumpet tube is fitted from the radially outer side of the centering tube portion.

According to a fourth means of the present invention, in any one of the first to third means,
A trumpet tube fitting guide portion is provided on the outer periphery of the tip portion of the centering tube portion on the trumpet tube side.

According to a fifth means of the present invention, in the third means,
Has a hexagonal inner peripheral shape of the centering cylinder unit is similar to the outer shape of the joint tube, characterized in that the thickness t2 of the tubular body radially of the centering cylinder portion is approximately equal on each side It is what.

The sixth means of the present invention includes
A trumpet tube having a hexagonal outer shape and made of ferritic stainless steel, and a hexagonal outer shape that is the same as the trumpet tube, made of austenitic stainless steel, and at the opening end that is one end For fast reactors, in which the abutting surface with which the opening end surface of the trumpet tube abuts and the joint pipe body having a centering tube portion extending in the axial direction of the trumpet tube continuously from the abutting surface are welded and integrated. A method for joining trumpet pipes,
A first step of abutting the open end of the wrapper tube fitted along the centering cylinder portion of the joint tube, the open end of the wrapper tube abutting surface of the joint tube,
Is performed after the first step, a second step of welding the abutting surface of the joint pipe body and the opening end face of said wrapper tube,
The performed after the second step and is characterized in that it comprises a third step of heat treating the assembly of the joint tube body and the wrapper tube.

The seventh means of the present invention is the sixth means,
A fourth step of removing the centering tube portion after the second step is further included.

  The present invention is configured as described above, and can provide a fast reactor trumpet tube and a joining method thereof with less bend after welding and high reliability.

  In particular, in the welding process, welding is not performed with the "wrapper tube thickness" but with the "wrapper tube thickness" + "weld joint thickness", making it easy to set welding conditions and improving the reliability of welding. Can be improved.

  Also, unlike the mechanical connection using screws, etc., the connection between the trumpet pipe and the joint member, and the joint member and the handling head is unnecessary, and it is possible to join at a low cost because it is a joint only by welding. it can.

  Furthermore, in the present invention, since all the joints are welded, holes for screws and the like are unnecessary, and the shape is very simplified, so that it is a necessary coolant in fuel for fast reactors and the like. Sodium decontamination work and decontamination work after radioactive contamination can be easily performed.

It is the front view which made a section of a trumpet pipe concerning the example of the present invention a section. It is a left view of the trumpet tube. It is the front view which made a part of joint pipe a section. It is a left view of the joint pipe body. It is the front view which made a cross section the part of the joined body of the trumpet pipe and the joint pipe body integrated by welding. It is a left view of the joined body. It is an expanded sectional view near the welding part of a trumpet pipe and a joint pipe body. It is the front view which made a cross section a part of joined body after cutting and removing the centering cylinder part. It is a left view of the joined body. It is a figure which shows the result of having measured the bending of the joined body of the trumpet pipe and a joint pipe body after welding. It is a front view for demonstrating the apparatus which measures the bending of the conjugate | zygote, and its measuring method. It is a side view for demonstrating the measuring apparatus and the measuring method. It is a figure for demonstrating how to determine the curvature of the joined body. 1 is an exploded cross-sectional view of a fast reactor fuel assembly according to an embodiment of the present invention. It is a flowchart for demonstrating the joining procedure of the fuel assembly for fast reactors. It is the front view which made a part of joint pipe concerning the 1st modification of the present invention a section. It is a left view of the joint pipe body. It is principal part sectional drawing which shows the state before and behind welding in the joining body of the trumpet pipe and joint pipe body which concerns on the 2nd modification of this invention. It is a disassembled perspective view of the upper part of a trumpet pipe proposed conventionally, a joint member, and a handling head. It is an expanded sectional view which shows the joining structure of the upper part of the trumpet pipe, a joint member, and a handling head.

  The present invention has the configuration as described above, and the fitting member (joint tube body) has a fitting structure (centering tube portion) with the trumpet tube, and the fitting structure portion after welding of the trumpet tube and the fitting member. As a result, the joint member has the same cross-sectional dimension as the trumpet tube, and a fast reactor trumpet tube with high dimensional accuracy can be obtained.

  Specifically, a stepped portion composed of a later-described side tube portion having the same size portion as the trumpet tube and a later-described abutting surface and a centering tube portion for fitting the trumpet tube to the joint member. The part which has is provided. The outside facing dimension of the step portion is matched to the inside facing dimension of the trumpet tube.

For joining the trumpet tube and the joint member, the trumpet tube is fitted to the step portion of the joint member, the centers of the trumpet tube and the joint member are matched, and then welding is performed by an appropriate method such as electron beam welding or TIG welding.
After joining the trumpet tube and the joint member, the protruding stepped portion of the joint member is deleted by an appropriate method such as cutting.
The δ ferrite structure generated by welding is extinguished by heat treatment either before or after cutting.

  As a result, the welding between the trumpet tube and the handling head or between the trumpet tube and the entrance nozzle is austenitic stainless steel, which can be welded by a conventional welding method.

Next, a fast reactor trumpet tube according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a front view of a trumpet pipe having a part in cross section, FIG. 2 is a left side view of the trumpet pipe, FIG. 3 is a front view of a joint pipe having a part in cross section, and FIG. Left side view, FIG. 5 is a front view in which a part of the joint of the trumpet pipe and the joint pipe body integrated by welding is cut, FIG. 6 is a left side view of the joint body, and FIG. 7 is the trumpet pipe and the joint. FIG. 8 is an enlarged cross-sectional view of the vicinity of the welded portion of the tube, FIG. 8 is a front view of a cross-section of a part of the joined body after cutting and removing the centering tube portion protruding inward after welding, and FIG. It is a left side view.

As shown in FIG. 1 and FIG. 2, the trumpet tube 1 is formed of a hexagonal tube, and has open end portions 2a and 2b at both ends. The trumpet tube 1 is manufactured by drawing. In this embodiment, the outer facing distance of the trumpet tube 1 is about 80 mm, and the radial thickness t1 is about 2 mm.
For the trumpet tube 1, ferritic stainless steel is used in order to improve swelling resistance. In this embodiment, ferritic / martensitic steel having the following chemical components is used.

C: 0.09 to 0.15 (% by weight)
Cr: 10.0 to 12.0 (% by weight)
Si: ≦ 0.10 (% by weight),
Mo: 0.30 to 0.70 (% by weight),
Mn: 0.40 to 0.80 (% by weight),
W: 1.70-2.30 (wt%),
P: ≦ 0.030 (% by weight)
V: 0.15-0.25 (% by weight),
S: ≦ 0.030 (% by weight),
Nb: 0.020 to 0.080 (wt%),
Ni: 0.20 to 0.60 (% by weight),
N: 0.030 to 0.070 (% by weight)
The remainder: Fe and inevitable impurities.

  The joint pipe 3 is welded to the open ends 2a or 2b on both sides of the trumpet 1. The joint pipe body 3 also has a side tube portion 4 having a hexagonal outer shape as in the case of the trumpet tube 1, and an open end surface 5 (see FIG. 1 and the abutting surface 6 and the centering tube portion 7 are provided adjacent to each other in the thickness direction along the radial direction of the joint tube body 3.

  In the case of the present embodiment, as shown in FIG. 3, the centering cylinder portion 7 is provided on the radially inner side of the abutting surface 6, and a wrapper is provided between the abutting surface 6 and the outer peripheral surface of the centering cylinder portion 7. A step 8 having substantially the same size as the wall thickness t1 of the tube 1 is formed.

  As shown in FIG. 5, the centering tube portion 7 extends in the axial direction of the trumpet tube 1, and the radial thickness t <b> 2 of the centering tube portion 7 is set larger than the radial thickness t <b> 1 of the trumpet tube 1. (In the case of this embodiment, 4 to 5 mm), the trumpet tube 1 has a mechanical strength that can be securely held when the trumpet tube 1 is fitted to the centering tube portion 7.

Further, the outer peripheral shape and the outer dimension of the centering tube portion 7 are set to be substantially the same as the inner peripheral shape and the inner dimension of the trumpet tube 1. Further, the perpendicularity between the abutting surface 6 and the outer peripheral surface of the centering tube portion 7 is ensured with high accuracy.
The joint pipe body 3 is made of the same austenitic stainless steel (for example, SUS316) as a handling head 14 and an entrance nozzle 15 (both see FIG. 14) described later.

  As shown in FIG. 5, one open end 2 a of the trumpet tube 1 is fitted on the centering tube portion 7. In order to perform this fitting smoothly, a round or tapered trumpet tube fitting guide portion 9 is provided on the outer periphery of the tip portion of the centering tube portion 7 on the trumpet tube side.

  By fitting the trumpet tube 1 to the centering tube portion 7 in this manner, the open end surface 5 of the trumpet tube 1 abuts against the abutting surface 6 of the joint tube body 3, and the trumpet tube 1 is in contact with the joint tube body 3. The tube 1 is not tilted, and the trumpet tube 1 is securely held in the same direction by the centering tube portion 7 so that the center axes of the trumpet tube 1 and the joint tube 3 are aligned.

  In this state, the joint 10 between the opening end face 5 of the trumpet pipe 1 and the abutting face 6 of the joint pipe body 3 is welded 10. For example, electron beam welding or tungsten-inert gas welding (TIG welding) is applied to the welding 10. The weld 10 is applied over the entire circumference of the joint portion between the trumpet pipe 1 and the joint pipe body 3 while rotating the joint body between the trumpet pipe 1 and the joint pipe body 3.

  FIG. 7 is an enlarged cross-sectional view of the vicinity of the welded portion between the trumpet pipe 1 and the joint pipe body 3. This figure is a diagram of an enlarged photograph of the welded portion. As is apparent from this figure, the penetration by welding 10 extends from the outer surface of the trumpet tube 1 and the joint tube 3 to the centering tube portion 7. Therefore, there are no problems such as undercut and poor penetration.

In the state in which the trumpet tube 1 and the joint tube 3 are welded, as shown in FIG. 5, the centering tube portion 7 protrudes inward in the joint tube 3 and is shown by a one-dot chain line in FIG. The centering tube portion 7 is removed to the position of the cutting line 11 by cutting. FIG. 8 and FIG. 9 show the state after the cutting process, and the inner surfaces of the trumpet pipe 1 and the joint pipe body 3 are flush with each other.
In this embodiment, the centering tube portion 7 is removed, but if the centering tube portion 7 does not get in the way, the centering tube portion 7 may be left as it is.

  The δ ferrite structure generated by the dissimilar material welding 10 can be eliminated by heat treatment before or after cutting. As a heat treatment, it has been experimentally confirmed that if the welded portion is normalized at 1050 ° C. for 10 minutes or more, the δ ferrite structure generated in the vicinity of the welded portion disappears almost completely.

  FIG. 10 is a diagram showing the result of measuring the bending of the joined joint of the trumpet pipe 1 and the joint pipe body 3 after welding. The general technique in FIG. This is a conventional method in which a joint pipe having a hexagonal pipe shape and a trumpet pipe are butt welded.

11 and 12 are a front view and a side view for explaining an apparatus for measuring the bending of the joined body and a measuring method thereof.
The points (1) to (8) shown in FIG. 11 indicate the measurement points on the joined body, and the points (6) and (7) are both the welded portions of the trumpet pipe 1 and the joint pipe body 3. It is a position 5 mm away from the center of the welding beat at the side position.

Next, a bending measuring method will be described.
1. A joined body of the trumpet pipe 1 and the joint pipe body 3 is placed horizontally on the base 12.
2. As shown in FIG. 12, the linear gauge 13 is attached to the measurement arm 14, and the linear gauge 13 is brought into contact with a substantially central position of the upper surface (hexagonal surface 1 in the figure) of the joined body. The measurement point (1) is “0” (reference point).
3. The linear gauge 13 is moved along the axial direction of the joined body, and the positions of the points (2) to (8) are measured.

4). The measurement points (1) to (8) are plotted as shown in FIG. 13, and the points (1) and (8) are connected by a straight line.

5. Of the widths from the straight line to the measurement points (2) to (7), the maximum width is the curvature of the surface. In the example of FIG. 13, since the point (4) is farthest from the straight line, the value of the point (4) is the curvature dimension of the surface.

6). The six surfaces of the joined body are sequentially measured by the measurement methods 1 to 5 described above, and the maximum value of the bending dimension from each surface is taken as the bending dimension of the joined body. In the method according to the present invention shown in FIG. 10, since the value 0.09 mm of the hexagonal surface 3 is the maximum value, the value becomes the bending dimension of the joined body.

  As is apparent from the measurement results of FIG. 10, the bent dimension of the joined body is 0.17 mm (hexagonal surface 2) in the conventional method according to the general technique, whereas the method according to the present invention is used. The bending dimension of the joined body was 0.09 mm (hexagonal surface 3), and the bending dimension of the joined body could be reduced by about 47% compared to the conventional art. Further, when viewed from the average value, the average bending dimension of the joined body is 0.11 mm in the case of a method according to a general technique, whereas the average bending dimension of the joined body is 0.06 mm in the case of the method according to the present invention. Thus, the average bending dimension of the joined body could be reduced by about 45% compared to the conventional case.

  This low bending of the joined body means that the joined body has a high straightness, so that it does not hinder the loading of the fuel cladding tube, etc., and further, it is the starting point of poor welding or destruction of the joined body. It means that there is almost no, and it is a highly reliable fast reactor trumpet tube.

  As shown in FIG. 14, the joint tube 3 a and the joint tube 3 b made of austenitic stainless steel (for example, SUS316) are welded to both ends of the trumpet tube 1. A handling head 14 made of the same austenitic stainless steel (for example, SUS316) is welded to the joint pipe body 3a, and an entrance nozzle 15 made of the same austenitic stainless steel (for example, SUS316) is welded to the joint pipe body 3b. A fuel assembly for a fast reactor is formed.

  Since the joint pipe body 3a and the handling head 14 and the joint pipe body 3b and the entrance nozzle 15 are both made of the same material, no δ ferrite structure is generated in the vicinity of the welded portion, such as electron beam welding or TIG welding. It can weld by an appropriate method.

  FIG. 15 is a flowchart summarizing the procedure for joining the fuel assemblies for a fast reactor according to the embodiment of the present invention.

S1: The abutting surface 6 and the centering tube portion 7 are formed at the opening end of the joint tube 3.
S2: The open end portions on both sides of the trumpet tube 1 are fitted into the centering tube portions 7 of the joint tube body 3, and the open end surface 5 of the trumpet tube 1 is brought into contact with the abutting surface 6 of the joint tube body 3.
S3: The opening end face 5 of the trumpet pipe 1 and the abutting face 6 of the joint pipe body 3 are welded.
S4: The centering tube portion 7 of the joint tube 3 is removed by cutting.
S5: The joined body of the trumpet pipe 1 and the joint pipe body 3 is heat-treated.
S6: The handling head 14 is welded to one joint pipe body 3a, and the entrance nozzle 15 is welded to the other joint pipe body 3b.

  In addition, if the centering cylinder part 7 does not get in the way, the cutting removal process (S4) of the centering cylinder part 7 is unnecessary. Moreover, it is also possible to put the heat treatment process of the joined body of S5 between the welding process of S3 and the cutting process of the centering tube portion 7 of S4.

  16 and 17 are views showing the joint pipe body 3 according to the first modification of the present invention. FIG. 16 is a front view of a part of the joint pipe body 3, and FIG. FIG. In this modified example, the difference from the joint tube 3 shown in FIGS. 3 and 4 is that the shape of the inner periphery of the centering tube portion 7 is circular.

  However, if the inner circumference of the centering tube portion 7 is made circular, the thin portion t2 and the thick portion of the centering tube portion 7 can be alternately formed, and when the centering tube portion 7 is cut, the thickness changes. Therefore, there is a difficulty that cutting is difficult. 3 and 4, the inner peripheral shape of the centering tube portion 7 is the same polygon as the outer shape of the joint tube portion 3, and the center tube portion 7 When the thickness t2 is substantially equal on each side, the cutting process of the centering tube portion 7 is easy.

  FIG. 18 is a view showing a state before and after welding in the joint of the trumpet pipe 1 and the joint pipe body 3 according to the second modified example of the present invention, and FIG. FIG. 4B is a cross-sectional view of the main part showing the state after welding.

  5 and FIG. 8 is different from the embodiment shown in FIGS. 5 and 8 in that the centering cylinder portion 7 is provided on the outside in the radial direction of the abutting surface 6 as shown in FIG. It is. Therefore, in the case of this modification, the shape and size of the inner periphery of the centering tube portion 7 are substantially the same as the shape and size of the outer periphery of the trumpet tube 1.

  As shown in FIG. 18 (a), the opening end 2 a of the trumpet tube 1 is fitted inside the centering tube portion 7, and the opening end surface 5 of the trumpet tube 1 is brought into contact with the abutting surface 6 of the joint tube body 3. The trumpet tube 1 is positioned, and the welded portion 10 is welded over the entire circumference of the joint between the opening end surface 5 and the abutting surface 6.

  Thereafter, as shown in FIG. 18B, the centering tube portion 7 of the joint tube 3 is ground and removed so that the outer peripheral surface of the trumpet tube 1 and the outer peripheral surface of the joint tube 3 are flush with each other. In the case of this modification, since the centering tube portion 7 of the joint tube 3 is exposed to the outside, the grinding operation is simple. In that case, since it can grind | polish in the state centered by the trumpet pipe part, there exists an effect which reduces the bending amount of a joined body more.

1: trumpet tube,
2a, 2b: open ends,
3, 3a, 3b: joint pipe,
4: Side tube,
5: Open end face,
6: Abutting surface,
7: Centering tube,
8: Stepped part,
9: Trumpet pipe fitting guide,
10: welding,
11: Cutting line,
14: Handling head,
15: Entrance nozzle,
t1: Wall thickness of the trumpet tube,
t2: Thickness of the centering tube part.

Claims (7)

In the fast reactor trumpet tube that welds and integrates the open end of the joint tube to the open end of the trumpet tube,
The trumpet tube has a hexagonal outer shape and is composed of ferritic stainless steel,
The joint pipe has the same hexagonal outer shape as the trumpet pipe and is made of austenitic stainless steel. The abutting surface with which the opening end surface of the trumpet pipe abuts the opening end thereof, and A centering tube portion extending in the axial direction of the trumpet tube continuously from the contact surface;
The open end of the wrapper tube fitted along the centering cylinder portion of the joint tube, the open end of the wrapper tube abutting surface of the joint tube while abutting, of the wrapper tube fast reactor for trumpet, characterized in that the open end faces and welding the abutting surfaces of the joint tube. In the fast reactor trumpet tube according to claim 1,
A fast tube tube for a fast reactor, wherein the tube tube radial thickness t2 of the joint tube is thicker than the tube tube radial wall thickness t1 (t2> t1). . The fast reactor trumpet tube according to claim 1 or 2,
The fast reactor trumpet tube, wherein the centering tube portion is formed on a radially inner side of the joint tube body, and an open end portion of the trumpet tube is fitted from a radially outer side of the centering tube portion. In the fast reactor trumpet tube according to any one of claims 1 to 3,
A fast tube reactor tube, wherein a trumpet tube fitting guide portion is provided on an outer periphery of a tip portion of the centering tube portion on the wrapper tube side. In the fast reactor trumpet tube according to claim 3,
Has a hexagonal inner peripheral shape of the centering cylinder unit is similar to the outer shape of the joint tube, characterized in that the thickness t2 of the tubular body radially of the centering cylinder portion is approximately equal on each side A fast tube for fast reactor. A trumpet tube having a hexagonal outer shape and made of ferritic stainless steel, and a hexagonal outer shape that is the same as the trumpet tube, made of austenitic stainless steel, and at the opening end that is one end For fast reactors, in which the abutting surface with which the opening end surface of the trumpet tube abuts and the joint pipe body having a centering tube portion extending in the axial direction of the trumpet tube continuously from the abutting surface are welded and integrated. A method for joining trumpet pipes,
A first step of abutting the open end of the wrapper tube fitted along the centering cylinder portion of the joint tube, the open end of the wrapper tube abutting surface of the joint tube,
Is performed after the first step, a second step of welding the abutting surface of the joint pipe body and the opening end face of said wrapper tube,
The performed after the second step, the bonding method of the fast reactor for trumpet, characterized in that it comprises a third step of heat treating the assembly of the joint tube body and the wrapper tube. In the joining method of the fast reactor trumpet tube according to claim 6 ,
A fast reactor trumpet joining method further comprising a fourth step of removing the centering tube portion after the second step .