CN109570690B - Radioactive source shell opening welding method and radioactive source shell opening structure - Google Patents
Radioactive source shell opening welding method and radioactive source shell opening structure Download PDFInfo
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- CN109570690B CN109570690B CN201811559794.XA CN201811559794A CN109570690B CN 109570690 B CN109570690 B CN 109570690B CN 201811559794 A CN201811559794 A CN 201811559794A CN 109570690 B CN109570690 B CN 109570690B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/0026—Arc welding or cutting specially adapted for particular articles or work
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/16—Arc welding or cutting making use of shielding gas
- B23K9/167—Arc welding or cutting making use of shielding gas and of a non-consumable electrode
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Abstract
The invention relates to a radioactive source cladding opening welding method and a radioactive source cladding opening structure, wherein the method comprises the steps of arranging a cladding opening at a welding joint to exhaust and release pressure in the welding process; the cladding opening is blocked by the liquid metal flow of the weld pool formed by welding. The structure comprises a cladding formed by splicing two half shells; the cladding opening is arranged on the splicing edge of one of the half shells, or the cladding opening is formed by splicing two half openings arranged on the splicing edges of the two half shells. The invention has the following beneficial effects: the technical scheme of the invention is adopted to weld a plurality of radioactive source cladding with a closed inner cavity structure, the problem of inner cavity exhaust and pressure relief in the cladding welding process can be solved, an additional hole plugging structure is not needed to be added to realize one-time cladding welding and sealing, the steps of the radioactive source cladding welding process are reduced, the radiation dose of operators is reduced, and meanwhile, the welding success rate and the welding seam quality can be effectively guaranteed.
Description
Technical Field
The invention relates to the field of radioactivity, in particular to a radioactive source cladding opening welding method and a radioactive source cladding structure.
Background
The radioactive source is generally composed of a radioactive source core and a single-layer or multi-layer metal cladding which is coated on the outer layer of the source core and protects the radioactive source core from safety under various use environments. The preparation process of the radioactive source is required to be carried out in a special box chamber isolated from the external environment, and after the radioactive source core is arranged in the metal cladding, the radioactive source core is sealed inside the metal cladding in a welding mode. The radioactive source cladding forms a closed inner cavity structure after being assembled, the high temperature generated in the welding process of the structure enables the air pressure in the cladding to be increased rapidly, the high internal pressure acts on a welding pool to cause the inner side of a welding line to be arched, the welding quality is influenced, and the welding defect of perforation is generated under the serious condition. The conventional method for solving the problem of internal pressure in the welding process of the closed inner cavity structure is to design a hole plugging structure, the structure plays a role in exhausting and relieving pressure in the welding process, and the hole plugging welding is carried out on an exhaust hole after the welding of a joint is completed to realize sealing. The radioactive source cladding adopts a hole-plugging structure mode, sealing can be realized only by carrying out welding operation at least twice, two welding seams are generated to form two weak points of cladding structure strength, and more irradiation doses of process personnel can be caused due to the increase of operation procedures and operation time; for compact radioactive sources, the increase in volume and mass due to the addition of the hole-blocking structure to the containment is unacceptable, and it is therefore desirable to develop a method for welding radioactive source containment to solve the above problems.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide the radioactive source cladding opening welding method and the radioactive source cladding opening structure.
The technical scheme of the invention is as follows:
a radioactive source cladding trepanning welding method is characterized in that a cladding trepanning is arranged at a welding joint to exhaust and release pressure in a welding process; the cladding opening is blocked by the liquid metal flow of the weld pool formed by welding.
Further, the above method for welding the opening of the radioactive source enclosure comprises:
(1) determining the welding initial position;
(2) and starting welding until the welding point reaches the welding starting position again and then stopping welding.
Further, in the above method for welding the opening of the radioactive source enclosure, the method for determining the welding start position in step (1) is:
and rotating the cladding, and determining the position of the welding point right after the welding point passes through the cladding hole as a welding starting position.
Further, in the above method for welding the opening of the radioactive source enclosure, the method for determining that the welding point just passes through the enclosure opening is as follows:
and arranging a mark corresponding to the position of the cladding opening hole on a clamping mould for clamping the cladding, wherein when the projection of the welding point on a plane in which the mark rotates along with the cladding just passes through the mark, the welding point just passes through the cladding opening hole can be determined.
Further, in the above-mentioned method for welding the opening of the radioactive source enclosure, the welding current is set to be not more than 0.5s for an uphill time so that a molten pool is formed after welding is started; and after the welding point reaches the welding starting position again, the open pore of the cladding is blocked by the liquid metal flow of the molten pool.
Furthermore, in the above method for welding the opening of the radioactive source enclosure, the downhill time of the welding current is set to be not longer than 5s so as to avoid the outward protrusion or perforation of the welding seam caused by the increase of the internal pressure due to the overlong downhill time of the welding.
Further, the above method for welding the opening of the radioactive source enclosure further comprises:
(3) and (5) detecting the welding quality.
Further, according to the radioactive source enclosure opening welding method, the welding quality detection comprises appearance, size and tightness detection.
The invention also provides a radioactive source cladding open pore structure, which comprises a cladding formed by splicing two half shells; the cladding opening is arranged on the splicing edge of one of the half shells, or the cladding opening is formed by splicing two half openings arranged on the splicing edges of the two half shells.
Further, the radioactive source enclosure opening structure further comprises a mark for determining the position of the enclosure opening; the mark is arranged on a clamping mould for clamping the cladding.
The invention has the following beneficial effects:
the technical scheme of the invention is adopted to weld the radioactive source cladding which forms a closed inner cavity structure after various assemblies, the problem of inner cavity exhaust and pressure relief in the cladding welding process can be solved, an additional hole blocking structure is not needed to be added to realize one-time cladding welding and sealing, the steps of the radioactive source cladding welding process are reduced, the radiation dose of operators is reduced, and meanwhile, the welding success rate and the welding seam quality can be effectively ensured.
Drawings
Fig. 1 is a flow chart of the high temperature radioactive source welding method of the present invention.
FIG. 2 is a schematic structural view of a half shell with a shell opening in an embodiment of the present invention.
Fig. 3 is a schematic view of the same embodiment of the enclosure as fig. 2.
FIG. 4 is a schematic view of a weld configuration for welding using the cladding structure of the present invention.
In the above drawings, 1, cladding; 2. opening a hole in the cladding; 3. installing a clamping mould; 4. marking; 5. a tungsten needle.
Detailed Description
The invention is described in detail below with reference to the figures and examples.
As shown in FIG. 1, the invention provides a radioactive source enclosure opening welding method, wherein an enclosure opening is arranged at a welding joint to exhaust and release air during welding; the cladding opening is blocked by the liquid metal flow of the weld pool formed by welding. The method specifically comprises the following steps:
s1 determining a welding starting position;
s2, starting welding until the welding point reaches the welding starting position again and then stopping welding;
and S3, welding quality detection is carried out.
The welding point is the position aligned with the tungsten needle of the welding gun.
The method for determining the welding start position in step S1 is as follows: and rotating the cladding, and determining the position of the welding point right after the welding point passes through the cladding hole as a welding starting position.
In the above steps, in order to fully utilize the exhaust and pressure release functions of the cladding open-pore structure in the welding process, the filling and hole plugging of the open pore needs to be completed before the lap joint sealing of the welding seam is approached through process control, and if the hole is plugged too early, the problem of internal pressure increase caused by unsmooth exhaust due to the sealing of the inner cavity can be solved.
In order to solve the problem that the radioactive source enclosure is welded in a special radioactive operation box chamber with a glass observation window, and the opening position is difficult to identify when the enclosure rotates in the welding process due to the small opening size of the enclosure, in the embodiment, the method for determining that the welding point just passes through the opening of the enclosure is as follows: and arranging a mark corresponding to the position of the cladding opening hole on a clamping mould for clamping the cladding, wherein when the projection of the welding point on a plane in which the mark rotates along with the cladding just passes through the mark, the welding point just passes through the cladding opening hole can be determined. Therefore, an obvious mark capable of being visually detected is designed on the jig for clamping the radioactive source cladding, the cladding is clamped in the welding jig after being assembled, the position of the cladding is adjusted to enable the open hole to be aligned with the mark position of the jig, and welding arc starting and arc extinguishing are controlled by observing the mark on the jig when the cladding rotates in the welding process. This facilitates control of the welding.
In the specific welding process, after the cladding is completely clamped, the clamping fixture is opened to rotate, after the mark (the opening position) on the clamping fixture is visually observed passes through the tungsten needle, arc starting welding is immediately started, short current ramp time (generally not more than 0.5 s) is set, after the tungsten needle passes through the cladding opening position, a molten pool is formed in cladding joint metal in a short time, and after the electric arc passes through the opening again, the molten pool liquid metal flows to complete filling and hole plugging so as to fully utilize the exhaust and pressure relief functions of the opening. The welding current, the welding speed and other technological parameters are determined according to the specific structure of the cladding. And observing the identification position of the rotary clamping fixture in the welding process, and after the identification (the position mark of the opening) passes through the tungsten needle again, quenching the arc to finish welding. In the process, proper current downhill time needs to be set, and because the pressure relief hole is blocked before arc-closing downhill, gas in the inner cavity is difficult to discharge, and the internal pressure is increased due to overlong downhill time to cause outward protruding or perforation of a welding line; and too short downhill time can lead to insufficient weld penetration at the arcing section due to short weld joint overlap length. Generally speaking, the welding current ramp down time is set to be less than or equal to 5 s.
The welding quality detection comprises appearance, size and tightness detection. Appearance detection mainly detects external welding defects such as dislocation, cracks, air holes, undercut and the like, and can carry out visual inspection according to standards or carry out standard comparison by adopting known technical means. The size detection mainly measures the height of the welded cladding and the diameter of a welding seam area, adopts a caliper to measure a plurality of positions/angles, and takes the maximum measurement values of the height and the diameter. Radioactive contamination may exist on the surface of the welded radioactive source cladding, and the tightness detection cannot be carried out by adopting helium mass spectrometry. According to GB15849-1995 'leak test method of sealed radioactive source', the hot liquid bubbling method is adopted to carry out the tightness test in a special radioactive operation cabinet chamber: and (3) putting the shell into a water bath at the temperature of 90-95 ℃, observing the top end of the shell at a depth of at least 5cm below the water surface for more than 1min to see whether bubbles escape from a sealing source, and judging that the shell is in a sealing state if no bubbles escape.
As shown in figure 4, the radioactive source envelope open-pore structure of the invention corresponding to the method comprises an envelope 1 formed by splicing two half shells (see figures 2 and 3); the envelope opening 2 is provided in the split edge of one of the half shells (see fig. 2), or the envelope opening is split from two half openings provided in the split edges of the two half shells. Additionally, an identifier for determining the location of the enclosure opening; the mark 4 is arranged on a clamping mould 3 for clamping the cladding. The tungsten needle 5 of the welding gun is aligned with the joint seam of the two half shells.
The technical scheme of the invention is adopted to weld a plurality of radioactive source cladding with a closed inner cavity structure, the problem of inner cavity exhaust and pressure relief in the cladding welding process can be solved, an additional hole plugging structure is not needed to be added to realize one-time cladding welding and sealing, the steps of the radioactive source cladding welding process are reduced, the radiation dose of operators is reduced, and meanwhile, the welding success rate and the welding seam quality can be effectively guaranteed.
Examples
The argon arc welding is carried out on the stainless steel radioactive source cladding with a closed inner cavity structure after butt joint and assembly:
stainless steel radioactive source cladding structure
The radioactive source cladding material of the embodiment is 316L stainless steel, the sealed cladding is formed by butt joint assembly of the open ends of two half shells with the same structure and argon arc welding, the half shells are of a structure with one open end and one closed end, and the size of the half shell structure is
The wall thickness is 0.8mm, and the bottom of the closed end is 0.8 mm.
Opening of envelope
An open slot with the thickness of 0.8mm and the thickness of 0.2mm penetrating through the open end joint of one half shell is machined at any position of the open end joint of the half shell, and burrs on the edge of the open slot are cleaned so as to avoid influencing the next assembly. The half-shell with holes and the half-shell without holes are cleaned and transferred to a special chamber for radioactive operation.
Can attachment and aperture alignment
The radioactive source core is assembled into the non-apertured half-shell in a special housing for radioactive operations, and the assembly of the containment shell and the source core is completed after the apertured half-shell is covered. After assembly, the cladding is clamped into a special clamping fixture with obvious marks, and the cladding is rotated to enable the opening hole to be aligned with the marking position of the clamping fixture.
Arcing
The uphill time was set to 0.5 s. And (3) starting the welding table to rotate, starting the cladding clamped in the clamping fixture to rotate, visually observing the position of the clamping fixture mark, and starting arc striking and welding immediately after the mark passes through the tungsten needle.
Process parameters
The stainless steel ladle shell welding process parameters of the structure size are set as follows:
| diameter of tungsten needle | Working distance | Diameter of nozzle | Argon flow | Welding current | Speed of welding |
| 1.6mm | 0.8mm | 8mm | 9L/min | 80A | 4.5mm/s |
Arc-closing
The downhill time is set to 4 s. And observing the position of the mold mark in real time in the welding rotation process, immediately closing the arc after the mark passes through the tungsten needle again, and extinguishing the arc after the welding current goes down the slope to finish welding.
Weld quality detection
And observing the macroscopic appearance of the welding line in a visual inspection mode, wherein the open hole of the original cladding is completely filled and covered, the welding line at the position is flat and smooth, and no external welding defects such as dislocation, cracks, air holes, undercut and the like are observed in the appearance of the whole welding line.
The caliper is adopted to measure the height of the cladding and the diameter of the welding seam area, and the height values of three positions and the diameters of three angle welding seam areas are measured respectively, so that the requirement of the subsequent assembly size is met.
And (3) putting the cladding into a water bath at the temperature of 90-95 ℃ at room temperature, and observing for more than 1min to ensure that no bubbles escape, so that the cladding can be judged to be in a sealed state.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include such modifications and variations.
Claims (10)
1. A radioactive source cladding opening welding method is characterized in that a cladding opening is arranged at a welding joint to exhaust and release pressure in the welding process; the open hole of the cladding is blocked by the liquid metal flow of a molten pool formed by welding;
the cladding is formed by splicing two half shells; the cladding opening is arranged on the splicing edge of one of the half shells, or the cladding opening is formed by splicing two half openings arranged on the splicing edges of the two half shells.
2. The radioactive source enclosure aperture welding method of claim 1, comprising:
(1) determining the welding initial position;
(2) and starting welding until the welding point reaches the welding starting position again and then stopping welding.
3. The radioactive source enclosure aperture welding method of claim 2, wherein: the method for determining the welding starting position in the step (1) comprises the following steps:
and rotating the cladding, and determining the position of the welding point right after the welding point passes through the cladding hole as a welding starting position.
4. The radioactive source enclosure aperture welding method of claim 3, wherein: the method of determining that the weld has just passed through the can opening is:
and arranging a mark corresponding to the position of the cladding opening hole on a clamping mould for clamping the cladding, wherein when the projection of the welding point on a plane in which the mark rotates along with the cladding just passes through the mark, the welding point just passes through the cladding opening hole can be determined.
5. The radioactive source enclosure aperture welding method of any one of claims 2 to 4, wherein: setting a welding current ramp-up time not longer than 0.5s so that a weld pool is formed after welding is started; and after the welding point reaches the welding starting position again, the open pore of the cladding is blocked by the liquid metal flow of the molten pool.
6. The radioactive source enclosure aperture welding method of any one of claims 2 to 4, wherein: the welding current downhill time is set to be not longer than 5s so as to avoid outward bulging or perforation of a welding seam caused by increase of internal pressure due to overlong welding downhill time.
7. The radioactive source enclosure aperture welding method of any one of claims 2 to 4, further comprising:
(3) and (5) detecting the welding quality.
8. The radioactive source enclosure aperture welding method of claim 7, wherein the weld quality tests include appearance, size, and seal tests.
9. A radioactive source enclosure opening structure, comprising: comprises a cladding formed by splicing two half shells; the cladding opening is arranged on the splicing edge of one of the half shells, or the cladding opening is formed by splicing two half openings arranged on the splicing edges of the two half shells.
10. The radioactive source enclosure aperture structure of claim 9, wherein: further comprising an identifier for determining the location of the enclosure opening; the mark is arranged on a clamping mould for clamping the cladding.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201811559794.XA CN109570690B (en) | 2018-12-19 | 2018-12-19 | Radioactive source shell opening welding method and radioactive source shell opening structure |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201811559794.XA CN109570690B (en) | 2018-12-19 | 2018-12-19 | Radioactive source shell opening welding method and radioactive source shell opening structure |
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| CN109570690B true CN109570690B (en) | 2020-10-09 |
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| CN109822197B (en) * | 2019-02-18 | 2021-01-26 | 哈尔滨工业大学（威海） | Full-automatic fuel rod assembling and welding device and method |
| CN110299212B (en) * | 2019-06-12 | 2021-01-05 | 中国原子能科学研究院 | Target cutting and solving device for irradiating uranium foil target |
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| JPH0266498A (en) * | 1988-09-01 | 1990-03-06 | Japan Nuclear Fuel Co Ltd<Jnf> | Neuclear fuel pellet loading device |
| GB8900788D0 (en) * | 1989-01-13 | 1989-03-08 | Telephone Cables Ltd | Splicing optical fibres |
| CN1164391C (en) * | 2001-09-10 | 2004-09-01 | 中国原子能科学研究院 | Sealing welding method for needle-shaped radioactive source |
| CN1233497C (en) * | 2002-10-14 | 2005-12-28 | 宁波君安药业科技有限公司 | Welding process for radioactive sealed seed casing |
| CN201397690Y (en) * | 2009-05-15 | 2010-02-03 | 北京树诚科技发展有限公司 | Radioactive source jacket |
| EP2476896A1 (en) * | 2011-01-13 | 2012-07-18 | Delphi Automotive Systems Luxembourg SA | Actuator arrangement for use in a fuel injector |
| CN106735754B (en) * | 2016-12-13 | 2019-09-17 | 中核北方核燃料元件有限公司 | A kind of welding method of annular fuel element |
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