JP2019150855A - Welding method and radioactive material storage device - Google Patents

Abstract

To provide a welding method capable of achieving an excellent weld quality by suppressing generation of distortion caused by weld heat in dissimilar metal welding; and to provide a radioactive material storage container manufacturable by using the method.SOLUTION: A welding method includes steps of: executing tack weld to a plurality of first temporary positions specified at each first interval on a weld line; specifying a second temporary position between adjacent first temporary positions, and executing tack weld from the second temporary position on the center side of the weld line toward the second temporary position on the outside of the weld line; and executing main welding.SELECTED DRAWING: Figure 8

Description

  The present disclosure relates to a welding construction method for constructing welding between members having different thermal conductivities, and a radioactive substance storage container that can be manufactured using the method.

  2. Description of the Related Art A radioactive substance storage container called a cask is known as a container for storing a radioactive substance (for example, spent nuclear fuel) handled in a nuclear reactor or the like. In this type of radioactive substance storage container, in order to release the decay heat generated from the radioactive substance stored inside, the main body cylinder for storing the radioactive substance and the outer cylinder coaxially arranged outside the main body cylinder Heat transfer fins are provided between them. Such a heat transfer fin is formed of a material having excellent thermal conductivity such as copper, and is welded to a main body body formed of carbon steel, stainless steel, or the like.

  Since stainless steel, carbon steel, etc. and copper have different thermal conductivities and are difficult to dissolve in each other, these dissimilar material welds are not compatible, and even if the penetration is deep, weld cracks are likely to occur. Thus, Patent Document 1 discloses that the quality of dissimilar material welding is improved by adopting composite welding in which one molten pool is formed by a TIG arc and a MIG arc. Moreover, in patent document 2, before constructing main welding by composite welding like patent document 1, it describes improving the weldability of dissimilar material welding by constructing temporary welding, and preventing a weld crack. Yes.

Japanese Patent Laid-Open No. 2006-11845 Japanese Patent Laid-Open No. 2006-107305

  In the said patent document 2, temporary welding is applied with respect to the temporary attachment position set with the predetermined space | interval on the welding line where this welding is applied. Although such temporary attachment positions are set at equal intervals on the weld line, depending on the order of temporary welding for each temporary attachment position, distortion due to welding heat occurs in the heat transfer fin having a longitudinal shape. There is a risk that. In particular, when a copper heat transfer fin is welded to a main body copper such as stainless steel or carbon steel, heat is likely to accumulate on the heat transfer fin side having excellent thermal conductivity, and distortion is likely to occur in the heat transfer fin.

  At least one embodiment of the present invention has been made in view of the above circumstances, and a welding construction method capable of realizing good welding quality by suppressing generation of distortion due to welding heat in dissimilar material welding, and the method It aims at providing the radioactive substance storage container which can be manufactured using.

(1) In order to solve the above problems, a welding method according to at least one embodiment of the present invention is
A welding construction method for welding a joint portion formed by abutting an end face along a longitudinal direction of a first member having a longitudinal shape with a second member having a thermal conductivity smaller than that of the first member. ,
On the weld line from the welding start position to the welding end position of the joint portion to be welded, a step of performing tack welding on a plurality of first tack positions defined for each first interval;
At least one second temporary attachment position is defined between each of the adjacent first temporary attachment positions, and the second temporary attachment position outside the weld line from the second temporary attachment position on the center side of the weld line. A process of performing tack welding toward the tacking position;
Applying main welding along the weld line including the first temporary attachment position and the second temporary attachment position;
Is provided.

  According to the above method (1), prior to the actual welding, the temporary welding is performed in order over the first temporary position and the second temporary position over two stages. The first tack position is set at a wider interval on the weld line than the second tack position, and by performing tack welding, accurate positioning can be performed while suppressing distortion due to welding heat. . One second temporary attachment position is set on the weld line at a narrower interval than the first temporary attachment position, and the second temporary attachment position located outside the weld line from the second temporary attachment position on the center side of the weld line. Temporary welding is performed toward the attachment position. Thereby, the distortion which arises at the time of construction of temporary welding can be escaped toward the outer side from the center side of a welding line, and it can prevent effectively that the crack of temporary welding is generated at the time of construction of main welding.

(2) In some embodiments, in the method of (1) above,
Temporarily setting a temporary attachment position at predetermined intervals on the weld line,
The temporary attachment position that is located at each first interval larger than the predetermined interval among the temporary attachment positions is set as the first temporary attachment position,
The remaining temporary attachment positions excluding the first temporary attachment position are set as second temporary attachment positions.

  According to the method (2), the first temporary attachment position and the second temporary attachment position can be accurately set on the weld line.

(3) In some embodiments, in the above method (1) or (2),
The main welding is formed by dividing a weld bead along the weld line into a plurality of sub-beads,
Both end portions of the sub beads correspond to the first temporary attachment position or the second temporary attachment position.

  According to the method (3), in the main welding, the weld bead along the weld line is formed by being divided into a plurality of sub-beads. Thereby, the distortion which generate | occur | produces with welding heat can be reduced effectively. In particular, each sub bead is formed so that both end portions thereof correspond to the first temporary attachment position or the second temporary attachment position, so that the molten pool at the time of forming the sub bead can be stopped at each temporary attachment position, Generation | occurrence | production of the poor fusion in a temporary attachment position can be prevented suitably.

(4) In some embodiments, in the method of (3) above,
The adjacent sub beads are formed to overlap each other at the first temporary attachment position or the second temporary attachment position.

  According to the above method (4), the adjacent sub-beads are formed so as to overlap each other at the temporary attachment position, whereby the occurrence of poor fusion at the temporary attachment position can be suitably prevented.

(5) In some embodiments, in the above method (3) or (4),
The main welding is performed so that the two continuously formed sub-beads are not adjacent to each other.

  According to the method of (5) above, the plurality of sub-beads are formed in the main welding so that the two sub-beads that are continuously formed are not adjacent to each other. Thereby, the welding heat which generate | occur | produces at the time of construction of this welding can be disperse | distributed over the whole welding line, and generation | occurrence | production of the distortion by welding heat can be prevented more effectively.

(6) In some embodiments, in the method of (5) above,
A first sub bead is formed at both ends of the weld line, and then a second sub bead is formed between the first sub beads.

  According to the method of (6) above, the first sub-bead is first formed at both ends of the weld line, and then the second sub-bead is formed between the first sub-beads, so that the distortion generated during the construction of the main welding can be reduced. It can be mitigated and the occurrence of weld cracks can be effectively prevented.

(7) In order to solve the above problems, a welding method according to at least one embodiment of the present invention,
A welding construction method for welding a joint portion formed by abutting an end face along a longitudinal direction of a first member having a longitudinal shape with a second member having a thermal conductivity smaller than that of the first member. ,
On the weld line from the welding start position to the welding end position of the joint portion to be welded, a step of applying tack welding to the tacking position defined for each predetermined interval;
The step of performing main welding by dividing the weld bead along the weld line into a plurality of sub-beads corresponding to the temporary attachment positions at both ends, and
Is provided.

  According to the method (7), when the main welding is performed after the temporary welding, the weld bead along the weld line is divided into a plurality of sub beads. Thereby, the distortion which generate | occur | produces with welding heat can be reduced effectively. In particular, each sub-bead is formed so that both end portions thereof correspond to the respective tacking positions, so that the molten pool at the time of forming the sub-beads can be stopped at each tacking position. Generation | occurrence | production can be prevented suitably.

(8) In some embodiments, in the method of (7) above,
The adjacent sub beads are formed so as to overlap each other at the temporary attachment position.

  According to the above method (8), the adjacent sub-beads are formed so as to overlap each other at the temporary attachment position, whereby the occurrence of poor fusion at the temporary attachment position can be suitably prevented.

(9) In some embodiments, in the method of (7) or (8) above,
The main welding is performed so that the two continuously formed sub-beads are not adjacent to each other.

  According to the method of (9) above, the formation of the plurality of sub beads in the main welding is performed so that two continuously formed sub beads are not adjacent to each other. Thereby, the welding heat which generate | occur | produces at the time of construction of this welding can be disperse | distributed over the whole welding line, and generation | occurrence | production of the distortion by welding heat can be prevented more effectively.

(10) In some embodiments, in the method of (9) above,
A first sub bead is formed at both ends of the weld line, and then a second sub bead is formed between the first sub beads.

  According to the method of (10) above, the first sub-bead is first formed at both ends of the weld line, and then the second sub-bead is formed between the first sub-beads, so that the distortion generated during the construction of the main welding can be reduced. It can be mitigated and the occurrence of weld cracks can be effectively prevented.

(11) In some embodiments, in any one of the above methods (1) to (10),
The first member is a heat transfer fin that is disposed to be inclined with respect to the radial direction of the main body cylinder between the main body cylinder and an outer cylinder that is coaxially disposed outside the main body cylinder.
The second member is a main body barrel capable of storing a radioactive substance therein.

  According to the above method (11), it is possible to suitably carry out the welding of the main body drum constituting the radioactive substance storage container and the heat transfer fins.

(12) In some embodiments, in the method of (11) above,
The joint portion is a fillet joint portion on the acute angle side formed by the outer surface of the body trunk and the heat transfer fin.

  According to the method of said (12), the above-mentioned welding construction method is applied to the acute angle side among fillet joint parts formed by the outer surface of the main body shell and the heat transfer fin. Thereby, favorable weld quality is realizable in the fillet joint part of the acute angle side where the throat thickness of a weld part becomes large compared with the obtuse angle side.

(13) In some embodiments, in the method of (11) above,
The joint portion is an obtuse fillet joint portion formed by the outer surface of the body trunk and the heat transfer fin.

  According to the above method (13), the above-described welding method is applied to the obtuse angle side of the fillet joint portion formed by the outer surface of the main body body and the heat transfer fin. Thereby, favorable weld quality is realizable in the fillet joint part on the obtuse angle side.

(14) In some embodiments, in the method of (11) above,
The joint portion is an acute angle side first fillet joint portion formed by the outer surface of the main body cylinder and the heat transfer fin, and an obtuse angle side formed by the outer surface of the main body cylinder and the heat transfer fin. Of the second fillet joint.

  According to the method of (14) above, the above-mentioned welding is applied to both the first fillet joint portion on the acute angle side and the second fillet joint portion on the obtuse angle side formed by the outer surface of the main body barrel and the heat transfer fin. Construction methods are applied. Thereby, favorable weld quality is realizable in the fillet joint part of an acute angle side and an obtuse angle side.

(15) In some embodiments, in the method of (14) above,
After any one of the above methods (1) to (10) is performed on the first fillet joint, any one of the above (1) to (10) is applied to the second fillet joint. It carries out against.

  According to the method of (15) above, after performing welding on the first fillet joint on the acute angle side where the throat thickness of the weld is larger than on the obtuse angle side, the second fillet joint on the obtuse angle side By performing welding with respect to, better welding quality can be realized.

(16) In some embodiments, in any one of the above methods (1) to (15),
The first member is made of copper;
The second member is made of carbon steel or stainless steel.

  According to the method of (16) above, dissimilar material welding of carbon steel or stainless steel and copper can be suitably performed.

(17) In order to solve the above problems, a radioactive substance storage container according to at least one embodiment of the present invention is provided.
The main body,
An outer cylinder coaxially arranged on the outside of the body trunk;
A heat transfer fin having a longitudinal shape and inclined between the main body barrel and the outer cylinder;
A welded portion extending along the longitudinal direction between an end surface along the longitudinal direction of the heat transfer fin and an outer surface of the main body body;
With
The weld is
A first tack welded portion formed at every first interval along the extending direction of the welded portion;
A second tack welding portion formed between each of the adjacent first tack welding portions;
A main weld formed along a weld line including the first tack weld and the second tack weld;
including.

  The radioactive substance storage container having the configuration of (17) can be suitably manufactured by the above-described welding method (including the above various forms). The radioactive substance storage container manufactured in this way is less susceptible to cracking of temporary welding during welding construction, and a high-quality finish can be obtained.

(18) In order to solve the above problems, a radioactive substance storage container according to at least one embodiment of the present invention is provided.
The main body,
An outer cylinder coaxially arranged on the outside of the body trunk;
A heat transfer fin having a longitudinal shape and inclined between the main body barrel and the outer cylinder;
A welded portion extending along the longitudinal direction between an end surface along the longitudinal direction of the heat transfer fin and an outer surface of the main body body;
With
The weld is
A plurality of tack welds formed at predetermined intervals along the extending direction of the welds;
A main weld including a plurality of sub-beads extending along the extending direction and having both end portions corresponding to the tack weld.
including.

  The radioactive substance storage container having the configuration of (18) can be suitably manufactured by the above-described welding method (including the above various forms). The radioactive substance storage container manufactured in this way is less susceptible to cracking of temporary welding during welding construction, and a high-quality finish can be obtained.

  According to at least one embodiment of the present invention, a welding construction method capable of realizing good welding quality by suppressing generation of distortion due to welding heat in dissimilar material welding, and a radioactive material that can be manufactured using the method A containment can be provided.

It is sectional drawing along the axial direction of a radioactive substance storage container. It is the sectional view on the AA line of FIG. It is an enlarged view of the heat transfer fin vicinity of FIG. It is a flowchart which shows roughly the whole process of the welding construction method which concerns on one Embodiment of this invention. It is a flowchart which shows an example of the setting method of the temporary attachment position in FIG.4 S10. It is a setting example of a temporary attachment position. It is an example of a setting of the 1st temporary attachment position. It is an example of a setting of the 2nd temporary attachment position. It is a figure which shows typically a mode that a welding bead is formed from a some sub bead by step S40. FIG. 10 is an enlarged cross-sectional view of a part of the weld bead in FIG. 9.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Absent.
For example, expressions expressing relative or absolute arrangements such as “in a certain direction”, “along a certain direction”, “parallel”, “orthogonal”, “center”, “concentric” or “coaxial” are strictly In addition to such an arrangement, it is also possible to represent a state of relative displacement with an angle or a distance such that tolerance or the same function can be obtained.
In addition, for example, expressions representing shapes such as quadrangular shapes and cylindrical shapes not only represent shapes such as quadrangular shapes and cylindrical shapes in a strict geometric sense, but also within the range where the same effect can be obtained. A shape including a chamfered portion or the like is also expressed.
On the other hand, the expressions “comprising”, “comprising”, “comprising”, “including”, or “having” one constituent element are not exclusive expressions for excluding the existence of the other constituent elements.

  First, a welded structure to which a welding construction method according to at least one embodiment of the present invention is applied will be described. In the following description, as shown in FIGS. 1 to 3, a radioactive substance storage container capable of storing a radioactive substance therein is exemplified as a welded structure. However, the present invention is not limited to this unless otherwise specified. It is not something.

  1 is a cross-sectional view of the radioactive substance storage container 1 along the axial direction, FIG. 2 is a cross-sectional view taken along line AA of FIG. 1, and FIG. 3 is an enlarged view of the vicinity of the heat transfer fin 10 of FIG. .

  The radioactive substance storage container 1 includes a main body barrel 2 in which a radioactive substance (for example, a spent fuel assembly) can be stored. The main body body 2 has a substantially cylindrical shape with a bottom, and is configured as a forged product made of carbon steel having a γ-ray shielding function. The opening 7 of the main body cylinder 2 is closed by attaching a lid 6 to the flange surface. The lid portion 6 has a substantially disk shape, and is formed of carbon steel, for example, like the main body barrel 2 described above.

  The main body 2 and the lid 6 may be made of stainless steel or cast products such as spheroidal graphite cast iron or carbon steel cast steel.

  Inside the main body cylinder 2, a basket 3 capable of individually storing a plurality of radioactive substances is provided. The basket 3 defines a plurality of cells for individually storing a plurality of radioactive substances by combining plate-like members in a lattice shape.

  An outer cylinder 4 is coaxially disposed outside the main body cylinder 2 with a predetermined gap. As shown in FIG. 2, a plurality of copper heat transfer fins 10 for heat transfer are provided between the outer peripheral surface of the main body cylinder 2 and the inner peripheral surface of the outer cylinder 4 at predetermined intervals. Yes. In the space defined by the main body 2, the outer cylinder 4 and the heat transfer fins 10, a resin (neutron shield) containing boron or a boron compound which is a polymer material containing a lot of hydrogen and has a neutron shielding function. In a fluid state, 8 is injected and solidified through a pipe (not shown).

  The heat transfer fin 10 is made of a copper plate material made of copper such as pure copper having high thermal conductivity. Thereby, the decay heat generated from the radioactive substance stored inside the main body body 2 is accelerated to the outside by the heat transfer fins 10, and the heat removal performance of the radioactive substance storage container 1 is improved.

  As shown in FIG. 2, the plurality of heat transfer fins 10 are inclined and disposed in a gap formed between the main body cylinder 2 and the outer cylinder 4. Here, as shown in FIG. 3, the end face 12 along the longitudinal direction on the main body cylinder 2 side of the heat transfer fin 10 is abutted with the outer surface 2 a of the main body cylinder 2 at a predetermined angle α, which will be described later. It is joined by the fillet joint portion 20 constructed by the welding construction method. The fillet joint portion 20 on the main body barrel 2 side has an acute-angle-side first fillet joint portion 20a and an obtuse-angle-side second fillet joint portion 20b each made of a weld bead.

  The end face 14 along the longitudinal direction on the outer cylinder 4 side of the heat transfer fin 10 is also abutted against the inner surface 4 a of the outer cylinder 4 and joined by the fillet joint portion 30. The fillet joint 30 on the outer cylinder 4 side has an acute-angle fillet joint 30a and an obtuse fillet joint 30b each made of a weld bead. In the following description, the case where the welding method according to this embodiment is applied to the fillet joint portion 20 on the main body barrel 2 side is illustrated, but the same applies to the fillet joint portion 30 on the outer cylinder 4 side. May be.

  Subsequently, the case where the fillet joint portion 20 on the main body barrel 2 side is formed by applying the welding method according to at least one embodiment of the present invention to the radioactive substance storage container 1 having the above configuration will be described as an example. . FIG. 4 is a flowchart schematically showing the whole process of the welding method according to one embodiment of the present invention.

  In this method, first, a temporary attachment position 40 is set for applying temporary welding to the first fillet joint 20a on the acute angle side (step S10). Here, the temporary welding is welding performed prior to the main welding, and is shorter than the welding bead 50 formed by the main welding with respect to the end surface 12 along the longitudinal direction of the heat transfer fin 10. It is welding that forms the bead 60.

  Such a tack welding includes a first tack welding and a second tack welding applied after the first tack welding. That is, the tack welding is performed in two stages, and the first tack position 40a where the first tack welding is performed and the second tack welding are performed at the tack position 40 set in step S10. Second temporary attachment position 40b.

  FIG. 5 is a flowchart showing an example of a setting method of the temporary attachment position 40 in step S10 of FIG. 4, FIG. 6 is an example of setting the temporary attachment position 40, and FIG. 7 is a setting of the first temporary attachment position 40a. FIG. 8 shows an example of setting the second temporary attachment position 40b.

When setting the temporary attachment position 40, first, the specification setting of the temporary attachment bead 60 formed by temporary attachment is performed (step S11). Specifically, a temporary attachment interval a and a temporary weld bead length b of the temporary weld bead 60 are set. The temporary attachment interval a and the temporary attachment bead length b of the temporary attachment bead 60 may be determined, for example, by comprehensively considering the following criteria.
-Is the supporting force for maintaining the posture of the heat transfer fin 10 before joining good?
-Is the distortion generated in the heat transfer fin 10 during temporary welding suppressed within an allowable range?
-Is the distortion generated in the heat transfer fin 10 caused by the welding heat during the main welding applied after the tack welding suppressed within an allowable range?
• Is the number of tack welding on the weld line appropriate?

  Considering the above criteria, the provisional interval a may be set to about 100 mm, for example. If the temporary attachment interval a is too long, the number of temporary attachments on the weld line is reduced, but it is difficult to obtain a supporting force for maintaining a good posture of the heat transfer fin 10 before joining. Moreover, it becomes difficult to suppress the distortion which arises in the heat-transfer fin 10 by the welding heat at the time of the main welding applied after tack welding within an allowable range. On the other hand, if the temporary attachment interval “a” is too short, it is easy to obtain a supporting force for maintaining a good posture of the heat transfer fin 10 before joining, and the heat is transferred by the welding heat at the time of the main welding applied after the temporary attachment. Although distortion generated in the heat fin 10 is easily suppressed within an allowable range, the number of tack weldings on the weld line increases, and the work load increases.

  In consideration of the above criteria, the temporary weld bead length b may be set to 15 ± 10 mm, for example. If the temporary welding bead length b is too large, it is easy to obtain a supporting force for maintaining a good posture of the heat transfer fin before joining, but the distortion generated in the heat transfer fin 10 during the temporary welding is within an allowable range. It is hard to suppress. On the other hand, if the temporary welding bead length b is too small, distortion generated in the heat transfer fins 10 during temporary welding is easily suppressed within an allowable range, but the posture of the heat transfer fins 10 before joining is favorably maintained. It becomes difficult to obtain support.

  Then, the length L of the welding line 70 constructed by this method is set (step S12). The length L of the welding line 70 is finally set so as to correspond to a range in which the main welding described later is performed. The length L of such a weld line may be set equal to the length of the end surface 12 along the longitudinal direction of the heat transfer fin 10 on the main body barrel 2 side, but in this embodiment, as shown in FIG. The length L of the weld line is set in consideration of providing non-welded portions 15 having a predetermined length c at both ends of the end surface 12. This is because it is necessary to provide the non-welded portion 15 at both ends of the end surface 12 in consideration of the fact that the base metal is likely to be melted down due to accumulation of welding heat during the main welding.

  Subsequently, based on the conditions set in Steps S11 and S12 (temporary welding interval a of temporary welding beads 60, temporary welding bead length b, and length L of welding line 70), temporary welding is performed. A provisional position 40 to be set is set (step S13). The temporary attachment positions 40 are set so that the temporary attachment positions 40 are evenly distributed over the length L of the welding line 70, for example. In the example of FIG. 6, a state in which 30 temporary attachment positions 40 are set at a predetermined interval a over the length L of the weld line is shown.

  In addition, the temporary attachment position 40 calculated | required based on the conditions (the temporary attachment interval a of the temporary attachment bead 60, the temporary attachment bead length b, and the length L of the weld line 70) set in steps S11 and S12. If not desirable, the temporary position 40 may be reset while finely adjusting each parameter of the condition within an allowable range. Such resetting of the temporary attachment position 40 may be performed, for example, by obtaining an optimal solution sequentially using an electronic arithmetic device such as a computer. In this case, the parameter to be finely adjusted may be the temporary attachment interval a of the temporary weld bead 60, the temporary weld bead length b, the length L of the weld line 70, or the length of the non-welded portion 15. It may be c.

  Subsequently, the first temporary attachment position 40a is selected from the temporary attachment positions 40 set in step S13 (step S14). The first temporary attachment position 40a is a place where temporary welding is performed prior to a second temporary attachment position 40b described later. This is because if the temporary welding is applied to all the temporary attachment positions 40 at once, the distortion of the heat transfer fin 10 is increased by the welding heat.

The selection of the first temporary attachment position 40a in step S14 may be determined, for example, by comprehensively considering the following criteria.
Is the heat transfer fin 10 evenly distributed as much as possible in order to support the heat transfer fins 10 evenly with respect to the outer surface 2a of the main body barrel 2?
-Is the supporting force required to accurately maintain the posture of the heat transfer fin 10 before joining?
-Is the distortion generated in the heat transfer fin 10 during the first tack welding suppressed within an allowable range?
-Since the heat transfer fin 10 before tack welding is supported by a predetermined support device in order to maintain the posture with respect to the outer surface 2a of the main body cylinder 2, is it a temporary position that does not interfere with the support device ( For example, when the heat transfer fin 10 is supported by the suction pad, is the suction pad in a position where it is not damaged by the temporary welding)?

  In the example of FIG. 7, among the 30 temporary attachment positions 40 set in step S13, five temporary attachment positions located at equal intervals (first intervals) including the outermost side are defined as the first temporary attachment positions 40a. (In FIG. 7, only three of the five first temporary attachment positions 40a are shown).

  Subsequently, the second temporary attachment position 40b is selected from the temporary attachment positions 40 set in step S13 (step S15). The second temporary attachment position 40b is selected as another temporary attachment position excluding the first temporary attachment position 40a selected in step S14. As a result, at least one second temporary attachment position 40b is located between the adjacent first temporary attachment positions 40a. In the example of FIG. 8, among the first temporary attachment positions 40a selected in step S16, a plurality of second temporary attachment positions 40b are located between adjacent first temporary attachment positions 40a.

  Returning to FIG. 4 again, when the temporary attachment position 40 (the first temporary attachment position 40a and the second temporary attachment position 40b) is set in this way, the first temporary attachment welding is first performed on the first temporary attachment position 40a. Is constructed (step S20). The first temporary welding is sequentially applied to the plurality of first temporary attachment positions 40a, but the order of application may be arbitrary. In the example of FIG. 7, the first temporary attachment positions 40a set at a total of five locations are sequentially constructed from the right side to the left side.

  Such first tack welding is performed, for example, in order to appropriately maintain the posture of the heat transfer fin 10 with respect to the outer surface 2a of the main body body 2. The heat transfer fin 10 before the tack welding is mechanically supported by a support device (not shown) with respect to the outer surface 2a of the main body 2 but is supported after the posture maintenance is secured by the first tack welding. The device can be removed.

  In addition, you may perform the construction order of the 1st tack welding with respect to the some 1st tack position 40a in order toward the outer side from the center part C of a weld line similarly to the 2nd tack tack welding mentioned later. In this case, it is advantageous in that the amount of distortion generated in the heat transfer fin 10 by the welding heat by the first tack welding can be reduced.

  When the first tack welding is completed, the second tack welding is applied to the second tack position 40b (step S30). The second tack welding is carried out for each of the plurality of second tack positions 40b, and the order of construction is from the second tack position 40b at the center C (center side) of the weld line to the outside of the weld line. It is performed toward a certain second temporary attachment position. In the example of FIG. 8, the second tack welding is performed in turn alternately from the second tack position 40 b close to the first tack position 40 a located in the center C. Thereby, the distortion which arises at the time of construction of temporary welding can be escaped toward the outer side from the center side of a welding line, and it can prevent effectively that the crack of temporary welding will generate | occur | produce at the time of construction of the following main welding.

  Thus, when a total of 30 tack welding operations are completed for the first tacking position 40a and the second tacking position 40b, the main welding is performed on the acute angle side (step S40). In the main welding, a weld bead 50 having a length L along the weld line is formed. The weld bead 50 is formed by being divided into a plurality of sub-beads 50a.

  FIG. 9 is a diagram schematically showing how the weld bead 50 is formed from the plurality of sub-beads 50a in step S40, and FIG. 10 is an enlarged cross-sectional view of a part of the weld bead 50 in FIG.

  As shown in FIG. 10, each sub bead 50a is formed by scanning the welding torch between the temporary attachment positions 40 (first temporary attachment position 40a or second temporary attachment position 40b) located at both ends of the sub bead 50a. . Thereby, the sub bead 50a whose both ends correspond to the temporary attachment position 40 is formed. Thus, by making the both ends of each sub bead 50a correspond to the temporary attachment position 40, the molten pool formed by the welding torch is stopped by the temporary welding bead previously formed at the temporary attachment position 40, and the molten pool droops. Therefore, it is possible to suitably prevent the occurrence of poor fusion such as a lack of penetration.

  Of the sub-beads 50a thus formed, adjacent sub-beads 50a are formed so as to overlap each other at the temporary attachment position 40 (the first temporary attachment position 40a or the second temporary attachment position 40b) located at the end. That is, when a certain sub-bead 50a is formed first and a sub-bead is formed in the adjacent position, welding is performed from a position where the temporary attachment position 40 corresponding to the end of the previously formed sub-bead 50a overlaps. By starting torch scanning, sub-beads are formed so that the sub-beads 50a overlap each other at the temporary attachment position 40. Thereby, even when the weld bead 50 is divided and formed into a plurality of sub beads 50a, it is possible to suitably prevent the occurrence of poor fusion between the sub beads 50a.

  Such a plurality of sub-beads 50a are formed in order so that two continuously formed sub-beads 50a are not adjacent to each other. Thereby, the welding heat which generate | occur | produces at the time of construction of this welding can be disperse | distributed over the whole welding line, and generation | occurrence | production of the distortion by welding heat can be prevented more effectively.

In particular, in the example of FIG. 9, first sub-beads (see sub-beads 50 a indicated by “1” and “2” in FIG. 9) are formed at both ends of the weld line 70, and then the first sub-beads are inserted between the first sub-beads. Two sub-beads (see sub-bead 50a indicated by “3” in FIG. 9) are formed. By forming the sub-beads in this order, it is possible to alleviate the distortion that occurs during the construction of the main welding and effectively prevent the occurrence of weld cracks.
In FIG. 9, the order of formation of the sub-beads 50a created after the fourth is also shown, but this is an example and can be changed as appropriate.

  In addition, when forming several sub bead 50a sequentially, you may prevent accumulation of welding heat in a base material by implementing a cooling process suitably.

  When the first fillet joint portion 20a on the acute angle side is thus formed, the second fillet joint portion 20b on the obtuse angle side is subsequently formed by performing main welding on the obtuse angle side (step S50). The main welding on the obtuse angle side may be divided into a plurality of sub-beads to form a welding bead, similarly to the main welding on the acute angle side in step S40. In this case, by forming the sub-beads in the same pattern as in step S50, the distortion of the heat transfer fins 10 due to welding heat can be reduced more effectively, and the risk of being melted off by welding on the acute angle side can also be handled. it can.

  In the present embodiment, the case where the welding method according to at least one embodiment of the present invention is applied to both the first fillet joint portion 20a and the second fillet joint portion 20b is exemplified. Even if it is a case where it applies only to either one of the part 20a or the 2nd fillet joint part 20b, favorable welding quality is realizable. In particular, since the first fillet joint portion 20a on the acute angle side has a larger throat thickness of the welded portion than the second fillet joint portion 20b on the obtuse angle side, the merit of applying the method is great.

  As described above, according to the above-described embodiment, prior to the actual welding, the temporary welding is sequentially applied to the first temporary attachment position 40a and the second temporary attachment position 40b in two stages. The first temporary attachment position 40a is set on the welding line at a wider interval than the second temporary attachment position 40b, and by performing temporary attachment, accurate positioning is performed while suppressing distortion due to welding heat. Can do. One second tacking position 40b is set at a narrower interval on the weld line than the first tacking position 40a, and tack welding is performed from the center side of the weld line toward the outside. Thereby, the distortion which arises at the time of construction of temporary welding can be escaped toward the outer side from the center side of a welding line, and it can prevent effectively that the crack of temporary welding is generated at the time of construction of main welding.

  As described above, according to at least one embodiment of the present invention, it is possible to provide a welding method capable of realizing good welding quality by suppressing the occurrence of distortion due to welding heat in dissimilar material welding.

  At least one embodiment of the present invention is applicable to a welding method for applying welding between members having different thermal conductivities, and a radioactive substance storage container that can be manufactured using the method.

DESCRIPTION OF SYMBOLS 1 Radioactive substance storage container 2 Main body trunk | drum 2a Outer surface 3 Basket 4 Outer cylinder 6 Cover part 7 Opening part 10 Heat-transfer fins 12 and 14 End surface 15 Non-welded part 20 and 30 Fillet joint part 40 Temporary attachment position 40a 1st provisional attachment Position 40b Second temporary attachment position 50 Welding bead 50a Sub bead 60 Temporary welding bead 70 Welding line

Claims (18)

A welding construction method for welding a joint portion formed by abutting an end face along a longitudinal direction of a first member having a longitudinal shape with a second member having a thermal conductivity smaller than that of the first member. ,
On the weld line from the welding start position to the welding end position of the joint portion to be welded, a step of performing tack welding on a plurality of first tack positions defined for each first interval;
At least one second temporary attachment position is defined between each of the adjacent first temporary attachment positions, and the second temporary attachment position outside the weld line from the second temporary attachment position on the center side of the weld line. A process of performing tack welding toward the tacking position;
Applying main welding along the weld line including the first temporary attachment position and the second temporary attachment position;
A welding construction method comprising: Temporarily setting a temporary attachment position at predetermined intervals on the weld line,
The temporary attachment position that is located at each first interval larger than the predetermined interval among the temporary attachment positions is set as the first temporary attachment position,
The welding construction method according to claim 1, wherein the remaining temporary attachment positions excluding the first temporary attachment positions are set as second temporary attachment positions. The main welding is formed by dividing a weld bead along the weld line into a plurality of sub-beads,
3. The welding method according to claim 1, wherein each end portion of the sub-bead corresponds to the first temporary attachment position or the second temporary attachment position.   The welding method according to claim 3, wherein the adjacent sub beads are formed so as to overlap each other at the first temporary attachment position or the second temporary attachment position.   The welding construction method according to claim 3 or 4, wherein the main welding is performed so that the two continuously formed sub-beads are not adjacent to each other. The welding method according to claim 5, wherein a first sub-bead is formed at both ends of the weld line, and then a second sub-bead is formed between the first sub-beads. A welding construction method for welding a joint portion formed by abutting an end face along a longitudinal direction of a first member having a longitudinal shape with a second member having a thermal conductivity smaller than that of the first member. ,
On the weld line from the welding start position to the welding end position of the joint portion to be welded, a step of applying tack welding to the tacking position defined for each predetermined interval;
The step of performing main welding by dividing the weld bead along the weld line into a plurality of sub-beads corresponding to the temporary attachment positions at both ends, and
A welding construction method comprising:   The welding method according to claim 7, wherein the adjacent sub beads are formed so as to overlap each other at the temporary attachment position.   The welding construction method according to claim 7 or 8, wherein the main welding is performed so that two continuously formed sub-beads are not adjacent to each other.   The welding method according to claim 9, wherein a first sub-bead is formed at both ends of the weld line, and then a second sub-bead is formed between the first sub-beads. The first member is a heat transfer fin that is disposed to be inclined with respect to the radial direction of the main body cylinder between the main body cylinder and an outer cylinder that is coaxially disposed outside the main body cylinder.
The welding construction method according to any one of claims 1 to 10, wherein the second member is a main body barrel capable of storing a radioactive substance therein.   The welding method according to claim 11, wherein the joint portion is a fillet joint portion on an acute angle side formed by an outer surface of the main body body and the heat transfer fin.   The welding construction method according to claim 11, wherein the joint portion is a fillet joint portion on an obtuse angle side formed by an outer surface of the main body trunk and the heat transfer fin.   The joint portion is an acute angle side first fillet joint portion formed by the outer surface of the main body cylinder and the heat transfer fin, and an obtuse angle side formed by the outer surface of the main body cylinder and the heat transfer fin. The welding construction method according to claim 11, including the second fillet joint.   After implementing the welding construction method as described in any one of Claim 1 to 10 with respect to the said 1st fillet joint part, the welding construction method as described in any one of Claim 1 to 10 is said. The welding construction method according to claim 14, which is performed on the two fillet joints. The first member is made of copper;
The welding method according to any one of claims 1 to 15, wherein the second member is formed of carbon steel or stainless steel. The main body,
An outer cylinder coaxially arranged on the outside of the body trunk;
A heat transfer fin having a longitudinal shape and inclined between the main body barrel and the outer cylinder;
A welded portion extending along the longitudinal direction between an end surface along the longitudinal direction of the heat transfer fin and an outer surface of the main body body;
With
The weld is
A first tack welded portion formed at every first interval along the extending direction of the welded portion;
A second tack welding portion formed between each of the adjacent first tack welding portions;
A main weld formed along a weld line including the first tack weld and the second tack weld;
Containing radioactive material. The main body,
An outer cylinder coaxially arranged on the outside of the body trunk;
A heat transfer fin having a longitudinal shape and inclined between the main body barrel and the outer cylinder;
A welded portion extending along the longitudinal direction between an end surface along the longitudinal direction of the heat transfer fin and an outer surface of the main body body;
With
The weld is
A plurality of tack welds formed at predetermined intervals along the extending direction of the welds;
A main weld including a plurality of sub-beads extending along the extending direction and having both end portions corresponding to the tack weld.
Containing radioactive material.

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